Endangered and Threatened Wildlife and Plants; Designation of Critical Habitat for the Northern Mexican Gartersnake

DEPARTMENT OF THE INTERIOR

Fish and Wildlife Service

50 CFR Part 17

[Docket No. FWS-R2-ES-2020-0011; FF09E21000 FXES11110900000 212]

RIN 1018-BD96

Endangered and Threatened Wildlife and Plants; Designation of Critical Habitat for the Northern Mexican Gartersnake

AGENCY:

Fish and Wildlife Service, Interior.

ACTION:

Final rule.

SUMMARY:

We, the U.S. Fish and Wildlife Service (Service), designate critical habitat for the northern Mexican gartersnake (

Thamnophis eques megalops

) under the Endangered Species Act of 1973 (Act), as amended. In total, approximately 20,326 acres (8,226 hectares) in La Paz, Mohave, Yavapai, Gila, Cochise, Santa Cruz, and Pima Counties, Arizona, and Grant County, New Mexico, fall within the boundaries of the critical habitat designation for the northern Mexican gartersnake. This rule extends the Act's protections to the northern Mexican gartersnake's designated critical habitat.

DATES:

This rule is effective May 28, 2021.

ADDRESSES:

This final rule is available on the internet at

http://www.regulations.gov.

Comments and materials we received, as well as supporting documentation we used in preparing this rule, are available for public inspection at

http://www.regulations.gov

at Docket No. FWS-R2-ES-2020-0011.

The coordinates or plot points or both from which the maps are generated are included in the administrative record for this critical habitat designation and are available at

http://www.regulations.gov

at Docket No. FWS-R2-ES-2020-0011 and on the Service's website at

https://www.fws.gov/southwest/es/arizona/.

Any additional tools or supporting information that we developed for this critical habitat designation will also be available on the Service's website and may also be included in the preamble and at

http://www.regulations.gov.

FOR FURTHER INFORMATION CONTACT:

Jeff Humphrey, Field Supervisor, U.S. Fish and Wildlife Service, Arizona Ecological Services Field Office, 9828 North 31st Ave #C3, Phoenix, AZ 85051-2517; telephone 602-242-0210. Persons who use a telecommunications device for the deaf (TDD) may call the Federal Relay Service at 800-877-8339.

SUPPLEMENTARY INFORMATION:

Executive Summary

Why we need to publish a rule.

Under the Act, if we determine that a species is an endangered or threatened species, we must designate critical habitat to the maximum extent prudent and determinable. On July 8, 2014, we published a final rule to list the northern Mexican gartersnake as a threatened species (79 FR 38678). Designations of critical habitat can be completed only by issuing a rule.

What this document does.

This rule designates critical habitat for the northern Mexican gartersnake of approximately 20,326 acres (ac) (8,226 hectares (ha)) in La Paz, Mohave, Yavapai, Gila, Cochise, Santa Cruz, and Pima Counties, Arizona, and Grant County, New Mexico.

The basis for our action.

Under section 4(a)(3) of the Act, if we determine that any species is an endangered or threatened species we must, to the maximum extent prudent and determinable, designate critical habitat. Section 3(5)(A) of the Act defines critical habitat as (i) the specific areas within the geographical area occupied by the species, at the time it is listed, on which are found those physical or biological features (I) essential to the conservation of the species and (II) which may require special management considerations or protections; and (ii) specific areas outside the geographical area occupied by the species at the time it is listed, upon a determination by the Secretary that such areas are essential for the conservation of the species. Under Section 4(b)(2) of the Act, the Secretary may exclude an area from critical habitat if she determines that the benefits of such exclusion outweigh the benefits of specifying such areas as part of critical habitat, unless she determines, based on the best scientific data available, that the failure to designate such area as critical habitat will result in the extinction of the species. Section 4(b)(2) of the Act states that the Secretary must make the designation on the basis of the best scientific data available and after taking into consideration the economic impact, the impact on national security, and any other relevant impacts of specifying any particular area as critical habitat.

The critical habitat we are designating in this rule, consisting of eight units comprising approximately 217 stream miles (mi) (349 kilometers (km)) in an area of 20,326 ac (8,226 ha) for the northern Mexican gartersnake, constitutes our current best assessment of the areas that meet the definition of critical habitat for the species.

Peer review and public comment.

During the proposed rule stage, we sought the expert opinions of eight appropriate specialists. We received responses from three specialists, which informed our determination. Information we received from peer review is incorporated into this final rule. We also considered all comments and information we received from the public during the comment period.

Previous Federal Actions

Please refer to the final listing rule (79 FR 38678; July 8, 2014), the original proposed critical habitat rule (78 FR 41550; July 10, 2013), and the revised proposed critical habitat rule (85 FR 23608; April 28, 2020) for the northern Mexican gartersnake for a detailed description of previous Federal actions concerning this species. Those rules included the narrow-headed gartersnake (

Thamnophis rufipunctatus

), but this rule designates critical habitat only for the northern Mexican gartersnake; we will address critical habitat for the narrow-headed gartersnake in future

Federal Register

publications.

Supporting Documents

In the revised proposed critical habitat rule (85 FR 23608; April 28, 2020), we stated that a draft analysis document under the National Environmental Policy Act (NEPA; 42 U.S.C. 4321

et seq.

) for the designation of critical habitat would be completed. We have now finalized an environmental assessment with a finding of no significant impact under NEPA. The document and finding of no significant impact is available at

http://www.regulations.gov

under Docket No. FWS-R2-ES-2020-0011 and from the Arizona Ecological Services Field Office at

https://www.fws.gov/southwest/es/arizona/.

See Required Determinations, below, for a discussion of our NEPA obligations for this designation.

No changes were made to our economic analysis after considering public comments on the draft document. The final economic analysis document (IEc 2019, entire) is available at

http://www.regulations.gov

under Docket No. FWS-R2-ES-2020-0011.

Summary of Changes From the Proposed Rule

We reviewed the comments related to critical habitat for the northern Mexican gartersnake (see Summary of Comments and Recommendations), completed our analysis of areas considered for exclusion under section 4(b)(2) of the

Act, reviewed our analysis of the physical or biological features (PBFs) essential to the long-term conservation of the northern Mexican gartersnake, and finalized the economic analysis of the designation. This final rule incorporates changes from our revised proposed critical habitat rule (85 FR 23608; April 28, 2020) based on the comments that we received, and have responded to in this document, and considers efforts to conserve the northern Mexican gartersnake.

As a result, our final designation of critical habitat reflects the following changes from the April 28, 2020, revised proposed rule (85 FR 23608):

(1) We revised unit areas for Tonto Creek Unit, Verde River Subunit (in the Verde River Subbasin Unit), and Cienega Creek Subunit (in the Cienega Creek Subbasin Unit) based on comments we received regarding areas that did or did not contain the PBFs essential to the conservation of the species. These changes resulted in a net reduction of 687 acres (278 ha) of critical habitat.

(2) We modified PBFs 1(D), 3, 6, and 6(C), as identified under Physical or Biological Features Essential to the Conservation of the Species, below.

(3) We excluded approximately 6,769 ac (2,739 ha) from entire or portions of units, as identified in Table 2, Areas excluded from critical habitat designation by critical habitat unit for the northern Mexican gartersnake.

(4) We corrected several errors in unit descriptions.

Summary of Comments and Recommendations

We requested written comments from the public on the original proposed critical habitat rule (78 FR 41550; July 10, 2013) and on the revised proposed critical habitat rule (85 FR 23608; April 28, 2020) for the northern Mexican gartersnake. The comment period for the original proposed critical habitat rule opened on July 10, 2013, and closed on September 9, 2013; the comment period for the revised proposed critical habitat rule opened on April 28, 2020, and closed on June 29, 2020.

For the original proposed critical habitat rule (78 FR 41550; July 10, 2013), we contacted appropriate Federal, State, Tribal governments, and local agencies; scientific organizations; and other interested parties and invited them to comment on the proposed critical habitat designation. For the revised proposed critical habitat rule (85 FR 23608; April 28, 2020), we again contacted all interested parties, including appropriate Federal and State agencies, Tribal governments, scientific experts and organizations, and other interested parties, and invited them to submit written comments on the revised proposal. In the April 28, 2020, revised proposed rule, we stated that any comments we received in response to the July 10, 2013, proposed rule need not be resubmitted as they would be fully considered in this final rule. Newspaper notices inviting general public comments were published throughout the range of the proposed critical habitat designation for both the original and revised proposed rules.

During the comment period on the original proposed critical habitat rule (78 FR 41550; July 10, 2013), we received approximately 30 written comment letters on the proposed critical habitat designation. During the comment period on the revised proposed critical habitat rule (85 FR 23608; April 28, 2020), we received an additional 40 comment letters on the revised proposed critical habitat designation or the draft economic analysis (IEc 2019, entire). We also received from several parties requests for exclusion of areas that were not identified in the revised proposed rule. We reviewed each exclusion request and whether the requester provided information or a reasoned rationale to initiate an analysis of exclusion or support an exclusion (see Policy Regarding Implementation of Section 4(b)(2) of the Endangered Species Act (81 FR 7226; February 11, 2016)). All substantive information provided during both comment periods has either been incorporated directly into this final determination or is addressed in our responses below.

We also note that we no longer use primary constituent elements (PCEs) to identify areas as critical habitat. We eliminated PCEs due to redundancy with the physical or biological features (PBFs). This change in terminology is in accordance with a February 11, 2016 (81 FR 7414), rule to implement changes to the regulations for designating critical habitat. In the revised proposed critical habitat rule (85 FR 23608; April 28, 2020), we used the comments and additional information to revise: (1) The PBFs that are essential to the conservation of the species and which may require special management considerations or protection under the Act; (2) the criteria used to define the areas occupied at the time of listing for the species; and (3) the criteria used to identify critical habitat boundaries. We then applied the revised PBFs and identification criteria for the species, along with additional information we received regarding where these PBFs exist on the landscape to determine the geographic extent of each critical habitat unit. We received comments on the original proposed critical habitat rule (78 FR 41550; July 10, 2013) that referred to PCEs, and our responses to those comments below correlate with the respective PBFs from the revised proposed critical habitat rule (85 FR 23608; April 28, 2020).

Peer Review

In accordance with our peer review policy published on July 1, 1994 (59 FR 34270), and our August 22, 2016, memorandum updating and clarifying the role of peer review actions under the Act, we solicited expert opinion on the original proposed critical habitat rule (78 FR 41550; July 10, 2013) from eight knowledgeable individuals with scientific expertise that includes familiarity with the northern Mexican gartersnake and the narrow-headed gartersnake and their habitats, biological needs, and threats. We received responses from three of the peer reviewers. In 2020, during the public comment period for the revised proposed critical habitat rule (85 FR 23608; April 28, 2020), we received comments from one of the peer reviewers regarding our revised proposed rule. We address these peer reviewer comments in this final rule as appropriate.

This rule designates critical habitat only for the northern Mexican gartersnake; therefore, in this rule, we limit our discussion of the peer reviewer and public comments we received to those concerning the northern Mexican gartersnake. We will respond to public comments on the narrow-headed gartersnake critical habitat designation when we finalize that rule. We reviewed all the comments we received from the peer reviewers for substantive issues and new information regarding the northern Mexican gartersnake and its habitat use and needs. The peer reviewers provided additional information, clarifications, and suggestions to improve the designation. Our revised proposed critical habitat rule (85 FR 23608; April 28, 2020) was developed in part to address some of the concerns and information raised by the peer reviewers in 2013. The additional details and information received or raised by the peer reviewers have been incorporated into this final rule, as appropriate. Substantive comments we received from peer reviewers as well as Federal, State, Tribal, and local governments, nongovernmental organizations, and the public are summarized below.

Comment 1:

One peer reviewer commented that nonnative fishes of the

Centrarchidae and Ictaluridae families characterized by the term “spiny-rayed fishes” are not the only nonnative fishes that are detrimental to native fishes that are the prey for the gartersnake. They stated that the red shiner in the Cyprinidae family, nonnative mosquitofish in the Poeciliidae family, and nonnative trouts in the Salmonidae family all negatively impact native fishes as well. A second peer reviewer also commented that brown trout are a harmful nonnative and would impact the physical or biological features related to lack of nonnative species in several subunits.

Our Response:

In determining the PBFs for the gartersnake, we intended to identify those species of nonnative fish that were both considered highly predatory on gartersnakes and also highly competitive with gartersnakes in terms of common prey resources. The nonnative fish species we view as most harmful to gartersnake populations include bass (

Micropterus

sp.), flathead catfish (

Pylodictis

sp.), channel catfish (

Ictalurus

sp.), sunfish (Centrarchidae), bullheads (

Ameiurus

sp.), bluegill (

Lepomis

sp.), crappie (

Pomoxis

sp.,) and brown trout. While other species may negatively impact native fishes, we highlighted the nonnative fish species that pose the greatest threat to northern Mexican gartersnakes.

Comment 2:

One peer reviewer stated that our application of the “adverse modification” standard to fish renovation efforts is flawed because we can salvage gartersnakes prior to stream renovations and release them after a native fish prey base has been reestablished.

Our Response:

For the public and section 7 practitioners to understand the types of actions considered to have potential effects to designated critical habitat, we generally identify those types of actions that could potentially result in adverse modification of designated critical habitat. The actual effects of a proposed action on designated critical habitat are dependent on many factors related to both the action being proposed and the project area. Conservation measures can be evaluated against specific attributes of the proposed action at the time of consultation for their suitability and potential implementation. We agree that salvaging gartersnakes prior to stream renovations and then releasing them after a native fish prey base has been reestablished could be a conservation recommendation identified during section 7 consultation to address effects of such a proposed action that includes fish renovation efforts.

Comment 3:

One peer reviewer stated that no areas should be excluded from the critical habitat designation based on existing habitat conservation plans because we cannot enforce implementation of conservation plans.

Our Response:

Section 4(b)(2) of the Act (16 U.S.C. 1531

et seq.

) states that we shall designate and make revisions to critical habitat on the basis of the best available scientific data after taking into consideration the economic impact, national security impact, and any other relevant impact of specifying any particular area as critical habitat. The Act provides that we may exclude an area from critical habitat if we determine that the benefits of such exclusion outweigh the benefits of specifying such area as part of the critical habitat, unless we determine, based on the best scientific data available, that the failure to designate such area as critical habitat will result in the extinction of the species. Under our Policy Regarding Implementation of Section 4(b)(2) of the Act, (81 FR 7226; February 11, 2016), when conducting this analysis we consider a number of factors including whether there are permitted conservation plans covering the species in the area such as habitat conservation plans, safe harbor agreements, or candidate conservation agreements with assurances, or whether there are non-permitted conservation agreements and partnerships that would be encouraged by designation of, or exclusion from, critical habitat. Under the policy, we analyze habitat conservation plans when weighing whether the benefits of exclusion outweigh the benefits of including these areas in the critical habitat designation and provides guidance on the analysis, including looking at whether the permittee is properly implementing the plan and is expected to continue doing so. We have conducted a weighing analysis to determine if the benefits of exclusion outweigh the benefits of including these areas and have used our discretion to determine if the existing habitat conservation plans are sufficient to conserve the species (see Exclusions, below).

