# Endangered and Threatened Wildlife and Plants; Revised Critical Habitat for the Riverside Fairy Shrimp

> Briefs, arguments, decisions, and more.

URL: https://www.frixlaw.com/law-library/documents/fr%3A2012-28250

## Record

- **Collection:** Federal Register
- **Document type:** Rule
- **Published:** December 4, 2012
- **Citation:** 77 FR 72070

## Text

DEPARTMENT OF THE INTERIOR
Fish and Wildlife Service
50 CFR Part 17
[Docket No. FWS-R8-ES-2011-0013; 4500030114]
RIN 1018-AX15
Endangered and Threatened Wildlife and Plants; Revised Critical Habitat for the Riverside Fairy Shrimp

AGENCY:

Fish and Wildlife Service, Interior.

ACTION:

Final rule.

SUMMARY:

We, the U.S. Fish and Wildlife Service, revise the critical habitat for the Riverside fairy shrimp under the Endangered Species Act of 1973, as amended. The previous critical habitat consisted of land in four units in Ventura, Orange, and San Diego Counties, California. We now designate land in three units in Ventura, Orange, and San Diego Counties, California, for a total of approximately 1,724 ac (698 ha), which represents critical habitat for this species. Areas in Riverside County are excluded from critical habitat in this final revised rule.

DATES:

This rule becomes effective on January 3, 2013.

ADDRESSES:

This final rule and the associated final economic analysis are available on the Internet at
http://www.regulations.gov.
Comments and materials received, as well as supporting documentation used in preparing this final rule, are available for public inspection, by appointment during normal business hours, at the U.S. Fish and Wildlife Service, Carlsbad Fish and Wildlife Office, 6010 Hidden Valley Road, Suite 101, Carlsbad, CA 92011; telephone 760-431-9440; facsimile 760-431-5901.

The coordinates or plot points or both from which the maps for this critical habitat designation were generated are included in the administrative record and are available on our Internet site (
http://www.fws.gov/carlsbad/
), at
http://www.regulations.gov
at Docket No. FWS-R8-ES-2011-0013, and at the Carlsbad Fish and Wildlife Office (see
FOR FURTHER INFORMATION CONTACT
). Any additional tools or supporting information developed for this critical habitat designation is available at the Fish and Wildlife Service Web site and Field Office set out above, and may also be on
http://www.regulations.gov.

FOR FURTHER INFORMATION CONTACT:

Jim Bartel, Field Supervisor, U.S. Fish and Wildlife Service, Carlsbad Fish and Wildlife Office, 6010 Hidden Valley Road, Suite 101, Carlsbad, CA 92011; telephone 760-431-9440; facsimile 760-431-5901. If you use a telecommunications device for the deaf (TDD), call the Federal Information Relay Service (FIRS) at 800-877-8339.

SUPPLEMENTARY INFORMATION:

Executive Summary

Why we need to publish a rule and the basis for our action.
Under the Endangered Species Act (Act), any species that is determined to be endangered or threatened shall, to the maximum extent prudent and determinable, have habitat designated that is considered to be critical habitat. Designations and revisions of critical habitat can only be completed by issuing a rule. We listed Riverside fairy shrimp as an endangered species on August 3, 1993 (58 FR 41384). We published our first rule designating critical habitat on May 30, 2001 (66 FR 29384). In response to a settlement agreement, we revised critical habitat in a final rule published April 12, 2005 (70 FR 19154). That rule was also challenged in court, and based on the provisions of the new settlement agreement, we are publishing this final revised critical habitat rule.

The critical habitat areas we are designating in this rule constitute our current best assessment of the areas that meet the definition of critical habitat for Riverside fairy shrimp. We are designating:

• Approximately 466 acres (ac) (189 hectares (ha)), in 2 subunits, as critical habitat in Ventura County.

• Approximately 396 ac (160 ha), in 4 subunits, as critical habitat in Orange County.

• Approximately 862 ac (348 ha), in 7 subunits, as critical habitat in San Diego County.

In total, we are designating approximately 1,724 ac (698 ha) as critical habitat for this species. We are also:

• Exempting 1,988 ac (804 ha) from critical habitat designation in Orange County and San Diego County.

• Excluding 1,259 ac (510 ha) from critical habitat designation in Orange County, Riverside County, and San Diego County.

We have prepared an economic analysis of the designation of critical habitat.
We announced the availability of the draft economic analysis (DEA) on March 1, 2012 (77 FR 12543), allowing the public to provide comments on our analysis. We have incorporated the comments and completed the final economic analysis (FEA).

Peer reviewer and public comment.
We sought comments from four independent specialists to ensure that our designation is based on scientifically sound data and analysis. We also considered all comments and information we received during the public comment periods.

Background

It is our intent to discuss in this final rule only those topics directly relevant to the revision of critical habitat for the Riverside fairy shrimp under the Act (16 U.S.C. 1531
et seq.
). For more information on the taxonomy, biology, and ecology of Riverside fairy shrimp, please refer to the final listing rule published in the
Federal Register
on August 3, 1993 (58 FR 41384); the first and second rules proposing critical habitat published in the
Federal Register
on September 21, 2000 (65 FR 57136), and April 27, 2004 (69 FR 23024), respectively; and the subsequent final critical habitat designations published in the
Federal Register
on May 30, 2001 (66 FR 29384), and April 12, 2005 (70 FR 19154). Additionally, more species information can be found in the 1998 Recovery Plan for the Vernal Pools of Southern California (1998 Recovery Plan) finalized on September 3, 1998 (Service 1998a, pp. 1-113), in the City of San Diego's 2002-2003 Vernal Pool Inventory (City of San Diego 2004, pp. 1-125), and in the Riverside fairy shrimp 5-year review (Service 2008, pp. 1-57). For new information on Riverside fairy shrimp genetics across the species' range and on the status and distribution of Riverside fairy shrimp, see the most recent proposed critical habitat rule published on June 1, 2011 (76 FR 31686). Information on the associated draft economic analysis (DEA) for the proposed rule to designate revised critical habitat was published in the
Federal Register
on March 1, 2012 (77 FR 12543).

