Part III

 
CONTENT

Federal Register: January 26, 2010 (Volume 75, Number 16)

Proposed Rules

Page 4173-4226

From the Federal Register Online via GPO Access [wais.access.gpo.gov]

DOCID:fr26ja10-18

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Part III

Environmental Protection Agency

40 CFR Part 131

Water Quality Standards for the State of Florida's Lakes and Flowing

Waters; Proposed Rule

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ENVIRONMENTAL PROTECTION AGENCY 40 CFR Part 131

EPA-HQ-OW-2009-0596; FRL-9105-1

RIN 2040-AF11

Water Quality Standards for the State of Florida's Lakes and

Flowing Waters

AGENCY: Environmental Protection Agency (EPA).

ACTION: Proposed rule.

SUMMARY: The Environmental Protection Agency (EPA) is proposing numeric nutrient water quality criteria to protect aquatic life in lakes and flowing waters, including canals, within the State of Florida and proposing regulations to establish a framework for Florida to develop

``restoration standards'' for impaired waters. On January 14, 2009, EPA made a determination under section 303(c)(4)(B) of the Clean Water Act

(``CWA'' or ``the Act'') that numeric nutrient water quality criteria for lakes and flowing waters and for estuaries and coastal waters are necessary for the State of Florida to meet the requirements of CWA section 303(c). Section 303(c)(4) of the CWA requires the Administrator to promptly prepare and publish proposed regulations setting forth new or revised water quality standards (``WQS'' or ``standards'') when the

Administrator, or an authorized delegate of the Administrator, determines that such new or revised WQS are necessary to meet requirements of the Act. This proposed rule fulfills EPA's obligation under section 303(c)(4) of the CWA to promptly propose criteria for

Florida's lakes and flowing waters.

DATES: Comments must be received on or before March 29, 2010.

ADDRESSES: Submit your comments, identified by Docket ID No. EPA-HQ-OW- 2009-0596, by one of the following methods: 1. www.regulations.gov: Follow the online instructions for submitting comments. 2. E-mail: ow-docket@epa.gov. 3. Mail to: Water Docket, U.S. Environmental Protection Agency,

Mail Code: 2822T, 1200 Pennsylvania Avenue, NW., Washington, DC 20460,

Attention: Docket ID No. EPA-HQ-OW-2009-0596. 4. Hand Delivery: EPA Docket Center, EPA West Room 3334, 1301

Constitution Avenue, NW., Washington, DC 20004, Attention: Docket ID

No. EPA-HQ-OW-2009-0596. Such deliveries are only accepted during the

Docket's normal hours of operation, and special arrangements should be made for deliveries of boxed information.

Instructions: Direct your comments to Docket ID No. EPA-HQ-OW-2009- 0596. EPA's policy is that all comments received will be included in the public docket without change and may be made available online at www.regulations.gov, including any personal information provided, unless the comment includes information claimed to be Confidential

Business Information (CBI) or other information whose disclosure is restricted by statute. Do not submit information that you consider to be CBI or otherwise protected through www.regulations.gov or e-mail.

The www.regulations.gov Web site is an ``anonymous access'' system, which means EPA will not know your identity or contact information unless you provide it in the body of your comment. If you send an e- mail comment directly to EPA without going through www.regulations.gov your e-mail address will be automatically captured and included as part of the comment that is placed in the public docket and made available on the Internet. If you submit an electronic comment, EPA recommends that you include your name and other contact information in the body of your comment and with any disk or CD-ROM you submit. If EPA cannot read your comment due to technical difficulties and cannot contact you for clarification, EPA may not be able to consider your comment. Electronic files should avoid the use of special characters, any form of encryption, and be free of any defects or viruses. For additional information about EPA's public docket visit the EPA Docket Center homepage at http://www.epa.gov/epahome/dockets.htm.

Docket: All documents in the docket are listed in the www.regulations.gov index. Although listed in the index, some information is not publicly available, e.g., CBI or other information whose disclosure is restricted by statute. Certain other material, such as copyrighted material, will be publicly available only in hard copy.

Publicly available docket materials are available either electronically in www.regulations.gov or in hard copy at a docket facility. The Office of Water (OW) Docket Center is open from 8:30 until 4:30 p.m., Monday through Friday, excluding legal holidays. The OW Docket Center telephone number is (202) 566-2426, and the Docket address is OW

Docket, EPA West, Room 3334, 1301 Constitution Avenue, NW., Washington,

DC 20004. The Public Reading Room is open from 8:30 a.m. to 4:30 p.m.,

Monday through Friday, excluding legal holidays. The telephone number for the Public Reading Room is (202) 566-1744.

Public hearings will be held in the following cities in Florida:

Tallahassee, Orlando, and West Palm Beach. The public hearing in

Tallahassee is scheduled for Tuesday, February 16, 2010 and will be held from 1 p.m. to 5 p.m. and 7 p.m. to 10 p.m. at the Holiday Inn

Capitol East, 1355 Apalachee Parkway, Tallahassee, FL 32301. The public hearing in Orlando is scheduled for Wednesday, February 17, 2010 and will be held from 1 p.m. to 5 p.m. and 7 p.m. to 10 p.m. at the Crowne

Plaza Orlando Universal, 7800 Universal Boulevard, Orlando, FL 32819.

The public hearing in West Palm Beach is scheduled for Thursday,

February 18, 2010 and will be held from 1 p.m. to 5 p.m. and 7 p.m. to 10 p.m. at the Holiday Inn Palm Beach Airport, 1301 Belvedere Road,

West Palm Beach, FL 33405. If you need a sign language interpreter at any of these hearings, you should contact Sharon Frey at 202-566-1480 or frey.sharon@epa.gov at least ten business days prior to the meetings so that appropriate arrangements can be made. For further information, including registration information, please refer to the following Web site: http://www.epa.gov/waterscience/standards/rules/florida/.

FOR FURTHER INFORMATION CONTACT: Danielle Salvaterra, U.S. EPA

Headquarters, Office of Water, Mailcode: 4305T, 1200 Pennsylvania

Avenue, NW., Washington, DC 20460; telephone number: 202-564-1649; fax number: 202-566-9981; e-mail address: salvaterra.danielle@epa.gov.

SUPPLEMENTARY INFORMATION: This supplementary information section is organized as follows:

Table of Contents

I. General Information

  1. Executive Summary

  2. What Entities May Be Affected by This Rule?

  3. What Should I Consider as I Prepare My Comments for EPA?

  4. How Can I Get Copies of This Document and Other Related

    Information?

    II. Background

  5. Nutrient Pollution

  6. Statutory and Regulatory Background

  7. Water Quality Criteria

  8. Agency Determination Regarding Florida

    III. Proposed Numeric Nutrient Criteria for the State of Florida's

    Lakes and Flowing Waters

  9. General Information

  10. Proposed Numeric Nutrient Criteria for the State of Florida's

    Lakes

  11. Proposed Numeric Nutrient Criteria for the State of Florida's

    Rivers and Streams

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  12. Proposed Numeric Nutrient Criteria for the State of Florida's

    Springs and Clear Streams

  13. Proposed Numeric Nutrient Criteria for South Florida Canals

  14. Comparison Between EPA's and Florida DEP's Proposed Numeric

    Nutrient Criteria for Florida's Lakes and Flowing Waters

  15. Applicability of Criteria When Final

    IV. Under What Conditions Will Federal Standards Be Either Not

    Finalized or Withdrawn?

    V. Alternative Regulatory Approaches and Implementation Mechanisms

  16. Designating Uses

  17. Variances

  18. Site-Specific Criteria

  19. Compliance Schedules

    VI. Proposed Restoration Water Quality Standards (WQS) Provision

    VII. Statutory and Executive Order Reviews

  20. Executive Order 12866: Regulatory Planning and Review

  21. Paperwork Reduction Act

  22. Regulatory Flexibility Act

  23. Unfunded Mandates Reform Act

  24. Executive Order 13132 (Federalism)

  25. Executive Order 13175 (Consultation and Coordination With

    Indian Tribal Governments)

  26. Executive Order 13045 (Protection of Children From

    Environmental Health and Safety Risks)

  27. Executive Order 13211 (Actions That Significantly Affect

    Energy Supply, Distribution, or Use)

    I. National Technology Transfer Advancement Act of 1995

  28. Executive Order 12898 (Federal Actions To Address

    Environmental Justice in Minority Populations and Low-Income

    Populations)

    I. General Information

  29. Executive Summary

    Excess loadings of nitrogen and phosphorus, commonly referred to as nutrient pollution, are one of the most prevalent causes of water quality impairment in the United States. Anthropogenic nitrogen and phosphorus over-enrichment in many of the Nation's waters is a widespread, persistent, and growing problem. Nutrient pollution can significantly impact aquatic life and long-term ecosystem health, diversity, and balance. More specifically, high nitrogen and phosphorus loadings, or nutrient pollution, result in harmful algal blooms (HABs), reduced spawning grounds and nursery habitats, fish kills, and oxygen- starved hypoxic or ``dead'' zones. Public health concerns related to nutrient pollution include impaired drinking water sources, increased exposure to toxic microbes such as cyanobacteria, and possible formation of disinfection byproducts in drinking water, some of which have been associated with serious human illnesses such as bladder cancer. Nutrient problems can exhibit themselves locally or much further downstream leading to degraded lakes, reservoirs, and estuaries, and to hypoxic zones where fish and aquatic life can no longer survive.

    In the State of Florida, nutrient pollution has contributed to severe water quality degradation. Based upon waters assessed and reported in the 2008 Integrated Water Quality Assessment for Florida, approximately 1,000 miles of rivers and streams, 350,000 acres of lakes, and 900 square miles of estuaries are known to be impaired for nutrients by the State.\1\ The actual number of stream miles, lake acres, and estuarine square miles of waters impaired for nutrients in

    Florida may be higher, as many waters currently are classified as

    ``unassessed.''

    \1\ Florida Department of Environmental Protection. 2008.

    Integrated Water Quality Assessment for Florida: 2008 305(b) Report and 303(d) List Update, p. 67.

    The challenge of nutrient pollution has been a top priority for

    Florida's Department of Environmental Protection (FDEP). Over the past decade or more, FDEP has spent over 20 million dollars collecting and analyzing data on the relationship between phosphorus, nitrogen, and nitrite-nitrate concentrations and the biological health of aquatic systems. Moreover, Florida is one of the few states that has in place a comprehensive framework of accountability that applies to both point and nonpoint sources and provides the enforceable authority to address nutrient reductions in impaired waters based upon the establishment of site-specific total maximum daily loads (TMDLs).

    Despite FDEP's intensive efforts to diagnose and control nutrient pollution, substantial water quality degradation from nutrient over- enrichment remains a significant problem. On January 14, 2009, EPA determined under CWA section 303(c)(4)(B) that new or revised WQS in the form of numeric nutrient water quality criteria are necessary to meet the requirements of the CWA in the State of Florida. The Agency considered (1) the State's documented unique and threatened ecosystems,

    (2) the high number of impaired waters due to existing nutrient pollution, and (3) the challenge associated with growing nutrient pollution resulting from expanding urbanization, continued agricultural development, and a significantly increasing population that is expected to grow 75% between 2000 to 2030.\2\ EPA also reviewed the State's regulatory nutrient accountability system, which represents an impressive synthesis of technology-based standards, point source control authority, and authority to establish enforceable controls for nonpoint source activities. However, the significant challenge faced by the water quality components of this system is its dependence upon an approach involving resource-intensive and time-consuming site-specific data collection and analysis to interpret non-numeric narrative nutrient criteria. EPA determined that Florida's reliance on a case-by- case interpretation of its narrative nutrient criterion in implementing an otherwise comprehensive water quality framework of enforceable accountability was insufficient to ensure protection of applicable designated uses. As part of the Agency's determination, EPA indicated that it expected to propose numeric nutrient criteria for lakes and flowing waters within 12 months, and for estuarine and coastal waters within 24 months, of the January 14, 2009 determination.

    \2\ http://www.census.gov/population/projections/

    SummaryTabA1.pdf.

    On August 19, 2009, EPA entered into a phased Consent Decree with

    Florida Wildlife Federation, Sierra Club, Conservancy of Southwest

    Florida, Environmental Confederation of Southwest Florida, and St.

    Johns Riverkeeper, committing to sign a proposed rule setting forth numeric nutrient criteria for lakes and flowing waters in Florida by

    January 14, 2010, and for Florida's estuarine and coastal waters by

    January 14, 2011, unless Florida submits and EPA approves State numeric nutrient criteria before EPA's proposal. The phased Consent Decree also provides that EPA issue a final rule by October 15, 2010 for lakes and flowing water, and by October 15, 2011 for estuarine and coastal waters, unless Florida submits and EPA approves State numeric nutrient criteria before a final EPA action.

    Accordingly, this proposal is part of a phased rulemaking process in which EPA will propose and take final action in 2010 on numeric nutrient criteria for lakes and flowing waters and for estuarine and coastal waters in 2011. The two phases of this rulemaking are linked because nutrient pollution in Florida's rivers and streams affects not only instream aquatic conditions but also downstream estuarine and coastal waters ecosystem conditions. The Agency could have waited to propose estuarine and coastal downstream protection criteria values for rivers and streams as part of the second phase of this rulemaking process. However, the substantial data, peer-reviewed methodologies, and extensive scientific

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    analyses available to and conducted by the Agency to date indicate that numeric nutrient water quality criteria for estuarine and coastal waters, when proposed and finalized in 2011, may result in the need for more stringent rivers and streams criteria to ensure protection of downstream water quality, particularly for the nitrogen component of nutrient pollution. Therefore, considering the numerous requests for the Agency to share its analysis and scientific and technical conclusions at the earliest possible opportunity to allow for full review and comment, EPA is including downstream protection values for total nitrogen (TN) as proposed criteria for rivers and streams to protect the State's estuaries and coastal waters in this notice.

    As described in more detail below and in the technical support document accompanying this notice, these proposed nitrogen downstream protection values are based on substantial data, thorough scientific analysis, and extensive technical evaluation. However, EPA recognizes that additional data and analysis may be available, including data for particular estuaries, to help inform what numeric nutrient criteria are necessary to protect Florida's waters, including downstream lakes and estuaries. EPA also recognizes that substantial site-specific work has been completed for a number of these estuaries. This notice and the proposed downstream protection values are not intended to address or be interpreted as calling into question the utility and protectiveness of these site-specific analyses. Rather, the proposed values represent the output of a systematic and scientific approach that was developed to be generally applicable to all flowing waters in Florida that terminate in estuaries for the purpose of ensuring the protection of downstream estuaries. EPA is interested in obtaining feedback at this time on this systematic and scientific approach. EPA is also interested in feedback regarding site-specific analyses for particular estuaries that should be used instead of this general approach for establishing final values.

    The Agency further recognizes that the proposed values in this notice will need to be considered in the context of the Agency's numeric nutrient criteria for estuarine and coastal waters scheduled for proposal in January of 2011.

    Regarding the criteria for flowing waters for protection of downstream lakes and estuaries, at this time, EPA intends to take final action on the criteria for protection of downstream lakes as part of the first phase of this rulemaking (by October 15, 2010) and to finalize downstream protection values in flowing waters as part of the second phase of this rulemaking process (by October 15, 2011) in coordination with the proposal and finalization of numeric nutrient criteria for estuarine and coastal waters in 2011. However, if comments, data and analyses submitted as a result of this proposal support finalizing these values sooner, by October 2010, EPA may choose to proceed in this manner. To facilitate this process, EPA requests comments and welcomes thorough evaluation on the technical and scientific basis of these proposed downstream protection values, as well as information on estuaries where site-specific analyses should be used, as part of the broader comment and evaluation process that this proposal initiates.

    In accordance with the terms of EPA's January 14, 2009 determination and the Consent Decree, EPA is proposing numeric nutrient criteria for Florida's lakes and flowing waters which include the following four water body types: Lakes, streams, springs and clear streams, and canals in south Florida. In developing this proposal, EPA worked closely with FDEP staff to review and analyze the State's extensive dataset of nutrient-related measurements as well as its analysis of stressor-response relationships and benchmark or modified- reference conditions. EPA also conducted further analyses and modeling, in addition to requesting an independent external peer review of the core methodologies and approaches that support this proposal.

    For lakes, EPA is proposing a classification scheme using color and alkalinity based upon substantial data that show that lake color and alkalinity play an important role in the degree to which TN and total phosphorus (TP) concentrations result in a biological response such as elevated chlorophyll a levels. EPA found that correlations between nutrients and biological response parameters in the different types of lakes in Florida were sufficiently robust, combined with additional lines of evidence, to support stressor-response criteria development for Florida's lakes. The Agency is also proposing an accompanying supplementary analytical approach that the State can use to adjust TN and TP criteria for a particular lake within a certain range where sufficient data on long-term ambient TN and TP levels are available to demonstrate that protective chlorophyll a criteria for a specific lake will still be maintained and attainment of the designated use will be assured. This information is presented in more detail in Section III.B below.

    Regarding numeric nutrient criteria for streams and rivers, EPA considered the extensive work of FDEP to analyze the relationship between TN and TP levels and biological response in streams and rivers.

    EPA found that relationships between nutrients and biological response parameters in rivers and streams were affected by many factors that made derivation of a quantitative relationship between chlorophyll a levels and nutrients in streams and rivers difficult to establish in the same manner as EPA did for lakes (i.e., stressor-response relationship). EPA considered an alternative methodology that evaluated a combination of biological information and data on the distribution of nutrients in a substantial number of healthy stream systems. Based upon a technical evaluation of the significant available data on Florida streams and related scientific analysis, the Agency concluded that reliance on a statistical distribution methodology was a stronger and a more sound approach for deriving TN and TP criteria in streams and rivers. This information is presented in more detail in Section III.C below.

    In developing these proposed numeric nutrient criteria for rivers and streams, EPA also evaluated their effectiveness for assuring the protection of downstream lake and estuary designated uses pursuant to the provisions of 40 CFR 130.10(b), which requires that WQS must provide for the attainment and maintenance of the WQS of downstream waters. For rivers and streams in Florida, EPA must ensure, to the extent that available science allows, that its nutrient criteria take into account the impact of near-field nutrient loads on aquatic life in downstream lakes and estuaries. EPA currently has evaluated the protectiveness of its rivers and streams TP criteria for lake protection and also the protectiveness of its rivers and streams TN criteria for 16 out of 26 of Florida's downstream estuaries using scientifically sound approaches for both estimating protective loads and deriving concentration-based upstream values. Of the ten downstream estuaries not completely evaluated to date, seven are in south Florida and receive TN loads from highly managed canals and waterways and three are in low lying areas of central Florida.

    As noted above, EPA used best available science and data related to downstream waters and found that there are cases where the nutrient criteria EPA is proposing to protect instream aquatic life may not be stringent enough to ensure protection of aquatic life in certain downstream lakes and estuaries. Accordingly, EPA is also proposing an

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    equation that would be used to adjust stream and river TP criteria to protect downstream lakes and a different methodology to adjust TN criteria for streams and rivers to ensure protection of downstream estuaries. These approaches as reflected in these proposed regulations and the revised criteria that would result from adjusting TN criteria for streams and rivers to ensure protection of downstream estuaries, based on certain assumptions, are detailed in Section III.C(6)(b) below. The Agency specifically requests comment on the available information, analysis, and modeling used to support the approaches EPA is proposing for addressing downstream impacts of TN and TP. EPA also invites additional stakeholder comment, data, and analysis on alternative technically-based approaches that would support the development of numeric nutrient WQS, or some other scientifically defensible approach, for protection of downstream waters. To the degree that substantial data and analyses are submitted that support a significant revision to downstream protection values for TN outlined in

    Section III.C(6)(b) below, EPA would intend to issue a supplemental

    Federal Register Notice of Data Availability (NODA) to present the additional data and supplemental analyses and solicit further comment and input. EPA anticipates obtaining the necessary data and information to compute downstream protection values for TP loads for many estuarine water bodies in Florida in 2010 and will also make this additional information available by issuing a supplemental Federal Register NODA.

    Regarding numeric nutrient criteria for springs and clear streams,

    EPA is proposing a nitrate-nitrite criterion for springs and clear streams based on experimental laboratory data and field evaluations that document the response of nuisance algae and periphyton to nitrate- nitrite concentrations. This criterion is explained in more detail in

    Section III.D below.

    For canals in south Florida, EPA is proposing a statistical distribution approach similar to its approach for rivers and streams, and based on sites meeting designated uses with respect to nutrients identified in four canal regions to best represent the necessary criteria to protect these highly managed water bodies. This approach is presented in more detail in Section III.E below. The Agency has also considered several alternative approaches to developing numeric nutrient criteria for canals and these are described, as well, for public comment and response.

    Stakeholders have expressed concerns that numeric nutrient criteria must be scientifically sound. Under the Clean Water Act and EPA's implementing regulations, numeric nutrient standards must protect the designated use of a water (as well as ensure protection of downstream uses) and must be based on sound scientific rationale. In the case of

    Florida, EPA and FDEP scientists completed a substantial body of scientific work; EPA believes that these proposed criteria clearly meet the regulatory standards of protection and that they are clearly based on a sound scientific rationale.

    Separate from and in addition to proposing numeric nutrient criteria, EPA is also proposing a new WQS regulatory tool for Florida, referred to as ``restoration WQS'' for impaired waters. This tool will enable Florida to set incremental water quality targets (uses and criteria) for specific pollutant parameters while at the same time retaining protective criteria for all other parameters to meet the full aquatic life use. The goal is to provide a challenging but realistic incremental framework in which to establish appropriate control measures. This provision will allow Florida to retain full aquatic life protection (uses and criteria) for its water bodies while establishing a transparent phased WQS process that would result in planned implementation of enforceable measures and requirements to improve water quality over a specified time period to ultimately meet the long- term designated aquatic life use. The phased numeric standards would be included in Florida's water quality regulations during the restoration period. This proposed regulatory tool is discussed in more detail in

    Section VI below.

    Finally, EPA is including in this notice a proposed approach for deriving Federal site-specific alternative criteria (SSAC) based upon

    State submissions of scientifically defensible recalculations that meet the requirements of CWA section 303(c). TMDL targets submitted to EPA by the State for consideration as new or revised WQS could be reviewed under this SSAC process. This proposed approach is discussed in more detail in Section V.C below.

    Overall, EPA is soliciting comments and data regarding EPA's proposed criteria for lakes and flowing waters, the derivation of these criteria, the protectiveness of the streams and rivers criteria for downstream waters, and all associated alternative options and methodologies discussed in this proposed rulemaking.

  30. What Entities May Be Affected by This Rule?

    Citizens concerned with water quality in Florida may be interested in this rulemaking. Entities discharging nitrogen or phosphorus to lakes and flowing waters of Florida could be indirectly affected by this rulemaking because WQS are used in determining National Pollutant

    Discharge Elimination System (``NPDES'') permit limits. Stakeholders in

    Florida facing obstacles in immediately achieving full aquatic life protection in impaired waters may be interested in the restoration standards concept outlined in this rulemaking. Categories and entities that may ultimately be affected include:

    Examples of potentially

    Category

    affected entities

    Industry............................... Industries discharging pollutants to lakes and flowing waters in the State of

    Florida.

    Municipalities......................... Publicly-owned treatment works discharging pollutants to lakes and flowing waters in the State of Florida.

    Stormwater Management Districts........ Entities responsible for managing stormwater runoff in

    Florida.

    This table is not intended to be exhaustive, but rather provides a guide for entities that may be directly or indirectly affected by this action. This table lists the types of entities of which EPA is now aware that potentially could be affected by this action. Other types of entities not listed in the table could also be affected, such as nonpoint source contributors to nutrient pollution in Florida's waters.

    Any parties or entities conducting activities within watersheds of the

    Florida waters covered by this rule, or who rely on, depend upon, influence, or contribute to the water quality of the lakes and flowing waters of Florida, might be affected by this rule. To determine whether your facility or activities may be affected by this action, you should examine this proposed rule. If you have questions regarding the applicability of this action to a particular entity, consult the person listed in the preceding FOR FURTHER INFORMATION CONTACT section.

  31. What Should I Consider as I Prepare My Comments for EPA? 1. Submitting CBI. Do not submit this information to EPA through http://www.regulations.gov or e-mail. Clearly mark the part or all of the information that you claim to be CBI. For CBI information in a disk or CD-ROM that

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    you mail to EPA, mark the outside of the disk or CD-ROM as CBI and then identify electronically within the disk or CD-ROM the specific information that is claimed as CBI. In addition to one complete version of the comment that includes information claimed as CBI, a copy of the comment that does not contain the information claimed as CBI must be submitted for inclusion in the public docket. Information so marked will not be disclosed except in accordance with procedures set forth in 40 CFR part 2. 2. Tips for Preparing Your Comments. When submitting comments, remember to: 1. Identify the rulemaking by docket number and other identifying information (subject heading, Federal Register date, and page number). 2. Follow directions--The agency may ask you to respond to specific questions or organize comments by referencing a Code of Federal

    Regulations (CFR) part or section number. 3. Explain why you agree or disagree; suggest alternatives and substitute language for your requested changes. 4. Describe any assumptions and provide any technical information and/or data that you used. 5. If you estimate potential costs or burdens, explain how you arrived at your estimate in sufficient detail to allow for it to be reproduced. 6. Provide specific examples to illustrate your concerns, and suggest alternatives. 7. Make sure to submit your comments by the comment period deadline identified.

  32. How Can I Get Copies of This Document and Other Related Information? 1. Docket. EPA has established an official public docket for this action under Docket Id. No. EPA-HQ-OW-2009-0596. The official public docket consists of the document specifically referenced in this action, any public comments received, and other information related to this action. Although a part of the official docket, the public docket does not include CBI or other information whose disclosure is restricted by statute. The official public docket is the collection of materials that is available for public viewing at the OW Docket, EPA West, Room 3334, 1301 Constitution Ave., NW., Washington, DC 20004. This Docket Facility is open from 8:30 a.m. to 4:30 p.m., Monday through Friday, excluding legal holidays. The Docket telephone number is 202-566-1744. A reasonable fee will be charged for copies. 2. Electronic Access. You may access this Federal Register document electronically through the EPA Internet under the ``Federal Register'' listings at http://www.epa.gov/fedrgstr/.