Comment 4:

One peer reviewer commented that it would be helpful to have a rating system for the PBFs about prey bases consisting of native fishes and an absence of nonnative fishes, to show a gradient among sites.

Our Response:

For recovery implementation purposes, we see value in understanding and tracking the status of the PBFs related to prey base and absence of nonnative aquatic predators, such as nonnative fishes. However, in terms of species composition or relative abundance, we do not currently have information on what the threshold of each nonnative aquatic predator or combination thereof is to be considered detrimental to the northern Mexican gartersnake. These thresholds would also vary depending on the condition of other PBFs, including organic and inorganic structural features in a stream or lentic water body.

Federal Agency Comments

Comment 5:

The U.S. Forest Service (USFS) commented that the term “spatially intermittent flow” used in PCE 1 of the original proposed critical habitat rule (78 FR 41550; July 10, 2013) is ambiguous because spacing between sections of flowing water can vary greatly and may not meet the biological needs of the gartersnake or its prey base. Also in response to that 2013 proposed critical habitat rule, another agency requested we justify inclusion of long ephemeral reaches of otherwise perennial streams (

i.e.,

San Pedro River) in critical habitat for the northern Mexican gartersnake.

Our Response:

In the revised proposed critical habitat rule (85 FR 23608; April 28, 2020) and this rule, we define perennial, intermittent, and ephemeral as related to stream flow included in PBF 1 for the northern Mexican gartersnake and clarify the spectrum of stream flow regimes that provide stream habitat for the species based on scientifically accepted stream flow definitions (Levick

et al.

2008, p. 6; Stromberg

et al.

2009, p. 330) (see “Stream Flow” in 85 FR 23608, April 28, 2020, p. 23613; and Physical or Biological Features Essential to the Conservation of the Species, below).

Comment 6:

USFS requested clarification of what level of water pollutants are “low enough not to affect recruitment” for PBFs 1(D) and 6(C) for the northern Mexican gartersnake in the revised proposed critical habitat rule (85 FR 23608; April 28, 2020).

Our Response:

We do not have specific data related to water pollutants that are “low enough to affect recruitment” for the northern Mexican gartersnake. Therefore, in this rule, we have amended these PBFs to read as follows: “Water quality that meets or exceeds applicable State surface water quality standards” (see Physical or Biological Features Essential to the Conservation of the Species, below). Although water quality is not identified as a threat to the northern Mexican gartersnake, it is a threat to its prey base. Water quality that is absent of pollutants or has low levels of pollutants is needed to support the aquatic prey base for the northern Mexican gartersnake. State

water quality standards identify levels of pollutants required to maintain communities of organisms that have a taxa richness, species composition, and functional organization that includes the aquatic prey base of the northern Mexican gartersnake.

Comment 7:

In response to the original proposed critical habitat rule (78 FR 41550; July 10, 2013), USFS commented that including stock tanks as critical habitat for the northern Mexican gartersnake may be problematic. USFS stated that maintaining stock tanks for recovery of the species may divert surface water that might otherwise contribute to better habitat, they may contribute to groundwater pumping, and they provide refuge and dispersal for American bullfrogs (

Rana catesbeiana

).

Our Response:

Six constructed ponds (small earthen empoundments) are included in this final designation of critical habitat for the northern Mexican gartersnake. Four of these constructed ponds were originally created for livestock and considered stock tanks. Three of these stock tanks are in the Cienega Creek Subbasin Unit, and one is in the Upper Santa Cruz River Subbasin Unit. Two additional constructed ponds are in the Upper San Pedro River Subbasin Unit. Similar to most constructed ponds in arid zones that collect surface water, each of the six constructed ponds included in the critical habitat designation collect surface water from a stream that would not otherwise be perennial or even intermittent, and therefore would not contribute to better habitat for the northern Mexican gartersnake. In addition to catching surface water run-off, the three stock tanks on Las Cienegas National Conservation Area (NCA) in the Cienega Creek Subbasin Unit are also supplied by groundwater supplied by adjacent wells. The amount of water that may be pumped for these three stock tanks is small and not likely to meaningfully contribute to declining groundwater levels in the Cienega Creek watershed.

While we understand that all ponds can facilitate the invasion of bullfrogs; bullfrog control efforts are ongoing in southeastern Arizona where these six constructed ponds occur. Bullfrogs have been eradicated from the three ponds on Las Cienegas NCA since 2013, and although the constructed pond that serves as a stock tank on USFS lands is currently infested with bullfrogs, there are plans to eradicate bullfrogs in this area once funding is obtained. The fifth constructed pond is on the Appleton-Whittell Research Ranch and has been regularly monitored for bullfrogs for at least five years. If a bullfrog is found, it is immediately removed. The sixth constructed pond is on USFS lands, has never been infested with bullfrogs, and is not within dispersal distance of currently known bullfrog sites.

All three constructed ponds on Las Cienegas NCA and one on USFS lands included in the final designation were recently renovated by the land manager to provide habitat for native aquatic species including the northern Mexican gartersnake, and we conclude that they contribute to the conservation of the species. All other constructed ponds that may also serve as stock tanks on the Las Cienegas NCA and USFS lands are no longer included in critical habitat because they are not considered occupied by the northern Mexican gartersnake (see Criteria Used to Identify Critical Habitat, below).

Comment 8:

In response to the original proposed critical habitat rule (78 FR 41550; July 10, 2013), a Federal agency stated that we should make it clear that when the 600-feet (ft) width of critical habitat falls outside the stream channel, such as when channels are constricted by narrow canyon walls, critical habitat does not include upland areas that would not be used by the northern Mexican gartersnake.

Our Response:

In the revised proposed critical habitat rule (85 FR 23608; April 28, 2020) and in this rule, for the northern Mexican gartersnake, we define the lateral extent of critical habitat to include the wetland or riparian zone adjacent to a stream or lentic water body, whichever is greater. We delineate based on riparian zone rather than delineating a set distance, as this approach more accurately captures areas used by the northern Mexican gartersnake for thermoregulation, shelter, foraging opportunities, brumation, and protection from predators. Thus, we conclude that the changes that we made address this comment.

Comment 9:

In response to the original proposed critical habitat rule (78 FR 41550; July 10, 2013), USFS stated that bankfull stage cannot be defined for reservoirs within the proposed critical habitat and we should consider defining critical habitat for reservoirs or lakes from the maximum capacity of the water body.

Our Response:

In the revised proposed critical habitat rule (85 FR 23608; April 28, 2020) and this rule, we define the extent of critical habitat around lentic water bodies as the riparian habitat adjacent to the ordinary high water mark. There are no reservoirs included in this final designation for northern Mexican gartersnake.

Comment 10:

In response to the original proposed critical habitat rule (78 FR 41550; July 10, 2013), USFS commented that the gartersnakes have strong fidelity for brumation or natal sites.

Our Response:

We are not aware of any literature supporting a conclusion that the northern Mexican gartersnake has strong fidelity for brumation or natal sites. In this designation, we include some areas that capture the physical or biological features of brumation sites that have been documented in telemetry studies conducted for the species that are described in the revised proposed critical habitat rule (85 FR 23608, April 28, 2020, see “Terrestrial Space Along Streams” on pp. 85 FR 23614-23616).

Comment 11:

In response to the original proposed critical habitat rule (78 FR 41550; July 10, 2013), a Federal agency requested more discussion related to including broad areas of terrestrial habitat in critical habitat for the northern Mexican gartersnake and that we explain why these areas are based on political rather than biological boundaries.

Our Response:

In the revised proposed critical habitat rule (85 FR 23608; April 28, 2020) and this rule, we do not include broad areas of terrestrial habitat in the critical habitat designation, and we do not base critical habitat on political boundaries (85 FR 23608, April 28, 2020, see “Overland Areas for Northern Mexican Gartersnake” on pp. 85 FR 23616-23617; and see Regulation Promulgation, below).

Comment 12:

In response to the original proposed critical habitat rule (78 FR 41550; July 10, 2013), USFS commented that PBF 3 for northern Mexican gartersnake should read “amphibians and/or fishes” as opposed to “both amphibians and fishes” because some sites might have one or the other and this species could persist without having both classes of vertebrates present.

Our Response:

In the revised proposed critical habitat rule (85 FR 23608; April 28, 2020), we expanded the prey base in PBF 3 to include “anurans, fishes, small mammals, lizards, and invertebrate species” to more accurately capture the northern Mexican gartersnake's primary prey across a variety of habitats (see “Prey Base” on p. 85 FR 23614). We did not intend to imply that both classes of aquatic vertebrate species need to be present in all critical habitat. To clarify this PBF, in this rule, we revise it to read, “a combination of amphibians, fishes, small mammals, lizards, and invertebrate species such that prey

availability occurs across seasons and years” (see Regulation Promulgation, below).

Comment 13:

In response to the original proposed critical habitat rule (78 FR 41550; July 10, 2013), several Federal entities commented that various areas in the proposal do not currently contain the PBFs for northern Mexican gartersnakes. USFS further stated that it would be more realistic if we limited critical habitat to the areas that had the PBFs, if the PBFs are clearly defined and determinable.

Our Response:

For the revised proposed critical habitat rule (85 FR 23608; April 28, 2020), we reevaluated all streams to determine which stream reaches contain PBFs. The revised proposed critical habitat rule and this rule do not include stream reaches where we determined that water flow became completely ephemeral along an otherwise perennial or spatially intermittent stream, hydrologic processes needed to maintain streams could not be recovered, nonnative aquatic predators outnumbered native prey species, or streams were outside the elevation range. The revised proposed critical habitat rule (85 FR 23608; April 28, 2020) and this rule include areas that were occupied at the time of listing but where PBFs concerning prey availability and presence of nonnative aquatic predators are often in degraded condition and need special management (see 85 FR 23608, April 28, 2020, Changes to Criteria Used to Identify Critical Habitat, pp. 85 FR 23617-23623; and see Regulation Promulgation, below).

Comment 14:

In response to the original proposed critical habitat rule (78 FR 41550; July 10, 2013), several Federal agencies provided lists of specific areas included in proposed critical habitat that do not have stream flow requirements defined in PBF 1A to support the northern Mexican gartersnakes or their corresponding prey species identified in PBF 3. These agencies identified reaches that lacked PBF 1A in some areas along the following streams included in the 2013 proposed critical habitat rule for northern Mexican gartersnake: Agua Fria River in the Agua Fria River Subbasin, Mule Creek in the Gila River Subbasin, and Spring Creek in the Verde River Subbasin. These areas included stream reaches where water flow became completely ephemeral along an otherwise perennial or spatially intermittent stream.

Our Response:

In the revised proposed critical habitat rule (85 FR 23608; April 28, 2020), we did not include stream reaches where water flow becomes completely ephemeral along an otherwise perennial or spatially intermittent stream, and we incorporated related information received from USFS and others regarding stream flow. We incorporated stream flow information received from USFS for Little Creek in the Verde River Subbasin Unit for northern Mexican gartersnake. Based on information from USFS and others related to lack of stream flow along Spring Creek, designated critical habitat for the northern Mexican gartersnake in Spring Creek ends 4 miles upstream of its confluence with Oak Creek. The rule set that we applied in the 2020 revised proposed critical habitat rule limited critical habitat to the known elevation range of the species and limited stream length by dispersal distance from confirmed gartersnake locations dated 1998 or later. When applied, these two factors of the rule set removed all other areas that USFS identified as not having stream flow requirements for the northern Mexican gartersnake.

Comment 15:

USFS and Fort Huachuca stated that many areas included in critical habitat in the original proposed critical habitat rule (78 FR 41550; July 10, 2013) do not have PBF 4: An absence of nonnative fish species of the families Centrarchidae and Ictaluridae, bullfrogs, and/or crayfish. USFS also stated that much of proposed critical habitat may not have the capacity to ever become recolonized by the northern Mexican gartersnake due to the current and likely future conditions of these nonnative invasive species. In 2020, USFS further commented that it will be difficult if not impossible for USFS to attain this PBF on its lands that it manages because nonnative species are managed by the State and not by USFS.

Our Response:

The revised proposed critical habitat rule (85 FR 23608; April 28, 2020) and this final rule include areas that were occupied at the time of listing, but areas that contain nonnative aquatic predators are often in degraded condition and require special management. While recognizing USFS concerns, these areas have the capacity to be managed to improve the condition of the PBFs for the northern Mexican gartersnake through cooperative efforts between State wildlife agencies and USFS, and these types of efforts have already successfully been undertaken by USFS and State wildlife agencies within the range of the northern Mexican gartersnake.

Comment 16:

In response to the revised proposed critical habitat rule (85 FR 23608; April 28, 2020), USFS stated that we did not provide much explanation for what might constitute special management considerations that may be needed in critical habitat, so it is not clear what types of management are likely to result in improved PBFs. USFS commented that there should be some recognition of the potential value of restorative actions that often have short-term adverse effects but are designed to result in beneficial effects (

e.g.,

channel restoration, prescribed fire, riparian vegetation improvements, etc.).

Our Response:

In the 2020 revised proposed critical habitat rule, we stated that we were not changing any of the special management considerations from the 2013 original proposed critical habitat rule for the northern Mexican gartersnake (see 85 FR 23608, April 28, 2020, Special Management Considerations or Protection, p. 85 FR 23624). However, the 2013 original proposed critical habitat rule did not include recognition of the potential value of restorative actions that often have short-term adverse effects but are designed to result in beneficial effects (see 78 FR 41550, July 10, 2013,

Special Management Considerations or Protection,

pp. 78 FR 41555-41556). To address this comment and the information lacking in the 2013 original proposed critical habitat rule, we have added this information to the discussion of special management considerations in this final rule.

Comment 17:

In response to the original proposed critical habitat rule (78 FR 41550; July 10, 2013), USFS commented that the portion of the Gila River upstream of the Cliff-Gila Valley included in proposed critical habitat is far removed from any known, post-1980 records for the northern Mexican gartersnake species and should be removed from critical habitat.