Previous Federal Actions

The Riverside fairy shrimp was listed as an endangered species on August 3, 1993 (58 FR 41384). For a history of Federal actions prior to 2001, please refer to the September 21, 2000, proposed critical habitat rule (65 FR 57136). On May 30, 2001, we published a final rule designating critical habitat for the Riverside fairy shrimp (66 FR 29384). On November 6, 2001, the Building Industry Legal Defense Foundation, Foothill/Eastern Transportation Corridor Agency, National Association of Home Builders, California Building Industry Association, and Building Industry Association of San Diego County filed a lawsuit in the U.S. District Court for the District of Columbia challenging the

designation of Riverside fairy shrimp critical habitat and alleging errors in our promulgation of the May 30, 2001, final rule. We requested a voluntary remand, and on October 30, 2002, critical habitat for this species was vacated by order of the U.S. District Court for the District of Columbia, and the Service was ordered to publish a new final rule with respect to the designation of critical habitat for the Riverside fairy shrimp (
Building Industry Legal Defense Foundation,
et al., v.
Gale Norton, Secretary of the Interior,
et al.,
and Center for Biological Diversity, Inc. and Defenders of Wildlife, Inc.
Civil Action No. 01-2311 (JDB) (U.S. District Court, District of Columbia)).

On April 27, 2004, we again proposed to designate critical habitat for the Riverside fairy shrimp (69 FR 23024). The final critical habitat rule was published in the
Federal Register
on April 12, 2005 (70 FR 19154). On January 14, 2009, the Center for Biological Diversity filed a complaint in the U.S. District Court for the Southern District of California challenging our 2005 designation of critical habitat for Riverside fairy shrimp (
Center for Biological Diversity
v.
U.S. Fish and Wildlife Service and Dirk Kempthorne, Secretary of the Interior,
Case No. 3:09-CV-0050-MMA-AJB). A settlement agreement was reached with the plaintiffs (Case No. 3:09-cv-00051-JM-JMA; November 16, 2009) in which we agreed to submit a proposed revised critical habitat designation for the Riverside fairy shrimp to the
Federal Register
by May 20, 2011, and submit a final revised critical habitat designation to the
Federal Register
by November 15, 2012. The proposed revised critical habitat designation was delivered to the
Federal Register
on May 20, 2011, and published on June 1, 2011 (76 FR 31686). This rule complies with the conditions of the settlement agreement.

Summary of Changes From Proposed Rule

(1) We added updated information on the general impacts of climate change and its potential impacts to Riverside fairy shrimp in the
Climate Change
section of this document. We also performed a climate change analysis using software available through Climate Wizard, a web-based climate change prediction program jointly produced by The Nature Conservancy, the University of Washington, and University of Southern Mississippi. We incorporated the results of our analysis into the
Climate Change
section of this rule.

(2) We added a discussion to the
Criteria Used To Identify Critical Habitat
section to supplement our discussion in the proposed rule (76 FR 31686; June 1, 2011) and the March 1, 2012, publication that made available our DEA of the proposed rule (77 FR 12543) and to clarify the rationale for designation of critical habitat units. At the time of listing, we did not have surveys confirming the presence of Riverside fairy shrimp in each critical habitat unit and subunit. However, we confirm that the vernal pool complexes within each unit and subunit were in existence at the time of listing (with the exception of Subunit 3g (Johnson Ranch Created Pool)), and the units and subunits in which the vernal pool complexes are found are within the geographical area occupied by the species at the time of listing and contain the physical or biological features essential to the conservation of the species. Therefore, we consider Unit 1 (1a, 1b), Unit 2 (2c, 2dA, 2dB, 2e, 2f, 2g, 2h, 2i), Unit 3 (3c, 3d, 3e, 3f, 3h), Unit 4 (4c), and Unit 5 (5a, 5b, 5c, 5d, 5e, 5f, 5g, 5h) to meet the definition of critical habitat under section 3(5)(A)(i) of the Act (i.e., to be areas within the geographical area occupied by the Riverside fairy shrimp at the time of listing) for the reasons explained in the March 1, 2012, publication (77 FR 12543) despite the absence of proof of occupancy at the time of listing.

Regardless of the occupancy status (documented or presumed; pre- or post-listing) of each unit, in Table 1 of the March 1, 2012, publication (77 FR 12543), we provided our justification for determining why these areas are essential for the conservation of the species under section 3(5)(A)(ii) of the Act. For those units for which we lack data confirming occupancy at the time of listing, we are alternatively designating them under section 3(5)(A)(ii) because they are essential for the conservation of Riverside fairy shrimp and a designation limited to areas confirmed to be occupied at the time of listing would be inadequate to ensure the conservation of the species. We provide further explanation of our method and rationale for defining critical habitat boundaries in the
Criteria Used To Identify Critical Habitat
section below.

(3) Based on a public comment, we updated the name of the vernal pool complex at Marine Corps Air Station (MCAS) Miramar from “AA 1-7, 9-13 East Miramar (Pool 10) (AA1 East)” to its recommended name “East Miramar (AA1 South + Group) (Pool 4786; previously Pool 12).”

(4) In the proposed revised critical habitat rule, Table 4 incorrectly identified 6 ac (3 ha) of land in Subunit 4c as State-owned. The land is actually owned by the North [San Diego] County Transit District. Table 3 in this final revised rule has been updated to show the correct land ownership.

(5) We are now excluding lands owned by the Department of Homeland Security (DHS) in Subunit 5b (29 ac (12 ha)) and a portion of the lands in Subunit 5h (11 ac (4 ha)) from this final critical habitat designation based on national security. This exclusion is consistent with the exclusion of DHS lands in our previous final critical habitat rule published April 12, 2005 (70 FR 19154), due to national security concerns related to the operation and maintenance of the Border Infrastructure System (BIS).

In our proposed revised critical habitat rule published June 1, 2011 (76 FR 31686), we sought comments on whether or not these Federal lands should be considered for exclusion under section 4(b)(2) of the Act for national security reasons, whether such exclusion is or is not appropriate, and whether the benefits of excluding any specific area outweigh the benefits of including that area as critical habitat and why. On October 16, 2012, DHS commented that designation of these lands could interfere with U.S. Customs and Border Patrol Protection activities along the border and urged exclusion of the lands for national security reasons. Based on the national security importance of DHS maintaining access to these border areas, the Secretary is exercising his discretion to exclude lands owned by DHS in this final critical habitat rule. Details on our rationale can be found in the “Exclusions Based on National Security Impacts” section below.

