Endangered and Threatened Wildlife and Plants; Designation of Critical Habitat for the Northern Mexican Gartersnake and Narrow-Headed Gartersnake
Federal Register, Volume 78 Issue 132 (Wednesday, July 10, 2013)
Federal Register Volume 78, Number 132 (Wednesday, July 10, 2013)
Proposed Rules
Pages 41549-41608
From the Federal Register Online via the Government Printing Office www.gpo.gov
FR Doc No: 2013-16520
Page 41549
Vol. 78
Wednesday,
No. 132
July 10, 2013
Part III
Department of the Interior
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Fish and Wildlife Service
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50 CFR Part 17
Endangered and Threatened Wildlife and Plants; Designation of Critical Habitat for the Northern Mexican Gartersnake and Narrow-Headed Gartersnake; Proposed Rule
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DEPARTMENT OF THE INTERIOR
Fish and Wildlife Service
50 CFR Part 17
Docket No. FWS-R2-ES-2013-0022; 4500030113
RIN 1018-AZ35
Endangered and Threatened Wildlife and Plants; Designation of Critical Habitat for the Northern Mexican Gartersnake and Narrow-Headed Gartersnake
AGENCY: Fish and Wildlife Service, Interior.
ACTION: Proposed rule.
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SUMMARY: We, the U.S. Fish and Wildlife Service, propose to designate critical habitat for the northern Mexican gartersnake (Thamnophis eques megalops) and narrow-headed gartersnake (Thamnophis rufipunctatus) in Arizona and New Mexico, under the Endangered Species Act of 1973, as amended (Act). If we finalize this rule as proposed, it would extend the Act's protections to these species' habitats. The effect of this regulation is to conserve northern Mexican and narrow-headed gartersnake habitat under the Act.
DATES: We will accept comments received or postmarked on or before September 9, 2013. Comments submitted electronically using the Federal eRulemaking Portal (see ADDRESSES section, below) must be received by 11:59 p.m. Eastern Time on the closing date. We must receive requests for public hearings, in writing, at the address shown in the FOR FURTHER INFORMATION CONTACT section by August 26, 2013.
ADDRESSES: You may submit comments by one of the following methods:
(1) Electronically: Go to the Federal eRulemaking Portal: http://www.regulations.gov. Search for Docket No. FWS-R2-ES-2013-0022, which is the docket number for this rulemaking. You may submit a comment by clicking on ``Comment Now!''
(2) By hard copy: Submit by U.S. mail or hand-delivery to: Public Comments Processing, Attn: FWS-R2-ES-2013-0022; Division of Policy and Directives Management; U.S. Fish and Wildlife Service; 4401 N. Fairfax Drive, MS 2042-PDM; Arlington, VA 22203.
We request that you send comments only by the methods described above. We will post all comments on http://www.regulations.gov. This generally means that we will post any personal information you provide us (see the Information Requested section below for more information).
The coordinates or plot points or both from which the critical habitat maps are generated are included in the administrative record for this rulemaking and are available at http://www.fws.gov/southwest/es/arizona, http://www.regulations.gov at Docket No. FWS-R2-ES-2013-
0022, and at the Arizona Ecological Services Field Office (see FOR FURTHER INFORMATION CONTACT). Any additional tools or supporting information that we may develop for this rulemaking will also be available at the Fish and Wildlife Service Web site and Field Office set out above, and may also be included in the preamble of this proposal and/or at http://www.regulations.gov.
FOR FURTHER INFORMATION CONTACT: Steve Spangle, Field Supervisor, U.S. Fish and Wildlife Service, Arizona Ecological Services Field Office, 2321 West Royal Palm Road, Suite 103, Phoenix, AZ 85021; telephone: 602-242-0210; facsimile: 602-242-2513. If you use a telecommunications device for the deaf (TDD), call the Federal Information Relay Service (FIRS) at 800-877-8339.
SUPPLEMENTARY INFORMATION:
Executive Summary
Why we need to publish a rule. Under the Act, once a species is determined to be an endangered or threatened species throughout all or a significant portion of its range, we are required to promptly publish a proposal in the Federal Register and make a determination on our proposal within 1 year. Additionally, critical habitat shall be designated, to the maximum extent prudent and determinable, for any species determined to be an endangered or threatened species under the Act. Designations and revisions of critical habitat can only be completed by issuing a rule. Elsewhere in today's Federal Register, we propose to list the northern Mexican and narrow-headed gartersnakes as threatened species under the Act.
This rule consists of: A proposed rule for designation of critical habitat for northern Mexican and narrow-headed gartersnakes. These gartersnakes are proposed for listing under the Act. This rule proposes designation of critical habitat necessary for the conservation of the species.
The basis for our action. Under the Act, when a species is proposed for listing, to the maximum extent prudent and determinable, we must designate critical habitat for the species. These species are proposed for listing as threatened. Therefore, we propose to designate critical habitat for the northern Mexican gartersnake in Greenlee, Graham, Apache, La Paz, Mohave, Yavapai, Navajo, Gila, Coconino, Cochise, Santa Cruz, Pima, and Pinal Counties in Arizona, as well as in Grant and Catron Counties in New Mexico, and critical habitat for the narrow-
headed gartersnake in Greenlee, Graham, Apache, Yavapai, Navajo, Gila, and Coconino Counties in Arizona, as well as in Grant, Hidalgo, Sierra, and Catron Counties in New Mexico.
We will seek peer review. We are seeking comments from knowledgeable individuals with scientific expertise to review our analysis of the best available science and application of that science and to provide any additional scientific information to improve this proposed rule. Because we will consider all comments and information received during the comment period, our final determinations may differ from this proposal.
Information Requested
We intend that any final action resulting from this proposed rule will be based on the best scientific and commercial data available and be as accurate and as effective as possible. Therefore, we request comments or information from other concerned governmental agencies, Native American tribes, the scientific community, industry, or any other interested parties concerning this proposed rule. We particularly seek comments concerning:
(1) The reasons why we should or should not designate habitat as ``critical habitat'' under section 4 of the Act (16 U.S.C. 1531 et seq.), including whether there are threats to the species from human activity, the degree of which can be expected to increase due to the designation, and whether that increase in threats outweighs the benefit of designation such that the designation of critical habitat is not prudent.
(2) Specific information on:
(a) The amount and distribution of northern Mexican or narrow-
headed gartersnakes and their habitat;
(b) What may constitute ``physical or biological features essential to the conservation of the species,'' within the geographical range currently occupied by the species;
(c) Where these features are currently found;
(d) Whether any of these features may require special management considerations or protection;
(e) What areas, that were occupied at the time of listing (or are currently occupied) and that contain features
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essential to the conservation of the species, should be included in the designation and why; and
(f) What areas not occupied at the time of listing are essential for the conservation of the species and why.