    An electronic version of the public docket is available through

    EPA's electronic public docket and comment system, EPA Dockets. You may use EPA Dockets at http://www.regulations.gov to view public comments, access the index listing of the contents of the official public docket, and to access those documents in the public docket that are available electronically. For additional information about EPA's public docket, visit the EPA Docket Center homepage at http://www.epa.gov/epahome/ dockets.htm. Although not all docket materials may be available electronically, you may still access any of the publicly available docket materials through the Docket Facility identified in Section

    I.D(1).

    II. Background

  33. Nutrient Pollution 1. What Is Nutrient Pollution?

    Excess anthropogenic concentrations of nitrogen (typically in oxidized, inorganic forms, such as nitrate) \3\ and phosphorus

    (typically as phosphate), commonly referred to as nutrient pollution, in surface waters can result in excessive algal and aquatic plant growth, referred to as eutrophication.\4\ One impact associated with eutrophication is low dissolved oxygen, due to decomposition of the aquatic plants and algae when these plants and algae die. As noted above, high nitrogen and phosphorus loadings also result in HABs, reduced spawning grounds and nursery habitats for aquatic life, and fish kills. Public health concerns related to eutrophication include impaired drinking water sources, increased exposure to toxic microbes such as cyanobacteria, and possible formation of disinfection byproducts in drinking water, some of which have been associated with serious human illnesses such as bladder cancer.5 6Nutrient problems can manifest locally or much further downstream in lakes, reservoirs, and estuaries.

    \3\ To be used by living organisms, nitrogen gas must be fixed into its reactive forms; for plants, either nitrate or ammonia.

    \4\ Eutrophication is defined as an increase in organic carbon to an aquatic ecosystem caused by primary productivity stimulated by excess nutrients--typically compounds containing nitrogen or phosphorus. Eutrophication can adversely affect aquatic life, recreation, and human health uses of waters.

    \5\ Villanueva, C.M. et al., 2006. Bladder Cancer and Exposure to Water Disinfection By-Products through Ingestion, Bathing,

    Showering, and Swimming in Pools. American Journal of Epidemiology, 165(2):148-156.

    \6\ U.S. EPA. 2009. What Is in Our Drinking Water. United States

    Environmental Protection Agency, Office of Research and Development. http://www.epa.gov/extrmurl/research/process/drinkingwater.html.

    Accessed December 2009.

    Excess nutrients in water bodies come from many sources, which can be grouped into five major categories: (1) Sources associated with urban land use and development, (2) municipal and industrial waste water discharge, (3) row crop agriculture, (4) animal husbandry, and

    (5) atmospheric deposition that may be increased by production of nitrogen oxides in electric power generation and internal combustion engines. These sources contribute significant loadings of nitrogen and phosphorus to surface waters causing major impacts to aquatic ecosystems and significant imbalances in the natural populations of flora and fauna.\7\

    \7\ National Research Council, 2000. Clean Coastal Waters:

    Understanding and Reducing the Effects of Nutrient Pollution. Report prepared by the Ocean Study Board and Water Science and Technology

    Board, Commission on Geosciences, Environment and Resources,

    National Resource Council. National Academy Press, Washington, DC;

    Howarth, R.W., A. Sharpley, and D. Walker. 2002. Sources of nutrient pollution to coastal waters in the United States: Implications for achieving coastal water quality goals. Estuaries. 25(4b):656-676;

    Smith, V.H. 2003. Eutrophication of freshwater and coastal marine ecosystems. Environ. Sci. and Poll. Res. 10(2):126-139; Dodds, W.K.,

    W.W. Bouska, J.L. Eitzmann, T.J. Pilger, K.L. Pitts, A.J. Riley,

    J.T. Schloesser, and D.J. Thornbrugh. 2009. Eutrophication of U.S. freshwaters: Analysis of potential economic damages. Environ. Sci.

    Tech.. 43(1):12-19.

    1. Adverse Impacts of Nutrient Pollution on Aquatic Life, Human Health, and the Economy

    To protect aquatic life, EPA regulates pollutants that have adverse effects on aquatic life. For most pollutants, these effects are typically negative impacts on growth, reproduction, and survival. As previously noted, excess nutrients can lead to increases in algal and other aquatic plant growth, including toxic algae that can result in

    HABs. Increases in algal and aquatic plant growth provide excess organic matter in a water body and can contribute to subsequent degradation of aquatic communities, human health impacts, and ultimately economic impacts.

    Fish, shellfish, and wildlife require clean water for survival.

    Changes in the environment resulting from elevated nutrient levels

    (such as algal blooms, toxins from HABs, and hypoxia/anoxia) can cause a variety of effects. When excessive nutrient loads change a water body's algae and plant species, the change in habitat and available food resources can induce changes affecting an entire food chain. Algal blooms block

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    sunlight that submerged grasses need to grow, leading to a decline of seagrass beds and decreased habitat for juvenile organisms. Algal blooms can also increase turbidity and impair the ability of fish and other aquatic life to find food.\8\ Algae can also damage or clog the gills of fish and invertebrates.\9\

    \8\ Hauxwell, J. C. Jacoby, T. Frazer, and J. Stevely. 2001.

    Nutrients and Florida's Coastal Waters. Florida Sea Grant.

    \9\ NOAA. 2009. Harmful Algal Blooms: Current Programs Overview.

    National Oceanic and Atmospheric Administration. http:// www.cop.noaa.gov/stressors/extremeevents/hab/welcome.html. Accessed

    December 2009.

    HABs can form toxins that cause illness or death for some animals.

    Some of the more commonly affected animals include sea lions, turtles, seabirds, dolphins, and manatees.\10\ More than 50% of unusual marine mortality events may be associated with HABs.\11\ Lower level consumers, such as small fish or shellfish, may not be harmed by algal toxins, but they bioaccumulate toxins, causing higher exposures for higher level consumers (such as larger predator fish), resulting in health impairments and possibly death.12 13

    \10\ NOAA. 2009. Harmful Algal Blooms: Current Programs

    Overview. National Oceanic and Atmospheric Administration. http:// www.cop.noaa.gov/stressors/extremeevents/hab/welcome.html. Accessed

    December 2009.

    \11\ WHOI. 2008. HAB Impacts on Wildlife. Woods Hole

    Oceanographic Institution. http://www.whoi.edu/redtide/ page.do?pid=9682. Accessed December 2009.

    \12\ WHOI. 2008. Marine Mammals. Woods Hole Oceanographic

    Institution. http://www.whoi.edu/redtide/page.do?pid=14215. Accessed

    December 2009.

    \13\ WHOI. 2008. HAB Impacts on Wildlife. Woods Hole

    Oceanographic Institution. http://www.whoi.edu/redtide/ page.do?pid=9682. Accessed December 2009.

    There are many examples of HAB toxins significantly affecting marine animals. For example, between March and April 2003, 107 bottlenose dolphins (Tursiops truncatus) died, along with hundreds of fish and marine invertebrates, along the Florida Panhandle.\14\ High levels of brevetoxin (a neurotoxin), produced by a harmful species of dinoflagellate (a type of algae), were measured in all of the stranded dolphins examined, as well as in their fish prey.\15\

    \14\ WHOI. 2008. Marine Mammals. Woods Hole Oceanographic

    Institution. http://www.whoi.edu/redtide/page.do?pid=14215. Accessed

    December 2009.

    \15\ WHOI. 2008. Marine Mammals. Woods Hole Oceanographic

    Institution. http://www.whoi.edu/redtide/page.do?pid=14215. Accessed

    December 2009.

    In freshwater, cyanobacteria can produce toxins that have been implicated as the cause of a large number of fish and bird mortalities.

    These toxins have also been tied to the death of pets and livestock that may be exposed through drinking contaminated water or grooming themselves after bodily exposure.\16\ A recent study showed that at least one type of cyanobacteria has been linked to cancer and tumor growth in animals.\17\

    \16\ WHOI. 2008. HAB Impacts on Wildlife. Woods Hole

    Oceanographic Institution. http://www.whoi.edu/redtide/ page.do?pid=9682. Accessed December 2009.

    \17\ Falconer, I.R., A.R. Humpage. 2005. Health Risk Assessment of Cyanobacterial (Blue-green Algal) Toxins in Drinking Water. Int.

  34. Environ. Res. Public Health. 2(1): 43-50.

    Excessive algal growth contributes to increased oxygen consumption associated with decomposition, potentially reducing oxygen to levels below that needed for aquatic life to survive and flourish.18 19Low oxygen, or hypoxia, often occurs in episodic ``events,'' which sometimes develop overnight. Mobile species, such as adult fish, can sometimes survive by moving to areas with more oxygen. However, migration to avoid hypoxia depends on species mobility, availability of suitable habitat, and adequate environmental cues for migration. Less mobile or immobile species, such as oysters and mussels, cannot move to avoid low oxygen and are often killed during hypoxic events.\20\ While certain mature aquatic animals can tolerate a range of dissolved oxygen levels that occur in the water, younger life stages of species like fish and shellfish often require higher levels of oxygen to survive.\21\ Sustained low levels of dissolved oxygen cause a severe decrease in the amount of aquatic life in hypoxic zones and affect the ability of aquatic organisms to find necessary food and habitat. In extreme cases, anoxic conditions occur when there is a complete lack of oxygen. Very few organisms can live without oxygen (for example some microbes), hence these areas are sometimes referred to as dead zones.\22\

    \18\ NOAA. 2009. Harmful Algal Blooms: Current Programs

    Overview. National Oceanic and Atmospheric Administration. http:// www.cop.noaa.gov/stressors/extremeevents/hab/welcome.html. Accessed

    December 2009.

    \19\ USGS. 2009. Hypoxia. U.S. Geological Survey. http:// toxics.usgs.gov/definitions/hypoxia.html. Accessed December 2009.

    \20\ ESA. 2009. Hypoxia. Ecological Society of America. http:// www.esa.org/education_diversity/pdfDocs/hypoxia.pdf. Accessed

    December 2009.

    \21\ USEPA. 2000. Ambient Aquatic Life Water Quality Criteria for Dissolved Oxygen (Saltwater): Cape Cod to Cape Hattaras.

    Environmental Protection Agency, Office of Water, Washington DC PA- 822-R-00-012.

    \22\ Ecological Society of America. 2009. Hypoxia. Ecological

    Society of America, Washington, DC. http://www.esa.org/education/ edupdfs/hypoxia.pdf. Accessed December 2009.

    Primary impacts to humans result directly from elevated nutrient pollution levels and indirectly from the subsequent water body changes that occur from increased nutrients (such as algal blooms and toxins).

    Direct impacts include effects on human health through drinking water or consuming toxic shellfish. Indirect impacts include restrictions on recreation (such as boating, swimming, and kayaking). Algal blooms can prevent opportunities to swim and engage in other types of recreation.

    In areas where recreation is determined to be unsafe because of algal blooms, warning signs are often posted to discourage human use of the waters.

    Highly elevated nitrogen levels, in the form of nitrate, in drinking water supplies and private wells can cause methemoglobinemia

    (blue baby syndrome, which refers to high levels of nitrate in a baby's blood that reduce the blood's ability to deliver oxygen to the skin and organs resulting in a bluish tinge to the skin; in severe cases methemoglobinemia can lead to coma and death).\23\ Monitoring of

    Florida Public Water Supplies from 2004-2007 indicates that violations of nitrate maximum contaminant levels (MCL) ranged from 34-40 violations annually.\24\ In addition, in the predominantly agricultural regions of Florida, of 3,949 drinking water wells analyzed for nitrate by the Florida Department of Agriculture and Consumer Services, (FDACS) and the FDEP, 2,483 (63%) contained detectable nitrate and 584 wells

    (15%) contained nitrate above the U.S. EPA MCL. Of the 584 wells statewide that exceeded the MCL, 519 were located in the Central

    Florida Ridge citrus growing region, encompassed primarily by Lake,

    Polk and Highland Counties.\25\ Human health can also be impacted by disinfection byproducts formed when disinfectants (such as chlorine) used to treat drinking water react with organic carbon (from the algae in source waters). Some disinfection byproducts have been linked to rectal, bladder, and colon cancers; reproductive health risks; and liver, kidney, and central nervous

    Page 4180

    system problems.26 27Humans can also be impacted by accidentally ingesting toxins, resulting from toxic algal blooms in water, while recreating or by consuming drinking water that still contains toxins despite treatment. For example, cyanobacteria toxins can sometimes pass through the normal water treatment process.\28\

    After consuming seafood tainted by toxic HABs, humans can develop gastrointestinal distress, memory loss, disorientation, confusion, and even coma and death in extreme cases. Some toxins only require a small dose to cause illness or death.\29\ EPA expects that by addressing protection of aquatic life uses through the application of the proposed numeric nutrient criteria in this rulemaking, risks to human health will also be alleviated, as nutrient levels that represent a balance of natural populations of flora and fauna will not produce HABs nor result in highly elevated nitrate levels.

    \23\ USEPA. 2007. Nitrates and Nitrites. U.S. Environmental

    Protection Agency. http://www.epa.gov/teach/chem_summ/Nitrates_ summary.pdf. Accessed December 2009.

    \24\ FDEP 2009. Chemical Data for 2004, 2005, 2006, 2007 and 2008. Florida Department of Environmental Protection. http:// www.dep.state.fl.us/water/drinkingwater/chemdata.htm. Accessed

    January 2010.

    \25\ Southern Regional Water Program. 2010. Drinking Water and

    Human Health in Florida. Southern Regional Water Program, http:// srwqis.tamu.edu/florida/program-information/florida-target-themes/ drinking-water-and-human-health.aspx. Accessed January 2010.

    \26\ USEPA. 2009. Drinking Water Contaminants. U.S.

    Environmental Protection Agency. Accessed http://www.epa.gov/ safewater/hfacts.html. December 2009.

    \27\ CFR. 2006. 40 CFR parts 9, 141, and 142: National Primary

    Drinking Water Regulations: Stage 2 Disinfectants and Disinfection

    Byproducts Rule. Code of Federal Regulations, Washington, DC. http:/

    /www.epa.gov/fedrgstr/EPA-WATER/2006/January/Day-04/w03.htm.

    Accessed December 2009.

    \28\ Carmichael, W.W. 2000. Assessment of Blue-Green Algal

    Toxins in Raw and Finished Drinking Water. AWWA Research Foundation,

    Denver, CO.

    \29\ NOAA. 2009. Marine Biotoxins. National Oceanic and

    Atmospheric Administration. http://www.nwfsc.noaa.gov/hab/habs_ toxins/marine_biotoxins/index.html. Accessed December 2009.

    Nutrient pollution and eutrophication can also impact the economy through additional reactive costs, such as medical treatment for humans who ingest HAB toxins, treating drinking water supplies to remove algae and organic matter, and monitoring water for shellfish and other affected resources.

    Economic losses from algal blooms and HABs can include reduced property values for lakefront areas, commercial fishery losses, and lost revenue from recreational fishing and boating trips, as well as other tourism-related businesses. Commercial fishery losses occur because of a decline in the amount of fish available for harvest due to habitat and oxygen declines. Some HAB toxins can make seafood unsafe for human consumption, and can reduce the amount of fish bought because people might question if eating fish is safe after learning of the presence of the algal bloom.\30\ To put the issue into perspective, consider the following estimates: For freshwater lakes, losses in fishing and boating trip-related revenues nationwide due to eutrophication are estimated to range from $370 million to almost $1.2 billion dollars and loss of lake property values from excessive algal growth are estimated to range from $300 million to $2.8 billion annually on a national level.\31\

    \30\ WHOI. 2008. Hearing on 'Harmful Algal Blooms: The

    Challenges on the Nation's Coastlines.' Woods Hole Oceanographic

    Institution. http://www.whoi.edu/page.do?pid=8916&tid=282

    &cid=46007. Accessed December 2009.

    \31\ Dodds, W.K., W.W. Bouska, J.L. Eitzmann, T.J. Pilger, K.L.

    Pitts, A.J. Riley, J.T. Schloesser, and D.J. Thornbrugh. 2009.

    Eutrophication of U.S. freshwaters: analysis of potential economic damages. Environ.l Sci. Tech.y. 43(1):12-19.

    1. Nutrient Pollution in Florida

    Water quality degradation resulting from excess nitrogen and phosphorus loadings is a documented and significant environmental issue in Florida. According to Florida's 2008 Integrated Report,\32\ approximately 1,000 miles of rivers and streams, 350,000 acres of lakes, and 900 square miles of estuaries are impaired for nutrients in the State. To put this in context, these values represent approximately 5% of the assessed river and stream miles, 23% of the assessed lake acres, and 24% of the assessed square miles of estuaries that Florida has listed as impaired in the 2008 Integrated Report.\33\ Nutrients are ranked as the fourth major source of impairment for rivers and streams in the State (after dissolved oxygen, mercury in fish, and fecal coliforms). For lakes and estuaries, nutrients are ranked first and second, respectively. As discussed above, impairments due to nutrient pollution result in significant impacts to aquatic life and ecosystem health. Nutrient pollution also represents, as mentioned above, an increased human health risk in terms of contaminated drinking water supplies and private wells.

    \32\ Florida Department of Environmental Protection. 2008.

    Integrated Water Quality Assessment for Florida: 2008 305(b) Report and 303(d) List Update.

    \33\ Florida Department of Environmental Protection. 2008.

    Integrated Water Quality Assessment for Florida: 2008 305(b) Report and 303(d) List Update.

    Florida is particularly vulnerable to nutrient pollution.

    Historically, the State has experienced a rapidly expanding population, which is a strong predictor of nutrient loading and associated effects, and which combined with climate and other natural factors, make Florida waters sensitive to nutrient effects. Florida is currently the fourth most populous state in the nation, with an estimated 18 million people.\34\ Population is expected to continue to grow, resulting in an expected increase in urban development, home landscapes, and wastewater. Florida's flat topography causes water to move slowly over the landscape, allowing ample opportunity for eutrophication responses to develop. Similarly, small tides in many of Florida's estuaries

    (especially on the Gulf coast) also allow for well-developed eutrophication responses in tidal waters. Florida's warm and wet, yet sunny, climate further contributes to increased run-off and subsequent eutrophication responses.\35\ Exchanges of surface water and ground water contribute to complex relationships between nutrient sources and the location and timing of eventual impacts.\36\

    \34\ U.S. Census Bureau. 2009. 2008 Population Estimates Ranked by State. http://factfinder.census.gov.

    \35\ Perry, W.B. 2008. Everglades restoration and water quality challenges in south Florida. Ecotoxicology 17:569-578.

    \36\ USGS. 2009. Florida Waters: A Water Resources Manual. http://sofia.usgs.gov/publications/reports/floridawaters/. Accessed

    June 9, 2009.

    In addition, extensive agricultural development and associated hydrologic modifications (e.g., canals and ditches) amplify the State's susceptibility to nutrient pollution. Many of Florida's inland areas have extensive tracts of agricultural lands. Much of the intensive agriculture and associated fertilizer usage takes place in locations dominated by poorly drained sandy soils and with high annual rainfall amounts, two conditions favoring nutrient-rich runoff. These factors, along with population increase, have contributed to a significant upward trend in nutrient inputs to Florida's waters.\37\ High historical water quality and the human and aquatic life uses of many waterways in Florida often means that very low nutrients, low productivity, and high water clarity are needed and expected to maintain uses.

    \37\ Florida Department of Environmental Protection. 2008.

    Integrated Water Quality Assessment for Florida: 2008 305(b) Report and 303(d) List Update.

  35. Statutory and Regulatory Background

    Section 303(c) (33 U.S.C. 1313(c)) of the CWA directs states to adopt WQS for their navigable waters. Section 303(c)(2)(A) and EPA's implementing regulations at 40 CFR part 131 require, among other provisions, that state WQS include the designated use or uses to be made of the waters and criteria that protect those uses. EPA regulations at 40 CFR 131.11(a)(1) provide that states shall ``adopt those water quality criteria

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    that protect the designated use'' and that such criteria ``must be based on sound scientific rationale and must contain sufficient parameters or constituents to protect the designated use.'' As noted above, 40 CFR 130.10(b) provides that ``In designating uses of a water body and the appropriate criteria for those uses, the state shall take into consideration the water quality standards of downstream waters and ensure that its water quality standards provide for the attainment and maintenance of the water quality standards of downstream waters.''

    States are also required to review their WQS at least once every three years and, if appropriate, revise or adopt new standards (CWA section 303(c)(1)). States are required to submit these new or revised

    WQS for EPA review and approval or disapproval (CWA section 303(c)(2)(A)). Finally, CWA section 303(c)(4)(B) authorizes the

    Administrator to determine, even in the absence of a state submission, that a new or revised standard is needed to meet CWA requirements. The criteria proposed in this rulemaking apply to lakes and flowing waters of the State of Florida. EPA's proposal defines ``lakes and flowing waters'' to mean inland surface waters that have been classified by

    Florida as Class I (Potable Water Supplies Use) or Class III

    (Recreation, Propagation and Maintenance of a Healthy, Well-Balanced

    Population of Fish and Wildlife Use) water bodies pursuant to Florida

    Administrative Code (F.A.C.) Rule 62-302.400, excluding wetlands, and which are predominantly fresh waters.

  36. Water Quality Criteria

    EPA has issued guidance for use by states when developing criteria.

    Under CWA section 304(a), EPA periodically publishes criteria recommendations (guidance) for use by states in setting water quality criteria for particular parameters to protect recreational and aquatic life uses of waters. When EPA has published recommended criteria, states have the option of adopting water quality criteria based on

    EPA's CWA section 304(a) criteria guidance, section 304(a) criteria guidance modified to reflect site-specific conditions, or other scientifically defensible methods. 40 CFR 131.11(b)(1).

    For nutrients, EPA has published under CWA section 304(a) a series of peer-reviewed, national technical approaches and methods regarding the development of numeric nutrient criteria for lakes and reservoirs,\38\ rivers and streams,\39\ and estuaries and coastal marine waters.\40\ Basic analytical approaches for nutrient criteria derivation include, but are not limited to: (1) Stressor-response analysis, (2) the reference condition approach, and (3) mechanistic modeling. The stressor-response, or effects-based, approach relates a water body's response to nutrients and identifies adverse effect levels. This is done by selecting a protective value based on the relationships of nitrogen and phosphorus field measures with indicators of biological response. This approach is empirical, and directly relates to the designated uses. The reference condition approach derives candidate criteria from distributions of nutrient concentrations and biological responses in a group of waters.

    Measurements are made of causal and response variables and a protective value is selected from the distribution. The mechanistic modeling approach predicts a cause-effect relationship using site-specific input to equations that represent ecological processes. Mechanistic models require calibration and validation. Each approach has peer review support by the broader scientific community, and would provide adequate means for any state to develop scientifically defensible numeric nutrient criteria.

    \38\ U.S. EPA. 2000a. Nutrient Criteria Technical Guidance

    Manual: Lakes and Reservoirs. Office of Water, Washington, DC. EPA- 822-B-00-001.

    \39\ U.S. EPA. 2000b. Nutrient Criteria Technical Guidance

    Manual: Rivers and Streams. Office of Water, Washington, DC. EPA- 822-B-00-002.

    \40\ U.S. EPA. 2001. Nutrient Criteria Technical Manual:

    Estuarine and Coastal Marine Waters. Office of Water, Washington,

    DC. EPA-822-B-01-003, and wetlands (U.S. EPA, 2007).

    In cases where scientifically defensible numeric criteria cannot be derived, EPA regulations provide that narrative criteria should be adopted. 40 CFR 131.11(b)(2). Narrative criteria are descriptions of conditions necessary for the water body to attain its designated use.

    Often expressed as requirements that waters remain ``free from'' certain characteristics, narrative criteria can be the basis for controlling nuisance conditions such as floating debris or objectionable deposits. States often establish narrative criteria, such as ``no toxics in toxic amounts,'' in order to limit toxic pollutants in waters where the state has yet to adopt an EPA-recommended numeric criterion and or where EPA has yet to derive a recommended numeric criterion. For nutrients, in the absence of numeric nutrient criteria, states have often established narrative criteria such as ``no nuisance algae.'' Reliance on a narrative criterion to derive NPDES permit limits, assess water bodies for listing purposes, and establish TMDL targets can often be a difficult, resource-intensive, and time- consuming process that entails conducting case-by-case analyses to determine the appropriate numeric target value based on a site-specific translation of the narrative criterion. Narrative criteria are most effective when they are supported by procedures to translate them into quantitative expressions of the conditions necessary to protect the designated use.

  37. Agency Determination Regarding Florida

    On January 14, 2009, EPA determined under CWA section 303(c)(4)(B) that new or revised WQS in the form of numeric nutrient water quality criteria are necessary to meet the requirements of the CWA in the State of Florida. Florida's currently applicable narrative nutrient criterion provides, in part, that ``in no case shall nutrient concentrations of a body of water be altered so as to cause an imbalance in natural populations of aquatic flora or fauna.'' Florida Administrative Code

    (F.A.C.) 62-302-530(47)(b). EPA determined that Florida's narrative nutrient criterion alone was insufficient to ensure protection of applicable designated uses. The determination recognized that Florida has a proactive and innovative program to address nutrient pollution through a strategy of comprehensive National Pollutant Discharge

    Elimination System (NPDES) permit regulations, Basin Management Action

    Plans (BMAPs) for implementation of TMDLs which include controls on nonpoint sources, municipal wastewater treatment technology-based requirements under the 1990 Grizzle-Figg Act, and rules to limit nutrient pollution in geographically specific areas like the Indian

    River Lagoon System, the Everglades Protection Area, and Wekiva

    Springs. However, the determination noted that despite Florida's intensive efforts to diagnose and control nutrient pollution, substantial water quality degradation from nutrient over-enrichment remains a significant challenge in the State and one that is likely to worsen with continued population growth and land-use changes.