(6) In the June 1, 2011, proposed revised rule, we stated that we were considering excluding lands owned by or under the jurisdiction of the Orange County Central-Coastal Natural Community Conservation Plan/Habitat Conservation Plan (NCCP/HCP), the Orange County Southern Subregion HCP, the Western Riverside County MSHCP, City of Carlsbad Habitat Management Plan (HMP) under the San Diego Multiple Habitat Conservation Program (MHCP), and County of San Diego Subarea Plan under the MSCP. We have now made a final determination that the benefits of exclusion outweigh the benefits of inclusion of lands covered by these plans. Therefore, the Secretary is exercising his discretion to exclude approximately 89 ac (36 ha) covered by the Orange County Central-Coastal NCCP/HCP, 233 ac (94 ha) covered by the Orange County Southern Subregion

HCP, 865 ac (350 ha) covered by the Western Riverside County MSHCP, 9 ac (4 ha) covered by the City of Carlsbad HMP, and 23 ha (9 ac) covered by the County of San Diego Subarea Plan under the MSCP. In all, the Secretary is exercising his discretion to exclude a total of 1,259 ac (510 ha). For a complete discussion of the benefits of inclusion and exclusion, see the Exclusions section below.

Table 1—Subunit Occupancy Status and Justifications for Determining Specific Areas Essential for the Conservation of Riverside Fairy Shrimp
1

Unit/subunit
2

Service status at

listing
3

Current status
4
; year of first record
5

Act section 3(5)(A)(i) justification
6

Act section 3(5)(A)(ii) justification
7

Ventura County

1a: Tierra Rejada Preserve
Presumed occupied
Occupied; 1998 (CNDDB, EO 9)
Primary Constituent Elements (PCEs) 1-3; may require management
Necessary to stabilize Riverside fairy shrimp populations per Recovery Plan (RP); possesses unique soils and habitat type; disjunct population maintains genetic diversity and population stability at species' northernmost distribution.

1b: South of Tierra Rejada Valley
Presumed occupied
Presumed occupied; no protocol surveys have been completed
PCEs 1-3; may require management
Provides appropriate inundation ponding; proximity and connectivity to 1a at northern distribution; protects existing vernal pool composition; ecological linkage.

Orange County

2c: MCAS El Toro
Confirmed occupied
Occupied; 1993 (Service 1993, MCAS El Toro survey)
PCEs 1-3; may require management.

2dA: Saddleback Meadow
Presumed occupied
Occupied; 1997 (HELIX 2009 Report #10537)
PCEs 1-3; may require management
Necessary to stabilize populations per RP; maintains current geographical, elevational, and ecological distribution; maintains current population structure; provides connectivity; large continuous block; ecological linkage.

2dB: O'Neil Regional Park (near Trabuco Canyon)
Presumed occupied
Occupied; 2001 (CNDDB, EO 17)
PCEs 1-3; may require management
Maintains current geographical, elevational, and ecological distribution; maintains current population structure; provides connectivity.

2e: O'Neil Regional Park (near Cañada Gobernadora)
Presumed occupied
Occupied; 1997 (CNDDB, EO 4)
PCEs 1-3; may require management
Maintains current geographical, elevational, and ecological distribution; maintains current population structure; provides connectivity.

2f: Chiquita Ridge
Presumed occupied
Occupied; 1997 (CNDDB, EO 5)
PCEs 1-3; may require management
Necessary to stabilize populations per RP; maintains current geographical, elevational, and ecological distribution; maintains current population structure; provides connectivity.

2g: Radio Tower Road
Presumed occupied
Occupied; 2001 (CNDDB, EO 15, 16)
PCEs 1-3; may require management
Maintains current geographical, elevational, and ecological distribution; maintains current population structure; provides connectivity.

2h: San Onofre State Beach, State Park leased land
Presumed occupied
Occupied; 1997 (CNDDB, EO 6)
PCEs 1-3; may require management
Unique soils and wetland type; maintains habitat function, genetic diversity, and species viability; ecological linkage.

2i: SCE Viejo Conservation Bank
Presumed occupied
Occupied; 1998 (CNDDB, EO 10)
PCEs 1-3; may require management
Maintains current geographical, elevational, and ecological distribution; maintains current population structure; provides connectivity.

Riverside County

3c: Australia Pool
Presumed occupied
Occupied; 1998 (CNDDB, EO 11)
PCEs 1-3; may require management
Maintains habitat function, genetic diversity, and species viability; ecological linkage.

3d: Scott Road Pool
Presumed occupied
Occupied; 2002 (CNDDB, EO 24)
PCEs 1-3; may require management
Maintains current geographical, elevational, and ecological distribution; disjunct habitat.

3e: Schleuniger Pool
Presumed occupied
Occupied; 1998 (CNDDB, EO 8)
PCEs 1-3; may require management
Maintains current geographical, elevational, and ecological distribution.

3f: Skunk Hollow and Field Pool
Confirmed occupied
Skunk Hollow: Occupied; 1988 (CNDDB, EO 3). Field Pool: Occupied; 1988 (Service, GIS ID 9)
PCEs 1-3; may require management.

3g: Johnson Ranch Created Pool
Created (in 2002)
Occupied; 2003 (Service, GIS ID 13)
PCEs 1-3; may require management
Provides connectivity among pools; maintains current population structure.

3h: Santa Rosa Plateau-Mesa de Colorado
Presumed occupied
Occupied; 2009 (Selheim and Searcy 2010, Report # 11005)
PCEs 1-3; may require management
Necessary to stabilize populations per RP; unique soils and habitat type; large continuous blocks of occupied habitat; ecological linkage.

San Diego County

4c: Poinsettia Lane Commuter Train Station (JJ2)
Presumed occupied
Occupied; 1998 (CNDDB, EO 7)
PCEs 1-3; may require management
Necessary to stabilize populations per RP; unique soils and habitat type; disjunct habitat; provides protection for existing vernal pool composition and structure.

5a: J33 (Sweetwater High School)
Presumed occupied
Occupied; 2003 (City of San Diego 2004)
PCEs 1-3; may require management
Maintains current population structure; genetic diversity.

5b: J15 (Arnie's Point)
Presumed occupied
Occupied; 2006 (ERS, Report #8639)
PCEs 1-3; may require management
Necessary to stabilize populations per RP; maintains current population structure; ecological linkage.

5c: East Otay Mesa
Presumed occupied
Occupied; 2000 GIS ID 4; 2001 (EDAW 2001) (CNDDB, EO 25)
PCEs 1-3; may require management
Unique soils and habitat type; maintains current geographical, elevational, and ecological distribution; disjunct habitat; protects existing vernal pool composition.

5d: J29-31
Confirmed occupied
Occupied; 1986 (Bauder 1986a); (Simovich and Fugate 1992) (CNDDB, EO 2)
PCEs 1-3; may require management.