(3) Land use designations and current or planned activities in the areas occupied by the species or proposed to be designated as critical habitat, and possible impacts of these activities on this species and proposed critical habitat.
(4) Any foreseeable economic, national security, or other relevant impacts that may result from designating any area that may be included in the final designation. We are particularly interested in any impacts on small entities, and the benefits of including or excluding areas from the proposed designation that are subject to these impacts.
(5) Whether our approach to designating critical habitat could be improved or modified in any way to provide for greater public participation and understanding, or to assist us in accommodating public concerns and comments.
(6) The likelihood of adverse social reactions to the designation of critical habitat and how the consequences of such reactions, if likely to occur, would relate to the conservation and regulatory benefits of the proposed critical habitat designation.
(7) If considered for exclusion from critical habitat designation under section 4(b)(2) of the Act, documentation that describes how lands are managed for wildlife and habitat and how that management specifically benefits either or both the northern Mexican or narrow-
headed gartersnake or their prey bases.
Please include sufficient information with your submission (such as scientific journal articles or other publications) to allow us to verify any scientific or commercial information you include.
Please note that submissions merely stating support for or opposition to the action under consideration without providing supporting information, although noted, will not be considered in making a determination, as section 4(b)(1)(A) of the Act directs that determinations as to whether any species is an endangered or threatened species must be made ``solely on the basis of the best scientific and commercial data available.''
You may submit your comments and materials concerning this proposed rule by one of the methods listed in the ADDRESSES section. We request that you send comments only by the methods described in the ADDRESSES section.
If you submit information via http://www.regulations.gov, your entire submission--including any personal identifying information--will be posted on the Web site. If your submission is made via a hardcopy that includes personal identifying information, you may request at the top of your document that we withhold this information from public review. However, we cannot guarantee that we will be able to do so. We will post all hardcopy submissions on http://www.regulations.gov.
Comments and materials we receive, as well as supporting documentation we used in preparing this proposed rule, will be available for public inspection on http://www.regulations.gov, or by appointment, during normal business hours, at the U.S. Fish and Wildlife Service, Arizona Ecological Services Field Office (see FOR FURTHER INFORMATION CONTACT).
Previous Federal Actions
All previous Federal actions are described in the proposal to list the northern Mexican and narrow-headed gartersnakes as threatened species under the Act published elsewhere in today's Federal Register.
Background
Critical habitat is defined in section 3 of the Act as:
(1) The specific areas within the geographical area occupied by the species, at the time it is listed in accordance with the Act, on which are found those physical or biological features
(a) Essential to the conservation of the species and
(b) Which may require special management considerations or protection; and
(2) Specific areas outside the geographical area occupied by the species at the time it is listed, upon a determination that such areas are essential for the conservation of the species.
Conservation, as defined under section 3 of the Act, means to use and the use of all methods and procedures that are necessary to bring an endangered or threatened species to the point at which the measures provided pursuant to the Act are no longer necessary. Such methods and procedures include, but are not limited to, all activities associated with scientific resources management such as research, census, law enforcement, habitat acquisition and maintenance, propagation, live trapping, and transplantation, and, in the extraordinary case where population pressures within a given ecosystem cannot be otherwise relieved, may include regulated taking.
Critical habitat receives protection under section 7 of the Act through the requirement that Federal agencies ensure, in consultation with the Service, that any action they authorize, fund, or carry out is not likely to result in the destruction or adverse modification of critical habitat. The designation of critical habitat does not affect land ownership or establish a refuge, wilderness, reserve, preserve, or other conservation area. Such designation does not allow the government or public to access private lands. Such designation does not require implementation of restoration, recovery, or enhancement measures by non-Federal landowners. Where a landowner requests Federal agency funding or authorization for an action that may affect a listed species or critical habitat, the consultation requirements of section 7(a)(2) of the Act would apply, but even in the event of a destruction or adverse modification finding, the obligation of the Federal action agency and the landowner is not to restore or recover the species, but to implement reasonable and prudent alternatives to avoid destruction or adverse modification of critical habitat.
Under the first prong of the Act's definition of critical habitat, areas within the geographic area occupied by the species at the time it was listed are included in a critical habitat designation if they contain physical or biological features (1) which are essential to the conservation of the species and (2) which may require special management considerations or protection. For these areas, critical habitat designations identify, to the extent known using the best scientific and commercial data available, those physical or biological features that are essential to the conservation of the species (such as space, food, cover, and protected habitat). In identifying those physical and biological features within an area, we focus on the principal biological or physical constituent elements (primary constituent elements such as roost sites, nesting grounds, seasonal wetlands, water quality, tide, soil type, etc.) that are essential to the conservation of the species. Primary constituent elements are the elements of physical or biological features that, when laid out in the appropriate quantity and spatial arrangement to provide for a species' life-history processes, are essential to the conservation of the species.
Under the second prong of the Act's definition of critical habitat, we can designate critical habitat in areas outside the geographic area occupied by
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the species at the time it is listed, upon a determination that such areas are essential for the conservation of the species. For example, an area currently occupied by the species, but that was not occupied at the time of listing, may be essential to the conservation of the species and may be included in the critical habitat designation. We designate critical habitat in areas outside the geographic area occupied by a species only when a designation limited to its range would be inadequate to ensure the conservation of the species.
Section 4 of the Act requires that we designate critical habitat on the basis of the best scientific data available. Further, our Policy on Information Standards Under the Endangered Species Act (published in the Federal Register on July 1, 1994 (59 FR 34271)), the Information Quality Act (section 515 of the Treasury and General Government Appropriations Act for Fiscal Year 2001 (Pub. L. 106-554; H.R. 5658)), and our associated Information Quality Guidelines, provide criteria, establish procedures, and provide guidance to ensure that our decisions are based on the best scientific data available. They require our biologists, to the extent consistent with the Act and with the use of the best scientific data available, to use primary and original sources of information as the basis for recommendations to designate critical habitat.
When we are determining which areas should be designated as critical habitat, our primary source of information is generally the information developed during the listing process for the species. Additional information sources may include the recovery plan for the species, articles in peer-reviewed journals, conservation plans developed by States and counties, scientific status surveys and studies, biological assessments, other unpublished materials, or experts' opinions or personal knowledge.
Habitat is dynamic, and species may move from one area to another over time. We recognize that critical habitat designated at a particular point in time may not include all of the habitat areas that we may later determine are necessary for the recovery of the species. For these reasons, a critical habitat designation does not signal that habitat outside the designated area is unimportant or may not be needed for recovery of the species. Areas that are important to the conservation of the species, both inside and outside the critical habitat designation, will be subject to: (1) Conservation actions implemented under section 7(a)(1) of the Act, (2) regulatory protections afforded by the requirement in section 7(a)(2) of the Act for Federal agencies to ensure their actions are not likely to jeopardize the continued existence of any endangered or threatened species, and (3) the prohibitions of section 9 of the Act if actions occurring in these areas may affect the species. Federally funded or permitted projects affecting listed species outside their designated critical habitat areas may still result in jeopardy findings in some cases. These protections and conservation tools will continue to contribute to recovery of this species. Similarly, critical habitat designations made on the basis of the best available information at the time of designation will not control the direction and substance of future recovery plans, habitat conservation plans (HCPs), or other species conservation planning efforts if new information available at the time of these planning efforts calls for a different outcome.