Our Response:

In the revised proposed critical habitat rule (85 FR 23608; April 28, 2020), we reviewed gartersnake occupancy to determine that a stream, stream reach, or lentic water body was occupied at the time of listing for the northern Mexican gartersnake if it is within the historical range of the species, contains PBFs for the species (although the PBFs concerning prey availability and presence of nonnative aquatic predators are often in degraded condition), and has a last known record of occupancy in 1998 or later (see Occupancy Records, 85 FR 23608, p. 23617-23619) (see Criteria Used To Identify Critical Habitat). We also delineated upstream and downstream critical habitat boundaries of a stream reach at 2.2 mi (3.6 km) from a known gartersnake observation record (see 85 FR 23608, April 28, 2020,

Stream

Length,

pp. 85 FR 23619-23623). As a result, the Gila River upstream of the Cliff-Gila Valley is not included in this final critical habitat designation for the northern Mexican gartersnake (See Criteria Used to Identify Critical Habitat).

Comment 18:

In response to the original proposed critical habitat rule (78 FR 41550; July 10, 2013), a Federal agency requested that we consider adding five aquatic conservation sites within the San Pedro Riparian National Conservation Area (NCA) to critical habitat for the northern Mexican gartersnake as they may provide habitat for the species.

Our Response:

In the revised proposed critical habitat rule (85 FR 23608; April 28, 2020), we determined that a stream, stream reach, or lentic water body was occupied at the time of listing for the northern Mexican gartersnake if it is within the historical range of the species, contains PBFs for the species (although the PBFs concerning prey availability and presence of nonnative aquatic predators are often in degraded condition), and has a last known record of occupancy in 1998 or later. The five aquatic conservation sites within the San Pedro Riparian NCA do not meet these requirements because they do not have a record of occupancy in 1998 or later and, therefore, are not included in this final critical habitat designation.

Comment 19:

In response to the original proposed critical habitat rule (78 FR 41550; July 10, 2013), a Federal agency requested we clarify the downstream boundary of the Tonto Creek Unit to a specific fixed elevation no lower than the maximum pool of Roosevelt Lake. In response to the revised proposed critical habitat rule (85 FR 23608; April 28, 2020), they stated that we incorrectly identified the spillway elevation of Roosevelt Lake as 2,120 ft and that it should be 2,100 ft.

Our Response:

Based on further inquiry with Bureau of Reclamation (Reclamation), in this rule we are changing the downstream terminus of Tonto Creek to 2,151 ft (656 meters (m)) because areas below this elevation do not meet the definition of critical habitat for the northern Mexican gartersnake under normal reservoir operations.

Comment 20:

In response to the original proposed critical habitat rule (78 FR 41550; July 10, 2013), USFS stated that proposed critical habitat will affect numerous livestock grazing allotments on the Tonto National Forest. In addition, another Federal agency stated concerns about current and potential future management of public lands within proposed designated critical habitat areas, including grazing and off-highway vehicle (OHV) use. There is a grazing permit renewal under review that would allow for grazing October through January within the Palmerita Ranch allotment on riparian and upland areas. The agency also stated that there is a special recreational permit issued for an annual 3-day OHV poker run event, which would occur partially on navigable washes on Federal lands.

Our Response:

With respect to livestock grazing and OHV use in areas of critical habitat, Federal agencies that authorize, carry out, or fund actions that may affect listed species or designated critical habitat are required to consult with us to ensure the action is not likely to jeopardize listed species or destroy or adversely modify designated critical habitat. This consultation requirement under section 7 of the Act is not a prohibition of Federal agency actions, rather it is a means by which they may proceed in a manner that avoids jeopardy or adverse modification. Even in areas absent designated critical habitat, if the Federal agency action may affect a listed species, consultation is still required to ensure the action is not likely to jeopardize the species. Because the areas designated as critical habitat are occupied and consultation will be required to meet the jeopardy standard, the impact of the critical habitat designation should be minimal and administrative in nature.

Comment 21:

In response to the original proposed critical habitat rule (78 FR 41550; July 10, 2013), USFS requested we define disturbance thresholds for actions “that would significantly increase sediment deposition or scouring within the stream channel” such as vegetation treatments, prescribed fire, and wildfire suppression. USFS also requested we include language addressing the scope, scale, and duration of actions “that would alter water chemistry beyond the tolerance limits of a gartersnake prey base” and actions “that would remove, diminish, or significantly alter the structural complexity of key natural structural habitat features in and adjacent to critical habitat.” USFS stated that these actions are extremely broad in scope and do not differentiate short-term impacts versus true long-term, more permanent impacts that could result in adverse modification.

Our Response:

The purpose of the designation of critical habitat to identify those areas critical to the conservation of the species. For the public and section 7 practitioners to understand the types of actions considered to have potential effects on designated critical habitat, we generally identify those types of actions that could potentially result in adverse modification of designated critical habitat. The actual effects of a proposed action on designated critical habitat are dependent on many factors related to both the action being proposed and the project area. Therefore, we cannot determine and include thresholds for adverse modification in this rule. The appropriate process for that determination is the section 7 process, during which specific factors within the proposed action and conditions within the project area can be evaluated.

Comment 22:

In response to the revised proposed critical habitat rule (85 FR 23608; April 28, 2020), USFS commented that “[a]ctions and structures that would physically block movement of gartersnakes and their prey species” should not include a discussion of predatory species. USFS argued that predatory species should not be included because the presence of nonnative aquatic predatory species in a waterbody reduces population viability, which is considered under actions included in those “that would directly or indirectly result in the introduction, spread, or augmentation of predatory nonnative species in gartersnake habitat.”

Our Response:

Including this language with regard to nonnative aquatic predatory species within the description of actions and structures that would block the movements of gartersnakes and their prey species, as well as within the description of actions that would result in the introduction, spread, and augmentation of predatory nonnative species, is important to clarify two different types of effects that result from similar actions. The presence of such nonnative aquatic predatory species can both act as a barrier to movement and reduce habitat quality due to presence of nonnative aquatic predatory species.

Comment 23:

In response to both the original proposed critical habitat rule (78 FR 41550; July 10, 2013) and the revised proposed critical habitat rule (85 FR 23608; April 28, 2020), the U.S. Army installation at Fort Huachuca requested exclusion of areas outside the installation along portions of the San Pedro and Babocomari Rivers that fall within the San Pedro Riparian NCA in the Upper San Pedro River Subbasin Unit for the northern Mexican gartersnake. Fort Huachuca stated that we did not conduct an adequate national security analysis as required by section 4(b)(2) of the Act and that the designation could require additional water mitigation requirements and

mission restrictions that would negatively impact national security. Fort Huachuca also stated that the proposed critical habitat outside this area is more than adequate for recovery of this species.

Our Response:

For exclusion of an area from critical habitat designation based on national security, we look to our Policy Regarding Implementation of Section 4(b)(2) of the Endangered Species Act (81 FR 7226; February 11, 2016), which outlines measures we consider when excluding any areas from critical habitat. We reviewed the commenter's request and applied the Policy Regarding Implementation of Section 4(b)(2) of the Endangered Species Act (81 FR 7226; February 11, 2016). Based on this analysis, we determined that the area should not be excluded from this final rule due to national security. Please see Exclusions (

Exclusions Based on Impacts on National Security and Homeland Security

), below, for our analysis of the Fort Huachuca request for exclusion for lands within the San Pedro Riparian NCA.

Comment 24:

In response to the revised proposed critical habitat rule (85 FR 23608; April 28, 2020), U.S. Customs and Border Protection (CBP) under the Department of Homeland Security (DHS) requested that the Roosevelt Reservation portion of critical habitat in Unnamed Drainage and Pasture 9 Tank Subunit, Unnamed Drainage and Sheehy Spring Subunit, and Santa Cruz River Subunit within the Upper Santa Cruz River Subbasin Unit along the U.S./Mexico border be considered for exclusion under section 4(b)(2) of the Act for national security reasons and for being exempt from environmental regulations (DHS 2020, entire). The Roosevelt Reservation is a 60-ft (18-m) wide strip of land owned by the Federal Government along the U.S. side of the U.S./Mexico border in California, Arizona, and New Mexico.

Our Response:

We have reviewed CBP's request and have excluded the 60-ft (18-m) area of the Roosevelt Reservation from this final critical habitat designation. Please see Exclusions (

Exclusions Based on Impacts on National Security and Homeland Security

), below, for our analysis of the CBP's request for exclusion for border units within the Roosevelt Reservation.

Comment 25:

In response to the original proposed critical habitat rule (78 FR 41550; July 10, 2013), a Federal agency stated that the portion of the Bill Williams River National Wildlife Refuge (NWR) included in the original proposed critical habitat does not provide habitat for the northern Mexican gartersnake and should be excluded from critical habitat. In response to the revised proposed critical habitat rule (85 FR 23608; April 28, 2020), the same agency requested exclusion of all critical habitat within the 914,200-acre Lower Colorado River Multi-Species Conservation Program (MSCP) planning area and off-site conservation areas. This includes the entire Bill Williams River Subunit in the Bill Williams River Subbasin Unit and the Lower Colorado River Unit. The agency stated that designating critical habitat in these two areas will create an unnecessary administrative burden, as actions to maintain the existing flood control and water delivery infrastructure would require additional consultation.

Our Response:

As a result of the Federal agency and other public comments on the original proposed critical habitat rule (78 FR 41550; July 10, 2013), we revised our rule set for determining the extent of the critical habitat for all critical habitat units in the revised proposed critical habitat rule (85 FR 23608; April 28, 2020). We determined that a stream, stream reach, or lentic water body was occupied at the time of listing for the gartersnake if it is within the historical range of the species, contains PBFs for the species (although the PBFs concerning prey availability and presence of nonnative predators are often in degraded condition), and has a last known record of occupancy in 1998 or later. We also delineated upstream and downstream critical habitat boundaries of a stream reach at 2.2 mi (3.6 km) from a known gartersnake observation record (see 85 FR 23608, April 28, 2020,

Stream Length,

pp. 85 FR 23619-23623). As a result of our review of occupancy and implementation of our rule set for stream length, the Bill Williams NWR is not included in this final critical habitat designation for the northern Mexican gartersnake.

With respect to the request for excluding all areas from critical habitat within the 914,200-acre Lower Colorado River MSCP planning area and off-site conservation areas, the Lower Colorado River Unit and Bill Williams River Subunit have been excluded from this final designation based on conservation and management of some areas and thus are not addressed further here (see Exclusions,

Private or Other Non-Federal Conservation Plans or Agreements and Partnerships, in General,

below).

Comment 26:

The U.S. Small Business Administration and other commenters stated that we should consider the full scope of economic impacts to small entities and conduct a thorough Regulatory Flexibility Act analysis for critical habitat rules.

Our Response:

Under the Regulatory Flexibility Act (RFA; 5 U.S.C. 601

et seq.

), as amended by the Small Business Regulatory Enforcement Fairness Act of 1996 (SBREFA; 5 U.S.C. 801

et seq.

), Federal agencies are only required to evaluate the potential incremental impacts of a rulemaking on directly regulated entities. The regulatory mechanism through which critical habitat protections are realized is section 7 of the Act, which requires Federal agencies, in consultation with the Service, to ensure that any action authorized, funded, or carried out by the agency is not likely to adversely modify critical habitat. Therefore, only Federal action agencies are directly subject to the specific regulatory requirement (avoiding destruction and adverse modification) imposed by critical habitat designation. Under these circumstances, it is our position that only Federal action agencies will be directly regulated by this designation. Therefore, because Federal agencies are not small entities, we certify that the proposed critical habitat rule will not have a significant economic impact on a substantial number of small entities (see Required Determinations, below). Thus, no regulatory flexibility analysis is required.

Comment 27:

The U.S. Small Business Administration commented that we should continue to engage with stakeholders early in the process and consider public comments.

Our Response:

Stakeholder engagement is important to balancing the long-term conservation of sensitive species and their habitats with the interests of stakeholders and the needs of the public. However, we are required to designate critical habitat for endangered and threatened species where we find the designation to be both prudent and determinable, as is the case with the northern Mexican gartersnake. In our development of critical habitat, we consider designating those areas occupied at the time of listing that contain the PBFs essential to the conservation of the species; this consideration is not based on land ownership, unless limiting the designation to only Federal lands would provide for the conservation of the species. In our original proposed critical habitat rule (78 FR 41550; July 10, 2013) and revised proposed critical habitat rule (85 FR 23608; April 28, 2020), we solicited information from the public regarding potential exclusions of areas based on management plans or other

conservation efforts including partnerships, as well as other information related to the species and potential impacts of designating critical habitat. This section of this final rule outlines our consideration of public comments received on both proposed rules.

State Comments

Comment 28:

Arizona Game and Fish Department (AGFD) commented that while they recognize the intent of our use of the term “predatory sportfish,” it is important to point out that all sportfish are predatory, as are all of our native fishes (

i.e.,

they all prey on other organisms) and all interactions with sportfish are not negative. Further, not all sportfish or native species eat snakes.

Our Response:

In the revised proposed critical habitat rule (85 FR 23608; April 28, 2020), we used the term “predatory sportfish” to explain how we delineated critical habitat: “We identified and removed stream reaches where stocking or management of predatory sportfish is a priority and is conducted on a regular basis.” In this document, we have removed the term “predatory sportfish” and replaced it with “nonnative fish species of the families Centrarchidae and Ictaluridae,” so that it is consistent with the description of species used in the PBF related to nonnative aquatic predators.

Comment 29:

In response to our original proposed critical habitat rule (78 FR 41550; July 10, 2013), New Mexico Department of Game and Fish (NMDGF) commented that there are no post-2000 records for northern Mexican gartersnake on its properties within or adjacent to the Upper Gila River Subbasin Unit. These properties include the Red Rock Wildlife Management Area, which is a public fishing and recreation area; the Bill Evans Fishing Area, which is a public fishing site; and the Heart Bar Wildlife Area, which is a public fishing and recreation area.

Our Response:

In the revised proposed critical habitat rule (85 FR 23608; April 28, 2020), we reviewed northern Mexican gartersnake occupancy to determine that a stream, stream reach, or lentic water body was occupied at the time of listing for the species if it is within the historical range of the species, contains PBFs for the species (although the PBFs concerning prey availability and presence of nonnative aquatic predators are often in degraded condition), and has a last known record of occupancy in 1998 or later. We also delineated upstream and downstream critical habitat boundaries of a stream reach at 2.2 mi (3.6 km) from a known northern Mexican gartersnake observation record (see 85 FR 23608, April 28, 2020,

Stream Length,

pp. 85 FR 23619-23623). As a result of our review of occupancy and implementation of our rule set for stream length, the Gila River upstream of the Cliff-Gila Valley is not included in this final critical habitat designation for northern Mexican gartersnake; therefore, this designation does not contain any NMDGF properties.