5e: J2 N, J4, J5
Presumed occupied
Occupied; 2003 (City of San Diego, 2004)
PCEs 1-3; may require management
Necessary to stabilize populations per RP; provides connectivity among pools; maintains current population structure.

5f: J2 S and J2 W
Presumed occupied
Occupied; 2001 (CNDDB, EO 18)
PCEs 1-3; may require management
Necessary to stabilize populations per RP; provides connectivity among pools; maintains current population structure.

5g: J14
Presumed occupied
Occupied; 2002 (HELIX 2002, Report #2386)
PCEs 1-3; may require management
Necessary to stabilize populations per RP; provides connectivity among pools; maintains current population structure.

5h: J11, J12, J16-18
Presumed occupied
Occupied; 2002 (City of San Diego 2004)
PCEs 1-3; may require management
Necessary to stabilize populations per RP; provides connectivity among pools; maintains current population structure.

1
As discussed above, we consider the areas for which we lack positive survey results to be “areas within the geographical area occupied by the species” under section 3(5)(A)(i) of the Act as explained in the March 1, 2012, publication at 77 FR 12543, pp. 12545-49. Table 1 summarizes the bases for that conclusion. However, we are alternatively designating areas that lack positive occupancy data at the time of listing under section 3(5)(A)(ii) of the Act because these areas are essential to the conservation of the species and a designation limited to known occupied areas would be inadequate to ensure the conservation of the species.

2
Unit/Subunit name as it appears in Table 1 of proposed revised rule (76 FR 31698). For additional information, see the Recovery Plan (RP) for Vernal Pools of Southern California (Service 1998a, 113+ pp.).

3
Service status: “Confirmed occupied” indicates that there is a record of occupancy at or before the time of listing; “Presumed occupied” indicates no documentation of occupancy for the specific areas (subunits) prior to 1993, but the areas are presumed to have been occupied at the time of listing based on best available science and post-1993 positive survey results in the possession of the Service. “Created” refers to a vernal pool enhancement or restoration after the time of listing.

4 5
Current status: “Occupied” indicates a positive survey result documenting species occurrence and “Presumed occupied” indicates no protocol surveys have been completed. The listed year is the year of first record followed by source. EO (element occurrence) is the number assigned to that occurrence, as defined and described according to the California Natural Diversity Data Base (CNDDB 2011). GIS ID is the occurrence information number for multiple species within jurisdiction of the Carlsbad Fish and Wildlife Office (Service 2011). City of San Diego (2004) is from the “Vernal pool inventory 2002-2003” or Contractor, and Report # is the number from a section 10(A)(1)(a) survey report, available in Service files.

6
Reasons determined essential to the conservation of the species, as defined according to criteria set forth in the proposed revised critical habitat rule, this document, and in section 3(5)(A)(i) of the Act, and based on current information on what we consider as the occupied geographic range of the species at the time of listing.

7
Reasons determined essential for the conservation of the species, as defined according to criteria set forth in the proposed revised critical habitat rule, this document, in the Recovery Plan (Service 1998a, Appendix F, pp. F-1-F-5) and in section 3(5)(A)(ii) of the Act. An empty box in the “Act section 3(5)(A)(ii) justification” column indicates this subunit is not proposed under section 3(5)(A)(ii) of the Act, and was confirmed occupied at the time of listing (see footnote 3).

* PCE: primary constituent element; SCE: Southern California Edison; GIS: geographic information system.

Critical Habitat

Background

Critical habitat is defined in section 3 of the Act as:

(1) The specific areas within the geographical area occupied by the species, at the time it is listed in accordance with the Act, on which are found those physical or biological features

(a) Essential to the conservation of the species and

(b) Which may require special management considerations or protection; and

(2) Specific areas outside the geographical area occupied by the species at the time it is listed, upon a determination that such areas are essential for the conservation of the species.

Conservation, as defined under section 3 of the Act, means to use and the use of all methods and procedures that are necessary to bring an endangered or threatened species to the point at which the measures provided pursuant to the Act are no longer necessary. Such methods and procedures include, but are not limited to, all activities associated with scientific resources management such as research, census, law enforcement, habitat acquisition and maintenance, propagation, live trapping, and transplantation, and, in the extraordinary case where population pressures within a given ecosystem cannot be otherwise relieved, may include regulated taking.

Critical habitat receives protection under section 7 of the Act through the requirement that Federal agencies ensure, in consultation with the Service, that any action they authorize, fund, or carry out is not likely to result in the destruction or adverse modification of critical habitat. The designation of critical habitat does not affect land ownership or establish a refuge, wilderness, reserve, preserve, or other conservation area. Such designation does not allow the government or public to access private lands. Such designation does not require implementation of restoration, recovery, or enhancement measures by non-Federal landowners. Only where a landowner requests Federal agency funding or authorization for an action that may affect a listed species or critical habitat would the consultation requirements of section 7(a)(2) of the Act apply.

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 within an area, we focus on the principal biological or physical constituent elements (primary constituent elements (PCEs) such as roost sites, nesting grounds, seasonal wetlands, water quality, tide, soil type) that are essential to the conservation of the species. PCEs are those specific elements of the physical or biological features that provide for a species' life-history processes and are essential to the conservation of the species.

Under the second prong of the Act's definition of critical habitat, we can designate critical habitat in areas outside the 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. For example, an area currently occupied by the species but that was not occupied at the time of listing may be essential to the conservation of the species and may be included in the critical habitat designation. We designate critical habitat in areas outside the geographical area occupied by a species only when a designation limited to its range would be inadequate to ensure the conservation of the species.

Section 4 of the Act requires that we designate critical habitat on the basis of the best scientific and commercial data available. Further, our Policy on Information Standards Under the Endangered Species Act (published in the
Federal Register
on July 1, 1994 (59 FR 34271)), the Information Quality Act (section 515 of the Treasury and General Government Appropriations Act for Fiscal Year 2001 (Pub. L. 106-554; H.R. 5658)), and our associated Information Quality Guidelines provide criteria, establish procedures, and provide guidance to ensure that our decisions are based on the best scientific data available. They require our biologists, to the extent consistent with the Act and with the use of the best scientific data available, to use primary and original sources of information as the basis for recommendations to designate critical habitat.

When we are determining which areas should be designated as critical habitat, our primary source of information is generally the information developed during the listing process for the species. Additional information sources may include the recovery plan for the species, articles in peer-reviewed journals, conservation plans developed by States and counties, scientific status surveys and studies, biological assessments, other unpublished materials, or experts' opinions or personal knowledge.