Prudency Determination
Section 4(a)(3) of the Act, as amended, and implementing regulations (50 CFR 424.12), require that, to the maximum extent prudent and determinable, the Secretary shall designate critical habitat at the time the species is determined to be an endangered or threatened species. Our regulations (50 CFR 424.12(a)(1)) state that the designation of critical habitat is not prudent when one or both of the following situations exist:
(1) The species is threatened by taking or other human activity, and identification of critical habitat can be expected to increase the degree of threat to the species, or
(2) Such designation of critical habitat would not be beneficial to the species.
There is currently no imminent threat of take attributed to collection or vandalism for either of these species, and identification and mapping of critical habitat is not expected to initiate any such threat. In the absence of finding that the designation of critical habitat would increase threats to a species, if there are any benefits to a critical habitat designation, then a prudent finding is warranted. Here, the potential benefits of designation include: (1) Triggering consultation under section 7 of the Act, in new areas for actions in which there may be a Federal nexus where it would not otherwise occur because, for example, it is or has become unoccupied or the occupancy is in question; (2) focusing conservation activities on the most essential features and areas; (3) providing educational benefits to State or county governments or private entities; and (4) preventing people from causing inadvertent harm to the species. Therefore, because we have determined that the designation of critical habitat would not likely increase the degree of threat to the species and may provide some measure of benefit, we find that designation of critical habitat is prudent for the northern Mexican and narrow-headed gartersnakes.
Critical Habitat Determinability
Having determined that designation is prudent, under section 4(a)(3) of the Act, we must find whether critical habitat for the northern Mexican and narrow-headed gartersnakes is determinable. Our regulations at 50 CFR 424.12(a)(2) state that critical habitat is not determinable when one or both of the following situations exist:
(i) Information sufficient to perform required analyses of the impacts of the designation is lacking, or
(ii) The biological needs of the species are not sufficiently well known to permit identification of an area as critical habitat. When critical habitat is not determinable, the Act allows the Service an additional year to publish a critical habitat designation (16 U.S.C. 1533(b)(6)(C)(ii)).
We reviewed the best available scientific and commercial information pertaining to the biological needs of the species and habitat characteristics where the species are located. Based on this information, we conclude that sufficient information is known regarding the species' needs and habitats to determine critical habitat for the northern Mexican and narrow-headed gartersnakes.
Physical or Biological Features
In accordance with section 3(5)(A)(i) and 4(b)(1)(A) of the Act and regulations at 50 CFR 424.12, in determining which areas within the geographic area occupied by the species at the time of listing to designate as critical habitat, we consider the physical or biological features that are essential to the conservation of the species and which may require special management considerations or protection. These include, but are not limited to:
(1) Space for individual and population growth and for normal behavior;
(2) Food, water, air, light, minerals, or other nutritional or physiological requirements;
(3) Cover or shelter;
(4) Sites for breeding, reproduction, or rearing (or development) of offspring; and
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(5) Habitats that are protected from disturbance or are representative of the historical, geographic, and ecological distributions of a species.
We derived the specific physical or biological features (PBFs) required for the northern Mexican and narrow-headed gartersnakes from the best available scientific and commercial information available, including research of these species' habitat, ecology, and life history as described below. Additional insight is provided by Rosen and Schwalbe (1988, pp. 14-48), Degenhardt et al. (1996, pp. 317-319, 326-
328), Rossman et al. (1996, pp. 55-116, 171-177, 241-248), and Ernst and Ernst (2003, pp. 391-393, 416-419). We have determined that the following physical or biological features are essential for northern Mexican and narrow-headed gartersnakes:
Space and Physical Habitat Requirements for Individual and Population Growth and for Normal Behavior
Both the northern Mexican and narrow-headed gartersnakes depend on the presence of water, primarily for the maintenance of their primary aquatic prey bases, not because their own physiology requires an aquatic environment. The northern Mexican gartersnake is a riparian obligate and occurs chiefly in streams, rivers, cienegas, stock tanks, and spring sources that are often found within large-river riparian woodlands and forests and streamside gallery forests (defined as well-
developed broadleaf deciduous riparian forests with limited, if any, herbaceous ground cover or dense grass) (Hendrickson and Minckley 1984, p. 131; Rosen and Schwalbe 1988, pp. 14-16; Arizona Game and Fish Department 2001, p. 2). Northern Mexican gartersnakes occur at elevations from 130 to 8,497 feet (ft) (40 to 2,590 meters (m)) (Rossman et al. 1996, p. 172), and in a wide range of biotic communities, including Sonoran Desertscrub at the lower elevations, through Semidesert Grassland, Interior Chaparral, and Madrean Evergreen Woodland and into the lower reaches of Petran Montane Conifer Forest as elevation increases (Brennan and Holycross 2006, p. 122). Narrow-headed gartersnakes are widely considered to be one of the most aquatic gartersnake species (Rossman et al. 1996, p. 246), and are strongly associated with clear, rocky streams, using predominantly pool and riffle habitat that includes cobbles and boulders (Rosen and Schwalbe 1988, pp. 33-34; Degenhardt et al. 1996, p. 327; Rossman et al. 1996, p. 246). Narrow-headed gartersnakes occur at elevations from approximately 2,300-8,200 ft (700 m-2,500 m), inhabiting Petran Montane Conifer Forest, Great Basin Conifer Woodland, Interior Chaparral, and the Arizona Upland subdivision of Sonoran Desertscrub communities (Rosen and Schwalbe 1988, p. 33; Brennan and Holycross 2006, p. 122; Burger 2008).