    Florida's implementation of its narrative water quality criterion for nutrients is based on site-specific detailed biological assessments and analyses, together with site-by-site outreach and stakeholder engagement in the context of specific CWA-related

    Page 4182

    actions, specifically NPDES permits, TMDLs required for both permitting and BMAP activities, and assessment and listing decisions. When deriving NPDES water quality-based permit limits, Florida initially conducts a site-specific analysis to determine whether a proposed discharge has the reasonable potential to cause or contribute to an exceedance of its narrative nutrient water quality criterion. The State then determines what levels of nutrients would ``cause an imbalance in natural populations of aquatic flora or fauna'' and translates those levels into numeric ``targets'' for the receiving water and any other affected waters. Determining on a water-by-water basis for thousands of

    State waters the levels of nutrients that would ``cause an imbalance in natural populations of aquatic flora or fauna'' is a difficult, lengthy, and data-intensive undertaking. This work involves performing detailed site-specific analyses of the receiving water and any other affected waters. If the State has not already completed this analysis for a particular water, it can be very difficult to accurately determine in the context and timeframe of the NPDES permitting process.

    For example, in some cases, adequate data may take several years to collect and therefore, may not be available for a particular water at the time of permitting issuance or re-issuance.

    When developing TMDLs, as it does when determining reasonable potential and deriving limits in the permitting context, Florida translates the narrative nutrient criterion into a numeric target that the State determines is necessary to meet its narrative criterion and protect applicable designated uses. This process also involves a site- specific analysis to determine the nutrient levels that would ``cause an imbalance in natural populations of aquatic flora or fauna'' in a particular water. Each time a site-specific analysis is conducted to determine what the narrative criterion means for a particular water body in developing a TMDL, the State takes site-specific considerations into account and devises a method that works with the available data and information.

    In adopting the Impaired Waters Rule (IWR), Florida took important steps toward improving implementation of its narrative nutrient criterion by establishing and publishing an assessment methodology to identify waters impaired for nutrients. This methodology includes numeric nutrient impairment ``thresholds'' above which waters are automatically deemed impaired. Even when a listing is made, however, development of a TMDL is then generally required to support issuance of a permit or development of a BMAP.

    Based on the considerations outlined above, EPA concluded that numeric criteria for nutrients will enable the State to take necessary actions to protect the designated uses, in a timelier manner. The resource intensive efforts to interpret the State's narrative criterion contribute to delays in implementing the criterion and therefore, affect the State's ability to provide the needed protections for applicable designated uses. EPA, therefore, determined that numeric nutrient criteria are necessary for the State of Florida to meet the

    CWA requirement to have criteria that protect applicable designated uses.

    The combined impacts of urban and agricultural activities, along with Florida's physical features and important and unique aquatic ecosystems, made it clear that the current use of the narrative nutrient criterion alone and the resulting delays that it entails do not ensure protection of applicable designated uses for the many State waters that are either unimpaired and need protection or have been listed as impaired and require loadings reductions. EPA determined that numeric nutrient water quality criteria would strengthen the foundation for identifying impaired waters, establishing TMDLs, and deriving water quality-based effluent limits in NPDES permits, thus providing the necessary protection for the State's designated uses in its waters. In addition, numeric nutrient criteria will support the State's ability to effectively partner with point and nonpoint sources to control nutrients, thus further providing the necessary protection for the designated uses of the State's water bodies. EPA's determination is available at the following Web site: http://www.epa.gov/waterscience/ standards/rules/fl-determination.htm.

    The January 14, 2009 determination stated EPA's intent to propose numeric nutrient criteria for lakes and flowing waters in Florida within twelve months of the January 14, 2009 determination, and for estuarine and coastal waters within 24 months of the determination. EPA has also entered into a Consent Decree with Florida Wildlife

    Federation, Sierra Club, Conservancy of Southwest Florida,

    Environmental Confederation of Southwest Florida, and St. Johns

    Riverkeeper, committing to the schedule stated in EPA's January 14, 2009 determination to propose numeric nutrient criteria for lakes and flowing waters in Florida by January 14, 2010, and for Florida's estuarine and coastal waters by January 14, 2011. The Consent Decree also requires that final rules be issued by October 15, 2010 for lakes and flowing waters, and by October 15, 2011 for estuarine and coastal waters.

    In accordance with the determination and EPA's Consent Decree, EPA is proposing numeric nutrient criteria for Florida's lakes and flowing waters with this proposed rule. As envisioned in EPA's determination, this time frame has allowed EPA to utilize the large data set collected by Florida as part of a detailed analysis of nutrient-impaired waters.

    In a separate rulemaking, EPA intends to develop and propose numeric nutrient criteria for Florida's estuarine and coastal waters by January 14, 2011. EPA's determination did not apply to Florida's wetlands, and as a result, Florida's wetlands will not be addressed in this rulemaking or in EPA's forthcoming rulemaking involving estuarine and coastal waters.

    III. Proposed Numeric Nutrient Criteria for the State of Florida's

    Lakes and Flowing Waters

  38. General Information

    (1) Which Water Bodies Are Affected by This Proposed Rule?

    The criteria proposed in this rulemaking apply to lakes and flowing waters of the State of Florida. EPA's proposal defines ``lakes and flowing waters'' to mean inland surface waters that have been classified as Class I (Potable Water Supplies) or Class III

    (Recreation, Propagation and Maintenance of a Healthy, Well-Balanced

    Population of Fish and Wildlife) water bodies pursuant to Rule 62- 302.400, F.A.C., excluding wetlands, and which are predominantly fresh waters. Pursuant to Rule 62-302.200, F.A.C., EPA's proposal defines

    ``predominantly fresh waters'' to mean surface waters in which the chloride concentration at the surface is less than 1,500 milligrams per liter (mg/L) and ``surface water'' means water upon the surface of the

    Earth, whether contained in bounds created naturally, artificially, or diffused. Waters from natural springs shall be classified as surface water when it exits from the spring onto the Earth's surface.

    In this rulemaking, EPA is proposing numeric nutrient criteria for the following four water body types: Lakes, streams, springs and clear streams, and canals in south Florida. EPA's proposal also includes definitions for each of these waters. ``Lake'' means a freshwater water body that is not a stream or other watercourse with some open contiguous water free from emergent vegetation. ``Stream'' means a free-flowing, predominantly fresh surface water in a

    Page 4183

    defined channel, and includes rivers, creeks, branches, canals (outside south Florida), freshwater sloughs, and other similar water bodies.

    ``Spring'' means the point where underground water emerges onto the

    Earth's surface, including its spring run. ``Spring run'' means a free- flowing water that originates from a spring or spring group whose primary (>50%) source of water is from a spring or spring group.

    Downstream waters from a spring that receive 50% or more of their flow from surface water tributaries are not considered spring runs. ``Clear stream'' means a free-flowing water whose color is less than 40 platinum cobalt units (PCU, which is assessed as true color free from turbidity). Classification of a stream as clear or colored is based on the instantaneous color of the sample. Consistent with Rule 62-312.020,

    F.A.C., ``canal'' means a trench, the bottom of which is normally covered by water with the upper edges of its two sides normally above water. Consistent with Rule 62-302.200, F.A.C., all secondary and tertiary canals wholly within Florida's agricultural areas are classified as Class IV waters, not Class III, and therefore, are not subject to this proposed rulemaking. The classes of waters, as specified in this paragraph and as subject to this proposed rulemaking, are hereinafter referred to as ``lakes and flowing waters'' in this proposed rule.

    The CWA requires adoption of WQS for ``navigable waters.'' CWA section 303(c)(2)(A). The CWA defines ``navigable waters'' to mean

    ``the waters of the United States, including the territorial seas.''

    CWA section 502(7). Whether a particular water body is a water of the

    United States is a water body-specific determination. Every water body that is a water of the United States requires protection under the CWA.

    EPA is not aware of any waters of the United States in Florida that are currently exempted from the State's WQS. For any privately owned water in Florida that is a water of the United States, the applicable numeric nutrient criteria for those types of waters would apply. This rule does not apply to waters for which the Miccosukee Tribe of Indians or

    Seminole Tribe of Indians has obtained Treatment as a State for Section 303 of the CWA, pursuant to Section 518 of the CWA.

    (2) Background on EPA's Derivation of Proposed Numeric Nutrient

    Criteria for the State of Florida's Lakes and Flowing Waters

    In proposing numeric nutrient criteria for Florida's lakes and flowing waters, EPA developed numeric nutrient criteria to support a balanced natural population of flora and fauna in Florida lakes and flowing waters, and to ensure, to the extent that the best available science allows, the attainment and maintenance of the WQS of downstream waters. Where numeric nutrient criteria do not yet exist, in proposed or final form, for a water body type that is downstream from a lake or flowing water (e.g., estuaries) in Florida, EPA has interpreted the currently applicable State narrative criterion, ``in no case shall nutrient concentrations of a body of water be altered so as to cause an imbalance in natural populations of aquatic flora or fauna,'' to ensure that the numeric criteria EPA is proposing would not result in nutrient concentrations that would ``cause an imbalance in natural populations of aquatic flora or fauna'' in such downstream water bodies. EPA's actions are consistent with and support existing Florida WQS regulations. EPA used the best available science to estimate protective loads to downstream estuaries, and then used these estimates (and assumptions about the distribution of the load throughout the watershed), along with mathematical models, to calculate concentrations in upstream flowing waters that would have to be met to ensure the attainment and maintenance of the State's narrative criterion applicable to downstream estuaries.

    EPA relied on an extensive amount of Florida-specific data, collected and analyzed, in large part, by FDEP and then reviewed by

    EPA. EPA worked extensively with FDEP on data interpretation and technical analyses for developing scientifically sound numeric nutrient criteria for this proposed rulemaking. Because EPA is committed to ensuring the use of the best available science, the Agency submitted its criteria derivation methodologies, developed by EPA in close collaboration with FDEP experts and scientists, to an independent, external, scientific peer review in July 2009.

    To support derivation of EPA's proposed lakes criteria, EPA searched extensively for relevant and useable lake data. In this case the effort resulted in 33,622 samples from 4,417 sites distributed among 1,599 lakes statewide.

    Regarding the derivation of EPA's proposed streams criteria, EPA evaluated water chemistry data from 11,761 samples from 6,342 sites statewide in the ``all streams'' dataset. EPA also used data collected for linking nutrients to specific biological responses that consisted of 2,023 sample records from more than 1,100 streams.

    For EPA's proposed springs and clear streams criteria, EPA evaluated data gathered and synthesized by FDEP using approximately 50 studies including historical accounts, laboratory nutrient amendment bioassays, field surveys, and TMDL reports that document increasing patterns of nitrate-nitrite levels and corresponding ecosystem level responses observed within the last 50 years. At least a dozen of these studies were used to develop and support the proposed nitrate-nitrite criterion for spring ecosystems.

    For EPA's proposed criteria for canals for south Florida, EPA started with more than 1,900,000 observations from more than 3,400 canal sites. These were filtered for data relevant to nutrient criteria development and resulted in observations at more than 500 sites for variables (nutrient parameter data and chlorophyll a data). Reliance on these extensive sets of data has enabled EPA to use the best available information and science to derive robust, scientifically sound criteria applicable to Florida's lakes and flowing waters.

    Section III describes EPA's proposed numeric nutrient criteria for

    Florida's lakes, streams, springs and clear streams, and canals and the associated methodologies EPA employed to derive them. These criteria are based on sound scientific rationale and will protect applicable designated uses in Florida's lakes and flowing waters. EPA solicits public comment on these criteria and their derivation. This preamble also includes discussions of alternative approaches that EPA considered but did not select as the preferred option to derive the proposed criteria. EPA invites public comment on the alternative approaches as well. In addition, EPA requests public comment on whether the proposed numeric nutrient criteria are consistent with Florida's narrative criterion with respect to nutrients at Rule 62-302.530(47)(a), F.A.C., specifying that the discharge of nutrients shall be limited as needed to prevent violations of other standards. EPA seeks scientific data and information on whether, for example, nutrient criteria should be more stringent to prevent exceedances of dissolved oxygen criteria.

    EPA has created a technical support document that provides detailed information regarding all methodologies discussed herein and the derivation of the proposed criteria. This document is entitled

    ``Technical Support Document for EPA's Proposed Rule For Numeric

    Nutrient Criteria for Florida's Inland Surface Fresh Waters''

    (hereafter, EPA TSD for Florida's Inland Waters) and is

    Page 4184

    located at www.regulations.gov, Docket ID No. EPA-HQ-OW-2009-0596.

  39. Proposed Numeric Nutrient Criteria for the State of Florida's Lakes

    Florida's 2008 Integrated Water Quality Assessment Report \41\ indicates that Florida lakes provide important habitats for plant and animal species and are a valuable resource for human activities and enjoyment. The State has more than 7,700 lakes, which occupy close to 6% of its surface area. The largest lake, Lake Okeechobee (covering 435,840 acres), is the ninth largest lake in surface area in the United

    States and the second largest freshwater lake wholly within the coterminous United States.\42\ Most of the State's lakes are shallow, averaging seven to 20 feet deep, although many sinkhole lakes and parts of other lakes are much deeper.

    \41\ FDEP. 2008. Integrated Water Quality Assessment for

    Florida: 2008 305(b) Report and 303(d) List Update. Florida

    Department of Environmental Protection.

    \42\ Fernald, E.A. and E.D. Purdum. 1998. Water Resources Atlas of Florida. Tallahassee: Institute of Science and Public Affairs,

    Florida State University.

    Florida's lakes are physically, chemically, and biologically diverse. Many lakes are spring-fed, others are seepage lakes fed by ground water, and still others (about 20%) are depression lakes fed by surface water sources. For purposes of developing numeric nutrient criteria, EPA identified two classifications of lakes, colored lakes and clear lakes, which respond differently to inputs of TN and TP, as discussed in detail below. EPA further classified the clear lakes into clear alkaline lakes (relatively high alkalinity) and clear acidic lakes (relatively low alkalinity), which have different baseline expectations for the level of nutrients present.

    (1) Proposed Numeric Nutrient Criteria for Lakes

    EPA is proposing the following numeric nutrient criteria and geochemical classifications for Florida's lakes classified as Class I or III waters under Florida law (Rule 62-302.400, F.A.C.):

    Baseline criteria \b\

    Modified criteria (within

    Long-term average lake color and Chlorophyll a --------------------------------

    these bounds) \c\ alkalinity

    \f\ ([mu]g/L)

    -------------------------------

    \a\

    TP (mg/L) \a\ TN (mg/L) \a\ TP (mg/L) \a\ TN (mg/L) \a\

    A

    B

    C

    D

    E

    F

    Colored Lakes > 40 PCU..........

    20

    0.050

    1.23

    0.050-0.157

    1.23-2.25

    Clear Lakes, Alkaline 50 mg/L CaCO3 \e\....

    Clear Lakes, Acidic 40 Platinum Cobalt Units (PCU), (2) Clear Lakes 50 mg/L calcium carbonate (CaCO3), and

    (3) Clear Lakes 3.

    Following original work conducted by FDEP, EPA considered several key characteristics to categorize Florida's lakes and tailor numeric nutrient criteria, recognizing that different types of lakes in Florida may respond differently to nutrients. Many of Florida's lakes contain dissolved organic matter leached from surface vegetation that colors the water. More color in a lake limits light penetration within the water column, which in turn limits algal growth. Thus, in lakes with colored water, higher levels of nutrients may occur without exceeding desired algal levels. EPA evaluated the relationships between nutrients and algal responses for these waters (as measured by chlorophyll a concentration), which indicated that water color influences algal responses to nutrients. Based on this analysis, EPA found color to be a significant factor for categorizing lakes. More specifically, EPA found the correlations between nutrients and chlorophyll a concentrations to be stronger and less variable when lakes were categorized into two distinct groups based on a threshold of 40 PCU. This threshold is consistent with the distinction between clear and colored lakes long observed in Florida.\45\ Different relationships between nutrients and chlorophyll a emerged when lakes were characterized by color, with clear lakes demonstrating greater sensitivity to nutrients as would be predicted by the increased light penetration, which promotes algal growth.

    \45\ Shannon, E.E. and P.L. Brezonik. 1972. Limnological characteristics of north and central Florida lakes. Limnol.

    Oceanogr. 17(1): 97-110.

    Within the clear lakes category, where color is not generally the controlling factor in algal growth, EPA evaluated alkalinity as an additional distinguishing characteristic. Calcium carbonate

    (CaCO3), dissolved from limestone formations and calcareous soils, affects the alkalinity and pH of groundwater that feeds into lakes. Alkalinity and pH increase when water is in contact with limestone or limestone-derived soil. Limestone is also a source of TP, and lakes that are higher in alkalinity in Florida are often associated with naturally elevated TP levels. These types of lakes are often in areas of the State where the underlying geology includes limestone. The alkalinity (measured as CaCO3) of Florida clear lakes ranges from zero to well over 200 mg/L. FDEP's Nutrient Criteria Technical

    Advisory Committee (TAC) evaluated available data from Florida lakes and concluded that 50 mg/L alkalinity as CaCO3is an appropriate threshold above which associated nutrient levels would be expected to be significantly elevated among clear lakes. EPA concluded that FDEP's proposed approach of using 50 mg/L alkalinity as

    CaCO3is an appropriate distinguishing characteristic in clear lakes in Florida because lakes with alkalinity 3represent a comprehensive group of lakes that may be naturally oligotrophic. Thus, EPA proposes to classify Florida clear lakes as either acidic (3) or alkaline (>50 mg/L alkalinity as CaCO3).

    EPA recognizes that in certain cases FDEP may not have historic alkalinity data on record to classify a particular clear lake as either alkaline or acidic. When alkalinity data are unavailable, EPA proposes a specific conductivity threshold of 250 microSiemens per centimeter

    ([mu]S/cm) as a substitute for the threshold of 50 mg/L alkalinity as

    CaCO3. Specific conductivity is a measure of the ionic activity in water and a data analysis performed by FDEP and re-examined by EPA found that a specific conductivity threshold value of 250 [mu]S/ cm is sufficiently correlated with alkalinity to serve as a surrogate measure. Of these two measures, alkalinity is the preferred parameter to measure because it is less variable and therefore, a more reliable indicator, and also because it is a more direct measure of the presence of underlying geology associated with elevated nutrient levels.

    EPA solicits comment on the proposed categorization scheme and associated thresholds used to classify Florida's lakes. Please see

    Section III.B(4)(b) below in which EPA invites comment on alternative lake categorization approaches that EPA considered, in particular, those approaches with respect to alkalinity classification and lakes occurring in sandhills of northwestern and central Florida.

    (b) Methodology for Proposed Chlorophyll a Criteria

    Because excess algal growth is associated with degradation in aquatic life and because chlorophyll a levels are a measure of algal growth, EPA is using chlorophyll a levels as indicators of healthy biological conditions, supportive of aquatic life in each of the categories of Florida's lakes described above. EPA found multiple lines of evidence supporting chlorophyll a criteria as an effective indicator of ambient conditions that would be protective of Florida's aquatic life use in lakes. These lines of evidence included trophic state of lakes, historical reference conditions in Florida lakes, and model results.

    As a primary line of evidence, EPA reviewed and evaluated the

    Trophic State Index (TSI) information in deriving chlorophyll a criteria that are protective of designated aquatic life uses in

    Florida's lakes. The TSI quantifies the degree of eutrophication

    (oligotrophic, mesotrophic, eutrophic) \46\ in a water body based on observed measurements of nutrients and chlorophyll a. These types of boundaries are commonly used in scientific literature and represent an

    Page 4186

    established, scientific classification system to describe current status and natural expectations for lake conditions with respect to nutrients and algal productivity.\47\ EPA's review of TSI studies

    \48\\49\ indicated that in warm-water lakes such as those in Florida, TSI values of 50, 60, and 70 are associated with chlorophyll a concentrations of 10, 20, and 40 micrograms per liter

    ([mu]g/L), respectively. Studies indicated that mesotrophic lakes in

    Florida have TSI values ranging from 50 to 60 and eutrophic lakes have

    TSI values ranging from 60 to 70. Thus a TSI value of 60 (chlorophyll a concentration of 20 [mu]g/L) represents the boundary between mesotrophy and eutrophy. EPA concluded that mesotrophic status is the appropriate expectation for colored and clear alkaline lakes because they receive significant natural nutrient input and support a healthy diversity of aquatic life in warm, productive climates such as Florida, and mesotrophy represents a lake maintaining a healthy balance between benthic macrophytes (i.e., plants growing on the lake bottom) and algae in such climates under such conditions. However, clear acidic lakes in

    Florida do not receive comparable natural nutrient input to be classified as mesotrophic, and for those lakes, EPA has developed criteria that correspond to an oligotrophic status. Oligotrophic lakes support less algal growth and have lower chlorophyll a levels. Studies indicate that a TSI value of 45 reflects an approximate boundary between oligotrophy and mesotrophy (corresponding to chlorophyll a at about 7 [mu]g/L). EPA requests comment on these conclusions regarding oligotrophic and mesotrophic status expectations for these categories of Florida lakes.

    \46\ Trophic state describes the nutrient and algal state of an aquatic system: Oligotrophic (low nutrients and algal productivity), mesotrophic (moderate nutrients and algal productivity), and eutrophic (high nutrients and algal productivity).

    \47\ Carlson, R.E. 1977. A trophic state index for lakes.

    Limnol. Oceanogr. 22:361-369.

    \48\ Carlson, R.E. 1977. A trophic state index for lakes.

    Limnol. Oceanogr. 22:361-369.

    \49\ Salas and Martino. 1991. A simplified phosphorus trophic state index for warm water tropical lakes. Wat. Res. 25:341-350.

    Another line of evidence that supports EPA's proposed chlorophyll a criteria is historical reference conditions. Diatoms are a very common type of free-floating algae (i.e., phytoplankton) that have shells or

    ``frustules'' made of silica that are preserved in the fossil record.

    Diatoms preserved in lake sediments can be used to infer chlorophyll a levels in lakes prior to any human disturbance. Paleolimnological studies \50\ that examined preserved diatom frustules in Florida lake sediments indicate that historical levels of chlorophyll a are consistent with mesotrophic expectations derived from the TSI studies described above, with chlorophyll a levels falling just below the selected criterion for mesotrophic lakes. (These studies did not evaluate lakes expected to be naturally oligotrophic so there is no comparable information for those lakes).

    \50\ Whitmore and Brenner. 2002. Paleologic characterization of pre-disturbance water quality conditions in EPA defined Florida lake regions. Univ. Florida Dept. Fisheries and Aquatic Sciences. 30 pp.

    In addition to this evidence, EPA used information from the application of a Morphoedaphic Index (MEI) model \51\ that predicts nutrient and chlorophyll a concentrations for any lake given its depth, alkalinity, and color to support the proposed chlorophyll a criteria.

    Scientists from the St. John's Water Management District presented modeling results for various Florida lakes in each colored and clear category at the August 5, 2009 meeting of the Nutrient Criteria TAC in

    Tallahassee. In addition to predicting natural or reference conditions, these scientists used the model to predict chlorophyll a and TP concentrations associated with a 10% reduction in water transparency for a set of lakes with varying color levels and alkalinities. Because submerged aquatic vegetation is dependent on light, maintaining a lake's historic balance between algae and submerged aquatic plants requires maintaining overall water transparency. The risk of disrupting the balance between algae and submerged aquatic plants increases when reductions in transparency exceed 10%. The MEI predictions corroborated the results from lake TSI studies and investigations of paleolimnological reference conditions because natural or reference predictions (i.e., a ``no effect'' level) were generally below selected criteria levels and 10% transparency loss predictions (i.e., a

    ``threshold effect'' level) were at or slightly above selected criteria levels. EPA considered these lines of evidence to develop the proposed chlorophyll a criteria, discussed below by lake class:

    \51\ Vighi and Chiaudani. 1985. A simple method to estimate lake phosphorus concentrations resulting from natural background loadings. Wat. Res.19:987-991.

    (i) Colored Lakes: EPA proposes a chlorophyll a criterion of 20

    mu g/L in colored lakes to protect Florida's designated aquatic life uses. As indicated by the warm-water TSI studies discussed above, chlorophyll a concentrations of 20 [mu]g/L represent the boundary between mesotrophy and eutrophy. Because mesotrophy maintains a healthy balance of plant and algae populations in these types of lakes, limiting chlorophyll a concentrations to 20 [mu]g/L would, therefore, protect colored lakes in Florida from the adverse impacts of eutrophication. Paleolimnological studies of six colored lakes in

    Florida demonstrated natural (i.e., before human disturbance) chlorophyll a levels in the range of 14-20 [mu]g/L and the MEI model predicted reference chlorophyll a concentrations of 1-25 [mu]g/L for a set of colored lakes in Florida. The model also predicted that concentrations of chlorophyll a ranging from 15-36 [mu]g/L in individual lakes would result in a 10% loss of transparency (all but two lakes were above 20 [mu]g/L). Because of natural variability, it is typical for ranges of natural or reference conditions to overlap with ranges of where adverse effects may begin occurring (such as the 10% transparency loss endpoint) for any sample population of lakes. In addition, these modeling results, as with any line of evidence, have uncertainty associated with any individual lake prediction. Given these considerations, EPA found that because the clear majority (eight of eleven) of lakes had predicted natural or referenced conditions below 20 [mu]g/L chlorophyll a and the clear majority (nine of eleven) of lakes had predicted 10% transparency loss above 20 [mu]g/L chlorophyll a, these results supported the TSI-based proposed chlorophyll a criterion.