Comment 30:

AGFD stated that the revised proposed critical habitat rule (85 FR 23608; April 28, 2020) is adequate for recovery of the northern Mexican gartersnake and that there are some areas that were occupied historically but from which the species has been extirpated. AGFD will continue the recovery efforts of reintroducing northern Mexican gartersnakes back into historically occupied habitats to contribute to recovery, regardless of their current occupied status or their critical habitat designation.

Our Response:

We will only consider unoccupied areas to be essential where a critical habitat designation limited to geographical areas occupied at the time of listing by the species would be inadequate to ensure the conservation of the species. In addition, for an unoccupied area to be considered essential, we must determine that there is a reasonable certainty both that the area will contribute to the conservation of the species and that the area contains one or more of the PBFs essential to the conservation of the species. At this point in time, we do not know what areas within the species' historical range will contribute to the conservation of the species. We appreciate the AGFD's partnership in the conservation and recovery of the northern Mexican gartersnake.

Comment 31:

Both AGFD and NMDGF stated concerns with the

Application of the “Adverse Modification” Standard

discussion in the revised proposed critical habitat rule (85 FR 23608, April 28, 2020, pp. 85 FR 23633-23634). AGFD pointed out that in the same discussion in the original proposed critical habitat rule (78 FR 41550, July 10, 2013, pp. 78 FR 41576-41577), we discuss activities “that may affect critical habitat, when carried out, funded, or authorized by a Federal agency should result in section 7 consultation,” but in the 2020 revised proposed critical habitat rule, we discuss the same activities but change the “may affect critical habitat” to “likely to destroy or adversely modify critical habitat.” AGFD recommended that in the final rule we use the same language in this discussion that we used in the 2013 original proposed critical habitat rule. AGFD went on to express concern that the 2020 revised proposed critical habitat rule essentially says that the effect has already been determined that any of these activities will destroy or adversely modify critical habitat.

Our Response:

In this rule's

Application of the “Adverse Modification” Standard

discussion, below, we include actions that could cause adverse effects to critical habitat, and not necessarily cause adverse modification to critical habitat, so that the public and section 7 practitioners can understand the types of actions we consider to have potential effects to designated critical habitat. The actual effects of a proposed action on designated critical habitat are dependent on many factors related to both the action being proposed and the project area. Therefore, we cannot determine and include thresholds for adverse modification in this rule. The appropriate process for that determination is the section 7 process, during which specific factors within the proposed action and conditions within the project area can be evaluated.

Comment 32:

Both AGFD and NMDGF stated concerns with some activities included in the analysis of the “adverse modification” standard because the activities are valuable to the restoration and recovery of native species even if they have temporary impacts to critical habitat. AGFD and NMDGF expressed concern about the time threshold we included in the

Application of the “Adverse Modification” Standard

discussion to determine that actions that would deliberately remove, diminish, or significantly alter the native or nonnative, soft-rayed fish component of the prey base within occupied habitat for a period of 7 days or longer would reach an adverse modification determination. AGFD recommended removing language that limits fish because the bulk of the northern Mexican gartersnake's diet consists of frogs and not fish. AGFD further explained that stream renovation projects are needed to ensure that a healthy native fish community exists and that gartersnakes will also thrive. Chemical renovations can take longer than 7 days for the chemicals to dissipate to levels that are safe for native fish, or multiple treatments may need to be conducted to be effective. NMDGF requested removing fish barriers, water diversion, fish habitat restoration, and chemical treatments from the

Application of the “Adverse Modification” Standard

discussion in the final rule.

Our Response:

In this rule's

Application of the “Adverse Modification” Standard

discussion, below, we acknowledge that some conservation actions will have short-term adverse effects but will ultimately result in long-term benefits to gartersnake critical habitat. The actual effects of a proposed action of designated critical habitat are dependent on many factors related to both the action being proposed and the project area. The appropriate process for that determination is the section 7 process, during which specific factors within the proposed action and conditions within the project area can be evaluated. We understand that the diet of the northern Mexican gartersnake is widely variable. Therefore, paragraph (7) under

Application of the “Adverse Modification” Standard

in the 2020 revised proposed rule specifically only pertained to narrow-headed gartersnakes, which are no longer included in this rule. Therefore, we removed paragraph (7) from this final rule.

Comment 33:

AGFD recommended excluding private and non-Federal lands enrolled in Chiricahua leopard frog (

Rana chiricahuensis

) or Gila topminnow (

Poeciliopsis occidentalis

) and desert pupfish (

Cyprinodon macularius

) safe harbor agreements from northern Mexican gartersnake critical habitat. AGFD stated that these private landowners are important conservation partners that are already contributing to native aquatic species conservation and recovery that can benefit the northern Mexican gartersnake. AGFD further stated that AGFD is committed to advancing recovery of this species on its properties that we also considered for exclusion, including Bubbling Ponds and Page Springs fish hatcheries adjacent to Oak Creek and Planet Ranch property on the Bill Williams River.

Our Response:

Based on our consideration of proposed exclusions and land management information received from AGFD, we found that Bubbling Ponds and Page Springs fish hatcheries, Planet Ranch, and private and non-Federal lands enrolled in Chiricahua leopard frog or Gila topminnow and desert pupfish safe harbor agreements are all managed in ways that promote conservation and restoration of habitat that is beneficial to the northern Mexican gartersnake. Additionally, the exclusion of these areas is likely to be beneficial in maintaining working partnerships with AGFD and private landowners. As a result of our exclusion/inclusion benefits analysis, we have determined it appropriate to exclude these areas from the designation. See Exclusions,

Private or Other Non-Federal Conservation Plans or Agreements and Partnerships, in General,

below.

Comment 34:

New Mexico Department of Agriculture (NMDA) expressed support for excluding private lands owned by Freeport-McMoran within the U-Bar Ranch property along Duck Creek and the Gila River from critical habitat for the northern Mexican gartersnake. NMDA stated that voluntary conservation planning and actions on the property are adequate for conserving the gartersnake.

Our Response:

Consideration of possible exclusions from critical habitat are in our discretion and generally follow our Policy Regarding Implementation of Section 4(b)(2) of the Endangered Species Act (81 FR 7226; February 11, 2016). With respect to the Upper Gila River Subbasin Unit for the northern Mexican gartersnake, we determined that that the benefits of exclusion do not outweigh the benefits of inclusion. See Exclusions,

Private or Other Non-Federal Conservation Plans or Agreements and Partnerships, in General,

below, for our discussion of private lands owned by Freeport-McMoran.

Comment 35:

NMDA commented that we should reconsider the value of critical habitat if we cannot identify a case in which consultation would require additional conservation measures.

Our Response:

We are required to designate critical habitat for listed species if we find that the designation is prudent and determinable, as we did for the northern Mexican gartersnake, regardless of whether we can foresee project modifications that may be required.

Comment 36:

NMDGF requested that we exclude developed, humanmade fish migration barrier structures from critical habitat because including them will hinder conservation efforts for native fish and snakes by delaying construction and maintenance efforts of these structures.

Our Response:

When determining critical habitat boundaries, we made efforts to avoid including developed areas such as lands covered by buildings, pavement, and other structures because such lands lack the PBFs. The humanmade fish barriers are in-water structures that fall within the boundaries of habitats used by northern Mexican gartersnakes. Because of this and the limitations of map scale, any developed lands, such as constructed fish barriers, left inside critical habitat boundaries are not considered critical habitat because they lack the necessary PBFs. However, a Federal action involving the fish barriers, such as maintenance, may trigger section 7 consultation with respect to critical habitat or the prohibition of adverse modification if the specific action would affect the PBFs in surrounding critical habitat.

Comment 37:

The New Mexico Interstate Stream Commission commented that the Service must complete an environmental impact statement (EIS) for designating critical habitat.

Our Response:

NEPA dictates that the Service determine the appropriate level of NEPA review (40 CFR 1501.3). The Service completed an environmental assessment (EA) to determine whether an EIS was necessary or if a finding of no significant impact (FONSI) could be determined. The Service released a draft EA that was available for public comment from December 18, 2020, to January 16, 2021, on the Arizona Ecological Services Field Office website; we received five comments on the draft EA. After addressing the public comments received, the Service finalized the EA and found that designating critical habitat for the northern Mexican gartersnake would not result in significant impacts to the environment. A copy of the final EA and FONSI is available at

http://www.regulations.gov

at Docket No. FWS-R2-ES-2020-0011. Therefore, the appropriate NEPA process was completed, and an EIS is not required.

Tribal Comments

In accordance with our requirements to coordinate with Tribes on a government-to-government basis, we solicited information from the following 17 Tribes regarding the designation of critical habitat for the northern Mexican gartersnake: Chemehuevi Indian Tribe, Cocopah Indian Tribe, Colorado River Indian Tribes, Fort McDowell Yavapai Nation, Fort Mojave Indian Tribe, Gila River Indian Community, Hopi Tribe, Hualapai Tribe, Mescalero Apache Tribe, Pascua Yaqui Tribe, Salt River Pima-Maricopa Indian Community, San Carlos Apache Tribe, Tohono O'odham Nation, Tonto Apache Tribe, White Mountain Apache Tribe, Yavapai-Apache Nation, and Yavapai-Prescott Indian Tribe. While all of these tribes may have interest in lands included in proposed critical habitat for northern Mexican gartersnake, the only Tribal land included in the revised proposed critical habitat designation was land owned by the Yavapai-Apache Nation. We also met with representatives of the Gila River Indian Community and

Yavapai-Apache Nation to discuss the proposed designation. The Gila River Indian Community expressed concern regarding potential effects that critical habitat may have on water allocation. The Yavapai-Apache provided revisions to ownership of their lands, expressed concern of economic impacts from designated critical habitat, and requested the Yavapai-Apache Nation be excluded from the designation.

Comment 38:

The Gila River Indian Community expressed concern about how designation of critical habitat for the northern Mexican gartersnake on the Bill Williams River might affect their Central Arizona Project water allocation, which is diverted downstream along the Colorado River.

Our Response:

For critical habitat off Tribal lands, we do not anticipate the Central Arizona Project water allocation to Gila River Indian Community to be impacted by this designation of critical habitat because we are excluding the Bill Williams River from critical habitat based on the Lower Colorado River MSCP Habitat Conservation Plan (LCR MSCP 2004, entire). In addition, the economic analysis outlines the substantial baseline protections currently afforded the northern Mexican gartersnake throughout the designation and has determined that the impacts of critical habitat will be minimal (See Exclusions,

Private or Other Non-Federal Conservation Plans Related to Permits Under Section 10 of the Act

).

Comment 39:

The Yavapai-Apache Nation requested that their lands be excluded from the designation of critical habitat based on their management and conservation of northern Mexican gartersnake habitat, because the designation would infringe on Tribal sovereignty and directly interfere with Tribal self-government, and because the designation would have a disproportionate economic impact on the Yavapai-Apache Nation. The Yavapai-Apache Nation further stated that our draft economic analysis failed to analyze the unique economic impacts of the potential designation of Tribal land and requested us to revise the proposed rule to consider the types of Tribal economic activities likely to occur and likely to be affected by the critical habitat designation.

Our Response:

We have reviewed the request for exclusion from the Yavapai-Apache Nation and excluded all Tribal lands from the final designation under section 4(b)(2) of the Act (See Exclusions, below). Because all Tribal lands have been excluded from this final critical habitat designation, any required conservation activities on Tribal lands will be based solely on the listing of the northern Mexican gartersnake, not critical habitat on Tribal lands. The economic analysis outlines the substantial baseline protections currently afforded to the northern Mexican gartersnake throughout the designation and has determined that the impacts of critical habitat will be minimal.

Public Comments

Comment 40:

Several commenters stated their view that designating critical habitat for the northern Mexican gartersnake is not prudent because disclosing where individuals can be found would increase illegal taking of the species. Several commenters also stated that designating critical habitat is not prudent because most of the stream reaches included in the proposed designation have already been designated as critical habitat for other listed species. Other commenters stated that designating critical habitat for the northern Mexican gartersnake is not prudent because there are insufficient populations in the United States and the species primarily occurs in Mexico.

Our Response:

As discussed in the final listing rule (79 FR 38678; July 8, 2014), there is no imminent threat of take attributed to illegal collection for this species, and identification and mapping of critical habitat is not expected to initiate any such threat.

Additionally, criteria used to determine if designation of critical habitat for the northern Mexican gartersnake is prudent pursuant to our regulations, 50 CFR 424.12(a)(1), may differ from criteria used to designate critical habitat for other listed species. Therefore, because none of the circumstances enumerated in our regulations at 50 CFR 424.12(a)(1) has been met and because there are no other circumstances we have identified for which this designation of critical habitat would not be prudent, we have determined that the designation of critical habitat is prudent for the species.

In development of the revised proposed critical habitat rule (85 FR 23608; April 28, 2020), we used the best scientific and commercial information available. In that revised proposed rule, we reassessed occupancy at the time of listing by reviewing all records for the northern Mexican gartersnake that we used in our original proposed critical habitat rule (78 FR 41550; July 10, 2013) in conjunction with expected survivorship of the species. We also used subsequent surveys in areas that had no detection of the species, and reviewed changes in threats that may have prevented occupancy at time of listing. We determined that the best available information reflecting occupancy at the time of listing supports a more recent date of records since 1998, which includes areas within the United States (see Criteria Used To Identify Critical Habitat). This and other information represent the best scientific and commercial data available and led us to determine areas of occupancy at the time of listing. Our review of the best scientific and commercial data available support the conclusion that the designation of critical habitat is prudent and determinable for the northern Mexican gartersnake.

Comment 41:

Multiple commenters stated that the available data are insufficient to identify the species' needs and impacts from wildfires in order to determine areas for critical habitat.

Our Response:

In development of the revised proposed critical habitat rule (85 FR 23608; April 28, 2020), we used the best scientific and commercial information available. We have sufficient information to determine the areas essential to the conservation of the species (

i.e.,

critical habitat) as documented in the 2020 revised proposed rule. In addition to reviewing gartersnake-specific survey reports, we also focused on survey reports and heritage data for fish and amphibians from State wildlife agencies, as they captured important data on the existing community ecology that affects the status of the northern Mexican gartersnake. In addition to species data sources, we used publicly available geospatial datasets depicting water bodies, stream flow, vegetation type, and elevation to identify critical habitat areas. We reviewed the available information pertaining to the biological needs of the species and habitat characteristics where the species is located. This and other information represent the best scientific and commercial data available and led us to conclude that the designation of critical habitat is determinable for the northern Mexican gartersnake.

As discussed in the final listing rule (79 FR 38678; July 8, 2014), landscape-scale wildfires have impacted the species and its habitats. We understand that wildfires can cause sedimentation that can reduce water quality and prey availability for the northern Mexican gartersnake, and we included areas in critical habitat that had records of the species from 1998 to 2019, but that may need special management to maintain PBFs 1 and 3 as a result of recent or future wildfires.