Northern Mexican gartersnakes employ a variety of strategies when foraging for prey. Rosen and Schwalbe (1988, p. 21) observed: (1) Aquatic and terrestrial ambush; (2) aquatic foraging in riffles, vegetation mats, and in open water (such as pool habitat, stock tanks, etc.); and (3) opportunistic capitalization on transitory concentrations of prey. These observations suggest that areas with slow riffles, pools, and backwater habitat are important for prey acquisition, because the prey of northern Mexican gartersnakes are largely aquatic and the snakes themselves need to remain somewhat stabilized to allow for striking behaviors. Narrow-headed gartersnakes often forage underwater, using concealment and ambush behaviors within and between boulder and cobble complexes along the bottom of streams (Rosen and Schwalbe 1988; p. 39). Hibbitts and Fitzgerald (2005, p. 364) described their hunting technique in greater detail, which included anchoring their body with their tail around rocks on the bottom of streams and orienting themselves in position with the current, with their head and neck exposed to the force of the water and the body unanchored on the substrate to allow for forward directed strikes. Narrow-headed gartersnakes are believed to be mainly visual hunters (Hibbitts and Fitzgerald 2005, p. 364) and heavily dependent on visual cues when foraging, based on comparative analyses among other species of gartersnakes (de Queiroz 2003, p. 381). However, foraging activity that occurs during the monsoon season, which is characterized by turbid water conditions, suggests they also use chemosensory abilities to direct strikes. This information suggests that the presence of rock structure along the bottom of streams is important to narrow-headed gartersnakes in compensating for the inertia of flow and for providing opportunities for camouflage-based ambush. However, Fitzgerald (1986; Table 4) also found narrow-headed gartersnakes foraging in stream and river reaches characterized as having sandy substrates. These observations suggest a more opportunistic nature of foraging behavior that may be based more on the presence of prey than the type of substrate.
Both northern Mexican and narrow-headed gartersnakes are largely dependent on native fish as a primary source of food, but have been observed using nonnative, soft-rayed fish species as prey on occasion; for narrow-headed gartersnakes, fish are the principle prey item (Rosen and Schwalbe 1988, pp. 18, 38-39; Degenhardt et al. 1996, p. 328; Rossman et al. 1996, p. 247; Nowak 2006, p. 22). Therefore, habitat-
based attributes that are important for the survival of fish prey species are equally important for the survival of northern Mexican and narrow-headed gartersnakes. Many species of native and nonnative soft-
rayed fish require unregulated flows (or flooding) for: (1) Removing excess sediment from some portions of the stream; (2) removing predatory nonnative, spiny-rayed fish species from a given area; and (3) increasing prey species diversity. Flows fluctuate seasonally, with snowmelt causing spring pulses and occasional floods, and late-summer or monsoonal rains producing floods of varying intensity and duration. These high flows likely rejuvenate spawning and foraging habitat for native and nonnative, soft-rayed fish (Propst et al. 1986, p. 3), break-up embedded bottom materials (Mueller 1984, p. 355), stimulate spawning, and enhance recruitment of native species by eliminating or reducing populations of harmful nonnative species (Stefferud and Rinne 1996a, p. 80), such as spiny-rayed fish. Flooding also allows for the scouring of sand and gravel in riffle areas, which reduces the degree of embeddedness of cobble and boulder substrates (Britt 1982, p. 45). Typically, sediment is carried along the bed of a stream and deposited at the downstream, undersurface side of cobbles and boulders. Over time, this can result in the filling of cavities under cobbles and boulders (Rinne 2001, p. 69). Flooding removes the extra sediment, and the cavities created under cobbles by the scouring action of the flood waters provide enhanced opportunities for spawning of native fish, as well as foraging opportunities, particularly for narrow-headed gartersnakes.
In addition to aquatic habitat, northern Mexican and narrow-headed gartersnakes rely on terrestrial habitat for thermoregulation, gestation, shelter, protection from predators, immigration, emigration, and brumation (cold-season dormancy). The northern Mexican gartersnake also uses terrestrial habitat for foraging opportunities when primary prey items, such as leopard frogs and
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native fish, are uncommon or absent from aquatic habitats. Rosen (1991, pp. 308-309) found that northern Mexican gartersnakes spent approximately 60 percent of their time moving, 13 percent of their time basking on vegetation, 18 percent of their time basking on the ground, and 9 percent of their time under surface cover. Foraging may occur spontaneously and opportunistically during any of these behaviors. In studying the Mexican gartersnake, Drummond and Marciacuteas-
Garciacutea (1983, pp. 24, 35) found individuals wandering hundreds of meters away from water, perhaps in response to a decline or disappearance of the prey base. Observation records for northern Mexican gartersnakes from semi-remote livestock tanks and spring sources suggest the species moves across the local landscape as part of its foraging ecology. Rosen and Schwalbe (1988, p. 47) suggested that vegetation such as knotgrass, deergrass, sacaton, cattails, tules, and spikerush were important to the northern Mexican gartersnake, as well as the presence of rock piles. Boyarski (2011, p. 3) found that four of five telemetered northern Mexican gartersnakes over-wintered along a hillside ``immediately south'' of hatchery ponds where they spent the majority of their time during the surface-active season, but the distance of those specific over-wintering sites was not disclosed. However, Rosen and Schwalbe (1988, p. 27) report observing northern Mexican gartersnakes at a distance of 330 ft (100 m) away from permanent water.
Important terrestrial habitat components for the narrow-headed gartersnake include cobbles, boulders, and bankside shrub vegetation for basking and foraging (Fleharty 1967, pp. 215-216; Rosen and Schwalbe 1988, p. 48; Ernst and Ernst 2003, p. 418). In the Black River and Oak Creek in Arizona, the majority of narrow-headed gartersnakes captured were observed under rocks or shoreline debris, which may indicate these habitat components are ecologically important (Brennan and Rosen 2009, pp. 7, 11). In order of preference, Jennings and Christman (2011, pp. 14, 20) found that narrow-headed gartersnakes used rocks, logs or stumps, and debris jams as cover. Narrow-headed gartersnake detections appear to correlate with the presence of large willows growing along the streambank, which are used for basking (Fernandez and Rosen 1996, p. 70). Holycross et al. (2006, p. 51) found that willows overhanging the stream channel are particularly important for adult narrow-headed gartersnakes. The greater need of narrow-headed gartersnakes to thermoregulate at higher elevations makes optimal basking sites, such as shrubs and snags, essential (Rosen and Schwalbe 1988, p. 34). Pregnant female narrow-headed gartersnakes are rarely encountered near streams, apparently moving away from water during gestation, in favor of the higher thermal environs of rock piles (Rosen and Schwalbe 1988, pp. 33-34, 48). Telemetry data presented in Nowak (2006, pp. 17-18) suggest that terrestrial habitat is important to narrow-headed gartersnakes; home ranges were often set up perpendicular to the stream channel, while others were parallel to the channel. This orientation of home ranges likely indicates the species uses both active and inactive channels, depending on the activity. Such channels are typically found within 600 ft (182.9 m) of active stream channels. For example, it is ecologically disadvantageous for an individual gartersnake to brumate within the bankfull boundary of an active stream because of the risk of flooding, and subsequent drowning, during the cold-season dormancy period. This hypothesis is supported by the findings of Nowak (2006, pp. 19-21), which found telemetered narrow-
headed gartersnakes using crevices in rock walls or large rock outcrops as over-wintering sites, some as far as 650 ft (200 m) away from the stream channel. Additionally, micro-sites chosen as cover for gartersnakes may be artificial or natural; Nowak (2006, p. 19) reported observing narrow-headed gartersnakes commonly using such items such as rock foundations and retaining walls, chimneys, and old water pipes under house foundations, vegetation thickets, burrows, boulders, and downed logs. The largest home range documented by Jennings and Christman (2011, p. 18) for narrow-headed gartersnakes was 239,077 square feet (22,211 square meters), but home range sizes in this study were considered to be underestimated by the authors.