    (ii) Clear, Alkaline Lakes: EPA proposes a chlorophyll a concentration of 20 [mu]g/L in clear, alkaline lakes to protect

    Florida's designated aquatic life uses. As noted in Section

    III.B(2)(a), alkalinity and TP are often co-occurring inputs to Florida lakes because of the presence of TP in limestone, which is often a feature of the geology in Florida. Clear, alkaline lakes, therefore, are likely to be naturally mesotrophic. EPA's analysis determined that aquatic life in clear, alkaline lakes is protected at similar chlorophyll a levels as colored lakes (at the TSI boundary between mesotrophy and eutrophy). The MEI model predicted reference chlorophyll a concentrations of 12-24 [mu]g/L for a set of clear, alkaline lakes in

    Florida, and predicted a 10% loss of transparency when chlorophyll a concentrations ranged from 19-33 [mu]g/L. Similar to the results for colored lakes, half of the clear, alkaline lakes had predicted natural or referenced conditions at or below 20 [mu]g/L chlorophyll a and all but one clear,

    Page 4187

    alkaline lake had predicted 10% transparency loss above 20 [mu]g/L chlorophyll a. Thus, EPA found this evidence to be supportive of the proposed chlorophyll a criterion. EPA solicits comment on this chlorophyll a criterion and the evidence EPA used to support the criterion.

    (iii) Clear, Acidic Lakes: EPA proposes a chlorophyll a concentration of 6 [mu]g/L in clear, acidic lakes to ensure balanced natural populations of flora and fauna (i.e., aquatic life) in these lakes. In contrast to colored lakes and clear, alkaline lakes, this category of lakes does not receive significant natural nutrient inputs from groundwater or other surface water sources. EPA has thus based the proposed criteria on an expectation that these lakes should be oligotrophic in order to support balanced natural populations of flora and fauna. Some of Florida's clear, acidic lakes, in the sandhills in northwestern and central Florida, have been identified as extremely oligotrophic \52\ with chlorophyll a levels of less than 2 [mu]g/L. As discussed above, warm water TSI studies suggest a chlorophyll a level of approximately 7 [mu]g/L at the oligotrophic-mesotrophic boundary.

    \52\ Canfield, D.E., Jr., M.J. Maceina, L.M. Hodgson, and K.A.

    Langeland. 1983. Limnological features of some northwestern Florida lakes. J. Freshw. Ecol. 2:67-79; Griffith, G.E., D.E. Canfield, Jr.,

    C.A. Horsburgh, J.M. Omernik, and S.H. Azevedo. 1997. Lake regions of Florida. Map prepared by U.S. EPA, Corvallis, OR; available at http://www.epa.gov/wed/pages/ecoregions/fl_eco.htm (accessed 10/09/ 2009).

    In July 2009, FDEP proposed a chlorophyll a criterion for clear, acidic lakes of 9 [mu]g/L.\53\ In comments sent to EPA via e-mail in

    October 2009,\54\ FDEP reported that the Nutrient TAC suggested in June 2009 that maintaining chlorophyll a below 10 [mu]g/L in clear, acidic lakes would be protective of the designated use, because a value of 3. In its July 2009 numeric nutrient criteria proposal,

    Florida considered a similar classification approach based on color and alkalinity but proposed a chlorophyll a criterion of 9 [micro]g/L to protect aquatic life in clear, acidic lakes. As discussed above, EPA believes that the scientific evidence more strongly supports a chlorophyll a criterion of 6 [micro]g/L to protect Florida's clear, acidic lakes that include the very oligotrophic lakes found in

    Florida's sandhills, principally in three areas: the Newhope Ridge/

    Greenhead slope north of Panama City (locally called the Sandhill Lakes region); the Norfleet/Springhill Ridge just west of Tallahassee, and

    Trail Ridge northeast of Gainesville.\58\ However, some stakeholders have suggested that many lakes in the clear, acidic class (as currently defined) might be sufficiently protected with a chlorophyll a criterion of 9 [micro]g/L. EPA believes the scientific basis for a 9 [micro]g/L chlorophyll a value may be more applicable to clear acidic lakes other than those in Florida's sandhills (i.e., other than those in the

    Sandhill Lakes region, the Norfleet/Springhill Ridge just west of

    Tallahassee and Trail Ridge northeast of Gainesville). To address this,

    EPA could separate clear, acidic lakes into two categories: one category for clear, acidic lakes in sandhill regions of Florida, and a second category for clear, acidic lakes in other areas of the State.

    EPA could assign the first category (clear, acidic sandhill lakes) a chlorophyll a criterion of 6 [micro]g/L and the second category (clear, acidic non-sandhill lakes) a chlorophyll a criterion of 9 [micro]g/L.

    \58\ Griffith, G.E., D.E. Canfield, Jr., C.A. Horsburgh, J.M.

    Omernik, and S.H. Azevedo. 1997. Florida lake regions. U.S. EPA,

    Corvallis, OR. http://www.epa.gov/wed/pages/ecoregions/fl_eco.htm.

    Alternatively, EPA could lower the defining alkalinity threshold to 20 mg/L CaCO3so that the clear, acidic lakes category would only include lakes with very acidic values and correspondingly low chlorophyll a, TN, and TP values. EPA's analysis of a distribution of alkalinity data from Florida's clear lakes found that lakes with alkalinity values >= 20 mg/L CaCO3had higher levels of nutrients and nutrient response parameters than lakes with alkalinity values 3.By adjusting the alkalinity threshold to 20 mg/L CaCO3, EPA would be creating a smaller group of clear, acidic lakes that may be more representative of naturally more acidic, oligotrophic conditions than the proposed alkalinity threshold of 50 mg/L CaCO3. EPA opted to propose a threshold of 50 mg/L CaCO3because it represents a more comprehensive group of lakes that may be naturally oligotrophic (i.e., ensures protection where there may be some uncertainty). EPA solicits comment on these alternative approaches to classifying Florida's lakes.

    EPA also notes, as discussed previously, that FDEP recommended a criterion of 9 [mu]g/L as being protective of all clear acidic lakes, including sandhill lakes and that the Nutrient Criteria TAC supported

    ``less than 10 [mu]g/L'' as protective. EPA also requests comment on 9

    mu g/L chlorophyll a as being protective of all clear acidic lakes, including sandhill lakes.

    (c) Modification To Include Upper Percentile Criteria

    EPA is considering promulgating upper percentile criteria for chlorophyll a, TN, and TP in colored, clear alkaline, and clear acidic lakes to provide additional aquatic life protection. Accordingly, EPA could add that the instantaneous concentration in the lake not surpass these criterion-magnitude concentrations more than 10% of the time

    (criterion-duration: instant; criterion-frequency: 10% of the time).

    EPA derived example upper percentile criteria using the observed standard deviation from the mean of lake samples meeting the respective criteria (lower values of the TN and TP ranges) within each lake class.

    Using this example, the calculated criteria-magnitude concentrations for chlorophyll a, TN, and TP respectively by lake class are: 63 [mu]g/

    L, 1.5 mg/L and 0.09 mg/L for colored lakes; 48 [mu]g/L, 1.8 mg/L and 0.05 mg/L for clear, alkaline lakes; and 15 [mu]g/L, 0.6 mg/L and 0.02 mg/L for clear, acidic lakes.

    These criteria would provide the means to protect lakes from episodic events that increase loadings for significant periods of time during the year, but are balanced out by lower levels in other parts of the year such that the annual geometric mean value is met. EPA chose not to propose such criteria because of the significant variability of chlorophyll a, TN, and TP, the variety of other factors that may influence levels of these parameters in the short-term, and that significant environmental damage from eutrophication is more likely when levels are elevated for longer periods of time. However, EPA solicits comment on this additional approach of promulgating upper percentile criteria for chlorophyll a, TN, and TP.

    (5) Request for Comment and Data on Alternative Approaches

    EPA is soliciting comment on the Agency's proposed approach, as well as the alternative approach to deriving numeric nutrient criteria for Florida's lakes and the supplemental modifications as described in

    Section III.B(4). EPA will evaluate all data and

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    information submitted by the close of the public comment period for this rulemaking with regard to nutrient criteria for Florida's lakes.

  40. Proposed Numeric Nutrient Criteria for the State of Florida's Rivers and Streams

    (1) Proposed Numeric Nutrient Criteria for Rivers and Streams

    EPA is proposing numeric nutrient criteria for TN and TP in four geographically distinct watershed regions of Florida's rivers and streams (hereafter, streams) classified as Class I or III waters under

    Florida law (Rule 62-302.400, F.A.C.).

    Instream protection value criteria

    Nutrient watershed region

    TN (mg/L) \a\ TP (mg/L) \a\

    Panhandle \b\...........................

    0.824

    0.043

    Bone Valley \c\.........................

    1.798

    0.739

    Peninsula \d\...........................

    1.205

    0.107

    North Central \e\.......................

    1.479

    0.359

    \a\ Concentration values are based on annual geometric mean not to be surpassed more than once in a three-year period. In addition, the long- term average of annual geometric mean values shall not surpass the listed concentration values. (Duration = annual; Frequency = not to be surpassed more than once in a three-year period or as a long-term average).

    \b\ Panhandle region includes the following watersheds: Perdido Bay

    Watershed, Pensacola Bay Watershed, Choctawhatchee Bay Watershed, St.

    Andrew Bay Watershed, Apalachicola Bay Watershed, Apalachee Bay

    Watershed, and Econfina/Steinhatchee Coastal Drainage Area.

    \c\ Bone Valley region includes the following watersheds: Tampa Bay

    Watershed, Sarasota Bay Watershed, and Charlotte Harbor Watershed.

    \d\ Peninsula region includes the following watersheds: Waccasassa

    Coastal Drainage Area, Withlacoochee Coastal Drainage Area, Crystal/

    Pithlachascotee Coastal Drainage Area, Indian River Watershed,

    Caloosahatchee River Watershed, St. Lucie Watershed, Kissimmee River

    Watershed, St. John's River Watershed, Daytona/St. Augustine Coastal

    Drainage Area, Nassau Coastal Drainage Area, and St. Mary's River

    Watershed.

    \e\ North Central region includes the Suwannee River Watershed.

    The following section describes the methodology used to derive the proposed numeric nutrient criteria for streams. EPA is soliciting comments and scientific data and information regarding these proposed criteria and their derivation.

    (2) Methodology for Deriving EPA's Proposed Criteria for Streams

    Like other aquatic ecosystems, excess nutrients in streams increases vegetative growth (plants and algae), and changes the assemblage of plant and algal species present in the system. These changes can affect the organisms that are consumers of algae and plants in many ways. For example, these changes can alter the available food resources by providing more dead plant material versus live plant material, or providing algae with a different cell size for filter feeders. These changes can also alter the habitat structure by covering the stream or river bed with periphyton (attached algae) rather than submerged aquatic plants, or clogging the water column with phytoplankton (floating algae). In addition, these changes can lead to the production of algal toxins that can be toxic to fish, invertebrates, and humans. Chemical characteristics of the water, such as pH and concentrations of dissolved oxygen, can also be affected by excess nutrients. Each of these changes can, in turn, lead to other changes in the stream community and, ultimately, to the stream ecology that supports the overall function of the linked aquatic ecosystem.

    Although the general types of adverse effects can be described, not all of these effects will occur in every stream at all times. For example, some streams are well shaded, which would tend to reduce the near-field effect of excess nutrients on primary production because light, which is essential for plant or algae growth, does not reach the water surface. Some streams are fast moving and pulses of nutrients are swiftly carried away before any effect can be observed. However, if the same stream widens and slows downstream or the canopy that provided shading opens up, then the nutrients present may accelerate plant and algal biomass production. As another example, the material on the bottom of some streams, referred to as substrate, is frequently scoured from intense rain storms. These streams may lack a natural grazing community to consume excess plant growth and may be susceptible to phytoplankton algae blooms during periods when water velocity is slower and water residence time is longer. The effects of excess nutrients may be subtle or dramatic, easily captured by measures of plant and algal response (such as chlorophyll a) or not, and may occur in some locations along a stream but not others.

    Notwithstanding natural environmental variability, there are well understood and documented analyses and principles about the underlying biological effects of TN and TP on an aquatic ecosystem. There is a substantial and compelling scientific basis for the conclusion that excess TN and TP will have adverse effects; however, it is often unclear where precisely the impacts will occur. The value of regional numeric nutrient criteria for streams is that the substantial expenditure of time and scarce public resources to document and interpret inevitable and expected stream variability on a site-by-site, segment-by-segment basis (i.e., as in the course of interpreting a narrative WQS for WQBELs and TMDL estimations) is no longer necessary.

    Rather, regional numeric nutrient criteria for streams allows an expedited and expanded level of aquatic protection across watersheds and greatly strengthens local and regional capacity to support and maintain State designated uses throughout aquatic ecosystems. In terms of environmental outcomes, the result is a framework of expectations and standards that is able to extend the protection needed to restore and maintain valuable aquatic resources to entire watersheds and associated aquatic ecosystems. At the same time, the ability to promulgate SSAC, as well as other flexibilities discussed in this proposal, allows the State to continue to address water bodies where substantial data and analyses show that the regional criteria may be either more stringent than necessary or not stringent enough to protect designated uses.

    As mentioned earlier, to effectively apply this well understood and documented science, EPA has recommended that nutrient criteria

    Page 4193

    include both causal (e.g., TN and TP) and response variables (e.g., chlorophyll a and some measure of clarity) for water bodies.\59\ EPA recommends causal variables, in part, to have the means to develop source control targets and, in part, to have the means to assess stream condition with knowledge that responses can be variable, suppressed, delayed, or expressed at different locations. EPA recommends response variables, in part, to have a means to assess stream condition that synthesizes the effect of causal variables over time, recognizing the daily, seasonal, and annual variability in measured nutrient levels.\60\

    \59\ U.S. EPA. 1998. National Strategy for the Development of

    Regional Nutrient Criteria. Office of Water, Washington, DC. EPA 822-R-98-002; Grubbs, G. 2001. U.S. EPA. (Memorandum to Directors of

    State Water Programs, Directors of Great Water Body Programs,

    Directors of Authorized Tribal Water Quality Standards Programs and

    State and Interstate Water Pollution Control Administrators on

    Development and Adoption of Nutrient Criteria into Water Quality

    Standards. November 14, 2001); Grumbles, B.H. 2007. U.S. EPA.

    (Memorandum to Directors of State Water Programs, Directors of Great

    Water Body Programs, Directors of Authorized Tribal Water Quality

    Standards Programs and State and Interstate Water Pollution Control

    Administrators on Nutrient Pollution and Numeric Water Quality

    Standards. May 25, 2007).

    \60\ U.S. EPA. 2000. Nutrient Criteria Technical Guidance

    Manual: Rivers and Streams. Office of Water, Washington, DC. EPA- 822-B-00-002.

    The ability to establish protective criteria for both causal and response variables depends on available data and scientific approaches to evaluate these data. Whereas, there are data available for water column chlorophyll a (phytoplankton) and algal thickness on various substrates (periphyton) for certain types of streams in Florida, there are currently no available approaches to interpret these data to infer scientifically supported thresholds for these nutrient-specific response variables in Florida streams. Additionally, in previously published guidance,\61\ EPA has recommended water clarity as a response variable for numeric nutrient criteria because algal density in a water column results in turbidity, and thus a related decrease in water clarity can serve as an indicator of excess algal growth. For water clarity, Florida has criteria for transparency and turbidity, applicable to all Class I and III waters, expressed in terms of a measurable deviation from natural background (32-302.530(67) and (69),

    F.A.C.). Therefore, EPA is not proposing criteria for any response variable in Florida's streams at this time, however, EPA will consider additional data that becomes available during the comment period. One approach for deriving criteria for water quality variables such as a measure for water clarity or chlorophyll a, could be to apply a statistical distribution approach to a population of streams for each of the proposed NWRs. This approach is further described in previous

    EPA guidance.\62\

    \61\ U.S. EPA. 2000. Nutrient Criteria Technical Guidance

    Manual: Lakes and Reservoirs. Office of Water, Washington, DC. EPA- 822-B-00-001; U.S. EPA. 2000. Nutrient Criteria Technical Guidance

    Manual: Rivers and Streams. Office of Water, Washington, DC. EPA- 822-B-00-002; U.S. EPA. 2001. Nutrient Criteria Technical Manual:

    Estuarine and Coastal Marine Waters. Office of Water, Washington,

    DC. EPA-822-B-01-003.

    \62\ U.S. EPA. 2000. Nutrient Criteria Technical Guidance

    Manual: Rivers and Streams. Office of Water. 4304. EPA-822-B-00-002.

    For Florida streams, EPA has determined that there are sufficient available data on TN and TP concentrations with corresponding information on biological condition for a wide variety of stream types that can be used to derive numeric nutrient criteria for those causal variables. EPA used multiple measures of stream condition (or metrics) that describe the biological condition of the benthic invertebrate community. EPA then coupled the stream condition metrics with associated measurements of TN and TP concentrations to provide the basis for deriving causal variable numeric nutrient criteria.

    EPA's proposed instream numeric nutrient criteria for Florida's streams are based upon EPA's evaluation of data on TN and TP levels in rivers and streams that have been carefully evaluated by FDEP, and subsequently by EPA, on a site-specific basis and identified as biologically healthy. EPA's approach results in numeric criteria that are protective of the streams themselves. EPA has determined, however, that these instream values may not always be protective of the designated uses in downstream lakes and estuaries. Therefore, EPA has also developed an approach for deriving TN and TP values for rivers and streams to ensure the protection of downstream lakes and estuaries.

    This approach is discussed in Section III.C(6).

    (a) Methodology for Stream Classification: EPA's Nutrient Watershed

    Regions (NWRs)

    EPA classified Florida's streams north of Lake Okeechobee by separating watersheds with a substantially different ratio of TN and TP export into Nutrient Watershed Regions (NWR). The resulting regions reflect the inherent differences in the natural factors that contribute to nutrient concentrations in streams (e.g., geology, soil composition, and/or hydrology). Reliance on a watershed-based classification approach reflects the understanding that upstream water quality affects downstream water quality. This watershed classification also facilitates the ability to address the effects of TN and TP from streams to downstream lakes or estuaries in the same watershed.

    EPA's classification approach results in four watershed regions: the Panhandle, the Bone Valley, the Peninsula, and the North Central

    (for a map of these regions, refer to the EPA TSD for Florida's Inland

    Waters or the list of watersheds in the table above). These four regions do not include the south Florida region (corresponding to

    FDEP's Everglades Bioregion) that is addressed separately in Section

    III.E which sets out EPA's proposed numeric nutrient criteria for canals in south Florida. All flowing waters in this region are either a canal or a wetland.

    When classifying Florida's streams, EPA identified geographic areas of the State as having phosphorus-rich soils and geology, such as the

    Bone Valley and the northern Suwannee River watershed. As indicated above, the Bone Valley region and the Suwannee River watersheds are classified in this proposal as separate NWRs because it is well established that the naturally phosphorus-rich soils in these areas significantly influence stream phosphorus concentrations in these watersheds. EPA would expect from a general ecological standpoint that the associated aquatic life uses, under these naturally-occurring, nutrient-rich conditions, would be supported. The Agency requests comment on this particular classification decision (regions based on phosphorus-rich soils), as well as an alternate classification approach that would not separate out the phosphorus-rich watersheds described in this notice. The latter approach is similar to the approach proposed by

    EPA, but would not result in separate NWRs for the Bone Valley and/or

    North Central. Rather these NWRs would be integrated within the other

    NWRs.

    (b) The Use of the Stream Condition Index as an Indicator of

    Biologically Healthy Conditions

    For EPA's proposed approach, the Agency utilized a multi-metric index of benthic macroinvertebrate community composition and taxonomic data known as the Stream Condition Index (SCI) developed by FDEP to assess the

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    biological health of Florida's streams.\63\ Of the metrics that comprise the SCI, some decrease in response to human disturbance-based stressors, such as excess nutrients; for example, (1) total taxa richness, (2) richness of Ephemeroptera (mayflies), (3) richness of

    Plecoptera (stoneflies), (4) percentage of sensitive taxa, and (5) percentage of filterers and suspension feeders. Other metrics increase in response to human disturbance-based stressors; for example, percent of very tolerant taxa (e.g., Genera Prostoma, Lumbriculus) and percent of the dominant taxa (i.e., numerical abundance of the most dominant taxon divided by the total abundance of all taxa).

    \63\ The SCI method was developed and calibrated by FDEP. See

    ``Fore et al. 2007. Development and testing biomonitoring tools for macroinvertebrates in Florida streams (Stream Condition Index and

    BioRecon). Final report to Florida Department of Environmental

    Protection'' and the EPA TSD for Florida's Inland Waters for more information on the SCI.

    The SCI was developed by FDEP in 2004, with subsequent revisions in 2007 to reduce the variability of results. In order to ensure that data are produced with the highest quality, field biologists and lab technicians must follow detailed Standard Operating Procedures (SOPs) and additional guidance for sampling and data use provided through a

    FDEP document entitled ``Sampling and Use of the Stream Condition Index

    (SCI) for Assessing Flowing Waters: A Primer (DEP-SAS-001/09).'' Field biologists must pass a rigorous audit with FDEP, and laboratory taxonomists are regularly tested and must maintain greater than 95% identification accuracy.

    EPA considered two lines of evidence in determining the SCI range of scores that would indicate biologically healthy systems. The first line of evidence was an evaluation of SCI scores in streams considered by FDEP to be least-disturbed streams in Florida. A statistical analysis balanced the probability of a stream being included in this reference set with the probability of a stream not being included in this reference set, and indicated that an SCI score of 40 was an appropriate threshold. SCI scores range from 1 to 100 with higher scores indicating healthier biology.

    A second line of evidence was the result of an expert workshop convened by FDEP in October 2006. The workshop included scientists with specific knowledge and expertise in stream macroinvertebrates. These experts were asked to individually and collectively evaluate a range of

    SCI data (i.e., macroinvertebrate composition and taxonomic data) and then assign those data into one of the six Biological Condition

    Gradient (BCG) \64\ categories, ranging from highly disturbed (Category 6) to pristine (Category 1). EPA analyzed the results of these categorical assignments using a proportional odds regression model \65\ that predicts the probability of an SCI score occurring within one of the BCG categories by overlapping the ranges of SCI scores associated with each category from the individual expert assignment. The results of the analysis provided support for identifying a range of SCI scores that minimized the probability of incorrectly assigning a low quality site to a high quality category, and incorrectly assigning a high quality site to a low quality category, using the collective judgment of expert opinion. The results indicated a range of SCI scores of 40-44 to represent an appropriate threshold of healthy biological condition.

    Please refer to the EPA TSD for Florida's Inland Waters for more information on such topics as EPA's estimates of the Type I and Type II error associated with various threshold values. Thus, two very different approaches yielded comparable results. A subsequent EPA statistical analysis indicated that nutrient conditions in Florida streams within different regions remain essentially constant within an

    SCI score range of 40-50 providing further support for a selection of 40 as a threshold that is sufficiently protective for this application.

    The resulting TN and TP concentrations associated with a SCI score of 40 versus 50 did not represent a statistical difference and 40 was more in line with other lines of evidence for a SCI score threshold.

    \64\ Appendix H in ``Fore et al. 2007. Development and testing biomonitoring tools for macroinvertebrates in Florida streams

    (Stream Condition Index and BioRecon). Final report to Florida

    Department of Environmental Protection''.

    \65\ See the EPA TSD for Florida's Inland Waters for more information on the proportional odds regression model.

    (c) Methodology for Calculating Instream Protection Values: The

    Nutrient Watershed Region Distribution Approach

    EPA evaluated several methodologies, including reference conditions and stressor-response relationships, to develop values that protect designated uses of Florida streams instream. EPA analyzed stressor- response relationships in Florida streams based on available data, but, as mentioned above, did not find sufficient scientific support for their use in the derivation of numeric nutrient criteria for Florida streams. More specifically, EPA was not able to demonstrate a sufficiently strong correlation between the biological response indicators (e.g., chlorophyll a, periphyton biomass, or SCI) and TN or

    TP concentrations. Thus, the Agency could not confidently predict a specific biological response (such as an SCI score) for an individual stream solely from the associated stream measurements of TN or TP concentrations.

    There may be several reasons why empirical relationships between field-derived data of nutrient stressor and biological response variables show a relatively weak correlation. First, the relationship between nutrient concentrations and a biological response, such as algal growth, can be confounded by the presence of other stressors. For example, other stressors, such as excessive scour could cause low benthic invertebrate diversity, as measured by the SCI, even where nutrients are low. Excessive scour could also suppress a biological response (such as chlorophyll a or periphyton biomass) when nutrients are high. Another reason for stressor-response relationships with low correlations is that algal biomass accumulation is difficult to characterize because dynamic conditions in an individual stream can allow algae to accumulate and be removed rapidly, which is difficult to capture with periodic monitoring programs.

    As an alternative to the stressor-response approach, EPA analyzed the TN and TP concentrations associated with a healthy biological condition in streams, and examined the statistical distributions of these data in order to identify an appropriate threshold for providing protection of aquatic life designated uses. To derive the instream protection values under this approach, EPA first assembled the available nutrient concentrations and biological response data for streams in Florida. EPA used FDEP's data from the IWR and STORET \66\ databases and identified sites where SCI scores were 40 and higher. EPA further screened these sites by cross-referencing them with Florida's

    CWA section 303(d) list for Florida and excluded sites with identified nutrient impairments or dissolved oxygen impairments associated with elevated nutrients. EPA grouped the remaining sites (hereafter, biologically healthy sites) according to its nutrient watershed regions

    (Panhandle, Bone Valley, Peninsula, and North Central). For each nutrient watershed region, EPA compiled nutrient data (TN and TP

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    concentrations) associated with the biologically healthy sites, and calculated distributional statistics for annual average TN and TP concentrations.

    \66\ FL IWR and STORET can be found at: http:// www.dep.state.fl.us/WATER/STORET/INDEX.HTM.