Habitat is dynamic, and species may move from one area to another over time. We recognize that critical habitat designated at a particular point in time may not include all of the habitat areas that we may later determine are necessary for the recovery of the species. For these reasons, a critical habitat designation does not signal that habitat outside the designated area is unimportant or may not be needed for recovery of the species. Areas that are important to the conservation of the species, both inside and outside the critical habitat designation, will 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 of section 9 of the Act if actions occurring in these areas may affect the species. Federally funded or permitted projects affecting listed species outside their designated critical habitat areas may still result in jeopardy findings in some cases. These protections and conservation tools will continue to contribute to recovery of this species. Similarly, critical habitat designations made on the basis of the best available information at the time of designation will not control the direction and substance of future recovery plans, habitat conservation plans (HCPs), or other species conservation planning efforts if new information available at the time of these planning efforts calls for a different outcome.

Climate Change

Our analyses under the Act include consideration of ongoing and projected changes in climate. The terms “climate” and “climate change” are defined by the Intergovernmental Panel on Climate Change (IPCC). The term “climate” refers to the mean and variability of different types of weather conditions over time, with 30 years being a typical period for such measurements, although shorter or longer periods also may be used (IPCC 2007a, p. 78). The term “climate change” thus refers to a change in the mean or variability of one or more measures of climate (e.g., temperature or precipitation) that persists for an extended period, typically decades or longer, whether the change is due to natural variability, human activity, or both (IPCC 2007a, p. 78).

Scientific measurements spanning several decades demonstrate that changes in climate are occurring, and that the rate of change has been faster since the 1950s. Examples include warming of the global climate system, and substantial increases in precipitation in some regions of the world and decreases in other regions. (For these and other examples, see IPCC 2007a, p. 30; and Solomon
et al.
2007, pp. 35-54, 82-85). Results of scientific analyses presented by the IPCC show that most of the observed increase in global average temperature since the mid-20th century cannot be explained by natural variability in climate, and is “very likely” (defined by the IPCC as 90 percent or higher probability) due to the observed increase in greenhouse gas (GHG) concentrations in the atmosphere as a result of human activities, particularly carbon dioxide emissions from use of fossil fuels (IPCC 2007a, pp. 5-6 and figures SPM.3 and SPM.4; Solomon
et al.
2007, pp. 21-35). Further confirmation of the role of GHGs comes from analyses by Huber and Knutti (2011, p. 4), who concluded it is extremely likely that approximately 75 percent of global warming since 1950 has been caused by human activities.

Scientists use a variety of climate models, which include consideration of natural processes and variability, as well as various scenarios of potential levels and timing of GHG emissions, to evaluate the causes of changes already observed and to project future changes in temperature and other climate conditions (for example, Meehl
et al.
2007, entire; Ganguly
et al.
2009, pp. 11555, 15558; Prinn
et al.
2011, pp. 527, 529). All combinations of models and emissions scenarios yield very similar projections of increases in the most common measure of climate change, average global surface temperature (commonly known as global warming), until about 2030. Although projections of the magnitude and rate of warming differ after about 2030, the overall trajectory of all the projections is one of increased global warming through the end of this century, even for the projections based on scenarios that assume that GHG emissions will stabilize or decline. Thus, there is strong scientific support for projections that warming will continue through the 21st century, and that the magnitude and rate of change will be influenced substantially by the extent of GHG emissions (IPCC 2007a, pp. 44-45; Meehl
et al.
2007, pp. 760-764 and 797-811; Ganguly
et al.
2009, pp. 15555-15558; Prinn
et al.
2011, pp. 527, 529). (See IPCC 2007b, p. 8, for a summary of other global projections of climate-related changes, such as frequency of heat waves and changes in precipitation. Also see IPCC 2011(entire) for a summary of observations and projections of extreme climate events.)

Various changes in climate may have direct or indirect effects on species. These effects may be positive, neutral, or negative, and they may change over time, depending on the species and other relevant considerations, such as interactions of climate with other variables (for example, habitat fragmentation) (IPCC 2007b, pp. 8-14, 18-19). Identifying likely effects often involves aspects of climate change vulnerability analysis. Vulnerability refers to the degree to which a species (or system) is susceptible to, and unable to cope with, adverse effects of climate change, including climate variability and extremes. Vulnerability is a function of the type, magnitude, and rate of climate change and variation to which a species is exposed, its sensitivity, and its adaptive capacity (IPCC 2007a, p. 89; see also Glick
et al.
2011, pp. 19-22). There is no single method for conducting such analyses that applies to all situations (Glick
et al.
2011, p. 3). We use our expert judgment and appropriate analytical approaches to weigh relevant information, including uncertainty, in our consideration of various aspects of climate change.

Global climate projections are informative, and, in some cases, the only or the best scientific information available for us to use. However, projected changes in climate and related impacts can vary substantially across and within different regions of the world (for example, IPCC 2007a, pp. 8-12). Therefore, we use “downscaled” projections when they are available and have been developed through appropriate scientific procedures, because such projections provide higher resolution information that is more relevant to spatial scales used for analyses of a given species (see Glick
et al.
2011, pp. 58-61, for a discussion of downscaling). The program Climate Wizard provides regional level projections of future climate patterns, using the World Climate Research Programme's (WCRP's) Coupled Model Intercomparison Project phase 3 (CMIP3) multi-model dataset (
http://www.climatewizard.org/
). These data project an average decrease of rainfall in coastal Southern California of approximately 5 percent by the year 2050.

Documentation of climate-related changes that have already occurred in California (Croke
et al.
1998, pp. 2128, 2130; Breshears
et al.
2005, p. 15144), and future drought predictions for California (for example, Field
et al.
1999, pp. 8-10; Lenihen
et al.
2003, p. 1667; Hayhoe
et al.
2004, p. 12422; Breshears
et al.
2005, p. 15144; Seager
et al.
2007, p. 1181) and North America (IPCC 2007a, p. 9), indicate prolonged drought and other climate-related changes will continue in the future. While climate change was not discussed in the 1993 listing rule, drought was noted in the rule as a stochastic (random or unpredictable) event that could have drastic effects on Riverside fairy shrimp, given its fragmented and restricted range (58 FR 41384, August 3, 1993, p. 41389; Service 1998a, p. 34). Local climate-related changes or drought-induced impacts that may negatively affect limited ephemeral wetland habitats include alterations in seasonal timing, ponding durations, or patterns of inundation and draw down (the drying period of a vernal pool). However, the magnitude and frequency of these factors remain untested.