Comment 42:

Two commenters stated that ephemeral reaches of streams, as

well as intermittent streams, can provide habitat for northern Mexican gartersnakes. Gartersnakes use them on a seasonal basis, and they may have lower densities of nonnative aquatic species. Therefore, they should be included in the critical habitat designation.

Our Response:

In development of the revised proposed critical habitat rule (85 FR 23608; April 28, 2020), we clarified the spectrum of stream flow regimes that provide stream habitat for the northern Mexican gartersnake based on scientifically accepted stream flow definitions (Levick

et al.

2008, p. 6; Stromberg

et al.

2009, p. 330). We define a “spatially intermittent” stream as a stream that is interrupted, perennially interrupted, or spatially intermittent; has perennial flow occurring in areas with shallow bedrock or high hydraulic connectivity to regional aquifers; and has ephemeral to intermittent flow occurring in areas with deeper alluvial basins or greater distance from the headwaters (Stromberg

et al.

2009, p. 330). The spatial patterning of wet and dry reaches on spatially intermittent streams changes through time in response to climatic fluctuations and to human modifications of the landscape (Stromberg

et al.

2009, p. 331).

We include spatially intermittent streams, as well as entirely ephemeral streams, in critical habitat for the northern Mexican gartersnake. We explain that streams that have perennial or spatially intermittent flow can provide stream habitat for the species. Ephemeral reaches of streams can serve as habitat for northern Mexican gartersnakes and are included in critical habitat as PBF 1 in streams with spatially intermittent flow if such reaches are between perennial sections of a stream that were occupied at the time of listing. We also include entirely ephemeral channels in critical habitat as PBF 7 if they connect perennial or spatially intermittent perennial streams to lentic wetlands in southern Arizona where water resources are limited. Streams that have ephemeral flow over their entire length are considered critical habitat when they may serve as corridors between perennial streams and lentic aquatic habitats, including springs, cienegas, and natural or constructed ponds that were occupied at the time of listing due to the propensity for higher prey densities where water conveys.

Comment 43:

One commenter stated that we should maintain a shoreline component as part of the PBFs that identify critical habitat, and we should include human-modified features such as stock tanks. They stated their view that eliminating the shoreline component could result in improperly leaving out habitats that northern Mexican gartersnakes use because they span the transition between upland riparian and in-stream habitats.

Our Response:

We removed the term “shoreline habitat” because shorelines fluctuate. Instead, we are focusing on the substrate. The key to the original primary constituent element for “shoreline habitat” was the substrate itself, not the fluctuating shoreline. The revised PBFs 1 and 6 focus on the organic and natural inorganic structural features important to the northern Mexican gartersnake that fall within the stream channel or lentic water body and still encompass the transition between in-stream habitat and riparian habitat.

Constructed ponds, including stock tanks, are still included in critical habitat for the northern Mexican gartersnake if they are within the historical range of the species, contain all PBFs for the species (although the PBFs concerning prey availability and presence of nonnative aquatic predators are often in degraded condition), and have a last known record in 1998 or later. Please see our response to

Comment 7,

above, for a summary of these sites.

Comment 44:

One commenter stated that there are no currently available data on the effects of pollutants on the recruitment of northern Mexican gartersnakes; therefore, including PBF 1D for the northern Mexican gartersnake, which concerns water quality with low to zero levels of pollutants, is not using the best available science.

Our Response:

We do not have specific data related to effects of water pollutants on the recruitment of the northern Mexican gartersnake. Therefore, in this rule, we have amended the relevant PBF to read as follows: “Water quality that meets or exceeds applicable State surface water quality standards” (For more information, see Physical or Biological Features Essential to the Conservation of the Species, below). Although water quality is not identified as a threat to the northern Mexican gartersnake, it is a threat to its prey base. Water quality that is absent of pollutants or has low levels of pollutants is needed to support the aquatic prey base for the northern Mexican gartersnake. State water quality standards identify levels of pollutants required to maintain communities of organisms that have a taxa richness, species composition, and functional organization that includes the aquatic prey base of the northern Mexican gartersnake.

Comment 45:

We received a variety of comments regarding the definition of the lateral extent of critical habitat for the northern Mexican gartersnake in the revised proposed critical habitat rule (85 FR 23608; April 28, 2020). Several commenters supported the use of PBFs to define the lateral extent of critical habitat for the northern Mexican gartersnakes in the 2020 revised proposed rule instead of using an arbitrary 600-ft straight-line distance from “bankfull width” that we used in the original proposed critical habitat rule (78 FR 41550; July 10, 2013). Comments suggested limiting the riparian zone defined in PBFs by a straight-line distance from water features based on the maximum distance the species has been recorded from water to define lateral extent of the critical habitat for the northern Mexican gartersnake. Another commenter stated by removing the 600-ft (183-m) lateral extent from the bankfull line of streams to only include riparian areas does not take into account the type of habitat that the gartersnake uses for dispersal, brumation, and foraging. Because northern Mexican gartersnakes may move 0.85 mi (1.2 km) overland during monsoon season, this distance should be incorporated as a minimum lateral distance on both sides of stream bankfull stage. Additionally, another commenter suggested using as large of a buffer as possible of terrestrial habitat for northern Mexican gartersnakes due to the variety of environmental conditions found within remaining populations of the species.

Our Response:

In the revised proposed critical habitat rule (85 FR 23608; April 28, 2020), we explained that although northern Mexican gartersnakes have been found in a variety of vegetation types within the riparian zone (

i.e.,

grasses, shrubs, and wetland plants), the underlying characteristic of this habitat needed by the gartersnake appears to be dense vegetation or other natural structural components that provide cover for the species. Size of the riparian zone and composition of plants within the riparian zone varies widely across the range of the northern Mexican gartersnake, and studies have not been conducted throughout its entire range. The width of critical habitat for the northern Mexican gartersnake along streams varies from approximately 50 to 7,000 ft (15 to 2,134 m). Because the width of wetland and riparian zone varies along and among streams, and some streams have little to no riparian habitat but have wetland habitat that

includes some terrestrial components, delineating these areas rather than delineating a set distance from the stream channel better captures the underlying characteristics of terrestrial habitat for the northern Mexican gartersnake. All of these areas are within the known distance northern Mexican gartersnakes have been recorded from water (85 FR 23608, April 28, 2020, see “Terrestrial Space Along Streams” on pp. 85 FR 23614-23616).

As explained in the revised proposed critical habitat rule (85 FR 23608; April 28, 2020), terrestrial habitat adjacent to the stream channel that includes riparian vegetation, small mammal burrows, boulder fields, rock crevices, and downed woody debris provides areas for thermoregulation, shelter, foraging opportunities, brumation, and protection from predators. This terrestrial habitat as defined in PBF 1C is not meant to provide dispersal habitat. Dispersal habitat is captured by stream lengths included in critical habitat and includes all known maximum longitudinal lengths of home ranges for the species (see 85 FR 23608, April 28, 2020,

Stream Length,

pp. 85 FR 23619-23623).

As defined, PBF 1C captures all known locations of northern Mexican gartersnakes outside of water in streams that are not ephemeral. The northern Mexican gartersnake found 3,937 ft (1,200 m) straight line distance from a perennial water source during monsoon season mentioned by the commenter was located in the floodplain of an intermittent channel. This channel is included in critical habitat. In the revised proposed critical habitat rule (85 FR 23608; April 28, 2020), we also explain that northern Mexican gartersnakes have not been detected in overland areas outside of stream floodplains, and while they likely use these areas while moving between habitats, specific habitat attributes in these areas that are essential to the snakes have not been identified (see 85 FR 23608, April 28, 2020, “Overland Areas for Northern Mexican Gartersnake,” pp. 85 FR 23616-23617).

Comment 46:

One commenter stated that we should determine occupancy at the time of listing (2014) from 1980 to today, as was done in the original proposed critical habitat rule (78 FR 41550; July 10, 2013), rather than 1998 to today, which was done in the revised proposed critical habitat rule (85 FR 23608; April 28, 2020). Repeated discoveries of populations of northern Mexican gartersnakes that were thought to be lost or were unknown indicates using 1980 as the earliest year to determine occupancy at the time of listing is therefore more appropriate. A lack of documentation of occupancy reflects incomplete survey effort than true non-occupancy.

Our Response:

As explained extensively in the revised proposed critical habitat rule (85 FR 23608; April 28, 2020), although it is possible that northern Mexican gartersnakes are still extant in areas where they were detected only during the 1980s or prior, we have determined that the best available information reflecting occupancy at the time of listing supports a more recent date of records since 1998.

Based on our analyses in the listing rule (79 FR 38678; July 8, 2014), we conclude that there has been a significant decline in the species over the past 50 years. This decline appeared to accelerate during the two decades immediately before listing occurred. From this observation, we conclude that many areas that were occupied by the species in surveys during the 1980s are likely no longer occupied because those populations have likely disappeared. To determine where loss of populations was most likely, we reviewed survey efforts after 1989 that did not detect northern Mexican gartersnakes in some of the areas included in the original proposed critical habitat rule (78 FR 41550; July 10, 2013). All of the surveys conducted since the 1980s that were considered included at least the same amount or more search effort than those surveys that detected the species in the 1980s. Since 1998, researchers have detected northern Mexican gartersnakes in many areas where they were found in the 1980s, and this includes some areas where they had not been found prior to the 2014 final listing rule (see Criteria Used To Identify Critical Habitat). An increase in a species' detection information often occurs as a result of a species being listed as an endangered or threatened species, due increased survey effort spurred by to consultation requirements under section 7, as well as recovery actions or State coordination efforts under section 6, of the Act. Additional occupancy information is also sometimes obtained as a result of academic research on a species. Because these areas were occupied at the time of listing, we have included these areas in critical habitat (see Criteria Used To Identify Critical Habitat).

Comment 47:

Multiple commenters suggested we consider using longer stream lengths to determine gartersnake occupancy. A species might use a stream's entire wetted length, rather than just certain reaches, and the northern Mexican gartersnake had previously been connected in large stretches of river that are part of high-quality, contiguous riparian habitat.

Our Response:

In the original proposed critical habitat rule (78 FR 41550; July 10, 2013), we included the entire stream length of a perennial or intermittent stream if it had at least one known record for the northern Mexican gartersnake and at least one record of a native prey species present. In doing so, we included many areas that were not within the known range of the species, did not have records of the species, or did not contain the PBFs. For the revised proposed critical habitat rule (85 FR 23608; April 28, 2020), we reevaluated all streams based on comments and reports on water availability, prey availability, and surveys to determine which reaches contain the PBFs.

In the revised proposed critical habitat rule (85 FR 23608; April 28, 2020) and this final rule, critical habitat includes occupied streams or stream reaches within the historical range with survey records of the northern Mexican gartersnake dated from 1998 to 2019 that have retained the necessary PBFs that will allow for the maintenance and expansion of existing populations. We placed outer boundaries on the portion of a stream that is considered occupied. We identified the most upstream and downstream records of the northern Mexican gartersnake along each continuous stream reach determined by presence of PBFs, and we extended the stream reach to include a dispersal distance of 2.2 mi (3.6 km). After identifying the stream reaches that meet the above parameters, we then connected those reaches with areas between that have the PBFs. We consider these areas between survey records occupied because the species occurs upstream and downstream and multiple PBFs are present that allow the species to move through these stream reaches.

Comment 48:

One commenter stated that critical habitat should include areas where native prey is limited and/or where nonnative species are present, for both occupied and unoccupied critical habitat, because northern Mexican gartersnakes can survive with low natural prey populations and the presence of nonnatives. Another commenter stated that we should not exclude stream reaches where other Federal, State, Tribal, or private entities may stock predatory sportfish regularly or as needed, because recovery of listed species should be prioritized in those areas.

Our Response:

This critical habitat designation includes many areas that are occupied by the northern Mexican

gartersnake, where native prey is limited, and where nonnative species that prey on gartersnakes are present. Please see Final Critical Habitat Designation, below, for unit descriptions, including why units meet the definition of critical habitat for the northern Mexican gartersnake.

Areas subject to stocking of predatory sportfish are not occupied by the northern Mexican gartersnake. We have not identified any unoccupied areas that meet the definition of critical habitat. Please see our response to

Comment 50,

below.

Comment 49:

One commenter stated that the gartersnake is currently distributed in stream reaches that are dominated by nonnative vertebrates and crayfish; therefore, the best available science does not support excluding areas as critical habitat based on an abundance of nonnative aquatic predators.

Our Response:

We acknowledge that the northern Mexican gartersnake is extant in some areas that have abundant nonnative aquatic predators, some of which also are prey for gartersnakes, so the presence of nonnative aquatic predators is not always indicative of absence of the gartersnake (Emmons and Nowak 2016a, p. 17; Emmons

et al.

2016, entire; Nowak

et al.

2016, pp. 6-8; Lashway 2015, p. 5). Although we acknowledge that we do not have a thorough understanding of northern Mexican gartersnake population dynamics in the presence of nonnative aquatic predators as compared to other areas (Burger 2016, pp. 13-15), areas with aquatic predators that are currently known to support gartersnake populations are included in critical habitat. However, we think it is reasonable to conclude based on the best scientific data currently available that streams, stream reaches, and lentic water bodies were not occupied at the time of listing if they have only northern Mexican gartersnake records older than 1998 and have experienced a rapid decline in native prey species coupled with an increase in nonnative aquatic predators since gartersnakes were detected in these areas in the 1980s.

Comment 50:

Several commenters stated that designation of unoccupied critical habitat is needed for the northern Mexican gartersnake. Specifically, habitat fragmentation, small populations, and genetics threaten extinction and thus make unoccupied critical habitat essential. Designating unoccupied habitat is also important to restore connectivity among populations, and the Service should also consider reintroduction of the gartersnake to unoccupied areas.

Our Response:

As discussed in the final listing rule (79 FR 38678; July 8, 2014), continued population decline and extirpations threaten the genetic representation of the northern Mexican gartersnake because some populations have become disconnected and isolated from neighboring populations. This can lead to a reduction in the species' redundancy and resiliency when isolated, small populations are at increased vulnerability to the effects of threats and stochastic events, without a means for natural recolonization.