Therefore, based on the information above, we identify the presence of aquatic habitats to support individual and population growth, and support normal behavior, and the presence of terrestrial habitats in appropriate proximity to occupied aquatic habitats to support individual and population growth, and support normal behavior, to be physical or biological features for these species.
Biotic Community Requirements for Individual and Population Growth
The success of northern Mexican and narrow-headed gartersnake populations appears to be uniquely tied to the presence of adequate native prey populations, and, in some cases, nonnative prey species consisting of larval and juvenile bullfrogs, as well as soft-rayed, nonnative fish species (Rosen and Schwalbe 1988, pp. 18, 20, 44; Holycross et al. 2006, p. 23). Generally, the diet of the northern Mexican gartersnake consists predominantly of amphibians and fishes, but other invertebrates and vertebrate species may also be used opportunistically (Gregory et al. 1980, pp. 87, 90-92; Rosen and Schwalbe 1988, pp. 18, 20; Holm and Lowe 1995, pp. 30-31; Degenhardt et al. 1996, p. 318; Rossman et al. 1996, p. 176; Manjarrez 1998). Marciacuteas-Garciacutea and Drummond (1988, pp. 129-134) found that adult northern Mexican gartersnakes in Hidalgo, Mexico, primarily fed on aquatic vertebrates, whereas juveniles often fed on invertebrates, such as earthworms and leeches. Narrow-headed gartersnakes specialize on fish (primarily native fish and, secondarily, nonnative, soft-rayed species, such as trout) as their principle prey item (Rosen and Schwalbe 1988, pp. 38-39; Nowak 2006, pp. 22-23; Degenhardt et al. 1996, p. 328; Rossman et al. 1996, p. 247). Detailed information on the diet of northern Mexican and narrow-
headed gartersnakes is presented in the proposed rule to list both species as threatened under the Act, which is published elsewhere in today's Federal Register.
Both the northern Mexican and narrow-headed gartersnakes have been documented as highly vulnerable to effects from nonnative species as a result of their competition with gartersnakes for prey and effects from direct predation on the gartersnakes themselves (Rosen and Schwalbe 1988, pp. 28-31, 32, 44-45). We conducted a broad review of all available scientific and commercial data, and have determined that nonnative species, such as bullfrogs, crayfish, and spiny-rayed fish, in the families Centrarchidae and Ictaluridae, continue to be the most significant threat to northern Mexican and narrow-headed gartersnakes throughout their respective ranges. Our analysis of the roles that the declines in the anuran prey base, declines in the native fish prey base, bullfrog predation, crayfish interactions, and effects from nonnative, spiny-rayed fish play with regard to the observed declines of the northern Mexican and narrow-headed gartersnakes is presented in detail in the proposed rule to list both species as threatened under the Act, which is
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published elsewhere in today's Federal Register.
Primary Constituent Elements for Northern Mexican and Narrow-Headed Gartersnakes
Under the Act and its implementing regulations, we are required to identify the physical or biological features essential to the conservation of northern Mexican and narrow-headed gartersnakes in areas occupied at the time of listing, focusing on the features' primary constituent elements (PCEs). We consider primary constituent elements to be the elements of physical or biological features that provide for a species' life-history processes and are essential to the conservation of the species.
Northern Mexican Gartersnake's PCEs
Based on our current knowledge of the physical or biological features and habitat characteristics required to sustain the species' life-history processes, we determine that the primary constituent elements specific to northern Mexican gartersnakes are:
(1) Aquatic or riparian habitat that includes:
-
Perennial or spatially intermittent streams of low to moderate gradient that possess appropriate amounts of in-channel pools, off-
channel pools, or backwater habitat, and that possess a natural, unregulated flow regime that allows for periodic flooding or, if flows are modified or regulated, a flow regime that allows for adequate river functions, such as flows capable of processing sediment loads; or
-
Lentic wetlands such as livestock tanks, springs, and cienegas; and
-
Shoreline habitat with adequate organic and inorganic structural complexity to allow for thermoregulation, gestation, shelter, protection from predators, and foraging opportunities (e.g., boulders, rocks, organic debris such as downed trees or logs, debris jams, small mammal burrows, or leaf litter); and
-
Aquatic habitat with characteristics that support a native amphibian prey base, such as salinities less than 5 parts per thousand, pH greater than or equal to 5.6, and pollutants absent or minimally present at levels that do not affect survival of any age class of the northern Mexican gartersnake or the maintenance of prey populations.
(2) Adequate terrestrial space (600 ft (182.9 m) lateral extent to either side of bankfull stage) adjacent to designated stream systems with sufficient structural characteristics to support life-history functions such as gestation, immigration, emigration, and brumation (extended inactivity).
(3) A prey base consisting of viable populations of native amphibian and native fish species.
(4) An absence of nonnative fish species of the families Centrarchidae and Ictaluridae, bullfrogs (Lithobates catesbeianus), and/or crayfish (Orconectes virilis, Procambarus clarki, etc.), or occurrence of these nonnative species at low enough levels such that recruitment of northern Mexican gartersnakes and maintenance of viable native fish or soft-rayed, nonnative fish populations (prey) is still occurring.
Narrow-Headed Gartersnake's PCEs
Based on our current knowledge of the physical or biological features and habitat characteristics required to sustain the species' life-history processes, we determine that the primary constituent elements specific to narrow-headed gartersnakes are:
(1) Stream habitat, which includes:
-
Perennial or spatially intermittent streams with sand, cobble, and boulder substrate and low or moderate amounts of fine sediment and substrate embeddedness, and that possess appropriate amounts of pool, riffle, and run habitat to sustain native fish populations;
-
A natural, unregulated flow regime that allows for periodic flooding or, if flows are modified or regulated, a flow regime that allows for adequate river functions, such as flows capable of processing sediment loads;
-
Shoreline habitat with adequate organic and inorganic structural complexity (e.g., boulders, cobble bars, vegetation, and organic debris such as downed trees or logs, debris jams), with appropriate amounts of shrub- and sapling-sized plants to allow for thermoregulation, gestation, shelter, protection from predators, and foraging opportunities; and
-
Aquatic habitat with no pollutants or, if pollutants are present, levels that do not affect survival of any age class of the narrow-headed gartersnake or the maintenance of prey populations.
(2) Adequate terrestrial space (600 ft (182.9 m) lateral extent to either side of bankfull stage) adjacent to designated stream systems with sufficient structural characteristics to support life-history functions such as gestation, immigration, emigration, and brumation.