In southern California, climatic variables affecting vernal pool habitats are most influenced by distance from the coast, topography, and elevation (Bauder and McMillian 1998, p. 64). As presence and persistence of Riverside fairy shrimp appear to be associated with precipitation patterns, draw-down factors, and other regional climatic factors, including aridity (Eriksen and Belk 1999, p. 71), the likely impacts of climate change on ecological processes for Riverside fairy shrimp are most closely tied to availability and persistence of ponded water during the winter and spring. Vernal pools are particularly sensitive to slight increases in evaporation or reductions in rainfall due to their relative shallowness and seasonality (Field
et al.
1999, p. 19). Based on existing data, weather conditions in which vernal pool flooding promotes hatching, but pools become dry (or too warm) before embryos are fully developed, are expected to have the greatest negative impact on Riverside fairy shrimp resistance and resilience. In the 2008 5-year review, we noted that climate change may potentially cause changes in vernal pool inundation patterns and pool consistency, and that drought may decrease or terminate reproductive output if pools fail to flood or dry up before reproduction is complete (Service 1998a, p. 34). Long-term or continuing drought conditions may deplete cysts (eggs) or cyst banks in affected pools due to the lack of new reproductive cysts.

Additionally, localized climate-related changes may alter the temporal

spatial array of occupied habitat patches across the species' geographic range (in other words, the presence of Riverside fairy shrimp across and between pool complexes). The ability of Riverside fairy shrimp to survive is likely to depend in part on their ability to disperse to pools where conditions are suitable (Bohonak and Jenkins 2003, p. 786) through passive dispersal mechanisms utilizing reproductive cysts (see the
Life History
section in the proposed rule, published June 1, 2011 (76 FR 31686)).

As discussed above, climate projections produced through Climate Wizard predict a decrease in annual rainfall by 2050. For a species that depends on long-term filling of vernal pools, any decrease in rainfall amount could affect the persistence of the species and the quality of available habitat. However, such projections are not straightforward, because filling of vernal pools may also depend on local watershed characteristics not directly related to annual rainfall. Additionally, the climate projections do not take storm events into account that could provide for filling of vernal pools. Therefore, designation of a wide variety of vernal pool habitat types is necessary to buffer against the projected future impacts of climate change. We find the designation herein provides for the array of habitat to provide for the conservation of the species.

Physical or Biological Features

In accordance with section 3(5)(A)(i) and 4(b)(1)(A) of the Act and regulations at 50 CFR 424.12, in determining which areas within the geographical area occupied by the species at the time of listing to designate as critical habitat, we consider the physical or biological features essential to the conservation of the species and which may require special management considerations or protection. These include, but are not limited to:

(1) Space for individual and population growth and for normal behavior;

(2) Food, water, air, light, minerals, or other nutritional or physiological requirements;

(3) Cover or shelter;

(4) Sites for breeding, reproduction, or rearing (or development) of offspring; and

(5) Habitats that are protected from disturbance or are representative of the historical, geographical, and ecological distributions of a species.

We derive the specific physical or biological features essential for the Riverside fairy shrimp from studies of this species' habitat, ecology, and life history as described in the Critical Habitat section of the proposed rule to designate critical habitat published in the
Federal Register
on June 1, 2011 (76 FR 31686), and in the information presented below. Additional information can be found in the final listing rule published in the
Federal Register
on August 3, 1993 (58 FR 41384), and the 1998 Recovery Plan (Service 1998a). We have determined that the Riverside fairy shrimp requires the physical or biological features described below.

Space for Individual and Population Growth and for Normal Behavior

Riverside fairy shrimp require vernal pool habitat to grow and reproduce. Their life cycle requires periods of inundation as well as dry periods (Ripley
et al.
2004, pp. 221-223). Habitats (ephemeral wetlands) that provide space for growth and persistence of Riverside fairy shrimp include areas that generally pond for 2 to 8 months and dry down for a period during the late spring to summer months. Habitats include natural and created pools (usually greater than 12 inches (in) (30 centimeters (cm)) deep) that support these longer inundation periods; some of these habitats are artificial pools (cattle watering holes and road embankments) that have been modified or deepened with berms (Hathaway and Simovich 1996, p. 670). Artificial depressions, often associated with degraded vernal pool habitat, are capable of functioning as habitat and can support vernal pool species, including Riverside fairy shrimp (Moran 1977, p. 155; Service 1998a, p. 22). Space for the Riverside fairy shrimp's normal growth and behavior requires an underlying soil series (typically clay soil inclusions with a subsurface claypan or hardpan component), which forms an impermeable layer that sustains appropriate inundation periods (water percolates slowly once filled) and provides necessary physiological requirements including, but not limited to, appropriate water temperature and water chemistry (mineral) regimes, a natural prey base, foraging opportunities, and areas for predator avoidance.

Intact vernal pool hydrology (including the seasonal filling and drying down of pools) is the essential feature that governs the life cycle of the Riverside fairy shrimp. An intact hydrological regime includes seasonal hydration (during most but not all years) followed by drying out of the substrate to promote overwintering of cysts and provide conditions for a viable cyst bank for the following season. Proper timing of precipitation and the associated hydrological and soil processes in the upland watershed contribute to the provision of space for growth and normal behavior. Seasonal filling and persistence of the vernal pool are necessary for cyst hatching and successful reproduction of Riverside fairy shrimp (see “Sites for Breeding, Reproduction, and Rearing (or Development) of Offspring”, below).

To maintain high-quality vernal pool ecosystems, the vernal pool basin (a specific vernal pool and surrounding landscape) or complex and its upslope watershed (adjacent vegetation and upland habitat) must be available and functional (Hanes and Stromberg 1998, p. 38). Adjacent upland habitat supplies important hydrological inputs to sustain vernal pool ecosystems. Protection of the upland habitat between vernal pools within the watershed is essential to maintain the space needs of Riverside fairy shrimp and to buffer the vernal pools from edge effects. Having the spatial needs that create pools of adequate depth also supports the temporal needs of Riverside fairy shrimp, as deep pools provide for inundation periods of adequate length to support the entire life-history function and reproductive cycles necessary for Riverside fairy shrimp.