As required by section 4(b) of the Act, we use the best scientific and commercial data available in determining areas within the geographical area occupied at the time of listing that contain the features essential to the conservation of a species and may require special management considerations or protection, and areas outside of the geographical area occupied at the time of listing that are essential for the conservation of the species. However, based on the best scientific data available we have not identified any unoccupied areas that that are essential for the conservation of the species. While we know the conservation of the species will depend on increasing the number and distribution of populations of the northern Mexican gartersnake, not all of its historical range will be essential to the conservation of the species, and we are unable to delineate any specific unoccupied areas that are essential at this time. A number of areas within these watersheds continue to contain some or could develop many of the physical and biological features upon which the species depends, although the best available scientific data indicate all these areas are currently unoccupied. Some areas in these watersheds with the potential to support the physical and biological features are likely important to the overall conservation strategy for the northern Mexican gartersnake. Any specific areas essential to the species' conservation within these watersheds are not currently identifiable due to our limited understanding regarding the ideal configuration for the development of future habitat to support the northern Mexican gartersnake's persistence, the ideal size, number, and configuration of these habitats. Although there may be a future need to expand the area occupied by the species to reach recovery, these areas have not been identified in recovery planning for the northern Mexican gartersnake. Therefore, we cannot identify unoccupied areas that are currently essential to the conservation of the species that should be designated as critical habitat.

Comment 51:

One commenter stated that only including areas occupied by the species at the time of listing does not allow for naturally occurring range expansion into other areas with suitable habitat that already exist or are newly created from habitat restoration activities.

Our Response:

Limiting critical habitat to areas occupied by a species at the time of listing does not prevent a species from naturally expanding into other areas. We designate those areas occupied at the time of listing that contain the PBFs and need special management considerations or protection, and any other unoccupied areas that are essential to conservation of the species. Based on the best scientific data available we have not identified any unoccupied areas that that are essential for the conservation of the species. Please see our response to

Comment 50,

above.

Comment 52:

One commenter stated that the northern Mexican gartersnake likely exists in the Verde River downstream of Beasley Flat from a sighting made by The Nature Conservancy, and that area should have been included the revised proposed critical habitat rule (85 FR 23608; April 28, 2020).

Our Response:

We could not confirm the sighting made by The Nature Conservancy, and are not aware of any other confirmed recorded sightings at the time of listing that document northern Mexican gartersnakes downstream of Beasley Flat, so this site is not included in this critical habitat designation because it does not meet our definition of an occupied reach for the species. We are aware of a 2019 confirmed record for northern Mexican gartersnake upstream of Beasley Flat, and this site is included in this critical habitat designation.

Comment 53:

One commenter stated that we should add Scotia Canyon, Garden Canyon, and Huachuca Canyon in the Huachuca Mountains to critical habitat for the northern Mexican gartersnake based on a record of the species in the upper portion of Scotia Canyon near the Fort Huachuca boundary. The commenter stated that Garden and Huachuca Canyons have PBFs 1, 2, and 3; that Fort Huachuca's Environmental and Natural Resources Division reduces crayfish at an acceptable level for PBF 4; and that lack of detections in these areas is likely due to absence of targeted survey efforts.

Our Response:

Scotia Canyon was included in the original proposed critical habitat rule (78 FR 41550; July

10, 2013) and the revised proposed critical habitat rule (85 FR 23608; April 28, 2020), and is included in this final rule in the Upper Santa Cruz River Subbasin Unit of critical habitat for the northern Mexican gartersnake. We are not aware of any records that document northern Mexican gartersnakes in Garden Canyon or Huachuca Canyon, so these sites are not included in our critical habitat designation because they do not meet our definition of an occupied reach for the species. Please also see our response to

Comment 50,

above.

Comment 54:

In response to the original proposed critical habitat rule (78 FR 41550; July 10, 2013), one commenter stated that we should consider including unoccupied habitat for the northern Mexican gartersnake in the San Francisco River, Sycamore Canyon near Buenos Aires NWR, Davidson Canyon in the Cienega Creek watershed, and Leslie Canyon NWR.

Our Response:

As explained above in our responses to

Comments 51

and

52,

we have not identified unoccupied areas that are essential to the conservation of the species and that should be designated as critical habitat. In addition, we are not aware of any historical records for the northern Mexican gartersnake in these areas.

Comment 55:

Several commenters stated that our use of historical data spanning two decades to characterize areas of critical habitat that are “occupied at the time of listing” for purposes of a designation under section 3(5)(A)(i) of the Act is not synonymous with a determination that habitat is currently occupied for purposes of a “take” analysis under sections 7 and 10 of the Act, and that the distinction between these two concepts needs to be fully acknowledged and its implications explained in the final rule.

Our Response:

We designate areas as critical habitat that are occupied at the time of listing if those areas have one or more of the PBFs present that are essential to the conservation of the species and may requires special management considerations or protection (81 FR 7413). In the 2020 revised proposed critical habitat rule (85 FR 23608; April 28, 2020), we estimated that maximum longevity for northern Mexican gartersnake is 15 years, so it is reasonable to conclude that a gartersnake detected in 1998 or later represents a population that could still be present at the time of proposed listing in 2013, depending on the extent of threats in the area. We also included northern Mexican gartersnake detections after the species was listed because these areas were likely occupied at the time of listing in 2014. As a result, there are areas in this final designation of critical habitat with records of gartersnakes from 1998 through 2019.

Under section 7 of the Act, Federal agencies are required to consult with the Service to ensure that the actions they carry out, fund, or authorize are not likely to jeopardize the continued existence of the species, or destroy or adversely modify critical habitat. For a jeopardy or “take” analysis, we analyze effects to a species if the species is present in the action area during the time of the action. For an adverse modification analysis, we analyze effects to critical habitat if critical habitat for a species is present in the action area. Therefore, defining where a species is occupied at the time of listing for critical habitat designation is not synonymous with a determination that an area is currently occupied for purposes of a jeopardy analysis under section 7 of the Act or a “take” analysis under section 10 of the Act. Those determinations depend on the best available information at the time of the analysis, and the likely effects and likelihood of take depend on the action under consideration.

Comment 56:

One commenter stated that livestock grazing would have a significant impact on habitat for the northern Mexican gartersnake and that special management considerations and protection would benefit the species.

Our Response:

As discussed in the final listing rule (79 FR 38678; July 8, 2014), livestock grazing is a largely managed land use, and, where closely managed, it is not likely to pose significant threats to the northern Mexican gartersnake. In cases where poor livestock management results in fence lines in persistent disrepair, allowing unmanaged livestock access to occupied habitat, adverse effects from loss of vegetative cover, sedimentation, or alteration of prey base may result. Activities that significantly reduce cover or increase sedimentation are addressed below under

Application of the “Adverse Modification” Standard

and Special Management Considerations or Protection.

Comment 57:

One commenter requested that we include a statement regarding the application of the “adverse modification” standard that existing activities are part of the baseline and, therefore, are presumed not to adversely modify critical habitat. The commenter further stated that we should affirmatively state that “adverse modification” will not be found where the agency, working with the project proponent, demonstrates that it will offset impacts to critical habitat through the protection and maintenance of alternative habitat within the designation, which is of comparable quality to the habitat that would be lost.

Our Response:

Section 7 of the Act requires us to ensure that any action authorized, funded, or carried out by the agency is not likely to destroy or adversely modify critical habitat. Therefore, only Federal action agencies are directly subject to the specific regulatory requirement (avoiding destruction and adverse modification) imposed by critical habitat designation. This adverse modification standard does not change whether the activities are ongoing or new, and we do not have a mechanism to determine that existing activities are presumed to not destroy or adversely modify critical habitat. Any new activity under section 7 will require evaluation of the effects of the action based on the specifics of the location of the project and its effects.

Comment 58:

Freeport-McMoRan Tyrone Inc. and Pacific Western Land Company (collectively known as “FMC”) stated that lands owned by FMC along the upper Gila River and Duck Creek in the Gila/Cliff Valley, Grant County, New Mexico, should be excluded from critical habitat pursuant to section 4(b)(2) of the Act based on their habitat management plans for spikedace (

Meda fulgida

) and loach minnow (

Rhinichthys cobitis

) and for southwestern willow flycatcher (

Empidonax traillii extimus

). FMC further stated that these management plans protect and support habitat for aquatic and riparian species, including native prey species for the northern Mexican gartersnake.

Our Response:

In response to FMC's request to exclude their lands along the upper Gila River and Duck Creek based on FMC habitat management plans for spikedace and loach minnow and for grazing management actions benefiting southwestern willow flycatcher, we have determined that the exclusion would not be appropriate for several reasons. Although we commend FMC for investing time, effort, and funding for conservation on the Gila River, the habitat conservation efforts to date that have been implemented are focused on management actions for spikedace, loach minnow, and southwestern willow flycatcher along the Gila River. There are no conservation efforts specific to the northern Mexican gartersnake included in these plans, and Duck Creek is not part of their planning area. In identifying critical habitat for the northern Mexican gartersnake, we identified those areas that meet the definition of critical habitat under

section 3(5)(A) of the Act. Although management actions for one listed species may overlap other species' habitat or be mutually beneficial to multiple listed species, the physical and biological features in occupied habitat for the northern Mexican gartersnake differ from the physical and biological features identified for spikedace, loach minnow, and southwestern willow flycatcher. As a result, excluding these areas based on management for listed fish and bird species does not meet our criteria for exclusion. See Exclusions,

Private or Other Non-Federal Conservation Plans or Agreements and Partnerships, in General,

below.

Comment 59:

Permittees of the Service-approved section 10 Salt River Project (SRP) Roosevelt Habitat Conservation Plan (HCP) requested that areas below the Modified Roosevelt Dam conservation space, or full pool elevation of 2,151 ft (656 m) (Roosevelt Lake Conservation Storage space), be removed or excluded from critical habitat for the northern Mexican gartersnake. Effects to northern Mexican gartersnakes within the Roosevelt Lake Conservation Storage space will be addressed in an upcoming modification to the SRP Roosevelt HCP that should be completed by December 2021, and this area does not contain PBFs 2 and 4 most of the time because of inundation that is entirely different from the natural periodic flooding that one would observe in a stream exhibiting a natural flow regime. The commenters further stated that any habitat that forms during interim periods is temporary and does not qualify as habitat essential to the conservation of the species.

The commenters also requested that the Roosevelt Lake flood control space (2,151 to 2,175 ft (656 to 663 m) elevation), which is under the jurisdiction of the U.S. Army Corps of Engineers (Corps), be excluded from critical habitat for the northern Mexican gartersnake. The commenters stated that this area will continue to be subject to minimization requirements under section 7 and impacts to the northern Mexican gartersnake would likely be quantified in terms of habitat loss. Therefore, designation of the area as critical habitat provides little, if any, additional benefit for species conservation.

Our Response:

As a result of discussions with SRP since the publication of the revised proposed critical habitat rule (85 FR 23608; April 28, 2020), in this final rule, we revised the extent of the critical habitat within the Tonto Creek Unit to its full pool elevation of 2,151 ft (656 m) to avoid those areas typically inundated by the lake in the Roosevelt Lake Conservation Storage space. Although the northern Mexican gartersnake may use these areas during periods of drought or at other times when the lake is drawn down, these areas are temporary and extremely variable, and may not contain the PBFs necessary for survival on a long-term basis.

With respect to flood control activities in the Roosevelt Lake flood control space included in critical habitat, Federal agencies that authorize, carry out, or fund actions that may affect listed species or designated critical habitat are required to consult with us to ensure the action is not likely to jeopardize listed species or destroy or adversely modify designated critical habitat. This consultation requirement under section 7 of the Act is not a prohibition of Federal agency actions; it is a means by which they may proceed in a manner that avoids jeopardy or adverse modification. Even in areas absent designated critical habitat, if the Federal agency action may affect a listed species, consultation is still required to ensure the action is not likely to jeopardize the species. Because the areas designated as critical habitat are occupied and consultation will be required to meet the jeopardy standard, the impact of the critical habitat designation should be minimal and administrative in nature. In addition, existing consultation processes also allow for emergency actions for risks to human life and property; critical habitat would not prevent the Corps from fulfilling those obligations.

In regards to the commenters' request to exclude the Roosevelt Lake flood control space from the critical habitat designation for the northern Mexican gartersnake, the commenters provided general statements of their desire to be excluded but no information or reasoned rationale as described in the preamble discussion of our Policy Regarding Implementation of Section 4(b)(2) of the Endangered Species Act (81 FR 7226; February 11, 2016) or as described in our revised proposed critical habitat rule (85 FR 23608; April 28, 2020). To properly evaluate an exclusion request, the commenters must provide information concerning how the Corps flood control activities would be limited or curtailed by the designation, and hence the need for exclusion. In addition, as noted above, the requirement to consult with us on Federal actions that may affect designated critical habitat is designed to allow actions to proceed while avoiding destruction or adverse modification of critical habitat.

In the Policy Regarding Implementation of Section 4(b)(2) of the Endangered Species Act (81 FR 7226; February 11, 2016), we outline the procedures we undertake when determining if an area should or should not be excluded. In determining whether to exclude an area, we are given a great deal of discretion for undertaking an exclusion analysis or determining to exclude an area. In our review of SRP's request for exclusion, we determined that the effect of having critical habitat designated in the Roosevelt Lake flood control space would require consultation with us for those Federal agency actions that may affect such designated critical habitat. In addition, we determined that this consultation requirement would not preclude these flood control activities from occurring, and subsequently would not result in a potential for increased risk of injury to human life and property.

Comment 60:

Permittees of the Service-approved Roosevelt HCP requested that the critical habitat within the SRP Camp Verde Riparian Preserve (Preserve) be designated as critical habitat for the northern Mexican gartersnake.

The commenters expressed that a designation of critical habitat on the Preserve would assist the public's understanding of the importance of year-round protection for the riparian habitat that supports the northern Mexican gartersnake population, as well as flycatchers and cuckoos that are present on the property.

Our Response:

In the revised proposed critical habitat rule (85 FR 23608; April 28, 2020), we identified approximately 96 ac (39 ha) within the Verde River Subunit of the Verde River Subbasin Unit owned by SRP covered by the Roosevelt HCP for the northern Mexican gartersnake. We are not excluding this area from the final designation. See Exclusions,

Private or Other Non-Federal Conservation Plans Related to Permits Under Section 10 of the Act,

below.

Comment 61:

One commenter stated that adequate surveys have not been conducted on properties managed by The Nature Conservancy along the Verde River, and there is no management plan to protect the species on these properties, so the properties should not be excluded from the critical habitat designation.

Our Response:

We did not receive a request for exclusion for The Nature Conservancy properties along the Verde River, although in the original proposed critical habitat rule (78 FR 41550; July 10, 2013) and in the revised proposed

critical habitat rule (85 FR 23608; April 28, 2020) we stated that we would consider The Nature Conservancy's Verde Springs Preserve and Verde Valley property for exclusion. The Nature Conservancy did not provide any supporting information, as described in our Policy Regarding Implementation of Section 4(b)(2) of the Endangered Species Act (81 FR 7226; February 11, 2016), or in response to our request for information in the revised proposed critical habitat rule (85 FR 23608; April 28, 2020). Although The Nature Conservancy is working with us to address conservation and recovery of the species in other areas, we have determined that the exclusion is not appropriate because we are not aware of any management plan for these properties along the Verde River that addresses conservation of the northern Mexican gartersnake. See Exclusions,

Private or Other Non-Federal Conservation Plans or Agreements and Partnerships, in General,

below.