    The second step in deriving instream protection values was to further characterize the distribution of TN and TP among biologically healthy sites. Specifically, EPA calculated the number of biologically healthy sites within integer log-scale ranges of TN and TP concentrations, as well as the cumulative distribution. These nutrient distributions from biologically healthy sites in each nutrient watershed region are represented on a log-scale because concentration data are typically log-normally distributed. A log-normal distribution is skewed, with a mode near the geometric mean rather than the arithmetic mean.

    The third step in deriving instream protection values was to determine appropriate thresholds from these distributions for providing protection of aquatic life designated uses. Selection of a central tendency of the distribution (i.e., the median or geometric mean of a log-normal distribution) would imply that half of the biologically healthy sites are not attaining their uses. In contrast, an extreme upper end of the distribution (e.g., the 90th or 95th percentile) may be the most likely to be heavily influenced by extreme event factors that are not representative of typically biologically healthy sites.

    This might be the case because the upper tail of the distribution might reflect a high loading year (landscape and/or atmospheric), and/or lack of nutrient uptake by algae (in turn due to a myriad of physical and biological factors like scour, grazing, light limitation, other pollutants). Thus, this tail of the distribution may just represent the most nutrient ``tolerant'' among the sites. Another possibility is that these streams may experience adverse effects from nutrient enrichment that are not yet reflected in the SCI score. A reasonable choice for a threshold is one which lies just above the vast majority of the population of healthy streams. This choice is reasonable because it reflects a point where most biologically healthy sites will still be identified as attaining uses, but avoids extrapolations into areas of the distribution characterized by only a few data points (as would be the case for the 90th or 95th percentile). When a threshold is established as a water quality criterion, sites well below that threshold might be allowed to experience an increase in nutrient levels up to the threshold level. There is little assurance that biologically healthy sites with nutrient concentrations well below the 90th or 95th percentile would remain biologically healthy if nutrient concentrations increased to those levels because relatively few sites with nutrient concentrations as high as those at the 90th or 95th percentile are demonstrated to be biologically healthy.

    The range between the 25th and 75th percentiles, or inter-quartile range, is a common descriptive statistic used to characterize a distribution of values. For example, statistical software packages typically include the capability to display distributions as ``box and whisker'' plots, which very prominently identify the inter-quartile range. The inter-quartile range of a log normal distribution spans a smaller range of values than the inter-quartile range of a distribution of the data evenly spread across the entire range of values. This means that the further a value goes past the 75th percentile of a log normal distribution, the less representative it is of the majority of data (in this case, less representative of biologically healthy sites). Within the inter-quartile range of a log normal distribution, the slope of the cumulative frequency distribution will be the greatest. The 75th percentile represents a reasonable upper bound of where there is the greatest confidence that biologically healthy sites will be represented. Beyond the inter-quartile range (i.e., below the 25th percentile and above the 75th percentile), there is a greater chance that measurements may represent anomalies that would not correspond to long-term healthy conditions in the majority of streams. Based on this analysis, EPA concluded that the 75th percentile represents an appropriate and well-founded protective threshold derived from a distribution of nutrient concentrations from biologically healthy sites. EPA solicits comment on its analysis of what constitutes a protective threshold.

    (d) Proposed Criteria: Duration and Frequency

    Aquatic life water quality criteria contain three components:

    Magnitude, duration, and frequency. For the TN and TP numeric criteria for streams, the derivation of the criterion-magnitude values is described above and these values are provided in the table in Section

    III.C(1). The criterion-duration of this magnitude is specified in footnote a of the streams criteria table as an annual geometric mean.

    EPA is proposing two expressions of allowable frequency, both of which are to be met. First, EPA proposes a no-more-than-one-in-three-years excursion frequency for the annual geometric mean criteria for lakes.

    Second, EPA proposes that the long-term arithmetic average of annual geometric means not to exceed the criterion-magnitude concentration.

    EPA anticipates that Florida will use their standard assessment periods as specified in Rule 62-303, F.A.C. (Impaired Waters Rule) to implement this second provision. These proposed duration and frequency components of the criteria are consistent with the data set used to derive these criteria, which applied distributional statistics to measures of annual geometric mean values from multiple years of record. EPA has determined that this frequency of excursions will not result in unacceptable effects on aquatic life as it will allow the stream ecosystem enough time to recover from an occasionally elevated year of nutrient loadings. The Agency requests comment on these proposed duration and frequency components of the stream numeric nutrient criteria.

    EPA notes that some scientists and resource managers have suggested that nutrient criteria duration and frequency expressions should be more restrictive to avoid seasonal or annual ``spikes'' from which the aquatic system cannot easily recover, whereas others have suggested that criteria expressed as simply a long-term average of annual geometric means, consistent with data used in criteria derivation, and would still be protective. EPA requests comment on alternative duration and frequency expressions that might be considered protective, including (1) a criterion-duration expressed as a monthly average or geometric mean, (2) a criterion-frequency expressed as meeting allowable magnitude and duration every year, (3) a criterion-frequency expressed as meeting allowable magnitude and duration in more than half the years of a given assessment period, and (4) a criterion-frequency expressed as meeting allowable magnitude and duration as a long-term average only. EPA further requests comment on whether an expression of the criteria in terms of an arithmetic average of annual geometric mean values based on rolling three-year periods of time would also be protective of the designated use.

    (3) Request for Comment and Data on Proposed Approach

    EPA is soliciting comments on the approaches taken by the Agency to derive these proposed criteria, the data underlying those approaches, and the proposed criteria specifically. EPA is requesting that the public submit any other scientific data and information that may be available related to nutrient concentrations and associated biological responses in Florida's streams. EPA is

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    soliciting comment specifically on the selection of criteria parameters for TN and TP; the proposed classification of streams into four regions based on aggregated watersheds; and the conclusion that the proposed criteria for streams are protective of designated uses and adequately account for the spatial and temporal variability of nutrients. In addition, EPA requests comment on folding the Suwannee River watershed in north central Florida into the larger Peninsula NWR (i.e., not having a separate North Central region) or, alternatively, making a smaller North Central region within Hamilton County alone where the highest phosphorus-rich soils are located, with the remainder of the

    North Central becoming part of the Peninsula Region.

    (4) Alternative Approaches Considered by EPA

    During EPA's review of the available data and information for derivation of numeric nutrient criteria for Florida's streams, EPA also considered an alternative approach for criteria derivation. EPA is specifically requesting comment on a modified reference condition approach called the benchmark distribution approach, as described below.

    (a) Benchmark Distribution Approach

    EPA's previously published guidance has recommended a variety of methods to derive numeric nutrient criteria.\67\ One method, the reference condition approach, relies on the identification of reference waters that exhibit minimal impacts from anthropogenic disturbance and are known to support designated uses. The thresholds of nutrient concentrations where designated uses are in attainment are calculated from a distribution of the available associated measurements of ambient nutrient concentrations at these reference condition sites.

    \67\ U.S. EPA. 2000. Nutrient Criteria Technical Guidance

    Manual: Rivers and Streams. Office of Water. 4304. EPA-822-B-00-002.

    EPA is seeking comment on a modified reference condition approach, which was developed by FDEP and is referred to as the benchmark distribution approach. The benchmark approach relies on least-disturbed sites rather than true reference, or minimally-impacted, sites. The benchmark distribution is a step-wise procedure used to calculate distributional statistics of TN and TP from identified least-disturbed streams.

    (i) Identification of Least-Disturbed Streams

    FDEP identified benchmark stream sites in the following step-wise manner (1) compiled a list of sites with low landscape development intensity using FDEP's Landscape Development Intensity Index,\68\ (2) eliminated any sites on Florida's CWA section 303(d) list of impaired waters due to nutrients, as well as certain sites impaired for dissolved oxygen, where the State determined the dissolved oxygen impairment was caused by nutrients, (3) eliminated any sites with nitrate concentrations greater than FDEP's 0.35 mg/L proposed nitrate- nitrite criterion in order to reduce the possibility of including sites with far-field human disturbance from groundwater impacts, (4) eliminated sites known by FDEP district scientists to be disturbed, (5) eliminated potentially erroneous data through outlier analysis, (6) verified sites using high resolution aerial photographs, and (7) verified a random sample of the sites in the field.

    \68\ A quantitative, integrated measure of the degree of human landscape disturbance within 100 meters on either side of a specified stream reach and extending to 10 kilometers upstream of the same stream reach.

    (ii) Calculation of Benchmark Distribution Approach and Selection of

    Percentiles From the Benchmark Distribution

    FDEP selected either the 75th or 90th percentile of the benchmark distribution approach from FDEP's proposed nutrient regions (75th percentile--Bone Valley; 90th percentile--Panhandle, North Central,

    Northeast, and Peninsula). FDEP's rationale for selecting either the 75th or 90th percentiles was based on the degree of certainty regarding the benchmark sites reflecting least-disturbed conditions and a probability (10% for the 90th percentile) of falsely identifying a least-disturbed site as being impaired for nutrients.

    With this approach, the distribution of available annual geometric means of nutrient concentrations for the benchmark sites within the regional classes of streams is calculated. To compute the numeric criteria for the causal variables, TN, and TP, EPA is seeking comment on whether the 75th or 90th percentile of the benchmark distribution for each nutrient stream region should be selected. As mentioned above, the rationale for selecting either the 75th or 90th percentiles is based on the degree of certainty regarding the benchmark sites reflecting least-disturbed conditions and a probability of falsely identifying a least-disturbed site as being impaired for nutrients or vice-versa. In cases where data are more limited for a given nutrient region (i.e., in the Bone Valley there were only four sites), the 75th percentile may be more appropriate because the 90th percentile may not be sufficiently robust (i.e., may be highly sensitive to a few data points). In other cases, the 90th percentile may be more appropriate when there is a more extensive data set. For further information, please refer to EPA's TSD for Florida's Inland Waters, Chapter 2:

    Methodology for Deriving U.S. EPA's Proposed Criteria for Streams.

    In evaluating whether to propose this approach, EPA determined that a considerable amount of uncertainty remained whether this approach would result in a list of benchmark sites that represented truly least- disturbed conditions. Specifically, EPA is concerned that nutrient concentrations at these sites may reflect anthropogenic sources (e.g., sources more than 100 meters away from and/or 10 kms upstream of the segment), even if the sites appear least-disturbed on a local basis.

    EPA is particularly concerned that several benchmark sites in the FDEP dataset appear to have a high potential to be affected by fertilizations associated with forestry activities. FDEP provided an analysis in which FDEP concluded that this is not likely.\69\ EPA solicits comment on this issue and more generally on whether the benchmark sites identified by FDEP in its July 2009 proposal are an appropriate set of least-disturbed sites on which to base the criteria calculations.

    \69\ FDEP document titled, ``Responses to Earthjustice's

    Comments on the Department's Reference Sites.'' Draft October 2, 2009. Located in the docket ID EPA-HQ-OW-2009-0596.

    (5) Request for Comment and Data on Alternative Approach

    EPA is soliciting comment on the alternative to deriving numeric nutrient criteria for Florida's streams as described in Section

    III.C(4).

    (6) Protection of Downstream Lakes and Estuaries

    Two key objectives of WQS are: First, to protect the immediate water body to which a criterion initially applies and, second, to ensure that criteria provide for protection of downstream WQS affected by flow of pollutants from the upstream water body. See 40 CFR 131.11 and 131.10(b). EPA WQS regulations reflect the importance of protecting downstream waters by requiring that upstream WQS ``provide for the attainment and maintenance of the water quality standards of

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    downstream waters.'' 40 CFR 131.10(b). Thus, in developing numeric nutrient criteria for Florida, EPA considered both instream aquatic conditions and downstream aquatic ecosystem needs. In addressing the issue of how, if at all, instream criteria values need to be adjusted to assure attainment of downstream standards, EPA necessarily examined the WQS for downstream lakes and estuaries. For lakes, this analysis starts with the numeric nutrient criteria proposed in this notice. For estuaries, this notice proposes an analytical approach to determine the loadings that a particular estuary can receive and still assure attainment and maintenance of the State's WQS for the estuary (i.e., a protective load). An approach is then proposed for translating those downstream loading values into criteria levels in the contributing watershed stream reaches in a manner that ensures that the protective downstream loadings are not exceeded.

    In connection with both lakes and estuaries, EPA fully recognizes that there are a range of important technical questions and related significant issues raised by this proposed approach for developing instream water quality criteria that are protective of downstream designated uses. With regard, in particular, to the protection of estuaries, the Agency is working closely with FDEP to derive estuarine numeric nutrient criteria for proposal and publication in 2011. Even though estuarine numeric nutrient criteria will be developed in 2011, there is already a substantial body of information, science, and analysis that presently exists that should be considered in determining flowing water criteria that are protective of downstream water quality.

    The substantial data, peer-reviewed methodologies, and extensive scientific analyses available to and conducted by the Agency to date indicate that numeric nutrient criteria for estuaries, when proposed and finalized in 2011, may result in the need for more stringent rivers and streams criteria to ensure protection of downstream water quality, particularly for the nitrogen component of nutrient pollution.

    Therefore, considering the numerous requests for the Agency to share its analysis and scientific and technical conclusions at the earliest possible opportunity to allow for full review and comment, EPA is including downstream protection values for TN as proposed criteria for rivers and streams to protect the State's estuaries in this notice.

    As described in more detail below and in EPA's TSD for Florida's

    Inland Waters accompanying this notice, these proposed nitrogen downstream protection values are based on substantial data, thorough scientific analysis, and extensive technical evaluation. However, EPA recognizes that additional data and analysis may be available for particular estuaries to help inform what water quality criteria are necessary to protect these waters. EPA also recognizes that substantial site-specific work (including some very sophisticated analyses in the context of certain TMDLs) has been completed for a number of these estuaries. This notice and the proposed downstream protection values are not intended to address or be interpreted as calling into question the utility and protectiveness of these site-specific analyses. Rather, the proposed values represent the output of a systematic and scientific approach that may be generally applicable to all flowing waters in

    Florida that terminate in estuaries for the purpose of ensuring the protection of downstream estuaries. EPA is interested in obtaining feedback at this time on this systematic and scientific approach. The

    Agency further recognizes that the proposed values in this notice will need to be considered in the context of the Agency's numeric nutrient criteria for estuaries scheduled for proposal in January of 2011. At this time, EPA plans to finalize any necessary downstream protection values for nitrogen in flowing waters as part of the second phase of this rulemaking process in coordination with the proposal and finalization of numeric criteria for estuarine and coastal waters in 2011. However, if comments, data and analyses submitted as a result of this proposal support finalizing such values sooner, by October 2010,

    EPA may choose to proceed in this manner. To facilitate this process,

    EPA requests comments and welcomes thorough evaluation on the need for and the technical and scientific basis of these proposed downstream protection values as part of the broader comment and evaluation process that this proposal initiates.

    EPA believes that a detailed consideration and related proposed approach to address protection of downstream water quality in this proposal is necessary for several reasons, including (1) water quality standards are required to protect downstream uses under Federal regulations at 40 CFR 131.10(b), meaning also for prevention of impairment; (2) it may be a relevant consideration in the development of any TMDLs, NPDES permits, and Florida BMAPs that the State completes in the interim period between the final rule for Florida lakes and flowing waters in October 2010 and a final rule for Florida estuarine and coastal waters in October of 2011; and (3) perhaps most importantly, it is essential for informing and supporting a transparent and engaged public consideration, evaluation, and discussion on the question of what existing information, tools, and analyses suggest regarding the need to ensure protection of downstream waters. The

    Agency continues to emphasize its interest in and request for additional information, further analysis, and any alternative technically-based approaches that may be available to address protection of downstream water quality. EPA also reiterates its commitment to a full evaluation of all comments received and notes the ability to issue a NODA to allow a full public review should significant new additional information and analysis become available as part of the comment period.

    In deriving criteria to protect designated uses, as noted above,

    Federal WQS regulations established to implement the CWA provide WQS must provide for the protection of designated uses in downstream waters. In the case of deriving numeric nutrient criteria for streams in Florida, EPA's analyses reflected in this notice indicate that the proposed criteria values for instream protection of streams may not fully protect downstream lakes and downstream estuaries. EPA's proposed criteria for lakes are, in some cases, more stringent than the proposed criteria for streams that flow into the lakes. For estuaries, EPA's analyses of protective loads delivered to a specific estuary, and the corresponding expected concentration values for streams that flow into that estuary, indicate the proposed criteria for instream protection may not always be sufficient to provide for the attainment and maintenance of the estuarine WQS. For more detailed information, please consult EPA's TSD for Florida's Inland Waters, Chapter 2: Methodology for Deriving U.S. EPA's Proposed Criteria for Streams.

    To address each of these issues, EPA is proposing first, for lakes, an equation that allows for input of lake characteristics to determine the concentration in flowing streams that is needed to attain and maintain the receiving lake's designated use and protective criteria.

    Second, for estuaries, EPA is proposing an approach for identifying the total nutrient loads a particular estuary can receive and still attain and maintain the State's designated use for the water body.

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    Third, also for estuaries, the Agency is proposing a methodology to derive protective concentration values for the instream criteria where necessary to assure that downstream estuarine loads are not exceeded.

    The following sections provide a more detailed explanation of the proposed downstream protective approach for lakes and then for estuaries.

    (a) Downstream Protection of Lakes

    EPA is proposing an equation to relate a lake TP concentration criterion to the concentration needed to be met in incoming streams to support the lake criterion. EPA proposes to apply the resulting stream concentration as the applicable criterion for all stream segments upstream of the lake. EPA used a mathematical modeling approach to derive this equation, with allowable input of lake-specific characteristics, to calculate protective criteria necessary to assure attainment and maintenance of the numeric lake nutrient criteria in this proposal. More specifically, EPA started with a phosphorus loading model equation first developed by Vollenweider.\70\ EPA assumed that rainfall exceeds evaporation in Florida lakes and that all external phosphorus loading comes from streams. EPA considers the first assumption reasonable given the rainfall frequency and volume in

    Florida. The second assumption is reasonable to the extent that surface runoff contributions are far greater than groundwater or atmospheric sources of TP in Florida lakes. EPA requests comment on both these assumptions. After expressing these assumptions in terms of the mathematical relationships among loading rates, stream flow, and lake and stream concentrations, EPA derived the following equation to relate a protective lake criterion to a corresponding protective stream concentration:

    \70\ Vollenweider, R.A. 1975. Input-output models with special reference to the phosphorus loading concept in limnology.

    Schweizerische Zeitschrift fur Hydrologie. 37: 53-84; Vollenweider,

    R.A. 1976. Advances in differing critical loading levels for phosphorus in lake eutrophication. Mem. Ist. Ital. Idrobid. 33:53:83.

    GRAPHIC

    TIFF OMITTED TP26JA10.000

    where:

    TP

    Sis the total phosphorus (TP) downstream lake protection value, mg/L

    TP

    Lis applicable TP lake criterion, mg/L cfis the fraction of inflow due to all stream flow, 0 fwis lake's hydraulic retention time (water volume divided by annual flow rate)

    The term

    GRAPHIC

    TIFF OMITTED TP26JA10.005 expresses the net phosphorus loss from the water column (e.g. via settling of sediment-sorbed phosphorus) as a function of the lake's retention time

    This model equation requires input of two lake-specific characteristics: The fraction of inflow due to stream flow and the hydraulic retention time. Water in a lake can come from a combination of groundwater sources, rainfall, and streams that flow into it. Using the model equation above, the calculated stream TP criterion to protect a downstream lake will be more stringent for lakes where the portion of its volume coming from streams flowing into it is the greatest. In addition, the calculated stream TP criterion to protect a downstream lake will be more stringent for lakes with short hydraulic retention times (how long water stays in a lake) because the longer the water stays in the lake, the more phosphorus will settle out in the underlying lake sediment.

    Because lake-specific input values may not always be readily available, EPA is providing preset values for percent contribution from stream flow and hydraulic retention time. In Florida lakes, rainfall and groundwater sources tend to contribute a large portion of the total volume of lake water. In fact, only about 20% of the more than 7,000

    Florida lakes have a stream flowing into them,\71\ with the rest entirely comprised of groundwater and rainwater sources. EPA evaluated representative values for percent contribution from stream flow \72\ and hydraulic retention time,\73\ and selected 50% stream flow contribution and 0.2 years (about two and a half months) retention time as realistic and representative preset values to provide a protective outcome for Florida lakes, in the absence of site-specific data. Using these preset values, streams that flow into colored lakes would have a

    TP criterion of 0.12 mg/L, and streams that flow into clear, alkaline lakes would have a TP criterion of 0.073 mg/L, with respect to downstream lake protection. In the Peninsula NWR, this compares to a 0.107 mg/L TP stream criterion protective of instream designated uses.

    EPA's proposed rule does offer the flexibility to use site-specific inputs to the Vollenweider equation for fraction of inflow from streamflow and hydraulic retention time, as long as data supporting such inputs are sufficiently robust and well-documented.

    \71\ Fernald, E.A. and E.D. Purdum. 1998. Water Resources Atlas of Florida. Tallahassee: Institute of Science and Public Affairs,

    Florida State University.

    \72\ Gao, X. 2006. Nutrient and Unionized Ammonia TMDLs for Lake

    Jesup, WBIDs 2981 and 2981A. Prepared by Florida Department of

    Environmental Protection, Division of Water Resource Management,

    Bureau of Watershed Management, Tallahassee, FL.

    \73\ Steward, J.S. and E.F. Lowe. In Press. General empirical models for estimating nutrient load limits for Florida's estuaries and inland waters. Limnol. Oceanogr. 55: (in press).

    EPA carefully evaluated use of a settling/loss term for phosphorus in the model equation. Florida lakes tend to be shallow, and internal loadings to the lake water (e.g. from re-suspension of settled phosphorus after storms that stir up lake sediment) may be substantial.

    A more detailed model might be able to simulate this phenomenon mechanistically, but would likely require substantial site-specific data for calibration. For this reason, EPA chose to use the model formulation above. EPA considered a simpler alternative to exclude the settling/loss term from the above equation, or even to reverse the sign on the settling/loss term so that it becomes a net source term, perhaps with the inclusion of a default multiplier. However, EPA did not have sufficient information to conclude that such a conservative approach was necessary as a general application to all Florida lakes. EPA remains open and receptive to comment on these alternatives or other technically sound and protective approaches. EPA's supporting analyses and detailed information on this downstream lake protection methodology are provided in the accompanying TSD for Florida's Inland Waters,

    Chapter 2: Methodology for Deriving U.S. EPA's Proposed Criteria for

    Streams.

    The same processes that occur in lakes and affect lake water phosphorus concentration may also occur in streams that feed lakes and affect stream water phosphorus concentrations. These processes include sorption to stream bed sediments, uptake into biota, and release into the water column from decaying vegetation. EPA took into consideration these processes when deciding whether it would be appropriate to add a term to the model equation to account for phosphorus loss or uptake within the streams in deriving stream criteria for downstream lake protection. However, the net result of these processes is nutrient spiraling, whereby nutrients released upstream gradually propagate downstream at a rate slower than that of the moving water, and cycle into and out of the food chain in the process. Over the short term, the result may be water concentrations that decrease in the downstream direction. However, unlike for nitrogen, there are no long-term phosphorus net removal processes at work in streams. Phosphorus adsorbed to sediment particles is eventually

    Page 4199

    carried downstream with the sediment, and phosphorus taken up by plants is eventually returned to the flowing water. Over the long term, upstream phosphorus inputs are in equilibrium with downstream phosphorus outputs. Recognizing this feature of stream systems and the conservative nature of phosphorus in aquatic environments, EPA concluded that it was not appropriate to include a phosphorus loss term that would apply to streams as they progress toward a downstream lake.

    For further information, please refer to EPA's TSD for Florida's Inland

    Waters, Chapter 2: Methodology for Deriving U.S. EPA's Proposed

    Criteria for Streams.

    EPA requests comment on the need for additional instream criteria to protect uses in downstream lakes. EPA further requests comment on the model equation approach presented here to protect downstream lakes, and also requests comment on use of an alternative model such as one with a negative or zero settling term (i.e., set (1+

    radic

    tauw) in the equation above either equal to zero or with the plus sign switched to a minus sign). EPA also requests comment on whether and how to address direct surface runoff into the lake.

    Where this input is substantial and land use around the lake indicates that phosphorus input is likely, EPA believes it may be appropriate to include this water volume contribution as part of the fraction of inflow considered to be streamflow to be protective and consistent with the assumption of no loading from sources other than streamflow. EPA specifically requests comment on use of the Land Development Index

    (LDI) as an indicator of how to treat this inflow, examination of regional groundwater phosphorus levels to see if a zero TP input from this source is appropriate, and potential development of regionally- specific preset values as inputs to the equation. In addition, EPA requests comment on the potential to develop a corollary approach for nitrogen.

    EPA is open to alternative technically-supported approaches based on best available data that offer the ability to address lake-specific circumstances. The Agency recognizes that more specific information may be readily available for individual lakes which could allow the use of alternative approaches such as the BATHTUB model.\74\ The Agency welcomes comment and technical analysis on the availability and application of these models. In this regard, EPA requests comment on whether there should be a specific allowance for use of alternative lake-specific models where demonstrated to be protective and scientifically defensible based upon readily and currently available data, and whether use of such alternatives should best be facilitated through use of the SSAC procedure described in Section V.C.

    \74\ Kennedy, R.H., 1995. Application of the BATHTUB Model to

    Selected Southeastern Reservoirs. Technical Report EL-95-14, U.S.

    Army Engineer Waterways Experiment Station, Vicksburg, MS. Walker,

    W.W., 1985. Empirical Methods for Predicting Eutrophication in

    Impoundments; Report 3, Phase II: Model Refinements. Technical

    Report E-81-9, U.S. Army Engineer Waterways Experiment Station,

    Vicksburg, MS.