(3) A prey base consisting of viable populations of native fish species or soft-rayed, nonnative fish species.
(4) An absence of nonnative fish species of the families Centrarchidae and Ictaluridae, bullfrogs (Lithobates catesbeianus), and/or crayfish (Orconectes virilis, Procambarus clarki, etc.), or occurrence of these nonnative species at low enough levels such that recruitment of narrow-headed gartersnakes and maintenance of viable native fish or soft-rayed, nonnative fish populations (prey) is still occurring.
Special Management Considerations or Protection
When designating critical habitat, we assess whether the specific areas within the geographic area occupied by the species at the time of listing contain features which are essential to the conservation of the species and which may require special management considerations or protection.
All areas proposed for designation as critical habitat will require some level of management to address the current and future threats to northern Mexican and narrow-headed gartersnakes and to maintain or restore the PCEs. Special management within proposed critical habitat will be needed to ensure these areas provide adequate water quantity, quality, and permanence or near permanence; cover (particularly in the presence of harmful nonnative species); an adequate prey base; and absence of or low numbers of harmful nonnative species that can affect population persistence. Activities that may be considered adverse to the conservation benefits of proposed critical habitat include those which: (1) Completely dewater or reduce the amount of water to unsuitable levels in proposed critical habitat; (2) result in a significant reduction of protective cover within proposed critical habitat when harmful nonnative species are present; (3) remove or significantly alter structural terrestrial features of proposed critical habitat that alter natural behaviors such as thermoregulation, brumation, gestation, and foraging; (4) appreciably diminish the prey base; and (5) directly promote increases in harmful nonnative species populations or result in the introduction of harmful nonnative species.
Common examples of these activities may include, but are not limited to, various types of development, channelization, diversions, road construction, erosion control, bank stabilization, wastewater discharge, enhancement or expansion of human recreation opportunities, fish community renovations, and stocking of nonnative, spiny-rayed fish species or promotion of policies that directly or indirectly introduce harmful nonnative species as bait.
The activities listed above are just a subset of examples that have the
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potential to affect critical habitat and PCEs if they are conducted within designated units; however, some of these activities, when conducted appropriately, may be compatible with maintenance of adequate PCEs.
Criteria Used To Identify Critical Habitat
As required by section 4(b)(2) of the Act, we use the best scientific data available to designate critical habitat. We review available information pertaining to the habitat requirements of the species. In accordance with the Act and its implementing regulation at 50 CFR 424.12(e), we consider whether designating additional areas--
outside those currently occupied as well as those occupied at the time of listing--are necessary to ensure the conservation of the species. We are not currently proposing to designate any areas outside the geographic area considered occupied by the northern Mexican or narrow-
headed gartersnake because occupied areas are distributed in several subbasins and currently provide a distribution and configuration of habitat areas sufficient for the conservation of these species.
To identify areas proposed for critical habitat for the northern Mexican and narrow-headed gartersnakes, we used a variety of sources which included riparian species survey reports, museum records, heritage data from State wildlife agencies, peer-reviewed literature, agency reports, interviews with species experts, and regional Geographic Information System (GIS) coverages. Some information sources were used heavily in determining the current and historical distributions of northern Mexican and narrow-headed gartersnakes such as Fitzgerald (1986, entire), Rosen and Schwalbe (1988, entire), Rosen et al. (2001, entire), and Holycross et al. (2006, entire), as they comprise the majority of rangewide survey information for these species. Hellekson (2012a, pers. comm.) was an important source of information pertaining to narrow-headed gartersnake status in New Mexico. In addition to reviewing gartersnake-specific survey reports, we also focused on survey reports for fish and amphibians as they captured important data on the existing community ecology that affects the status of these gartersnakes within their range.
Critical habitat for both gartersnake species is being proposed in areas considered currently occupied. Survey information for both species is significantly lacking in many streams, and both species of gartersnake are cryptic, secretive, difficult to detect, quick to escape underwater, and capable of persisting in low or very low population densities that make positive detections nearly impossible in structurally complex habitat. Therefore, we considered factors such as the date of the last known records of either species in an area, as well as records of one or more native prey species. We used all records for each species that were dated 1980 or later because the 1980s marked the first systematic survey efforts for these species across their ranges (see Rosen and Schwalbe (1988, entire) and Fitzgerald (1986, entire)) and previous records were often dated several decades prior and may not as accurately represented the likelihood for occupation in current times. Additionally, in evaluating whether a site should be considered currently occupied by these gartersnake species, a record of a native prey species suggests that a source of prey may still be available to gartersnakes in areas invaded by harmful nonnative species. This provides evidence that either gartersnake may still likely occur in a given area if other sensitive, native, aquatic or riparian species are also present, despite limited or negative survey data. Specifically, for both species, we considered a stream or geographic area as occupied if it is within the historical range of the species, contains suitable habitat, and meets both of the following: (1) Has a last known record for either species dated 1980 or later, and (2) has at least one native prey species also present.
The shape, size, and scope of proposed critical habitat can be evaluated in terms of its length (number of stream miles), width (lateral extent, in feet), or area (number of acres). With respect to length (in proposed designations based on flowing streams), the proposed areas were designed to provide sufficient aquatic and terrestrial habitat for normal behaviors of northern Mexican and narrow-headed gartersnakes of all age classes. In addition, with respect to width, we evaluated the lateral extent (terrestrial space) necessary to support the PCEs for northern Mexican and narrow-headed gartersnakes. The resulting designations take into account the naturally dynamic nature of riverine systems, floodplains, and riparian habitat (including adjacent upland areas) that are an integral part of these gartersnakes' ecology. For example, riparian areas are seasonally flooded habitats (i.e., wetlands) that are major contributors to a variety of functions vital to the gartersnakes' fish prey base within the associated stream channel (Brinson et al. 1981, pp. 2-61, 2-69, 2-
72, 2-75, 2-84 through 2-85; Federal Interagency Stream Restoration Working Group 1998, p. 2-61). Riparian areas filter runoff, absorb and gradually release floodwaters, recharge groundwater, maintain streamflow, protect stream banks from erosion, and provide shade and cover for fish and other aquatic species; all of these functions contribute to the physical quality of gartersnake habitat.
Healthy riparian and adjacent upland areas help ensure water courses maintain the habitat important for aquatic species (e.g., see USFS 1979, pp. 18, 109, 158, 264, 285, 345; Middle Rio Grande Biological Interagency Team 1993, pp. 64, 89, 94; Castelle et al. 1994, pp. 279-281) that are prey for northern Mexican and narrow-headed gartersnakes, as well as for the snakes themselves. Habitat quality within the mainstem river channels in the historical range of the northern Mexican and narrow-headed gartersnakes is intrinsically related to the character of the floodplain and the associated tributaries, side channels, and backwater habitats that contribute to important habitat features that provide gartersnakes opportunities for foraging and basking in these reaches. We have determined that a relatively intact riparian area, along with periodic flooding in a generally natural pattern, is important for maintaining the PCEs necessary for long-term conservation of the northern Mexican and narrow-headed gartersnakes, as well as their primary prey species.