Comment 62:

One commenter stated that we should not exclude Page Springs and Bubbling Ponds State Fish Hatcheries along Oak Creek in Yavapai County, Arizona, from the critical habitat designation because road mortality is high on the hatchery properties, and construction on the hatcheries will adversely modify habitat for the northern Mexican gartersnake. Another commenter stated that although AGFD has conservation projects and management actions for the species at these sites, it has not been consistent. They also stated construction at Bubbling Ponds Fish Hatchery impacts the species.

Our Response:

We identified this area for possible exclusion in the original proposed critical habitat rule (78 FR 41550; July 10, 2013) and in the revised proposed critical habitat rule (85 FR 23608; April 28, 2020), and we have excluded it in this final rule based on AGFD's comprehensive management plan for its Page Springs Aquatic Resources Complex. Based on our consideration of proposed exclusions, we found that AGFD has demonstrated a commitment to management practices that have conserved and benefited the northern Mexican gartersnake population in the area and is currently managing northern Mexican gartersnake habitat successfully. Additionally, the exclusion of these areas is likely to be beneficial in maintaining working partnerships with AGFD and private landowners. As a result of our exclusion/inclusion benefits analysis, we have determined that it is appropriate to exclude the area from the designation. Our rationale for excluding Page Springs and Bubbling Ponds State Fish Hatcheries is outlined below under Exclusions,

Private or Other Non-Federal Conservation Plans or Agreements and Partnerships, in General.

Comment 63:

Permittees of the Service-approved section 10 Pima County Multi-Species Conservation Plan (MSCP) requested that the critical habitat within the Cienega Creek Natural Area managed by Pima County Regional Flood Control District that falls within the Pima County MSCP planning area be designated as critical habitat.

The commenters expressed their confidence in the ability to deliver conservation benefit to the northern Mexican gartersnake by way of the mitigation, management, and monitoring strategies in the MSCP. However, large-scale Federal actions outside of Pima County's control could have significant negative impacts on species and lands under their management. The designation of critical habitat would require Federal agencies to use an additional standard of review when conducting section 7 consultations with the Service for federally permitted activities not controlled by Pima County. Keeping the area as critical habitat would further serve to benefit the conservation of species and its habitat (Murray 2020, entire). The commenters stated that maintaining northern Mexican gartersnake critical habitat on lands managed by the Pima County Regional Flood Control District would not impact their section 10(a)(1)(B) permit or their partners. The commenters therefore requested that critical habitat for the northern Mexican gartersnake be maintained on District-owned and leased properties and on the Federal lands within Las Cienegas NCA.

Our Response:

In the revised proposed critical habitat rule (85 FR 23608; April 28, 2020), we identified approximately 12 mi (19 km) of Cienega Creek within 543 ac (220 ha) of the Cienega Creek Subunit of the Cienega Creek Subbasin Unit owned by Pima County Regional Flood Control District covered by the Pima County MSCP for the northern Mexican gartersnake. We are not excluding this area from this final critical habitat designation. See Exclusions,

Private or Other Non-Federal Conservation Plans Related to Permits Under Section 10 of the Act,

below. We did not consider Federal lands within the Las Cienegas NCA for exclusion from critical habitat.

Comment 64:

We received several comments regarding exclusion from critical habitat designation of areas in the Upper San Pedro River Subbasin Unit that fall within the San Pedro Riparian NCA. One commenter requested that lands managed by the BLM, Arizona State Land Department, and private entities within the San Pedro River Subunit and Babocomari River Subunit, totaling approximately 5,745 ac, be excluded under section 4(b)(2) of the Act due to national security. The commenter stated that the proposed designation of critical habitat within these areas does not create a benefit to the northern Mexican gartersnake, yet it creates a significant economic burden that impairs the ability of the Department of Defense to protect national security. Several other commenters stated that the San Pedro River watershed area should not be excluded because the Army's request that lands controlled by other jurisdictions (

i.e.,

BLM, State of Arizona, private landowners) would increase its regulatory burden and negatively impact national security operations is too speculative and simplistic. One commenter stated that we should not exclude from critical habitat designation the San Pedro River Subunit and the Babocomari River Subunit based on natural security impacts because the military base is not actually located within the proposed critical habitat, and groundwater pumping threatens the San Pedro River community, which included a vast majority of the proposed critical habitat for the northern Mexican gartersnake.

Our Response:

For exclusion of an area from critical habitat designation based on national security, we look to our Policy Regarding Implementation of Section 4(b)(2) of the Endangered Species Act (81 FR 7226; February 11, 2016), which outlines measures we consider when excluding areas from critical habitat. A Federal agency must request exclusion based on National Security concerns and Fort Huachuca requested this exclusion. We reviewed Fort Huachuca's request for exclusion and determined that we are not considering the subject areas for exclusion from this final critical habitat designation due to national security. Please see Exclusions (

Exclusions Based on Impacts on National Security and Homeland Security

) for our analysis of the Fort Huachuca request for exclusion of lands within the San Pedro River and Babocomari River Subunits, which are within the San Pedro River NCA.

Comment 65:

Several commenters stated that we should consider the full scope of economic impacts to small entities for critical habitat rules. They also stated that the economic impact of the proposed designation would be

significant on agricultural and ranching operations.

Our Response:

For the revised proposed critical habitat rule (85 FR 23608; April 28, 2020), we made available, and requested public comments on, a draft economic analysis to examine the incremental costs associated with the designation of critical habitat. Our draft economic analysis did not find that there would be significant economic impacts to agriculture from this designation of critical habitat. This includes impacts to third-party entities, such as local governments and private landowners. Critical habitat does not restrict private landowner access to their property, and private landowners would only need to consult with the Service under section 7 of the Act if Federal agency funding or permitting for an activity is needed. Because the areas are considered occupied, most costs are not associated with the critical habitat designation, but rather with listing of the species as threatened. In our mapping of critical habitat, we focused on areas that contain the PBFs for the species. We do not anticipate requesting additional modifications for livestock grazing or agricultural operations, or cost-share projects undertaken with agencies such as the U.S. Department of Agriculture's Natural Resources Conservation Service (NRCS), as a result of the critical habitat designation beyond those required for the species itself. The economic analysis outlines the substantial baseline protections currently afforded the northern Mexican gartersnake through its listed status under the Act and the presence of the species in all designated critical habitat units, as well as overlap with the designated critical habitat of other, similar listed species. As a result of these protections, the economic analysis concludes that incremental impacts associated with section 7 consultations for the gartersnake are likely limited to additional administrative effort. Many of the areas designated as critical habitat for the gartersnake are already designated critical habitat for other listed species, and thus would not cause an incremental increase in effects due to the designation of critical habitat for the northern Mexican gartersnake.

However, we recognize the potential for landowners' perceptions of the Act to influence land use decisions, including decisions to participate in Federal programs such as those managed by NRCS. Several factors can influence the magnitude of perception-related effects, including the community's experience with the Act and understanding of the degree to which future section 7 consultations could delay or affect land use activities. Information is not available to predict the impact of the designation of critical habitat on landowners' decisions to pursue cost-share projects with NRCS in the future. However, incremental effects due to the designation of critical habitat for the northern Mexican gartersnake are likely to be minimized because the species is already listed.

Comment 66:

One commenter requested we update the economic analysis to account for the impact of COVID-19 on economic conditions.

Our Response:

We do not anticipate any additional effects on economic conditions as a result of the impact of the COVID-19 pandemic. For the revised proposed critical habitat rule (85 FR 23608; April 28, 2020), we made available, and requested public comments on, a draft economic analysis to examine the incremental costs associated with the designation of critical habitat. The draft economic analysis did not identify significant impacts. Because the critical habitat areas are considered occupied, the majority of costs are not associated with the critical habitat designation, but rather with listing of the species as threatened. If Federal funding is involved, the Federal agency providing the funding is the party responsible for meeting the Act's obligations to consult on projects on private lands. We have considered and applied the best available scientific and commercial information in determining the economic impacts associated with designating critical habitat. Critical habitat designation may also generate ancillary benefits by protecting the PBFs on which the species depends. As a result, management actions undertaken to conserve the species or its habitat may have coincident, positive social welfare implications, such as increased recreational opportunities in a region or improved property values on nearby parcels.

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.

Our regulations at 50 CFR 424.02 define the geographical area occupied by the species as an area that may generally be delineated around species' occurrences, as determined by the Secretary (

i.e.,

range). Such areas may include those areas used throughout all or part of the species' life cycle, even if not used on a regular basis (

e.g.,

migratory corridors, seasonal habitats, and habitats used periodically, but not solely by vagrant individuals).

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. Designation also does not allow the government or public to access private lands, nor does designation 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 Federal agency would be required to consult with the Service under section 7(a)(2) of the Act. However, even if the Service were to conclude that the proposed activity would result in destruction or adverse modification of the critical habitat, the Federal action agency and the landowner are not required to abandon the proposed activity, or to restore or recover the species; instead, they must 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 geographical 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 or biological features that occur in specific occupied areas, we focus on the specific features that are essential to support the life-history needs of the species, including, but not limited to, water characteristics, soil type, geological features, prey, vegetation, symbiotic species, or other features. A feature may be a single habitat characteristic or a more complex combination of habitat characteristics. Features may include habitat characteristics that support ephemeral or dynamic habitat conditions. Features may also be expressed in terms relating to principles of conservation biology, such as patch size, distribution distances, and connectivity.

Under the second prong of the Act's definition of critical habitat, we can designate critical habitat in 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. When designating critical habitat, the Secretary will first evaluate areas occupied by the species. The Secretary will only consider unoccupied areas to be essential where a critical habitat designation limited to geographical areas occupied by the species would be inadequate to ensure the conservation of the species. In addition, for an unoccupied area to be considered essential, the Secretary must determine that there is a reasonable certainty both that the area will contribute to the conservation of the species and that the area contains one or more of those physical or biological features essential to 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 from the species status assessment (SSA) report and information developed during the listing process for the species. Additional information sources may include any generalized conservation strategy, criteria, or outline that may have been developed for the species; 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 continue to 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 found in section 9 of the Act. 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.

Physical or Biological Features Essential to the Conservation of the Species

In accordance with section 3(5)(A)(i) of the Act and the applicable regulations at 50 CFR 424.12(b) (2012), in determining which areas we will designate as critical habitat from within the geographical area occupied by the species at the time of listing, we consider the physical or biological features that are essential to the conservation of the species and that may require special management considerations or protection. The regulations at 50 CFR 424.02 define “physical or biological features essential to the conservation of the species” as the features that occur in specific areas and that are essential to support the life-history needs of the species, including, but not limited to, water characteristics, soil type, geological features, sites, prey, vegetation, symbiotic species, or other features. A feature may be a single habitat characteristic or a more complex combination of habitat characteristics. Features may include habitat characteristics that support ephemeral or dynamic habitat conditions. Features may also be expressed in terms relating to principles of conservation biology, such as patch size, distribution distances, and connectivity. For example, physical features essential to the conservation of the species might include gravel of a particular size required for spawning, alkaline soil for seed germination, protective cover for migration, or susceptibility to flooding or fire that maintains necessary early-successional habitat characteristics. Biological features might include prey species, forage grasses, specific kinds or ages of trees for roosting or nesting, symbiotic fungi, or a particular level of nonnative species consistent with conservation needs of the listed species. The features may also be combinations of habitat characteristics and may encompass the relationship between characteristics or the necessary amount of a characteristic essential to support the life history of the species.

In considering whether features are essential to the conservation of the species, the Service may consider an appropriate quality, quantity, and spatial and temporal arrangement of habitat characteristics in the context of the life-history needs, condition, and status of the species. These

characteristics include, but are not limited to, space for individual and population growth and for normal behavior; food, water, air, light, minerals, or other nutritional or physiological requirements; cover or shelter; sites for breeding, reproduction, or rearing (or development) of offspring; and habitats that are protected from disturbance.

Summary of Essential Physical or Biological Features

We derive the specific physical or biological features essential to the conservation of the northern Mexican gartersnake from studies of the species' habitat, ecology, and life history as described below. We have determined that the following physical or biological features are essential to the conservation of the northern Mexican gartersnake:

1. Perennial or spatially intermittent streams that provide both aquatic and terrestrial habitat that allows for immigration, emigration, and maintenance of population connectivity of northern Mexican gartersnakes and contain:

(A) Slow-moving water (walking speed) with in-stream pools, off-channel pools, and backwater habitat;

(B) Organic and natural inorganic structural features (

e.g.,

boulders, dense aquatic and wetland vegetation, leaf litter, logs, and debris jams) within the stream channel for thermoregulation, shelter, foraging opportunities, and protection from predators;

(C) Terrestrial habitat adjacent to the stream channel that includes riparian vegetation, small mammal burrows, boulder fields, rock crevices, and downed woody debris for thermoregulation, shelter, foraging opportunities, brumation, and protection from predators; and

(D) Water quality that meets or exceeds applicable State surface water quality standards.

2. Hydrologic processes that maintain aquatic and terrestrial habitat through:

(A) A natural flow regime that allows for periodic flooding, or if flows are modified or regulated, a flow regime that allows for the movement of water, sediment, nutrients, and debris through the stream network; and

(B) Physical hydrologic and geomorphic connection between a stream channel and its adjacent riparian areas.

3. A combination of amphibians, fishes, small mammals, lizards, and invertebrate prey species such that prey availability occurs across seasons and years.

4. An absence of nonnative fish species of the families Centrarchidae and Ictaluridae, American 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 is not inhibited and maintenance of viable prey populations is still occurring.

5. Elevations from 130 to 8,497 feet (40 to 2,590 meters).

6. Lentic wetlands including off-channel springs, cienegas, and natural and constructed ponds (small earthen impoundment) with:

(A) Organic and natural inorganic structural features (

e.g.,

boulders, dense aquatic and wetland vegetation, leaf litter, logs, and debris jams) within the ordinary high water mark for thermoregulation, shelter, foraging opportunities, brumation, and protection from predators;

(B) Riparian habitat adjacent to ordinary high water mark that includes riparian vegetation, small mammal burrows, boulder fields, rock crevices, and downed woody debris for thermoregulation, shelter, foraging opportunities, and protection from predators; and

(C) Water quality that meets or exceeds applicable State surface water quality standards.

7. Ephemeral channels that connect perennial or spatially intermittent perennial streams to lentic wetlands in southern Arizona where water resources are limited.