    Walker, W.W., 1987. Empirical Methods for Predicting

    Eutrophication in Impoundments; Report 4, Phase III: Applications

    Manual. Technical Report E-81-9, U.S. Army Engineer Waterways

    Experiment Station, Vicksburg, MS.

    (b) Downstream Protection of Estuaries

    (i) Overview

    EPA is proposing a methodology for calculation of applicable criteria for streams that flow into estuaries and provide for their protection. The proposed methodology would allow the State to utilize either (1) EPA's downstream protection values (DPVs), or (2) the EPA

    DPV methodology utilizing EPA's estimates of protective loading to estuaries but with the load re-distributed among the tributaries to each estuary, or (3) an alternative quantitative methodology, based on scientifically defensible approaches, to derive and quantify the protective load to each estuary and the associated protective stream concentrations. The DPV methodology with a re-distributed load may be used if the State provides public notice and opportunity for comment.

    To use an alternative technical approach, based on scientifically defensible methods to derive and quantify the protective load to each estuary and the associated protective stream concentrations, the State must go through the process for a Federal SSAC as described in Section

    V.C. In some cases, the substantial and sophisticated analyses and scientific effort already completed in the context of the TMDL process may provide sufficient support for a SSAC. In such circumstances, EPA encourages FDEP to submit these through the SSAC process and EPA looks forward to working with FDEP in this process.

    EPA's approach to developing nutrient criteria for streams to protect downstream estuaries in Florida involves two separate steps.

    The first step is determining the average annual nutrient load that can be delivered to an estuary without impairing designated uses. This is the protective load. The second step is determining nutrient concentrations throughout the network of streams and rivers that discharge into an estuary that, if achieved, are expected to result in nutrient loading to estuaries that do not exceed the protective load.

    These concentrations, called ``downstream protection values'' or DPVs, depend on the protective load for the receiving estuary and account for nutrient losses within streams from natural biological processes. In this way, higher DPVs may be appropriate in stream reaches where a significant fraction of either TN or TP is permanently removed within the reach before delivery to downstream receiving waters. EPA's approach utilizes results obtained from a watershed modeling approach called SPAtially Referenced Regressions on Watershed attributes, or

    SPARROW.\75\ The specific model that was used is the South Atlantic,

    Gulf and Tennessee (SAGT) regional SPARROW model.\76\ EPA selected this model because it provided the information that was needed at the appropriate temporal and spatial scales and it applies to all waters that flow to Florida's estuaries.\77\ SPARROW was developed by the

    United States Geological Survey (USGS) and has been reviewed, published, updated and widely applied over the last two decades. It has been used to address a variety of scientific applications, including management and regulatory applications.\78\ In order to fully understand EPA's methodology for developing DPVs, it is useful to understand how the approach utilizes results from SPARROW, as well some aspects of how SPARROW works.

    \75\ http://water.usgs.gov/nawqa/sparrow.

    \76\ Hoos, A.B., and G. McMahon. 2009. Spatial analysis of instream nitrogen loads and factors controlling nitrogen delivery to stream in the southeastern United Sates using spatially referenced regression on watershed attributes (SPARROW) and regional classification frameworks. Hydrological Processes. DOI: 10.1002/ hyp.7323.

    \77\ Hoos, A.B., S. Terziotti,, G. McMahon, K. Savvas, K.C.

    Tighe, and R. Alkons-Wolinsky. 2008. Data to support statistical modeling of instream nutrient load based on watershed attributes, southeastern United States, 2002: U.S. Geological Survey Open-File

    Report 2008-1163, 50 p.

    \78\ USGS SPARROW publications Web site: http://water.usgs.gov/ nawqa/sparrow/intro/pubs.html.

    Page 4200

    GRAPHIC

    TIFF OMITTED TP26JA10.001

    The remaining discussion focuses on TN, for which EPA has already computed DPVs. The approach for computing DPVs for TP from estimates of the protective TP load is expected to be essentially the same as for

    TN. However, there is some question as to whether the same approach used to determine the protective TN load will also apply to TP. EPA requests comment on this issue.

    (ii) EPA Approach to Estimating Protective Nitrogen Loads for Estuaries

    The first step in EPA's approach is to narrow the range of possible values. The protective TN load is expected to vary widely among Florida estuaries because they differ significantly in their size and physical and biological attributes. For example, well flushed estuaries are able to receive higher TN loading without adverse effect compared to poorly flushed estuaries. EPA recognized that it may be possible to narrow this initially very broad range of possible protective loads using one consistent approach, and then consider whether additional information might enable a further reduction in uncertainty. EPA is soliciting credible scientific evidence that may improve these estimates and further reduce uncertainty surrounding the proposed protective loads.

    The most useful evidence would provide a scientific rationale, an alternative estimate of the protective load, and an associated confidence interval for the estimate. For further information, please refer to EPA's TSD for Florida's Inland Waters, Chapter 2: Methodology for Deriving U.S. EPA's Proposed Criteria for Streams.

    EPA first narrowed the range of possible protective loads by establishing an estimate of current loading as an upper bound. Most of

    Florida's estuaries are listed as impaired to some extent by nutrients or nutrient-related causes. Florida's 1998 CWA section 303(d) verified list of impaired waters under the Impaired Waters Rule (FAC 62-303) identify many estuaries or estuary segments that are impaired by nutrients, chlorophyll a, or low dissolved oxygen. Many or most estuaries have reduced water clarity and substantial loss of seagrass habitats. The National Estuarine Eutrophication Assessment \79\ reports that current conditions are poor for many estuaries in Florida. This information implies that current levels of TN loading are at least an upper limit for the protective load and likely exceed the protective load in many estuaries.

    \79\ Bricker, S., B. Longstaff, W. Dennison, A. Jones, K.

    Boicourt, C. Wicks and J. Woerner, 2007. Effects of nutrient enrichment in the Nation's estuaries: A decade of change. NOAA

    Coastal Ocean Program Decision Analysis Series No. 26. National

    Centers for Coastal Ocean Science, Silver Spring, MD 322.

    EPA used the SAGT-SPARROW regional watershed model to estimate current loading to each estuary in Florida. While nitrogen loads have been estimated from monitored gauge stations in many stream and rivers, a large fraction of Florida streams and watersheds are not gauged and thus load estimates were not previously available. An approach was needed to spatially extrapolate the available measurements of loading to obtain estimates of loading for all streams including those in unmonitored watersheds or portions of watersheds. The SAGT SPARROW model provided these estimates for all Florida estuarine watersheds.

    The SPARROW modeling approach utilizes a multiple regression equation to describe the relationship between watershed attributes (i.e., the predictors) and measured instream nutrient loads (i.e., the responses).

    The statistical methods incorporated into SPARROW help explain instream nutrient water quality data (i.e., the mass flux of nitrogen) as a function of upstream sources and watershed attributes. The SAGT-SPARROW model utilized period of record monitored streamflow and nutrient water quality data from Florida and across the SAGT region for load estimation. SAGT-SPARROW also used extensive geospatial data sets describing topography, land-use, climate, and soil characteristics, nitrogen loading for point sources in Florida obtained from EPA's permit compliance system, and estimates of nitrogen in fertilizer and manure from county-level fertilizer sales, census of agriculture, and population estimates. TN load estimates explain 96% of the variation in observed loads from monitoring sites across the region with no spatial bias at Florida sites.\80\ A more thorough description of the SAGT-

    SPARROW model, the data sources, and analyses are found in the EPA TSD for Florida's Inland Waters and in USGS publications.\81\

    \80\ Hoos, A.B., and G. McMahon. 2009. Spatial analysis of instream nitrogen loads and factors controlling nitrogen delivery to stream in the southeastern United Sates using spatially referenced regression on watershed attributes (SPARROW) and regional classification frameworks. Hydrological Processes. DOI: 10.1002/ hyp.7323.

    \81\ Hoos, A.B., S. Terziotti,, G. McMahon, K. Savvas, K.C.

    Tighe, and R. Alkons-Wolinsky. 2008. Data to support statistical modeling of instream nutrient load based on watershed attributes, southeastern United States, 2002: U.S. Geological Survey Open-File

    Report 2008-1163, 50 p.

    EPA further narrowed the range of possible protective loads by establishing the background load as a lower bound. EPA recognizes that a measure of natural background TN loading is the true lower limit, yet

    EPA recognizes also that some level of anthropogenic nutrient loading is acceptable, difficult to avoid, and unlikely to cause adverse biological responses. The current TN load minus the fraction of TN loading estimated to result from anthropogenic sources is used as an estimate of the background TN load. EPA used the SAGT-SPARROW regional watershed model to estimate background loading. SAGT-SPARROW empirically associates 100% of the measured nutrient loading into one of five classes (fertilizer, manure, urban, point sources, and atmospheric). EPA recognizes that some watershed models define more types of sources, according to their modeling objectives; however, it is important to recognize that these are

    Page 4201

    source classes, not sources, and that 100% of the measured loading is accounted for explicitly or implicitly by SPARROW in terms of these source classes.

    The class termed ``atmospheric'' reflects all loading that cannot be empirically attributed to causal variables associated with the other classes. EPA used the estimate for this class of loading as the background TN load. EPA recognizes that the SPARROW-estimated

    ``atmospheric'' load includes anthropogenic contributions associated with regional-scale nitrogen emissions and does not represent pre- industrial or true ``natural'' background loading. The ``atmospheric'' source term from SPARROW is also not equal to atmospheric nitrogen deposition as measured by the National Atmospheric Deposition Program

    (NADP). To properly interpret the TN load attributed to the

    ``atmospheric'' source term in SPARROW, it is useful to recognize that

    SPARROW is a nonlinear regression model that seeks to explain measured

    TN loads in streams and rivers in terms of a series of explanatory variables. The atmospheric term is in all cases less, and often much less, than the measured deposition because not all the nitrogen deposited to the landscape is transported to streams, and not all of the nitrogen transported in streams reaches estuaries. The atmospheric source term from SPARROW excludes all the loading associated with both local anthropogenic nitrogen sources and factors contributing to increased transport of nitrogen from all sources (e.g., impervious surfaces). Therefore, EPA expects that reasonable values for the protective TN load are not likely to be less than these values.

    The protective TN load should be less than the current load and greater than the background load. Although this recognition may appear to be trivial, it is important. EPA estimates that TN loads to estuaries across Florida vary approximately 25-fold (~2 to 50 grams of nitrogen per square meter of estuary area). However, the ratio of the current load to the background load varies only between 1.7 and 5; for most estuaries, the range is between 2 and 4. Alternatively stated, current TN loads, which include local anthropogenic nitrogen sources, are two to four-fold higher than the background loads which do not include those sources. Thus, for any specific estuary, there is a relatively narrow range between the upper and lower bounds of potential protective loads.

    EPA acknowledges that not all the TN entering estuaries comes directly from the streams within its watershed. In some estuaries, direct atmospheric nitrogen deposition to the estuary surface may be an important source of TN loading to the estuary. Similarly, point sources such as industrial or wastewater treatment plant discharges directly to the estuary can be significant. In general, these sources are most significant when the ratio of watershed area to estuary area is relatively small compared to other estuaries (e.g., St. Andrew Bay,

    Sarasota Bay). In a few cases in Florida, point source loads directly to the estuary account for a large fraction of the aggregate load from all sources.

    As a second step, EPA sought to further reduce the range of possible protective loading values by considering additional evidence.

    One line of evidence EPA considered is previous estimates of protective loads. These have been developed as part of TMDLs for Florida estuaries or as part of Florida's Pollutant Load Reduction Goal or PLRG program.

    The scientific approaches utilized for TMDLs and PLRGs vary from simple to sophisticated and have recommended TN loading reductions between 3% and 63%, with a median of 38%. Higher reductions are typically associated with portions of estuaries currently receiving higher anthropogenic loading. Unfortunately, these analyses have not been completed for all of Florida's estuaries. Steward and Lowe (2009) \82\ showed that the TN loading limits suggested by TMDLs and PLRGs for a variety of aquatic ecosystems in Florida, including estuaries, could be statistically related to water residence time for the receiving water.

    EPA evaluated these relationships as an additional line of evidence for estimating protective TN loads for estuaries. EPA found these relationships to confirm in most cases, but not all, that the loading limits were likely between the bounds EPA previously established using

    SPARROW. However, the limits of uncertainty associated with the relationship were nearly as large as those already established.

    Nonetheless, the models provide additional support for EPA's estimates of protective estuary loads, but no further refinement of the estimates.

    \82\ Steward, J.S. and E.F. Lowe. 2010. General empirical models for estimating nutrient load limits for Florida's estuaries and inland waters. Limnology and Oceanography 55(1):433-445.

    Another approach to considering existing TMDLs and PLRGs is to consider directly the loading rate reductions recommended from those efforts, the median of which is 38% in Florida. This percent TN reduction is similar to the scientific consensus for several well- studied coastal systems elsewhere (e.g., Chesapeake Bay, northern Gulf of Mexico) which have been subjected to increased TN loads from known anthropogenic sources. EPA recognizes that the magnitude of anthropogenic TN loads varies across Florida estuaries and that applying a uniform percent reduction across all estuaries does not account for the variable extent of anthropogenic loads and could lead to estimates below background load. An alternative approach is to assume that the appropriate loading reduction is proportional to the magnitude of anthropogenic enrichment. Thus, EPA suggests that protective TN loading may be estimated by assuming that the anthropogenic component of TN loading should be reduced by a constant fraction.

    As a result, EPA computed the protective TN load by reducing the current TN load by one half of the anthropogenic contribution to that load. EPA's protective load estimates are on average 25% less than current TN loading (range = 5 to 40%), consistent with most TMDLs and

    PLRGs for Florida estuaries.

    EPA developed protective TN loads for 16 estuarine water bodies in

    Florida for the purpose of computing DPVs for streams that are protective of uses in the estuarine receiving waters. EPA did not develop loading targets for the seven estuarine water bodies in south

    Florida (Caloosahatchee, St. Lucie, Biscayne Bay, Florida Bay, North and South Ten Thousand Islands, and Rookery Bay), because requisite information related to TN loading from the highly managed canals and waterways cannot be derived from SAGT-SPARROW and were not available otherwise, and three in central Florida (coastal drainage areas of the

    Withlacoochee River, Crystal-Pithlachascotee River and Daytona-St.

    Augustine) because EPA is still evaluating appropriate protective loads and the flows necessary to derive DPVs.

    EPA notes that some stakeholders, including FDEP staff,\83\ have raised

    Page 4202

    concerns about the suitability of the SAGT SPARROW to address downstream protection of estuaries and have suggested alternative models and approaches that have been applied for several of Florida's larger estuaries and their watersheds. These concerns include known limitations of the SPARROW model, particularly related to inadequate resolution of complex hydrology in several parts of the State. EPA also recognizes this limitation and as a result, has not used SAGT SPARROW to propose protective loads and associated downstream protection values for ten estuaries and their watersheds in Florida. EPA acknowledges that other approaches and models may also provide defensible estimates of protective loads.

    \83\ For further information on concerns raised by FDEP regarding the use of SPARROW, refer to ``Florida Department of

    Environmental Protection Review of SPARROW: How useful is it for the purposes of supporting water quality standards development?,''

    ``Assessment of FDEP Panhandle Stream proposed benchmark numeric nutrient criteria for downstream protection of Apalachicola Bay,'' and ``Analysis of Proposed Freshwater Stream Criteria's Relationship to Protective Levels in the Lower St. Johns River Based on the Lower

    St. Johns River Nutrient TMDL.'' located in EPA's docket ID No. EPA-

    HQ-OW-2009-0596.

    Among the technical concerns that stakeholders including FDEP staff have raised are that: (1) SPARROW is useful for general pattern, but the large scale calibration lead to large errors for specific areas,

    (2) SPARROW only utilizes four source inputs, and (3) SPARROW was calibrated to only one year's worth of data. As presented in the above sections, but to briefly reiterate here: (1) SPARROW is calibrated across a larger area, but it utilizes a large amount of Florida site- specific data and it explains 96% of the variation in observed loads from monitoring sites, (2) SPARROW accounts for all sources, but groups them into four general categories, and (3) SPARROW uses available data from the 1975-2004 period at monitored sites. This last concern may be confused with the technical procedure of presenting loading estimates as ``detrended to 2002''. This procedure accounts for long-term, inter- annual variability to ensure that long-term conditions and trends are represented. The year 2002 was selected as a baseline because it has the best available land use/land cover information available, but the loading estimates, in fact, represent a long-term condition representative of many years of record. EPA encourages technical reviewers to consult with the technical references cited in this section for the complete explanations of technical procedures.

    EPA requests comment on its use of the SPARROW model to derive protective loads for downstream estuaries, as well as data and analyses that would support alternate methods of deriving downstream loads, or alternate methods of ensuring protection of designated uses in estuaries. For estuaries where sophisticated scientific analyses have been completed, relying on ample site-specific data to derive protective loads in the context of TMDLs, EPA encourages FDEP to submit resulting alternative DPVs under the SSAC process.

    (iii) Computing Downstream Protection Values (DPVs)

    Once an estimate of protective TN loads is derived, EPA developed a methodology for computing DPVs, for streams that, if achieved, are expected to result in an average TN loading rate that does not exceed the protective load. EPA's methodology, which is used as the narrative translator, allows for the fraction of the protective TN loading contributed from each tributary within the watershed of an estuary to be determined by the fraction of the total freshwater flow contributed by that tributary. The DPV is specified as an average TN concentration, which is computed by dividing the protective TN load by the aggregate average freshwater inflow from the watershed. This approach results in the same DPV for each stream or river reach that terminates into a given estuary.

    EPA's methodology accounts for instream losses of TN. EPA recognizes that not all the TN transported within a stream network will ultimately reach estuaries. Rather, some TN is permanently lost from streams. This is not the same as reversible transformations of TN, such as algal uptake. Losses of TN are primarily associated with bacterially-mediated processes in stream sediments that convert biologically available nitrogen into inert N2gas, which enters the atmosphere (a process called denitrification). This occurs more rapidly in shallow streams and at almost negligible rates in deeper streams and rivers. EPA refers to the fraction of nitrogen transported in streams that ultimately reaches estuaries as the

    ``fraction delivered.'' Estimates of the fraction delivered in Florida are less than 50% in streams very distant from the coast, but is between 80 and 100% in approximately half the stream reaches in

    Florida's estuarine watersheds.

    EPA's approach relies on estimating the fraction of TN delivered to downstream estuaries. Measuring instream loss rates at the appropriate time and space scale is exceedingly difficult, and it is not possible to do State-wide. EPA is not aware of other models or data suitable to estimating nitrogen losses in streams across the State of Florida. EPA obtained estimates from the SAGT-SPARROW model,\84\ which is possibly the best generally applicable approach to obtaining these estimates.

    One reason is that SPARROW estimates watershed-scale instream losses at the annual time scales across the entire region. Estimates of instream losses are modeled in SPARROW using a first-order decay rate as a function of time-of-travel in the reach. The inverse exponential relationship is consistent with scientific understanding that nitrogen losses decrease with increasing stream size and with results from experimental reach-scale studies using a variety of methods.\85\ EPA recognizes that stream attributes other than reach time-of-travel or size may influence instream loss rates and though the SPARROW model did not include these, the lack of spatial bias in model residuals suggests that inclusion of other potential subregional-scale or State-wide stream attributes may not improve modeled instream loss estimates.

    \84\ Hoos, A.B., and G. McMahon. 2009. Spatial analysis of instream nitrogen loads and factors controlling nitrogen delivery to streams in the southeastern United States using spatially referenced regression on watershed attributes (SPARROW) and regional classification frameworks. Hydrological Processes. DOI: 10.1002/ hyp.7323.

    \85\ Bohlke, J.K., R.C. Antweiler, J.W. Harvey, A.E. Laursen,

    L.K. Smith, R.L. Smith, and M.A. Voytek. 2009. Multi-scale measurements and modeling of Denitrification in streams with varying flow and nitrate concentration in the upper Mississippi River basin,

    USA. Biogeochemistry 93: 117-141. DOI 10.1007/s10533-008-9282-8.

    EPA developed and applied this methodology to compute DPVs for every stream reach in each of 16 estuarine watersheds starting with estuarine-specific estimates of the protective load. These estuarine watersheds align with the Nutrient Watershed Regions (NWR) used to derive instream protection values (IPVs). It is important to note that the scale at which protective loads and DPVs were derived is smaller than for IPVs (i.e., 16 estuarine watersheds vs. 4 nutrient watershed regions). EPA's recognition that some fraction of nitrogen transported in streams is retained or assimilated before reaching estuarine waters help ensure that the DPVs are not overprotective of downstream use in any particular estuary.

    In determining TN DPVs, EPA considered the contribution of TN inputs from wastewater discharged in shoreline catchments directly to the estuary. EPA found these point source inputs to be significant (> 5% of total loading) in three (St. Andrew's Bay, St. Marys, St. John's) of the 16 estuaries. However, for the purpose of computing stream reach

    DPVs for a given estuarine watershed, EPA considered only those TN loads delivered from the estuarine watershed stream network and did not

    Page 4203

    include TN inputs from wastewater discharged in shoreline catchments directly to an estuary because these loads do not originate from upstream sources. However, point sources loads directly to the estuary would need to be considered in developing TMDLs based on estuary- specific criteria.

    EPA's computation of DPVs using estimates of protective loading for each estuary and the fraction-delivered to estuaries is shown by equation (1):

    GRAPHIC

    TIFF OMITTED TP26JA10.002 where the terms are defined as follows for a specific or (ith) stream reach:

    Ci maximum flow-averaged nutrient concentration for a specific (the ith) stream reach consistent with downstream use protection (i.e., the DPV) k fraction of all loading to the estuary that comes from the stream network resolved by SPARROW

    Lest protective loading rate for the estuary, from all sources

    QW combined average freshwater discharged into the estuary from the portion of the watershed resolved by the SPARROW stream network

    Fi fraction of the flux at the downstream node of the specific (ith) reach that is transported through the stream network and ultimately delivered to estuarine receiving waters (i.e., Fraction Delivered).

    Note that the quantity kLest is equal to the loading to the estuary from sources resolved by SPARROW. For the purposes of practical implementation, EPA classified each stream water body (i.e., Water Body

    Identification or ``WBID'' using the FDEP term) according to the estuarine receiving water and one of six categories based on the fraction of TN delivered (0 to 50%, 51-60%, 61-70%, 71-80%, 81-90%, and 91-100%). For each category, the upper end of the range was utilized to compute the applicable DPV for streams in the category, resulting in a value that will be protective. This approach reduces the number of unique DPVs from thousands to less than 100. Because the stream network utilized by the SAGT-SPARROW watershed model (ERF1) does not recognize all of the smaller streams in Florida (i.e., it is on a larger scale),

    EPA mapped WBIDs to the applicable watershed-scale unit, or

    ``incremental watersheds,'' of the ERF1 reaches, assigning to each WBID the fraction of TN delivered estimated for the ERF1 reach whose incremental watershed includes the WBID. Where the WBID includes portions of the incremental watersheds of more than one ERF1 reach, EPA computed a weighted-average based on the proportion of WBID area in the watershed of each ERF1 reach.

    Given an even distribution of reaches within each 10% interval,

    EPA's ``binning'' approach to the fraction-delivered estimates results in a 5% to 10% margin of safety for the average reach in each range

    (closer to 10% for the lower fraction-delivered ranges). Potentially larger margins are possible within the 0 to 50% range, where the fraction delivered might be 20%, but the DPV would be computed assuming a fraction delivered of 50%. However, only one watershed in Florida for which EPA is proposing DPVs, the St. Johns River, has a substantial number of reaches estimated to have less than 50% TN delivered to estuarine waters. The SAGT-SPARROW watershed model estimates that 17% of the stream reaches in the St. Johns watershed are in this category, with about half the reaches delivering nearly 50% of TN and a substantial number delivering only 20% of TN. Given EPA's DPV for terminal reaches in the St. Johns watershed, however, the DPV for reaches with a fraction delivered less than 50% will be higher than the

    IPV, and therefore, will not apply. EPA requests comment on the binning approach for calculating DPVs, which allows for a relatively simple table of DPVs to be presented as compared to using the actual estimate of fraction TN delivered to calculate a DPV unique to each WBID using formula (1), above.

    At this time, EPA has not calculated protective TP loads for

    Florida's estuaries or DPVs for TP. However, advances in the application of regional watershed models, such as SPARROW, that address the sources and terrestrial and aquatic processes that influence the supply and transport of TP in the watershed and delivery to estuaries are currently in advanced stages of development.\86\ EPA anticipates obtaining the necessary data and information to compute TP loads for the estuarine water bodies in Florida in 2010 and could make this additional information available by issuing a supplemental Federal

    Register Notice of Data Availability (NODA), which would also be posted in the public docket for this proposed rule. EPA intends to derive proposed protective loads and DPVs for TP using an analogous approach as used for TN DPVs. EPA expects the approach will recognize that TP, like TN, is essential for estuarine processes but in excess will adversely impact aquatic life uses.

    \86\ Hoos, A.B., S. Terziotti, G. McMahon, K. Savvas, K.C.

    Tighe, and R. Alkons-Wolinsky. 2008. Data to support statistical modeling of instream nutrient load based on watershed attributes, southeastern United States, 2002: U.S. Geological Survey Open-File

    Report 2008--1163, 50 p.

    (iv) EPA Downstream Protection Values (DPVs)

    The following criteria tables and corresponding DPVs for a given stream reach category have been geo-referenced to specific WBIDs which are managed by FDEP as the principal assessment unit for Florida's surface waters. To see where the criteria are geographically applicable, refer to EPA's TSD for Florida's Inland Waters, Appendix B- 18: In-Stream and Downstream Protection Value (IPV/DPV) Tables with DPV

    Geo-Reference Table to Florida WBIDs.