Vernal pools generally occur in complexes, which are defined as two or more vernal pools in the context of a larger vernal pool watershed. The local watershed associated with a vernal pool complex includes all surfaces in the surrounding area that flow into the vernal pool complex. Within a vernal pool complex, vernal pools are hydrologically connected to one another within the local geographical context. These vernal pool complexes may connect by either surface or subsurface flowing water. Pools and complexes are dependent on adjacent geomorphology and microtopography for maintenance of their unique hydrological conditions (Service 1998a, p. 23). Water may flow over the surface from one vernal pool to another (over-fill or overbanking), throughout a network of swales or low-point depressions within a watershed. Due to an impervious clay or hardpan layer, water can also flow and collect below ground, such that the soil remains saturated with water. The result of the movement of water through vernal pool systems is that pools fill and hold water continuously for a number of days, weeks, or months following the initial rainfall (Hanes
et al.
1990, p. 51). Some hydrological systems have watersheds covering a large area, which contributes to filling and the hydrological dynamics of the system,

while other hydrologic systems have very small watersheds and fill almost entirely from direct rainfall. It is also possible that subsurface inflows from surrounding soils within a watershed contribute to filling some vernal pools (Hanes
et al.
1990, p. 53; Hanes and Stromberg 1998, p. 48).

Impervious subsurface layers of clay or hardpan soils, combined with flat to gently sloping topography, inhibit rapid infiltration of rainwater and result in ponded water in vernal pools (Bauder and McMillian 1998, pp. 57-59). These soils also act as a buffer that moderates the water chemistry and rate of water loss to evaporation (Zedler 1987, pp. 17-30). In Ventura County, soil series known to support Riverside fairy shrimp include, but are not limited to, the Azule, Calleguas, Cropley, and Linne soil series. In Orange County, soils series include the Alo, Balcom, Bosanko, Calleguas, Cieneba, Myford, and Soper soil series. In western Riverside County, vernal pool habitat known to support Riverside fairy shrimp includes the Altamont, Auld, Bosanko, Cajalco, Claypit, Murrietta, Porterville, Ramona, Traver, and Willows soil series. In San Diego County, vernal pool habitat known to support Riverside fairy shrimp includes the Diablo, Huerhuero, Linne, Placentia, Olivenhain, Salinas, Stockpen, and Redding soil series. Soil series data are based on 2008 Soil Survey Data and are available online at:
http://websoilsurvey.nrcs.usda.gov.
For additional information on soils, see the “Primary Constituent Elements for Riverside Fairy Shrimp” section below.

Food, Water, Air, Light, Minerals, or Other Nutritional or Physiological Requirements

Many fairy shrimp species are filter feeders with a diet that consists mostly of algae, bacteria, and other microorganisms (Parsick 2002, pp. 37-41, 65-70). In a natural vernal pool setting, these food items are readily available. Typically, an undisturbed, intact surface and subsurface soil structure (not permanently altered by anthropogenic land use activities such as deep, repetitive discing or grading), and the associated hydrogeomorphic processes within the basin and upland watershed, are necessary to provide food, water, minerals, and other physiological needs for Riverside fairy shrimp. Water temperature, water chemistry, and length of time that vernal pools are inundated are the important factors in the hatching and temporal appearance of Riverside fairy shrimp (Gonzalez
et al.
1996, pp. 315-316; Hathaway and Simovich 1996, p. 669). Riverside fairy shrimp hatch and reproduce in water at temperatures that range generally from 5 to 20 degrees Celsius (C) (41 to 68 degrees Fahrenheit (F)), and typically do not hatch at temperatures greater than 25 degrees C (77 degrees F) (Hathaway and Simovich 1996, pp. 674-675). Riverside fairy shrimp have a wider thermal tolerance than San Diego fairy shrimp (
Branchinecta sandiegonensis
), which allows Riverside fairy shrimp to hatch later in the season when deeper vernal pools are still filled with water.

Cover or Shelter

Ponding of vernal pool habitat (water) also provides cover and shelter for Riverside fairy shrimp. During the period when these habitats are inundated, water plays an important role in providing the necessary aquatic environment (shelter) for the fairy shrimp to complete its life-history requirements. Without water to protect them from desiccation, fairy shrimp would be unable to hatch, grow, mature, reproduce, and disperse within the vernal pool habitat (Helm 1998, p. 136; Service 1998a, p. 34; Eriksen and Belk 1999, pp. 71, 105). Additionally, the wet (ponding) period excludes plant and animal species that are exclusively terrestrial, providing a level of shelter from predation and competition for the fairy shrimp, which are adapted to short-lived, ephemeral wetland habitats.

The undisturbed soil bank also provides cover and shelter for fairy shrimp cysts during the draw-down period of the vernal pool habitat. The drying phase allows reproductive cysts to overwinter, as they lay dormant in the soil. Basin soils provide cover and shelter to Riverside fairy shrimp as the vernal pool dries out (Simovich and Hathaway 1997, p. 42; Eriksen and Belk 1999, p. 105). By maintaining the population in a dormant state, reproductive cysts and the undisturbed soil in which they rest protect Riverside fairy shrimp from predators and competitors during the vernal pool dry period. Cyst dormancy is an important life-history adaptation for surviving arid phases, and is important for synchronizing life cycles in unstable and ephemeral wetland habitats (Belk and Cole 1975, pp. 209-210). Like the wet period exclusion of terrestrial plants, the draw-down period excludes species that are exclusively aquatic (such as fish), providing shelter for specially adapted Riverside fairy shrimp.

Sites for Breeding, Reproduction, and Rearing (or Development) of Offspring

Mature Riverside fairy shrimp are typically observed from mid-March through April (Eng
et al.
1990, p. 259). In years with early or late rainfall, the hatching period may be extended. Riverside fairy shrimp can reach sexual maturity and begin mating approximately 8 weeks from the time a vernal pool fills with water (Hathaway and Simovich 1996, p. 673). Length of time to maturity restricts Riverside fairy shrimp to a small subset of relatively long-lasting vernal pools and ephemeral wetlands in southern California (Hathaway and Simovich 1996, p. 673). This maturation rate, which is distinctly longer than for other fairy shrimp, presumably restricts Riverside fairy shrimp typically to moderate to deep vernal pools and ephemeral basins (generally ranging from 12 in (30 cm) to 5 to 10 feet (ft) (1.5 to 3 meters (m)) in depth) (Hathaway and Simovich 1996, p. 675).