The lateral extent (width) of riparian corridors fluctuates considerably between a stream's headwaters and its mouth. The appropriate width of riparian terrestrial habitat to protect stream function has been the subject of several studies and varies depending on the specific function (Castelle et al. 1994, pp. 879-881). Most Federal and State agencies generally consider a zone 75 to 150 ft (23 to 46 m) wide on each side of a stream to be adequate (Natural Resource Conservation Service 1998, pp. 2-3; Moring et al. 1993, p. 204; Lynch et al. 1985, p. 164), although widths as wide as 500 ft (152 m) have been recommended for achieving flood attenuation benefits (U.S. Army Corps 1999, pp. 5-29). In most instances, however, adequate riparian space is primarily intended to reduce detrimental impacts to the stream from sources outside the river channel, such as pollutants, in adjacent areas. Consequently, while a riparian corridor 75 to 150 ft (23 to 46 m) in width may protect water quality and provide some level of riparian habitat protection, a wider area would provide full
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protection of riparian habitat because the stream itself can move within the floodplain in response to high flow events, and also provide terrestrial space required by northern Mexican and narrow-headed gartersnakes to engage in normal behaviors such as foraging, basking, gestation, brumation, establishing home ranges, dispersal, and so forth. Using telemetry data (Nowak 2006, pp. 19-21), the farthest distance a narrow-headed gartersnake has been detected from water is 650 ft (200 m), while Rosen and Schwalbe (1988, p. 27) report observing a northern Mexican gartersnake at a distance of 330 ft (100 m) away from permanent water. Based on the literature, we expect the majority of terrestrial activity for both species occurs within 600 ft (182.9 m) of permanent water in lotic habitat.
We believe a 600-ft (182.9-m) lateral extent to either side of bankfull stage will sufficiently protect the majority of important terrestrial habitat; provide brumation, gestation, and dispersal opportunities; and reduce the impacts of high flow events, thereby providing adequate protection to proposed critical habitat areas. We believe this width is necessary to accommodate stream properties such as meandering and high flows, and ensure these designations contain ample terrestrial space such that features essential to the conservation of these gartersnakes and their prey species can occur naturally. Bankfull stage is defined as the upper level of the range of channel-forming flows, which transport the bulk of available sediment over time. Bankfull stage is generally considered to be that level of stream discharge reached just before flows spill out onto the adjacent floodplain. The discharge that occurs at bankfull stage, in combination with the range of flows that occur over a length of time, govern the shape and size of the river channel (its geomorphology) (Rosgen 1996, pp. 2-2 to 2-4; Leopold 1997, pp. 62- 63, 66). The use of bankfull stage and 600 ft (182.9 m) on either side recognizes the naturally dynamic nature of riverine systems, recognizes that floodplains are an integral part of the stream ecosystem, and contains sufficient terrestrial space and associated features essential to the conservation of the northern Mexican and narrow-headed gartersnakes. Bankfull stage is not an ephemeral feature, meaning it does not disappear. Bankfull stage can always be determined and delineated for any stream we have designated as critical habitat. We acknowledge that the bankfull stage of any given stream may change depending on the magnitude of a flood event, but it is a definable and standard measurement for stream systems. Unlike trees, cliff faces, and other immovable habitat elements, stream systems provide habitat that is in constant change. Following high flow events, stream channels can move from one side of a canyon to the opposite side, for example.
Designating critical habitat based on the location of the stream on a specific date is problematic for maintaining important habitat elements. For example, the area within such a designation could transition from providing aquatic habitat and prey to become a dry channel in a short period of time as a result of a high flow event and the subsequent shift in the location of the channel.
We determined the 600-ft (182.9-m) lateral extent for several reasons. Although we considered using either the 100-year or 500-year floodplain, as defined by the Federal Emergency Management Agency, we found that the information was not readily available from the Federal Emergency Management Agency or from the U.S. Army Corps of Engineers for remote areas we are proposing for designation. Therefore, we selected the 600-ft (182.9-m) lateral extent, rather than some other delineation, for four biological reasons: (1) The biological integrity and natural dynamics of the river system and associated riparian habitat are maintained within this area (i.e., the floodplain and its riparian vegetation provide space for natural flooding patterns and latitude for necessary natural channel adjustments to maintain appropriate channel morphology and geometry, store water for slow release to maintain base flows, provide protected side channels and other protected areas, and allow the river to meander within its main channel in response to large flow events); (2) conservation of the adjacent riparian area also helps to provide important nutrient recharge to benefit the food web and protection from sediment and pollutants; (3) vegetated lateral zones are widely recognized as providing a variety of aquatic habitat functions and values (e.g., aquatic habitat for prey such as fish and other aquatic organisms and detritus for aquatic food webs) and help improve or maintain local water quality (see U.S. Army Corps of Engineers' Final Notice of Issuance and Modification of Nationwide Permits, March 9, 2000, 65 FR 12818); and (4) a 600-ft (182.9-m) buffer contributes to the functioning of a river or stream system and provides adequate terrestrial space for normal northern Mexican and narrow-headed gartersnake behaviors, thereby supporting the PCEs needed for suitable northern Mexican and narrow-headed gartersnake habitat as described by the best available scientific and commercial information.
When determining proposed critical habitat boundaries, we made every effort to avoid including large developed areas such as lands covered by buildings, pavement, and other structures because such lands lack physical or biological features for the northern Mexican and narrow-headed gartersnakes. While reptiles, including gartersnakes, may use artificial materials for cover, areas that have been significantly altered by construction-related development are not generally suitable for gartersnakes or their prey species. The scale of the maps we prepared under the parameters for publication within the Code of Federal Regulations may not reflect the exclusion of such developed lands. Any such lands inadvertently left inside critical habitat boundaries shown on the maps of this proposed rule have been excluded by text in the proposed rule and are not proposed for designation as critical habitat. Therefore, if critical habitat is finalized as proposed, a Federal action involving these lands would not trigger section 7 consultation with respect to critical habitat and the requirement of no adverse modification, unless the specific action would affect the physical or biological features in the adjacent critical habitat.
We are proposing for designation of critical habitat lands that we have determined are occupied at the time of listing and contain sufficient elements of physical or biological features to support life-
history processes essential for the conservation of the species.
Units are proposed for designation based on sufficient elements of physical or biological features being present to support the northern Mexican and narrow-headed gartersnakes' life-history processes. Some units contain all of the identified elements of physical or biological features and support multiple life-history processes. Some segments contain only some elements of the physical or biological features necessary to support the northern Mexican and narrow-headed gartersnakes' particular use of that habitat.