    (mg L-1)

    TP (mg L-1)

    River/stream reach category--percent

    ------------------------------------------------------------------- delivered to estuary \4\

    TN IPV \5\

    TN DPV \6\

    TP IPV \7\

    TP DPV \8\

    Perdido Bay Watershed \PH\ (EDA Code: \1\ G140x)

    Protective TN Load for the Estuary: \2\: 847,520 kg y-\1\

    Protective TP Load for the Estuary: \3\ TBD

    Less than 50%...............................

    NR

    NR

    0.043

    TBD 50.1-60.0%..................................

    NR

    NR

    0.043

    TBD 60.1-70.0%..................................

    NR

    NR

    0.043

    TBD 70.1-80.0%..................................

    NR

    NR

    0.043

    TBD 80.1-90.0%..................................

    0.824

    0.34

    0.043

    TBD 90.1-100%...................................

    0.824

    0.30

    0.043

    TBD

    Page 4204

    Pensacola Bay Watershed \PH\ (EDA Code: \1\ G130x)

    Protective TN Load for the Estuary: \2\ 4,388,478 kg y-\1\

    Protective TP Load for the Estuary: \3\ TBD

    Less than 50%...............................

    NR

    NR

    0.043

    TBD 50.1-60.0%..................................

    NR

    NR

    0.043

    TBD 60.1-70.0%..................................

    NR

    NR

    0.043

    TBD 70.1-80.0%..................................

    NR

    NR

    0.043

    TBD 80.1-90.0%..................................

    0.824

    0.48

    0.043

    TBD 90.1-100%...................................

    0.824

    0.43

    0.043

    TBD

    Choctawhatchee Bay Watershed \PH\ (EDA Code: \1\ G120x)

    Protective TN Load for the Estuary: \2\ 2,875,861 kg y-\1\

    Protective TP Load for the Estuary: \3\ TBD

    Less than 50%...............................

    NR

    NR

    0.043

    TBD 50.1-60.0%..................................

    NR

    NR

    0.043

    TBD 60.1-70.0%..................................

    NR

    NR

    0.043

    TBD 70.1-80.0%..................................

    0.824

    0.48

    0.043

    TBD 80.1-90.0%..................................

    0.824

    0.43

    0.043

    TBD 90.1-100%...................................

    0.824

    0.39

    0.043

    TBD

    St. Andrew Bay Watershed \PH\ (EDA Code: \1\ G110x)

    Protective TN Load for the Estuary: \2\ 310,322 kg y-\1\

    Protective TP Load for the Estuary: \3\ TBDK

    Less than 50%...............................

    0.824

    0.48

    0.043

    TBD 50.1-60.0%..................................

    NR

    NR

    0.043

    TBD 60.1-70.0%..................................

    NR

    NR

    0.043

    TBD 70.1-80.0%..................................

    0.824

    0.30

    0.043

    TBD 80.1-90.0%..................................

    0.824

    0.27

    0.043

    TBD 90.1-100%...................................

    0.824

    0.24

    0.043

    TBD

    Apalachicola Bay Watershed \PH\ (EDA Code: \1\ G100x)

    Protective TN Load for the Estuary: \2\ 10,971,582 kg y-\1\

    Protective TP Load for the Estuary: \3\ TBD

    Less than 50%...............................

    0.824

    0.91

    0.043

    TBD 50.1-60.0%..................................

    NR

    NR

    0.043

    TBD 60.1-70.0%..................................

    0.824

    0.65

    0.043

    TBD 70.1-80.0%..................................

    0.824

    0.57

    0.043

    TBD 80.1-90.0%..................................

    0.824

    0.51

    0.043

    TBD 90.1-100%...................................

    0.824

    0.46

    0.043

    TBD

    Apalachee Bay Watershed \PH\ (EDA Code: \1\ G090x)

    Protective TN Load for the Estuary: \2\ 2,539,883 kg y-\1\

    Protective TP Load for the Estuary: \3\ TBD

    Less than 50%...............................

    NR

    NR

    0.043

    TBD 50.1-60.0%..................................

    NR

    NR

    0.043

    TBD 60.1-70.0%..................................

    NR

    NR

    0.043

    TBD 70.1-80.0%..................................

    0.824

    0.67

    0.043

    TBD 80.1-90.0%..................................

    0.824

    0.59

    0.043

    TBD 90.1-100%...................................

    0.824

    0.53

    0.043

    TBD

    Econfina/Steinhatchee Coastal Drainage Area \PH\ (CDA Code: \1\ G086x)

    Protective TN Load for the Estuary: \2\ 185,301 kg y-\1\

    Protective TP Load for the Estuary: \3\ TBD

    Less than 50%...............................

    NR

    NR

    0.043

    TBD 50.1-60.0%..................................

    NR

    NR

    0.043

    TBD 60.1-70.0%..................................

    NR

    NR

    0.043

    TBD 70.1-80.0%..................................

    NR

    NR

    0.043

    TBD 80.1-90.0%..................................

    0.824

    0.41

    0.043

    TBD 90.1-100%...................................

    0.824

    0.37

    0.043

    TBD

    Suwannee River Watershed\NC\ (EDA Code: \1\G080x)

    Protective TN Load for the Estuary: \2\ 5,421,050 kg y-\1\

    Protective TP Load for the Estuary: \3\ TBD

    Less than 50%...............................

    NR

    NR

    0.359

    TBD 50.1-60.0%..................................

    NR

    NR

    0.359

    TBD 60.1-70.0%..................................

    1.479

    0.78

    0.359

    TBD

    Page 4205

    70.1-80.0%..................................

    1.479

    0.69

    0.359

    TBD 80.1-90.0%..................................

    1.479

    0.61

    0.359

    TBD 90.1-100%...................................

    1.479

    0.55

    0.359

    TBD

    Waccasassa Coastal Drainage Area \PN\ (CDA Code: \1\ 078x)

    Protective TN Load for the Estuary: \2\ 433,756 kg y-\1\

    Protective TP Load for the Estuary: \3\ TBD

    Less than 50%...............................

    NR

    NR

    0.107

    TBD 50.1-60.0%..................................

    NR

    NR

    0.107

    TBD 60.1-70.0%..................................

    NR

    NR

    0.107

    TBD 70.1-80.0%..................................

    NR

    NR

    0.107

    TBD 80.1-90.0%..................................

    1.205

    0.45

    0.107

    TBD 90.1-100%...................................

    1.205

    0.40

    0.107

    TBD

    Withlacoochee Coastal Drainage Area \PN\ (CDA Code: \1\ G076x)

    Protective TN Load for the Estuary: \2\ TBD

    Protective TP Load for the Estuary: \3\ TBD

    Less than 50%...............................

    1.205

    TBD

    0.107

    TBD 50.1-60.0%..................................

    1.205

    TBD

    0.107

    TBD 60.1-70.0%..................................

    1.205

    TBD

    0.107

    TBD 70.1-80.0%..................................

    1.205

    TBD

    0.107

    TBD 80.1-90.0%..................................

    1.205

    TBD

    0.107

    TBD 90.1-100%...................................

    1.205

    TBD

    0.107

    TBD

    Crystal/Pithlachascotee Coastal Drainage Area \PN\ (CDA Code: \1\ G074x)

    Protective TN Load for the Estuary: \2\ TBD

    Protective TP Load for the Estuary: \3\ TBD

    Less than 50%...............................

    1.205

    TBD

    0.107

    TBD 50.1-60.0%..................................

    NR

    TBD

    0.107

    TBD 60.1-70.0%..................................

    NR

    TBD

    0.107

    TBD 70.1-80.0%..................................

    NR

    TBD

    0.107

    TBD 80.1-90.0%..................................

    1.205

    TBD

    0.107

    TBD 90.1-100%...................................

    1.205

    TBD

    0.107

    TBD

    Tampa Bay Watershed \BV\ (EDA Code: \1\ G070x)

    Protective TN Load for the Estuary: \2\ 1,289,671 kg y-\1\

    Protective TP Load for the Estuary: \3\ TBD

    Less than 50%...............................

    1.798

    1.11

    0.739

    TBD 50.1-60.0%..................................

    1.798

    0.93

    0.739

    TBD 60.1-70.0%..................................

    1.798

    0.80

    0.739

    TBD 70.1-80.0%..................................

    1.798

    0.70

    0.739

    TBD 80.1-90.0%..................................

    1.798

    0.62

    0.739

    TBD 90.1-100%...................................

    1.798

    0.56

    0.739

    TBD

    Sarasota Bay Watershed \BV\ (EDA Code: \1\ G060x)

    Protective TN Load for the Estuary: \2\ 155,576 kg y-\1\

    Protective TP Load for the Estuary: \3\ TBD

    Less than 50%...............................

    NR

    NR

    0.739

    TBD 50.1-60.0%..................................

    NR

    NR

    0.739

    TBD 60.1-70.0%..................................

    NR

    NR

    0.739

    TBD 70.1-80.0%..................................

    NR

    NR

    0.739

    TBD 80.1-90.0%..................................

    NR

    NR

    0.739

    TBD 90.1-100%...................................

    1.798

    0.54

    0.739

    TBD

    Charlotte Harbor Watershed \BV\ (EDA Code: \1\ G050w)

    Protective TN Load for the Estuary: \2\ 2,710,107 kg y-\1\

    Protective TP Load for the Estuary: \3\ TBD

    Less than 50%...............................

    NR

    NR

    0.739

    TBD 50.1-60.0%..................................

    1.798

    1.58

    0.739

    TBD 60.1-70.0%..................................

    1.798

    1.35

    0.739

    TBD 70.1-80.0%..................................

    1.798

    1.18

    0.739

    TBD 80.1-90.0%..................................

    1.798

    1.05

    0.739

    TBD 90.1-100%...................................

    1.798

    0.95

    0.739

    TBD

    Page 4206

    Indian River Watershed \PN\ (EDA Code: \1\ S190x)

    Protective TN Load for the Estuary: \2\ 463,724 kg y-\1\

    Protective TP Load for the Estuary: \3\ TBD

    Less than 50%...............................

    NR

    NR

    0.107

    TBD 50.1-60.0%..................................

    NR

    NR

    0.107

    TBD 60.1-70.0%..................................

    NR

    NR

    0.107

    TBD 70.1-80.0%..................................

    1.205

    0.87

    0.107

    TBD 80.1-90.0%..................................

    1.205

    0.77

    0.107

    TBD 90.1-100%...................................

    1.205

    0.69

    0.107

    TBD

    Caloosahatchee River Watershed PN,# (EDA Code: \1\ G050a)

    Protective TN Load for the Estuary: \2\ TBD

    Protective TP Load for the Estuary: \3\ TBD

    Less than 50%...............................

    1.205

    TBD

    0.107

    TBD 50.1-60.0%..................................

    1.205

    TBD

    0.107

    TBD 60.1-70.0%..................................

    1.205

    TBD

    0.107

    TBD 70.1-80.0%..................................

    1.205

    TBD

    0.107

    TBD 80.1-90.0%..................................

    1.205

    TBD

    0.107

    TBD 90.1-100%...................................

    1.205

    TBD

    0.107

    TBD

    St. Lucie River Watershed PN,# (EDA Code: \1\ S190x)

    Protective TN Load for the Estuary: \2\ TBD

    Protective TP Load for the Estuary: \3\ TBD

    Less than 50%...............................

    1.205

    TBD

    0.107

    TBD 50.1-60.0%..................................

    1.205

    TBD

    0.107

    TBD 60.1-70.0%..................................

    1.205

    TBD

    0.107

    TBD 70.1-80.0%..................................

    1.205

    TBD

    0.107

    TBD 80.1-90.0%..................................

    1.205

    TBD

    0.107

    TBD 90.1-100%...................................

    1.205

    TBD

    0.107

    TBD

    Kissimmee River Watershed PN,[caret]

    Protective TN Load for the Estuary: \2\ TBD

    Protective TP Load for the Estuary: \3\ TBD

    Less than 50%...............................

    1.205

    TBD \9\

    0.107

    TBD \9\ 50.1-60.0%..................................

    1.205

    TBD \9\

    0.107

    TBD \9\ 60.1-70.0%..................................

    1.205

    TBD \9\

    0.107

    TBD \9\ 70.1-80.0%..................................

    1.205

    TBD \9\

    0.107

    TBD \9\ 80.1-90.0%..................................

    1.205

    TBD \9\

    0.107

    TBD \9\ 90.1-100%...................................

    1.205

    TBD \9\

    0.107

    TBD \9\

    St. John's River Watershed; \PN\ (EDA Code: \1\ S180x)

    Protective TN Load for the Estuary: \2\ 4,954,662 kg y-\1\

    Protective TP Load for the Estuary: \3\ TBD

    Less than 50%...............................

    1.205

    1.41

    0.107

    TBD 50.1-60.0%..................................

    1.205

    1.17

    0.107

    TBD 60.1-70.0%..................................

    1.205

    1.00

    0.107

    TBD 70.1-80.0%..................................

    1.205

    0.88

    0.107

    TBD 80.1-90.0%..................................

    1.205

    0.78

    0.107

    TBD 90.1-100%...................................

    1.205

    0.70

    0.107

    TBD

    Daytona/St. Augustine Coastal Drainage Area \PN\ (CDA Code: \1\ S183x)

    Protective TN Load for the Estuary: \2\ TBD

    Protective TP Load for the Estuary: \3\ TBD

    Less than 50%...............................

    NR

    TBD

    0.107

    TBD 50.1-60.0%..................................

    NR

    TBD

    0.107

    TBD 60.1-70.0%..................................

    NR

    TBD

    0.107

    TBD 70.1-80.0%..................................

    NR

    TBD

    0.107

    TBD 80.1-90.0%..................................

    1.205

    TBD

    0.107

    TBD 90.1-100%...................................

    1.205

    TBD

    0.107

    TBD

    Nassau Coastal Drainage Area \PN\ (CDA Code: \1\ S175x)

    Protective TN Load for the Estuary: \2\ 131,389 kg y-\1\

    Protective TP Load for the Estuary: \3\ TBD

    Less than 50%...............................

    1.205

    0.59

    0.107

    TBD 50.1-60.0%..................................

    NR

    NR

    0.107

    TBD 60.1-70.0%..................................

    NR

    NR

    0.107

    TBD

    Page 4207

    70.1-80.0%..................................

    NR

    NR

    0.107

    TBD 80.1-90.0%..................................

    1.205

    0.33

    0.107

    TBD 90.1-100%...................................

    1.205

    0.30

    0.107

    TBD

    St. Mary's River Watershed \PN\ (EDA Code: \1\ S170x)

    Protective TN Load for the Estuary: \2\ 562,644 kg y-\1\

    Protective TP Load for the Estuary: \3\ TBD

    Less than 50%...............................

    NR

    NR

    0.107

    TBD 50.1-60.0%..................................

    NR

    NR

    0.107

    TBD 60.1-70.0%..................................

    NR

    NR

    0.107

    TBD 70.1-80.0%..................................

    1.205

    0.43

    0.107

    TBD 80.1-90.0%..................................

    1.205

    0.38

    0.107

    TBD 90.1-100%...................................

    1.205

    0.34

    0.107

    TBD

    Footnotes associated with this table:

    \1\ Watershed delineated by NOAA's Coastal Assessment Framework and associated Florida Department of

    Environmental Protection's estuarine and coastal water body identifier (WBID).

    \2\ Estimated TN load delivered to the estuary protective of aquatic life use. These estimates may be revised pursuant to the EPA final rule for numeric nutrient criteria for Florida's estuaries and coastal waters

    (October 2011).

    \3\ Estimated TP load delivered to the estuary protective of aquatic life use. These estimates are currently under development. Preliminary estimates may be revised pursuant to the EPA final rule for numeric nutrient criteria for Florida's estuaries and coastal waters (October 2011).

    \4\ River/Stream reach categories within each estuarine watershed are linked spatially to a specific FDEP water body identifier (WBID). See Appendix B-18 of the ``Technical Support Document for EPA's Proposed Rule for

    Numeric Nutrient Criteria for Florida's Inland Surface Fresh Waters.''

    \5\ Instream Protection Value (IPV) is the TN concentration protective of instream aquatic life use.

    \6\ Downstream protection values (DPVs) are estimated TN concentrations in the river/stream reach that meet the estimated TN load, protective of aquatic life use, delivered to the estuarine waters. These estimates may be revised pursuant to the EPA final rule for numeric nutrient criteria for Florida's estuaries and coastal waters (October 2011).

    \7\ Instream Protection Value (IPV) is the TP concentration protective of instream aquatic life use.

    \8\ Downstream protection values (DPVs) are estimated TP concentrations in the river/stream reach that meet the estimated TP load, protective of aquatic life use, delivered to the estuarine waters. These estimates are currently under development. Preliminary estimates may be revised pursuant to the EPA final rule for numeric nutrient criteria for Florida's estuaries and coastal waters (October 2011).

    \9\ EPA's proposed TN and TP criteria for colored lakes (>40 PCU) are 1.2 and 0.050 mg L-\1\, respectively.

    Estimated TN and TP loads protective of aquatic life in the Caloosahatchee and St. Lucie River estuaries, and in turn estimated TN and TP concentrations that would meet those protective loads, could not be calculated using EPA's downstream protection approach. An alternative downstream protection approach will be proposed in EPA's proposed rule for FL estuaries (January 2011).

    caret

    Kissimmee River watershed does not have an EDA or CDA code because it does not drain directly to an estuary or coastal area, but rather indirectly through Lake Okeechobee and the south Florida canal system.

    A protective TN and TP load for Lake Okeechobee has not been calculated, however, a TMDL is in effect for TP.

    EPA's proposed colored lake criteria (> 40 PCU) could be used to develop DPVs for TN and TP for the Kissimmee watershed (see footnote 9).

    \LO\ DPVs to be based on protective TN and TP loads for Lake Okeechobee. EPA's proposed colored lake criteria

    (>40 PCU) could be used to develop DPVs for TN and TP for the Kissimmee watershed (see footnote 9).

    \NR\ There are no stream reaches present in this watershed that have a percent-delivered within this range and thus criteria are not applicable.

    \PH\ Panhandle Nutrient Watershed Region.

    \BV\ Bone Valley Nutrient Watershed Region.

    \PN\ Peninsula Nutrient Watershed Region.

    \NC\ North Central Nutrient Watershed Region.

    \TBD\ To be determined.

    (v) Application of DPVs for Downstream Estuary Protection

    The following discussion further explains the conceptual relationship between IPVs and DPVs for stream criteria. EPA developed

    IPVs to protect the uses that occur within the stream itself at the point of application, such as protection of the benthic invertebrate community and maintenance of a healthy balance of phytoplankton species. In contrast, EPA developed DPVs for streams to protect WQS of downstream waters. EPA derived DPVs in Florida streams by distributing the protective load from the aggregate stream network identified for each downstream estuary (that is protective of estuarine conditions) across the watershed in proportion to the amount of flow contributed by each stream reach. EPA's approach also accounts for attenuation of nutrients (or loss from the system) as water travels from locations upstream in the watershed to locations near the mouth of the estuary.

    When comparing an IPV and DPV that are each deemed to apply to a particular stream segment, the more stringent of the two values is the numeric nutrient criterion that would need to be met when implementing

    CWA programs. Water bodies can differ significantly in their sensitivity to nutrients in general and to TN specifically. Although not universally true, freshwaters are generally phosphorus-limited and thus more sensitive to phosphorus enrichment because nitrogen is present in excess. Enriching freshwaters with phosphorus does not usually drive these systems into nitrogen limitation but can simply encourage growth of nitrogen-fixing algal species which can convert atmospheric nitrogen into ammonia. Conversely, estuaries are more often nitrogen limited and thus more sensitive to adverse impacts from nitrogen enrichment. As a result, it is not at all surprising that DPVs for TN in Florida are often less than the corresponding IPVs.

    Adjustments to DPVs are possible with a redistribution approach, which revises the original uniform assignment of protective downstream estuarine loadings across the estuarine drainage area using the DPV methodology, or by revising either the protective load delivered to the downstream estuary and/or the equivalent DPVs using a technical approach of comparable scientific rigor and the Federal SSAC procedure described in section V.C of this notice.

    Page 4208

    Re-distributing the allocation of protective loading within an estuarine drainage area, or subset of an estuarine drainage area, is appropriate and protective because the total load delivered to the mouth of the estuary would still meet the protective load. DPVs may be a series of values for each reach in the upstream drainage area such that the sum of reach-specific incremental loading delivered to the estuary equals the protective loading rate taking into account that downstream reaches must reflect loads established for upstream reaches.

    Adjustments to DPVs may also factor in additional nutrient attenuation provided by already existing landscape modifications or treatment systems, such as constructed wetlands or stormwater treatment areas, where the attenuation is sufficiently documented and not a temporary condition. Unlike re-allocation of an even distribution of loading, these types of adjustments, as well as other site-specific information on alternative fractions delivered, would require use of the SSAC procedure under this proposal. EPA requests comment on whether these adjustments should be allowed to occur in the implementation of the re- allocation process rather than as a SSAC.

    A technical approach of comparable scientific rigor will include a systematic data driven evaluation and accompanying analysis of relevant factors to identify a protective load delivered to the estuary. An acceptable alternate numeric approach also includes a method to distribute and apply the load to streams and other waters within the estuarine drainage area in a manner that recognizes conservation of mass and makes use of a peer-reviewed model (empirical or mechanistic) of comparable or greater rigor and scientific defensibility than the

    USGS SPARROW model. To use an alternative technical approach, the State must go through the process for a Federal SSAC procedure as described in Section V.C.

    EPA requests comment on the DPV approach, the technical merit of the estimated protective loadings, and the technical merit of the method for calculating stream reach values. EPA also requests comment on other scientifically defensible approaches for ensuring protection of designated uses in estuaries. At this time, EPA plans to take final action with respect to downstream protection values for nitrogen as part of the second phase of this rulemaking process in coordination with the proposal and finalization of numeric standards for estuarine and coastal waters in 2011. However, if comments, data and analyses submitted as a result of this proposal support finalizing these values sooner, by October 2010, EPA may choose to proceed in this manner. To facilitate this process, EPA requests comments and welcomes thorough evaluation on the technical and scientific basis of these proposed downstream protection values as part of the broader comment and evaluation process that this proposal initiates.

  41. Proposed Numeric Nutrient Criteria for the State of Florida's

    Springs and Clear Streams

    (1) Proposed Numeric Nutrient Criteria for Springs and Clear Streams

    Springs and their associated spring runs in Florida are a unique class of aquatic ecosystem, highly treasured for their biological, economic, aesthetic, and recreational value. Globally, the largest number of springs (per unit of area), occur in Florida; Florida has over 700 springs and associated spring runs. Many of the larger spring ecosystems in Florida have likely been in existence since the end of the last major ice age (approximately 15,000 to 30,000 years ago). The productivity of the diverse assemblage of aquatic flora and fauna in

    Florida springs is primarily determined by the naturally high amount of light availability of these waters (naturally high clarity).\87\ As recently as 50 years ago, these waters were considered by naturalists and scientists to be some of the most unique and exceptional waters in the State of Florida and the Nation as a whole.

    \87\ Brown M.T., K. Chinners Reiss, M.J. Cohen, J.M. Evans, P.W.

    Inglett, K. Sharma Inglett, K. Ramesh Reddy, T.K. Fraze, C.A.

    Jacoby, E.J. Phlips, R.L. Knight, S.K. Notestein, R.G. Hamann, and

    K.A. McKee. 2008. Summary and Synthesis of the Available Literature on the Effects of Nutrients on Spring Organisms and Systems. http:// www.dep.state.fl.us/springs/reports/files/UF_SpringsNutrients_

    Report.pdf, University of Florida, Gainesville, Florida.

    In Florida, springs are also highly valued as a water resource for human use: people use springs for a variety of recreational purposes and are interested in the intrinsic aesthetics of clear, cool water emanating vigorously from beneath the ground. A good example of the value of springs in Florida is the use of the spring boil areas that have sometimes been modified to encourage human recreation (bathing or swimming).\88\

    \88\ Scott, T.M., G.H. Means, R.P. Meegan, R.C. Means, S.B.

    Upchurch, R.E. Copeland, J. Jones, T. Roberts, and A. Willet. 2004.

    Springs of Florida. Bulletin No, 66. Florida Geological Survey.

    Tallahassee, FL. 677 pp.

    Over the past two decades, scientists have identified two significant anthropogenic factors linked to adverse changes in spring ecosystems that have the potential to permanently alter Florida's spring ecosystems. These are: (1) Pollution of groundwater,\89\ principally with nitrate-nitrite, resulting from human land use changes, cultural practices, and explosive population growth; and (2) simultaneous reductions in groundwater supply from human withdrawals.\90\ Pollution associated with human activities is one of the most critical issues affecting the health of Florida's springs.\91\

    \89\ Katz, B.G., H.D. Hornsby, J.F. Bohlke and M.F. Mokray. 1999. Sources and chronology of nitrate contamination in spring water, Suwannee River Basin, Florida. U.S. Geological Survey Water-

    Resources Investigations Report 99-4252. Reston, VA.

    \90\ Brown M.T., K. Chinners Reiss, M.J. Cohen, J.M. Evans, P.W.

    Inglett, K. Sharma Inglett, K. Ramesh Reddy, T.K. Fraze, C.A.

    Jacoby, E.J. Phlips, R.L. Knight, S.K. Notestein, R.G. Hamann, and

    K.A. McKee. 2008. Summary and Synthesis of the Available Literature on the Effects of Nutrients on Spring Organisms and Systems. http:// www.dep.state.fl.us/springs/reports/files/UF_SpringsNutrients_

    Report.pdf, University of Florida, Gainesville, Florida.

    \91\ Ibid.

    Excess nutrients, in particular excess nitrogen, seep into the soils and move to groundwater.\92\ When in excess, nutrients lead to eutrophication of groundwater-fed springs, allowing algae and invasive plant species to displace native plants, which in turn results in an ecological imbalance.\93\ Excessive growth of nuisance algae and noxious plant species in turn result in reduced habitat and food sources for native wildlife,\94\ excess organic carbon production, accelerated decomposition, and lowered quality of the floor or

    ``bottom'' of springs and spring runs, all of which adversely impact the overall health and aesthetics of Florida's springs.