Special Management Considerations or Protection

When designating critical habitat, we assess whether the specific areas within the geographical 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.

A detailed discussion of activities influencing the northern Mexican gartersnake and its habitat can be found in the final listing rule (79 FR 38678; July 8, 2014). All areas of critical habitat will require some level of management to address the current and future threats to the northern Mexican gartersnake and to maintain or restore the PBFs. Special management within 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 nonnative aquatic predators); an adequate prey base; and absence of or low numbers of nonnative aquatic predators that can affect population persistence. Activities that may be considered adverse to the conservation benefits of critical habitat include those which: (1) Completely dewater or reduce the amount of water to unsuitable levels in critical habitat; (2) result in a significant reduction of protective cover within critical habitat when nonnative aquatic predators species are present; (3) remove or significantly alter structural terrestrial features of critical habitat that alter natural behaviors such as thermoregulation, brumation, gestation, and foraging; (4) appreciably diminish the prey base for a period of time determined to likely cause population-level effects; and (5) directly promote increases in nonnative aquatic predator populations, result in the introduction of nonnative aquatic predators, or result in the continued persistence of nonnative aquatic predators. 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 nonnative aquatic predators as bait. The activities listed above are just a subset of examples that have the potential to affect critical habitat and PBFs if they are conducted within designated units; however, some of these activities, when conducted appropriately, may be compatible with maintenance of adequate PBFs or even improve upon their value over time.

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. In accordance with the Act and our applicable implementing regulations 50 CFR 424.12(b) (2012), to make a critical habitat designation, we review available information pertaining to the habitat requirements of the species and identify specific areas within the geographical area occupied by the species at the time of listing and any specific areas outside the geographical area occupied by the species that are determined to be essential to the conservation of the species. We are not designating any areas outside the geographical area occupied by the species because we have not identified any unoccupied areas that meet the definition of critical habitat. We are not designating any areas as critical habitat outside the geographical area occupied by the species at the time of listing. Sites

within the Upper Gila River, Upper Salt River, Verde River, Agua Fria River, San Pedro River, Santa Cruz River, and Black Draw watersheds were previously occupied by the northern Mexican gartersnake. While we know the conservation of the species will depend on increasing the number and distribution of populations of the northern Mexican gartersnake, not all of its historical range will be essential to the conservation of the species, and we are unable to delineate any specific unoccupied areas that are essential at this time. A number of areas within these watersheds continue to contain some or could develop many of the physical and biological features upon which the species depends, although the best available scientific data indicate all these areas are currently unoccupied. Some areas in these watersheds with the potential to support the physical and biological features are likely important to the overall conservation strategy for the northern Mexican gartersnake. Any specific areas essential to the species' conservation within these watersheds are not currently identifiable due to our limited understanding regarding the ideal configuration for the development of future habitat to support the northern Mexican gartersnake's persistence, the ideal size, number, and configuration of these habitats. Finally, the specific areas needed for conservation will depend in part on landowner willingness to restore and maintain the species' habitat in these areas. Therefore, although there may be a future need to expand the area occupied by the northern Mexican gartersnake to reach recovery, there are no unoccupied areas that are currently essential to the species' conservation and that should be designated as critical habitat.

To identify critical habitat units for the northern Mexican gartersnake, we used a variety of sources for species data, including riparian species survey reports, museum records, heritage data from State wildlife agencies, peer-reviewed literature, agency reports, and incidental sight records accompanied by photo vouchers and other supporting documentation verified by interviews with species experts. Holycross

et al.

(2020, entire) was a key source of information for vouchered historical and current records of the northern Mexican gartersnake species across its range. Other sources for current records of the northern Mexican gartersnake included Cotten

et al.

(2014, entire), Holycross

et al.

(2006, entire), and Rosen

et al.

(2001, entire). In addition to reviewing gartersnake-specific survey reports, we also focused on survey reports and heritage data from State wildlife agencies for fish and amphibians, as they captured important data on the existing community ecology that affects the status of the northern Mexican gartersnake within its range. In addition to species data sources, we used publicly available geospatial datasets depicting water bodies, stream flow, vegetation type, and elevation to identify areas for critical habitat designation.

We determined that a stream, stream reach, or lentic water body was occupied at the time of listing for northern Mexican gartersnake if it is within the historical range of the species, contains all PBFs for the species, (although the PBFs concerning prey availability and presence of nonnative predators are often in degraded condition), and a last known record of occupancy in 1998 or later. We determined occupancy at the time of listing for northern Mexican gartersnake by reviewing all records for the species in conjunction with expected survivorship of each species, subsequent surveys in areas that had no detection of the corresponding gartersnake species, and changes in threats over time that may have prevented occupancy at time of listing. Understanding longevity of a species can inform how long we can reasonably expect a species is still extant in an area, regardless of detection probability. The oldest estimated northern Mexican gartersnake is between 14 and 16 years old, although growth rate calculations are still preliminary (Ryan 2020, pers. comm.). The longest years between recaptures from these mark-recapture studies is 9 years (Ryan 2020, pers. comm.). Based on this information, we estimate maximum longevity for each gartersnake species is 15 years, so that it is reasonable to conclude that a gartersnake detected in 1998 or later represents a population that could still be present at the time of proposed listing in 2013, depending on the extent of threats in the area. Although it is possible that gartersnakes are still extant in areas where they were detected prior to 1998, we have determined that the best available information reflecting occupancy at the time of listing supports a more recent date of records since 1998.

Based on our analyses in the rule listing northern Mexican gartersnakes (79 FR 38678; July 8, 2014), we conclude that there has been a significant decline in the species over the past 50 years. This decline appeared to accelerate during the two decades immediately before listing occurred. From this observation, we conclude that many areas that were occupied by the species in surveys during the 1980s are likely no longer occupied because those populations have disappeared. To determine where loss of populations was likely, we reviewed survey efforts after 1989 that did not detect gartersnakes to determine whether the cryptic nature of the species was a valid argument for considering areas that only have gartersnake records from the 1980s as still occupied at the time of listing in 2013. All of the surveys conducted since the 1980s included at least the same amount or more search effort than those surveys that detected each species in the 1980s. Since 1998, researchers have detected northern Mexican gartersnakes in many areas where they were found in the 1980s. Areas where the species was found after 1997 are included in this final rule. Additionally, comparable surveys did detect gartersnakes in other areas where the species was present in the 1980s. Finally, we would expect that some populations would be lost during the decades preceding listing when numbers of gartersnakes were declining. These declines are what eventually led to the need to list the northern Mexican gartersnake.

As explained extensively in the final listing rule for northern Mexican gartersnake species (79 FR 38678, July 8, 2014, pp. 79 FR 38688-79 FR 38702), aquatic vertebrate survey efforts throughout the range of the northern Mexican gartersnake indicate that native prey species of northern Mexican gartersnakes have decreased or are absent, while nonnative predators, including bullfrogs, crayfish, and spiny-rayed fish, continue to increase in many of the areas where northern Mexican gartersnakes were present in the 1980s (Emmons and Nowak 2012, pp. 11-14; Gibson

et al.

2015, pp. 360-364; Burger 2016, pp. 21-32; Emmons and Nowak 2016a, pp. 43-44; Hall 2017, pp. 12

-

13). We acknowledge that northern Mexican gartersnakes are extant in some areas that have abundant nonnative, aquatic predators, some of which also are prey for gartersnakes, so presence of nonnative aquatic predators is not always indicative of absence of these gartersnakes (Emmons and Nowak 2012, p. 31; Emmons and Nowak 2016a, p. 13; Emmons

et al.

2016, entire; Nowak

et al.

2016, pp. 5-6; Lashway 2015, p. 5). We also acknowledge that we do not have a good understanding of why gartersnake populations are able to survive in some areas with aquatic predators and not in other areas (Burger 2016, pp. 13-15). However, we think it is reasonable to conclude that streams, stream reaches, and lentic water bodies

were not occupied at the time of listing if they have only gartersnake records older than 1998 and have experienced a rapid decline in native prey species coupled with an increase in nonnative aquatic predators since gartersnakes were detected in these areas in the 1980s.

We included detections of northern Mexican gartersnake that occurred after the species was listed because these areas were likely occupied at the time of listing in 2014. As stated earlier, the species is cryptic in nature and may not be detected without intensive surveys. Because populations for these species are generally small, isolated, and in decline it is not likely that the species have colonized new areas since 2014; these areas were most likely occupied at the time of listing, but either had not been surveyed or the species were present but not detected during surveys. However, we did not include streams or lentic water bodies where northern Mexican gartersnakes were released for recovery purposes after the species was listed that had not been historically occupied by the species.

Stream reaches that lack PBFs include areas where water flow became completely ephemeral along an otherwise perennial or spatially intermittent stream, hydrologic processes needed to maintain streams could not be recovered, nonnative aquatic predators outnumbered native prey species, or streams were outside the elevation range. In addition, reaches with multiple negative surveys without a subsequent positive survey or reaches that have no records of northern Mexican gartersnake species are not included. We do include stream reaches that lack survey data for the species, if they have positive observation records of the species dated 1998 or later both upstream and downstream of the stream reach and have all of the PBFs.

We also reviewed the best available information we have on home range size and potential dispersal distance for northern Mexican gartersnake species to inform upstream and downstream boundaries of each unit and subunit of critical habitat. The maximum longitudinal distance measured across home range areas of northern Mexican gartersnake tracked for at least one year was 4,852 ft (1,478.89 m) for one individual, and ranged from 587.9 to 2,580 ft (179.2 to 481.58 m) for eight other northern Mexican gartersnakes (Nowak et al. 2019, pp. 24-25). These longitudinal home range distances were all determined from adult gartersnakes and did not inform how juvenile gartersnakes are dispersing along a stream. Juvenile dispersal is important because snakes of different age classes behave differently, and juvenile gartersnakes may move farther along a stream as they search for and establish suitable home ranges than do adults with established home ranges. Because we have no information on how juvenile northern Mexican gartersnakes disperse, we used information from a long-term dispersal study on neonate, juvenile, and adult age classes of the Oregon gartersnake (

Thamnophis atratus hydrophilus

) in a free-flowing stream environment in northern California (Welsh

et al.

2010, entire). This is the only dispersal study available for another aquatic

Thamnophis

species in the United States, so we used it as a surrogate for determining upstream and downstream movements of northern Mexican gartersnakes. The greatest movement was made by a juvenile recaptured as an adult 2.2 mi (3.6 km) upstream from the initial capture location (Welsh

et al.

2010, p. 79). Therefore, in this final rule, we delineate upstream and downstream critical habitat boundaries of a stream reach at 2.2 mi (3.6 km) from a known northern Mexican gartersnake observation record.

The maps define the critical habitat designation, as modified by any accompanying regulatory text, presented at the end of this document under Regulation Promulgation. We include more detailed information on the boundaries of the critical habitat designation in the preamble of this document.

In summary, for areas within the geographic area occupied by the species at the time of listing, we delineated critical habitat unit boundaries using the following criteria:

1. We mapped records of observations of northern Mexican gartersnakes from 1998 to 2019. We then examined these areas to determine if northern Mexican gartersnakes could still occur in them, as described below.

2. We identified streams in which northern Mexican gartersnakes were found since 1980 (used flowline layer in the U.S. Geological Survey (USGS) National Hydrography Dataset to represent stream centerlines).

3. We identified and removed upstream and downstream ends of streams that were below 130 ft or above 8,500 ft elevation using USGS National Elevation Dataset.

4. We identified perennial, intermittent, and ephemeral reaches of streams. We removed end reaches of streams that are ephemeral based on FCode attribute of the flowline layer in the USGS National Hydrography Dataset or information from peer review and public comments.

5. We identified prey species along each stream using geospatial datasets, literature, peer review, and public comments. We removed stream reaches that were documented to not contain prey species.

6. We identified and removed stream reaches with an abundance of nonnative aquatic predators including fish, crayfish, or bullfrogs. (We used a combination of factors to determine nonnative presence and impact to the species. This evaluation included records from 1980 by looking at subsequent negative survey data for northern Mexican gartersnakes along with how the nonnative aquatic predator community had changed since those gartersnakes were found, in addition to the habitat condition and complexity. Most of the areas surveyed in the 1980s that had been re-surveyed with negative results for northern Mexican gartersnakes had significant changes to the nonnative aquatic predator community, which also decreased prey availability for the gartersnakes. These areas were removed in our revised proposed critical habitat rule (85 FR 23608; April 28, 2020).

7. We identified and removed stream reaches where stocking or management of nonnative fish species of the families Centrarchidae and Ictaluridae is a priority and is conducted on a regular basis.

8. We identified and included those stream reaches on private land without public access that lack survey data but that have positive survey records from 1998 forward both upstream and downstream of the private land and have stream reaches with PBFs 1 and 2.

9. We used a surrogate species to determine potential neonate dispersal along a stream, which is 2.2 mi (3.6 km). We then identified the most upstream and downstream records of the northern Mexican gartersnake along each continuous stream reach determined by criteria 1 through 8, above, and extended the stream reach to include this dispersal distance.

10. After identifying the stream reaches that met the above parameters, we then connected those reaches between that have the PBFs. We consider these areas between survey records occupied because the species occurs upstream and downstream and multiple PBFs are present that allow the species to move through these stream reaches.

11. We identified the springs, cienegas, and natural or constructed ponds in which records of observations of the species from 1998 to 2019 were

found and included them in the critical habitat designation.

12. We identified ephemeral reaches of occupied perennial or intermittent streams that serve as corridors between springs, cienegas, and natural or constructed ponds.

13. We identified and included the wetland and riparian area adjacent to streams, springs, cienegas, and ponds to capture the wetland and riparian habitat needed by the species for thermoregulation, foraging, and protection from predators. We used the wetland and riparian layers of the Service's National Wetlands Inventory dataset and aerial photography in Google Earth Pro to identify these areas.

When determining critical habitat boundaries, we made every effort to avoid including developed areas such as lands covered by buildings, pavement, and other structures because such lands lack physical or biological features necessary for the northern Mexican gartersnake. 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 rule have been excluded by text in the rule and are not designated as critical habitat. Therefore, a Federal action involving these lands will not trigger section 7 consultation with respect to critical habitat and the requirement of no adverse modification unless the specific action would affect the PBFs in the adjacent critical habitat. However, constructed fish barriers in streams within the designated critical habitat are part of the designation and are needed to manage the exclusion of nonnative species. Accordingly, section 7 consultation would apply to actions involving such fish barriers.

We are designating as critical habitat lands that we have determined are occupied at the time of listing (

i.e.,

currently occupied) and that contain one or more of the physical or biological features that are essential to support life-history processes of the species. As described above, we are not designating any areas outside the geographical area occupied by t

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