The critical habitat designation is defined by the maps, as modified by any accompanying regulatory text, presented at the end of this document in the Proposed Regulation Promulgation section. We include more detailed information on the proposed boundaries of the critical habitat designation in the preamble of this document. We will make the coordinates or plot points or both on which each map is based
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available to the public on http://www.regulations.gov at Docket No. FWS-R2-ES-2013-0022, on our Internet site at http://www.fws.gov/southwest/es/arizona, and at the field office responsible for the designation (see FOR FURTHER INFORMATION CONTACT above).
Proposed Critical Habitat Designation
We are proposing 14 units as critical habitat for the northern Mexican gartersnake and 6 units as critical habitat for the narrow-
headed gartersnake. The critical habitat areas we describe below constitute our current best assessment of areas that meet the definition of critical habitat for the northern Mexican and narrow-
headed gartersnakes. The 14 units we propose as critical habitat for the northern Mexican gartersnake include lands in the following areas: (1) Gila River Mainstem; (2) Mule Creek; (3) Bill Williams River; (4) Agua Fria River Subbasin; (5) Upper Salt River Subbasin; (6) Tonto Creek; (7) Verde River Subbasin; (8) Upper Santa Cruz River Subbasin; (9) Redrock Canyon; (10) Buenos Aires National Wildlife Refuge; (11) Cienega Creek Subbasin; (12) San Pedro River Subbasin; (13) Babocomari River Subbasin; and (14) the San Bernardino National Wildlife Refuge (SBNWR). The six units we propose as critical habitat for the narrow-
headed gartersnake are: (1) Upper Gila River Subbasin; (2) Middle Gila River Subbasin; (3) San Francisco River Subbasin; (4) Salt River Subbasin; (5) Tonto Creek Subbasin; and (6) Verde River Subbasin. All units for both species are considered occupied. It is important to recognize that while all units for both species are considered occupied, the majority of populations in these proposed critical habitat units are currently considered likely not viable into the future. We have concluded that 83 percent of the northern Mexican gartersnake's populations in the United States and 76 percent of the narrow-headed gartersnake's populations occur at low densities and are likely not viable. Please see Appendix A (available at http://www.regulations.gov under Docket No. FWS-R2-ES-2013-0022) for detailed information on occupancy status.
Table 3a--Land Ownership for Proposed Critical Habitat Units for the Northern Mexican Gartersnake
Area estimates reflect all land within critical habitat unit boundaries. County-owned lands are considered as private lands
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Land ownership by type
Unit Subunit -------------------------------------------------------------------------------- Size of unit
Federal State Tribal Private
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Upper Gila River................ .................. 10,845 ac (4,389 467 ac (189 ha)... .................. 9,822 ac (3,975 21,135 ac (8,553
ha). ha). ha).
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Unit Total.................. .................. 10,845 ac (4,389 467 ac (189 ha)... .................. 9,822 ac (3,975 21,135 ac (8,553
ha). ha). ha).
Mule Creek...................... .................. 1,327 ac (537 ha). .................. .................. 1,253 ac (507 ha). 2,579 ac (1044
ha).
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Unit Total.................. .................. 1,327 ac (537 ha). .................. .................. 1,253 ac (507 ha). 2,579 ac (1044
ha).
Bill Williams River............. .................. 3,820 ac (1,546 516 ac (209 ha)... .................. 1,076 ac (435 ha). 5,412 ac (2,190
ha). ha).
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Unit Total.................. .................. 3,820 ac (1,546 516 ac (209 ha)... .................. 1,076 ac (435 ha). 5,412 ac (2,190
ha). ha).
Agua Fria River Subbasin........ Agua Fria River 3,313 ac (1,341 918 ac (372 ha)... .................. 2,758 ac (1,116 6,989 ac (2,828
Mainstem. ha). ha). ha).
Little Ash Creek.. 877 ac (355 ha)... .................. .................. 80 ac (32 ha)..... 957 ac (387 ha).
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Unit Total.................. .................. 4,010 ac (1,696 918 ac (372 ha)... .................. 2,838 ac (1,148 7,946 ac (3,215
ha). ha). ha).
Upper Salt River Subbasin....... Black River....... 2,632 ac (1,065 .................. 13,760 ac (5,569 .................. 16,392 ac (6,634
ha). ha). ha).
Big Bonito Creek.. .................. .................. 5,826 ac (2,358 .................. 5,826 ac (2,358
ha). ha).
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Unit Total.................. .................. 2,632 ac (1,065 .................. 19,586 ac (7,927 .................. 22,218 ac (8,991
ha). ha). ha).
Tonto Creek..................... .................. 7,766 ac (3,143 .................. .................. 1,170 ac (474 ha). 8,936 ac (3,616
ha). ha).
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Unit Total.................. .................. 7,766 ac (3,143 .................. .................. 1,170 ac (474 ha). 8,936 ac (3,616
ha). ha).
Verde River Subbasin............ Upper Verde River. 13,903 ac (5,626 1,209 ac (489 ha). 192 ac (78 ha).... 5,223 ac (2,114 20,526 ac (8,307
ha). ha). ha).
Oak Creek......... 1,873 ac (758 ha). 274 ac (111 ha)... .................. 3,386 ac (1,370 5,533 ac (2,239
ha). ha).
Spring Creek...... 2,572 ac (1,041 188 ac (76 ha).... .................. 371 ac (150 ha)... 3,131 ac (1,267
ha). ha).
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Unit Total.................. .................. 18,348 ac (7,425 1,671 ac (676 ha). 192 ac (78 ha).... 8,980 ac (3,634 29,191 ac (11,813
ha). ha). ha).
Upper Santa Cruz River Subbasin. .................. 77,387 ac (31,318 3,969 ac (1,606 .................. 32,538 ac (13,168 113,895 ac (46,092
ha). ha). ha). ha).
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Unit Total.................. .................. 77,387 ac (31,318 3,969 ac (1,606 .................. 32,538 ac (13,168 113,895 ac (46,092
ha). ha). ha). ha).
Redrock Canyon.................. .................. 1,423 ac (576 ha). .................. .................. 549 ac (222 ha)... 1,972 ac (798 ha).
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Unit Total.................. .................. 1,423 ac (576 ha). .................. .................. 549 ac (222 ha)... 1,972 ac (798 ha).
Buenos Aires National Wildlife .................. 117,313 ac (47,475 .................. .................. .................. 117,313 ac (47,475
Refuge. ha). ha).
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Unit Total.................. .................. 117,313 ac (47,475 .................. .................. .................. 117,313 ac (47,475
ha). ha).
Cienega Creek Subbasin.......... Cienega Creek..... 24 ac (10 ha)..... 1,078 ac (436 ha). .................. 11 ac (4 ha)...... 1,113 ac (450 ha).
Las Cienegas 39,913 ac (16,152 5,105 ac (2,066 .................. 1 ac (