    \92\ Katz, B.G., H.D. Hornsby, J.F. Bohlke and M.F. Mokray. 1999. Sources and chronology of nitrate contamination in spring water, Suwannee River Basin, Florida. U.S. Geological Survey Water-

    Resources Investigations Report 99-4252. Reston, VA.

    \93\ Doyle, R.D. and R.M. Smart. 1998. Competitive reduction of noxious Lyngbya wollei mats by rooted aquatic plants. Aquatic Botany 61:17-32.

    \94\ Stevenson, R.J., A. Pinowska, A. Albertin, and J.O.

    Sickman. 2007. Ecological condition of algae and nutrients in

    Florida springs: The Synthesis Report. Prepared for the Florida

    Department of Environmental Protection. Tallahassee, FL. 58 pp.

    Bonn, M.A. and F.W. Bell. 2003. Economic Impact of Selected

    Florida Springs on Surrounding Local Areas. Report prepared for the

    Florida Department of Environmental Protection. Tallahassee, FL.

    Adverse impacts on the overall health of Florida's springs have been evident over the past several decades. Within the last 20-30 years, observations at

    Page 4209

    several of Florida's springs suggest that nuisance algae species have proliferated, and are now out-competing and replacing native submerged vegetation. Numerous biological studies have documented excessive algal growth at many major springs. In some of the more extreme examples, such as Silver Springs and Weeki Wachee Springs, algal mat accumulations have become over three feet thick.\95\\,\\96\

    \95\ Pinowska, A., R.J. Stevenson, J.O. Sickman, A. Albertin, and M. Anderson. 2007. Integrated interpretation of survey for determining nutrient thresholds for macroalgae in Florida Springs:

    Macroalgal relationships to water, sediment and macroalgae nutrients, diatom indicators and land use. Florida Department of

    Environmental Protection, Tallahassee, FL.

    \96\ Stevenson, R.J., A. Pinowska, and Y.K. Wang. 2004.

    Ecological condition of algae and nutrients in Florida springs.

    Florida Department of Environmental Protection, Tallahassee, FL.

    As a result of human-induced land use changes, cultural practices, and explosive population growth, there has been an increase in the level of pollutants, especially nitrate, in groundwater over the past decades.\97\ Because there is no geologic source of nitrogen in springs, all of the nitrogen emerging in spring vents originates from that which is deposited on the land. Historically, nitrate concentrations in Florida's spring discharges were thought to have been around 0.05 mg/L or less, which is sufficiently low to restrict growth of algae and vegetation under ``natural'' conditions.\98\

    \97\ Scott, T.M., G.H. Means, R.P. Meegan, R.C. Means, S.B.

    Upchurch, R.E. Copeland, J. Jones, T. Roberts, and A. Willet. 2004.

    Springs of Florida. Bulletin No, 66. Florida Geological Survey.

    Tallahassee, FL. 677 pp.

    \98\ Maddox, G.L., J.M. Lloyd, T.M. Scott, S.B. Upchurch and R.

    Copeland. 1992. Florida's Groundwater Quality Monitoring Program--

    Background Hydrochemistry. Florida Geological Survey Special

    Publication 34. Tallahassee, FL.

    Regions where springs emanate in Florida have experienced unprecedented population growth and changes in land use over the past several decades.\99\ With these changes in population and growth came a transfer of nutrients, particularly nitrate, to groundwater. Of 125 spring vents sampled by the Florida Geological Survey in 2001-2002, 42% had nitrate concentrations exceeding 0.50 mg/L and 24% had concentrations greater than 1.0 mg/L.\100\ Similarly, a recent evaluation of water quality in 13 springs shows that mean nitrate- nitrite levels have increased from 0.05 mg/L to 0.9 mg/L between 1970 and 2002. Overall, data suggest that nitrate-nitrite concentrations in many spring discharges have increased from 10 to 350 fold over the past 50 years, with the level of increase closely correlated with anthropogenic activity and land use changes within the karst regions of

    Florida where springs predominate.

    \99\ Katz, B.G., H.D. Hornsby, J.F. Bohlke and M.F. Mokray. 1999. Sources and chronology of nitrate contamination in spring water, Suwannee River Basin, Florida. U. S. Geological Survey Water-

    Resources Investigations Report 99-4252. Reston, VA.

    Brown M.T., K. Chinners Reiss, M.J. Cohen, J.M. Evans, P.W.

    Inglett, K. Sharma Inglett, K. Ramesh Reddy, T.K. Fraze, C.A.

    Jacoby, E.J. Phlips, R.L. Knight, S.K. Notestein, R.G. Hamann, and

    K.A. McKee. 2008. Summary and Synthesis of the Available Literature on the Effects of Nutrients on Spring Organisms and Systems. http:// www.dep.state.fl.us/springs/reports/files/UF_SpringsNutrients_

    Report.pdf, University of Florida, Gainesville, Florida.

    \100\ Scott, T.M., G.H. Means, R.P. Meegan, R.C. Means, S.B.

    Upchurch, R.E. Copeland, J. Jones, T. Roberts, and A. Willet. 2004.

    Springs of Florida. Bulletin No, 66. Florida Geological Survey.

    Tallahassee, FL. 677 pp.

    As nitrate-nitrite concentrations have increased during the past 20 to 50 years, many Florida springs have undergone adverse environmental and biological changes. According to FDEP, there is a general consensus in the scientific community that nitrate is an important factor leading to the observed changes in spring ecosystems, and their associated biological communities. Nitrogen, particularly nitrate-nitrite, appears to be the most problematic nutrient problem in Florida's karst region.\101\

    \101\ Brown M.T., K. Chinners Reiss, M.J. Cohen, J.M. Evans,

    P.W. Inglett, K. Sharma Inglett, K. Ramesh Reddy, T.K. Fraze, C.A.

    Jacoby, E.J. Phlips, R.L. Knight, S.K. Notestein, R.G. Hamann, and

    K.A. McKee. 2008. Summary and Synthesis of the Available Literature on the Effects of Nutrients on Spring Organisms and Systems. http:// www.dep.state.fl.us/springs/reports/files/UF_SpringsNutrients_

    Report.pdf, University of Florida, Gainesville, Florida.

    Because nitrate-nitrite has been linked to many of the observed detrimental impacts in spring ecosystems, there is an immediate need to reduce nitrate-nitrite concentrations in spring vents and groundwater.

    A critical step in achieving reductions in nitrate-nitrite is to develop a numeric nitrate-nitrite criterion for spring systems that will be protective of these unique and treasured resources.\102\

    \102\ Brown M.T., K. Chinners Reiss, M.J. Cohen, J.M. Evans,

    P.W. Inglett, K. Sharma Inglett, K. Ramesh Reddy, T.K. Fraze, C.A.

    Jacoby, E.J. Phlips, R.L. Knight, S.K. Notestein, R.G. Hamann, and

    K.A. McKee. 2008. Summary and Synthesis of the Available Literature on the Effects of Nutrients on Spring Organisms and Systems. http:// www.dep.state.fl.us/springs/reports/files/UF_SpringsNutrients_

    Report.pdf, University of Florida, Gainesville, Florida.

    To protect springs and clear streams and to provide assessment levels and restoration goals for those that have already been impaired by nutrients, EPA is proposing numeric nutrient criteria for the following parameter for Florida's springs and clear streams (3\-\)+Nitrite (NO2\-\) shall not surpass a concentration of 0.35 mg/L as an annual geometric mean more than once in a three-year period, nor surpassed as a long-term average of annual geometric mean values.

    In addition to the nitrate-nitrite criterion, TN and TP criteria developed for streams on a watershed basis are also applicable to clear streams. See Section III.C(1) ``Proposed Numeric Nutrient Criteria for the State of Florida's Rivers and Streams'' for the table of proposed

    TN and TP criteria that would apply to clear streams located within specific watersheds.

    (2) Methodology for Deriving EPA's Proposed Criteria for Springs and

    Clear Streams

    EPA's proposed nitrate-nitrite criterion for springs and clear streams are derived from a combination of FDEP laboratory data, field surveys, and analyses which include analyses conducted to determine the stressor response-based thresholds that link nitrate-nitrite levels to biological risk in springs and clear streams. These data document the response of nuisance algae, Lyngbya wollei and Vaucheria sp., and periphyton to nitrate-nitrite concentrations. Please refer to EPA's TSD for Florida's Inland Waters, Chapter 3: Methodology for Deriving U.S.

    EPA's Proposed Criteria for Springs and Clear Streams.

    As described in Section III.C(2), the ability to establish protective criteria for both causal and response variables depends on available data and scientific approaches to evaluate these data. EPA has not undertaken the development of TP criteria for springs because phosphorus has historically been present in Florida's springs, given the State's naturally phosphorus-rich geology, and the lack of an increasing trend of phosphorus concentrations in most spring discharges. EPA is not proposing chlorophyll a and clarity criteria due to the lack of available data for these response variables in spring systems. Furthermore, scientific evidence examining the strong relationship between rapid periphyton survey data (measurements of the thickness of algal biomass attached to substrate rather than free- floating) and nutrients in clear streams (those with color 1: Estimate STA inflow loads resulting in WQS in downstream waters'', and Section 4.2.2.2 of the

    TMDL document, ``Approach 2: Simple modeling approach.'' The first approach takes into account the downstream criterion of the EvPA and the performance of the stormwater treatment areas (STAs). Based on these considerations, inflowing TP concentrations within the EAA to the

    STAs were derived to meet the downstream EvPA TP criterion of 0.010 mg/

    L. The second approach used a model that extrapolated natural background TP concentrations, based on land use changes, for specific

    WBIDs within the EAA. These approaches could support the derivation of numeric nutrient criteria for TP within the EAA region. Approach 1 would result in a TP concentration of 0.10 mg/L, while

    Approach 2 would result in a TP concentration of 0.087 mg/L.

    \110\ Proposed Total Maximum Daily Load (TMDL) for Dissolved

    Oxygen and Nutrient in the Everglades. Prepared by U.S. EPA Region 4. September 2007.

    (5) Request for Comment and Data on Alternative Approaches

    The alternatives for Class III south Florida canal criteria in this proposed rule represent alternative approaches given the availability of data in the State of Florida to date and are consistent with the requirements of both the CWA and EPA's implementing regulations. EPA is soliciting comment on the alternative approaches considered by the

    Agency in this proposal, the data underlying those approaches, and the proposed alternatives themselves, including criteria expressed as an upper percentile maxima not to be exceeded more than 10% of the time in one year, similar to those discussed for lakes. For further information on the upper percentile criteria for canals, refer to EPA's TSD on

    Florida's Inland Waters, Chapter 4: Methodology for Deriving U.S. EPA's

    Proposed Criteria for Canals. EPA is seeking other pertinent data and information related to nutrient concentrations or nutrient responses in

    Class III canals in south Florida.

  42. Comparison Between EPA's and Florida DEP's Proposed Numeric Nutrient

    Criteria for Florida's Lakes and Flowing Waters

    To date, Florida has invested significant resources in its statewide nutrient criteria effort, and has made substantial progress toward developing numeric nutrient criteria. For several years, FDEP has been actively working with EPA on the development of numeric nutrient criteria and EPA has worked extensively with FDEP on data interpretation and technical analyses for developing EPA's recommended numeric nutrient criteria proposed in this rulemaking.

    On January 14, 2009, EPA formally determined that numeric nutrient criteria were necessary to protect Florida's lakes and flowing waters and should be developed by January 14, 2010. FDEP, independently from

    EPA, initiated its own State rulemaking process to adopt numeric nutrient water quality criteria protective of Florida's lakes and flowing waters. According to FDEP, the State initiated its rulemaking process to facilitate the assessment of designated use attainment for

    Florida's waters and to provide a better means to protect its waters from the adverse effects of nutrient over-enrichment. Florida established a technical advisory committee, which met over a number of years, to help develop its proposed numeric nutrient criteria. The

    State also held several public workshops to solicit

    Page 4215

    comment on the draft WQS. While FDEP was progressing with its State rulemaking, EPA moved forward to develop Federal numeric nutrient criteria for Florida's lakes and flowing waters, consistent with EPA's

    January 14, 2009 determination and based on the best available science.

    Most recently, in July 2009, FDEP solicited public comment on its proposed numeric nutrient criteria for lakes and flowing waters. In

    October 2009, FDEP decided not to bring the draft criteria before the

    Florida Environmental Regulation Commission (ERC), as had been previously scheduled. FDEP did not make any final decisions as to whether it might be appropriate to ask the ERC to adopt the criteria or some portions of the criteria at a later date.

    As described in Section III., EPA is proposing numeric nutrient criteria for the following four water body types: Lakes, streams, springs and clear streams, and canals in south Florida. Given that FDEP has made its proposed numeric nutrient criteria available to the public via its Web site (http://www.dep.state.fl.us/water/wqssp/nutrients/ index.htm), it is worth providing a comparative overview between the criteria and approaches that EPA is proposing in this rulemaking and the criteria and approaches FDEP had initially proposed. Both EPA and

    FDEP developed numeric criteria recognizing the hydrologic and spatial variability of nutrients in Florida's lakes and flowing waters. As FDEP indicated on its Web site, FDEP's preferred approach is to develop cause and effect relationships between nutrients and valued ecological attributes, and to establish nutrient criteria based on those cause and effect relationships that ensure that the designated uses of Florida's waters are protected and maintained. As described in EPA's guidance,

    EPA also recommends this approach when scientifically defensible data are available. Where cause and effect relationships could not be demonstrated, however, both FDEP and EPA relied on a distribution-based approach to derive numeric nutrient criteria protective of applicable designated uses.

    To set numeric nutrient criteria for lakes, EPA, like FDEP, is proposing a classification scheme using color and alkalinity based upon substantial data that show that lake color and alkalinity play an important role in the degree to which TN and TP concentrations result in a biological response such as elevated chlorophyll a levels. EPA and

    FDEP both found that correlations between nutrients and response parameters were sufficiently robust to use for criteria development in

    Florida's lakes. EPA is proposing the same chlorophyll a criteria for colored lakes and clear alkaline lakes as FDEP proposed, however, EPA is proposing a lower chlorophyll a criterion for clear acidic lakes.

    EPA, like FDEP, is also proposing an accompanying supplementary analytical approach that Florida can use to adjust general TN and TP lake criteria within a certain range where sufficient data on long-term ambient TN and TP levels are available to demonstrate that protective chlorophyll a criteria for a specific lake will still be maintained and attainment of the designated use will be assured.

    EPA proposed criteria

    Florida proposed criteria

    Lake class

    Chl a, [mu]g/L

    TN, mg/L

    TP, mg/L

    Chl a, [mu]g/L

    TN, mg/L

    TP, mg/L

    Colored Lakes > 40 PCU..................................

    20

    1.23-2.25

    0.050-0.157

    20

    1.23-2.25

    0.05-0.157

    Clear Lakes, Alkaline 50 mg/L CaCO3.....

    20

    1.00-1.81

    0.030-0.087

    20

    1.00-1.81

    0.03-0.087

    Clear Lakes, Acidic 50%) source of water is from a spring or spring group.

    (9) State shall mean the State of Florida, whose transactions with the U.S. EPA in matters related to this regulation are administered by the Secretary, or officials delegated such responsibility, of the

    Florida Department of Environmental Protection (FDEP), or successor agencies.

    (10) Stream means a free-flowing, predominantly fresh surface water in a defined channel, and includes rivers, creeks, branches, canals

    (outside south Florida), freshwater sloughs, and other similar water bodies.

    (11) Surface water means water upon the surface of the earth, whether contained in bounds created naturally or artificially or diffused. Water from natural springs shall be classified as surface water when it exits from the spring onto the Earth's surface.

    (c) Criteria for Florida waters--

    (1) Criteria for lakes. The applicable criterion for chlorophyll a, total nitrogen (TN), and total phosphorus (TP) for lakes within each respective lake class is shown on the following table:

    Baseline criteria \b\

    Modified criteria (within

    Long-term average lake color and Chlorophyll a --------------------------------

    these bounds) \c\ alkalinity

    \f\ ([mu]g/L)

    -------------------------------

    \a\

    TP (mg/L) \a\ TN (mg/L) \a\ TP (mg/L) \a\ TN (mg/L) \a\

    A

    B

    C

    D

    E

    F

    Colored Lakes > 40 PCU..........

    20

    0.050

    1.23

    0.050-0.157

    1.23-2.25

    Clear Lakes, Alkaline 50 mg/L CaCO3 \e\....

    Clear Lakes, Acidic Sis the total phosphorus (TP) downstream lake protection value, mg/L

    TP

    Lis applicable TP lake criterion, mg/L cfis the fraction of inflow due to all streamflow, 0 fwis lake's hydraulic retention time (water volume divided by annual flow rate)

    The term

    GRAPHIC

    TIFF OMITTED TP26JA10.006 expresses the net phosphorus loss from the water column (e.g., via settling of sediment-sorbed phosphorus) as a function of the lake's retention time.

    (B) The preset values for cfand [tau]w, respectively, are 0.5 and 0.2. The State may substitute site-specific values for these preset values where the State determines that they are appropriate and documents the site-specific values in an easily accessible and publicly available location, such as an official State

    Web site.

    (iii) Criteria for protection of downstream estuarine waters.

    (A) The applicable criteria for a stream that flows into downstream estuary is the more stringent of the values from the preceding table in paragraph (c)(2)(i) of this section or downstream protection values derived from the following equation to protect the downstream estuary.

    EPA's preset DPVs are listed in the Technical Support Document (TSD) for Florida's Inland Waters located at www.regulations.gov, Docket ID

    No. EPA-HQ-OW-2009-0569, and calculated for each stream reach as the average reach-specific concentration (Ci) equal to the average reach- specific annual loading rate (Li) divided by the average reach-specific flow (Qi) where:

    GRAPHIC

    TIFF OMITTED TP26JA10.004 and where the terms are defined as follows for a specific or

    (ith) stream reach:

    Ci maximum flow-averaged nutrient concentration for a specific (the ith) stream reach consistent with downstream use protection (i.e., the DPV) k fraction of all loading to the estuary that comes from the stream network resolved by SPARROW

    Lest protective loading rate for the estuary, from all sources

    Qw combined average freshwater discharged into the estuary from the portion of the watershed resolved by the SPARROW stream network

    Fi fraction of the flux at the downstream node of the specific

    (ith) reach that is transported through the stream network and ultimately delivered to estuarine eceiving waters (i.e.

    Fraction Delivered).

    DPVs may not exceed other criteria established for designated use protection in this section, nor result in an exceedance of other criteria for other water quality parameters established pursuant to

    Rule 62-302, F.A.C.

    (B) The State may calculate alternative DPVs as above for Ci except that Li is determined as a series of values for each reach in the upstream drainage area such that the sum of reach-specific incremental loading rates equals the target loading rate to the downstream water protective of downstream uses, taking into account that downstream reaches must reflect loads established for upstream reaches.

    Alternative DPVs may factor in additional nutrient attenuation provided by already existing landscape modifications or treatment systems, such as constructed wetlands or stormwater treatment areas. For alternative

    DPVs to become effective for Clean Water Act purposes, the State must provide public notice and opportunity for comment.

    (C) To use an alternative technical approach of comparable scientific rigor to quantitatively determine the protective load to the estuary and associated protective stream concentrations, the State must go through the process for a Federal site-specific alternative criterion pursuant to paragraph (e) of this section.

    (3) Criteria for springs, spring runs, and clear streams. The applicable nitrate-nitrite criterion is 0.35 mg/L as an annual geometric mean not to be surpassed more than once in a three year period, nor surpassed as a long-term average of annual geometric mean values. In addition to this nitrate-nitrite criterion, criteria identified in paragraph (c)(2) of this section are applicable to clear streams.

    (4) Criteria for south Florida canals. The applicable criterion for chlorophyll a, total nitrogen (TN), and total phosphorus (TP) for canals within each respective canal geographic classification area is shown on the following table:

    Total

    Chlorophyll a phosphorus

    Total nitrogen

    ([mu]g/L) \a\

    (TP) (mg/L)

    (TN) (mg/L)

    \a\ \b\

    \a\

    Canals..........................................................

    4.0

    0.042

    1.6

    \a\ Concentration values are based on annual geometric mean not to be surpassed more than once in a three-year period. In addition, the long-term average of annual geometric mean values shall not surpass the listed concentration values. (Duration = annual; Frequency = not to be surpassed more than once in a three-year period or as a long-term average).

    \b\ Applies to all canals within the Florida Department of Environmental Protection's South Florida bioregion, with the exception of canals within the Everglades Protection Area (EvPA) where the TP criterion of 0.010 mg/L currently applies.

    (5) Criteria for estuaries. [Reserved]

    (6) Criteria for coastal waters. [Reserved]

    (d) Applicability.

    (1) The criteria in paragraphs (c)(1) through (4) of this section apply to surface waters of the State of Florida designated as Class I

    (Potable Water Supplies) or Class III (Recreation, Propagation and

    Maintenance of a Healthy, Well-Balanced Population of Fish and

    Wildlife) water bodies pursuant to Rule 62-302.400, F.A.C., excluding wetlands, and apply concurrently with other applicable water quality criteria, except when:

    (i) State regulations contain criteria which are more stringent for a particular parameter and use;

    (ii) The Regional Administrator determines that site-specific alternative criteria apply pursuant to the procedures in paragraph (e) of this section;

    (iii) The State adopts and EPA approves a water quality standards variance to the Class I or Class III designated use pursuant to Sec. 131.13 that meets the applicable provisions of State law and the applicable Federal regulations at Sec. 131.10; or

    Page 4226

    (iv) The State adopts and EPA approves restoration standards pursuant to paragraph (g) of this section.

    (2) The criteria established in this section are subject to the

    State's general rules of applicability in the same way and to the same extent as are the other federally-adopted and State-adopted numeric criteria when applied to the same use classifications.

    (i) For all waters with mixing zone regulations or implementation procedures, the criteria apply at the appropriate locations within or at the boundary of the mixing zones; otherwise the criteria apply throughout the water body including at the point of discharge into the water body.

    (ii) The State shall use an appropriate design flow condition, where necessary, for purposes of permit limit derivation or load and wasteload allocations that is consistent with the criteria duration and frequency established in this section (e.g., average annual flow for a criterion magnitude expressed as an average annual geometric mean value).

    (iii) The criteria established in this section apply for purposes of determining the list of impaired waters pursuant to section 303(d) of the Clean Water Act, subject to the procedures adopted pursuant to

    Rule 62-303, F.A.C., where such procedures are consistent with the level of protection provided by the criteria established in this section.

    (e) Site-specific alternative criteria.

    (1) Upon request from the State, the Regional Administrator may determine that site-specific alternative criteria shall apply to specific surface waters in lieu of the criteria established in paragraph (c) of this section. Any such determination shall be made consistent with Sec. 131.11.

    (2) To receive consideration from the Regional Administrator for a determination of site-specific alternative criteria, the State must submit a request that includes proposed alternative numeric criteria and supporting rationale suitable to meet the needs for a technical support document pursuant to paragraph (e)(3) of this section.

    (3) For any determination made under paragraph (e)(1) of this section, the Regional Administrator shall, prior to making such a determination, provide for public notice and comment on a proposed determination. For any such proposed determination, the Regional

    Administrator shall prepare and make available to the public a technical support document addressing the specific surface waters affected and the justification for each proposed determination. This document shall be made available to the public no later than the date of public notice issuance.

    (4) The Regional Administrator shall maintain and make available to the public an updated list of determinations made pursuant to paragraph

    (e)(1) of this section as well as the technical support documents for each determination.

    (5) Nothing in this paragraph (e) shall limit the Administrator's authority to modify the criteria in paragraph (c) of this section through rulemaking.

    (f) Effective date. All criteria will be in effect [date 60 days after publication of final rule].

    (g) Restoration Water Quality Standards (WQS). The State may, at its discretion, adopt restoration WQS to allow attainment of a designated use over phased time periods where the designated use is not currently attainable as a result of nutrient pollution but is attainable in the future. In establishing restoration WQS, the State must:

    (1) Demonstrate that the designated use is not attainable during the time periods established for the restoration phases based on one of the factors identified in Sec. 131.10(g)(1) through (6);

    (2) Specify the designated use to be attained at the termination of the restoration period, as well as the criteria necessary to protect such use, provided that the final designated use and corresponding criteria shall include, at a minimum, uses and criteria that are consistent with CWA section 101(a)(2) ;

    (3) Establish interim restoration designated uses and water quality criteria, that apply during each phase that will result in maximum feasible progress toward the highest attainable designated use and the use identified in paragraph (g)(2) of this section. Such interim uses and criteria may not provide for further degradation of a water body and may be revised prior to the end of each phase in accordance with

    Sec. Sec. 131.10 and 131.20 and submitted to EPA for approval;

    (4) Establish the time periods for each restoration phase that will result in maximum feasible progress toward the highest attainable use and the designated use identified in paragraph (g)(2) of this section, except that the sum of such time periods shall not exceed twenty years from the initial date of establishment of the restoration WQS under this section;

    (5) Specify the spatial extent of applicability for all affected waters;

    (6) Meet the requirements of Sec. Sec. 131.10 and 131.20; and

    (7) Include, in its State water quality standards, a specific provision that if the interim restoration designated uses and criteria established under paragraph (g)(3) of this section are not met during any phased time period established under paragraph (g)(4) of this section, the restoration WQS will no longer be applicable and the designated use and criteria identified in paragraph (g)(2) of this section will become applicable immediately.

    (8) Provide that waters for which a restoration water quality standard is adopted will be recognized as impaired for the purposes of listing impaired waters under section 303(d) of the CWA until the use designated identified in paragraph (g)(2) of this section is attained.

    FR Doc. 2010-1220 Filed 1-25-10; 8:45 am

    BILLING CODE 6560-50-P