Because the length of time that pools remain filled in vernal pool ecosystems is highly variable, Riverside fairy shrimp have become adapted to some degree of unpredictability in their habitat (Eriksen and Belk 1999, pp. 104-105) and to a system where the requisite conditions are transitory. Depending on rainfall and environmental conditions, a vernal pool may fill and recede numerous times. Often, the pool may evaporate before Riverside fairy shrimp are able to mature and reproduce (Ripley
et al.
2004, pp. 221-223). The females' eggs begin to develop as soon as they are fertilized and then the development stops at an early stage (after a few cell divisions) and the eggs enter diapause (become dormant) as cysts or resting eggs (Lavens and Sorgeloos 1987, p. 29; Ericksen and Belk 1999, p. 105). Riverside fairy shrimp cysts are smaller than a tip of a pencil and contain a dormant fairy shrimp embryo encased in a hard outer shell. Cysts are generally retained in a brood pouch on the underbelly of the female until she dies, when both drop to the bottom of the vernal pool to become part of a cyst bank in the soil. During subsequent filling events, eggs may emerge from dormancy and hatch, or continue to diapause. Signals that break diapause include temperature and oxygen concentrations (Belk and Cole 1975, p. 216; Thorp and Covich 2001, p. 767). Resting eggs of freshwater crustaceans such as fairy shrimp have been shown to survive drying, heat, freezing, and ingestion by birds (Fryer 1996, pp. 1-14). Resting stages (dormancy) appear to be an adaptation

to temporary habitats and may aid in long-distance dispersal because they can survive unfavorable conditions during dispersal by birds or tires of off-highway vehicles (OHVs) (Belk and Cole 1975, pp. 209, 222; Williams 1985, p. 97).

Researchers have found that only a small proportion of Riverside fairy shrimp cysts in the cyst bank hatch each time the vernal pool fills. Therefore, if the pool dries before the species is able to mature and reproduce, there are still many more cysts left in the soil that may hatch the next time the pool fills (Simovich and Hathaway 1997, p. 42). Simovich and Hathaway (1997, pp. 40-43) referred to this as bet-hedging and concluded that it allows fairy shrimp, including Riverside fairy shrimp, to survive in an unpredictable environment. Bet-hedging ensures that some cysts will be available for hatching when the vernal pools hold water for a period long enough for Riverside fairy shrimp to complete their entire life cycle. Thus, reproductive output is spread over several seasons for small aquatic crustaceans, such as fairy shrimp, living in variable environments. Allowing conditions within the above parameters to occur on a natural basis is essential for the survival and conservation of Riverside fairy shrimp.

Habitats That Are Protected From Disturbance or Are Representative of the Historical, Geographical, and Ecological Distributions of the Species

Pools that support Riverside fairy shrimp are generally found in flat or moderately sloping areas, primarily in annual, disturbed (such as grazed or deep disced) grassland and chaparral habitats. The majority of complexes and pools that currently support Riverside fairy shrimp have experienced some level of disturbance, primarily from agriculture, cattle, and OHV activity.

Estimates of the historical distribution of Riverside fairy shrimp suggest that 90 to 97 percent of vernal pool habitat has been lost in southern California (Mattoni and Longcore 1997, pp. 71-73, 86-88; Bauder and McMillan 1998, p. 66; Keeler-Wolf
et al.
1998, p. 10; Service 1998a, p. 45). Consideration should be given to conserve much of the remaining Riverside fairy shrimp occurrences from further loss and degradation in a configuration that maintains habitat function and species viability (Service 1998a, p. 62). Historically, there were larger complexes of vernal pools, including areas on the Los Angeles coastal prairie (Mattoni and Longcore 1997, p. 88). In other places, such as Riverside County, which has not yet been developed and fragmented to the same extent as Los Angeles County, we believe it is possible that additional occurrences of the Riverside fairy shrimp may be documented through more intensive survey efforts and reporting.

The conservation of Riverside fairy shrimp is dependent on several factors including, but not limited to, maintenance of areas (of sufficient size and configuration to sustain natural ecosystem components, functions, and processes) that provide appropriate inundation and ponding durations, natural hydrological regimes and appropriate soils, intermixed wetland and upland watershed, connectivity among pools within geographic proximity to facilitate gene flow among complexes, and protection of existing vernal pool composition and structure.

In a few locations, two species of fairy shrimp—San Diego fairy shrimp and Riverside fairy shrimp—are known to co-occur (Hathaway and Simovich 1996, p. 670). However, where these species do co-occur, they rarely have been observed to coexist as adults (Hathaway and Simovich 1996, p. 670). San Diego fairy shrimp are usually found earlier in the season than Riverside fairy shrimp, due to the Riverside fairy shrimp's slower rate of development (Hathaway and Simovich 1996, p. 675). Maturation rates are responsible for the sequential appearance of the species as adults in pools where they co-occur (Hathaway and Simovich 1996, p. 675). Neither species is found in the nearby desert or mountain areas, as temperature has been shown to play an important role in the spatial and temporal appearance of fairy shrimp.

Primary Constituent Elements for Riverside Fairy Shrimp

Under the Act and its implementing regulations, we are required to identify the physical or biological features essential to the conservation of Riverside fairy shrimp in areas occupied at the time of listing, focusing on the features' primary constituent elements. Primary constituent elements are those specific elements of the physical or biological features that provide for a species' life-history processes and are essential to the conservation of the species.

Based on our current knowledge of the physical or biological features and habitat characteristics required to sustain the species' life-history processes, we determine that the primary constituent elements specific to Riverside fairy shrimp are:

(1) Ephemeral wetland habitat consisting of vernal pools and ephemeral habitat that have wet and dry periods appropriate for the incubation, maturation, and reproduction of the Riverside fairy shrimp in all but the driest of years, such that the pools:

(a) Are inundated (pond) approximately 2 to 8 months during winter and spring, typically filled by rain, and surface and subsurface flow;

(b) Generally dry down in the late spring to summer months;

(c) May not pond every year; and

(d) Provide the suitable water chemistry characteristics to support the Riverside fairy shrimp. These characteristics include physiochemical factors such as alkalinity, pH, temperature, dissolved solutes, dissolved oxygen, which can vary depending on the amount of recent precipitation, evaporation, or oxygen saturation; time of day; season; and type and depth of soil and subsurface layers. Vernal pool habitat typically exhibits a range of conditions but remains within the physiological tolerance of the species. The general ranges of conditions include, but are not limited to:

(i) Dilute, freshwater pools with low levels of total dissolved solids (low ion levels (sodium ion concentrations generally below 70 millimoles per liter (mmol/l)))

(ii) Low alkalinity levels (lower than 80 to 1,000 milligrams per liter (mg/l)); and

(iii) A range of pH levels from slightly acidic to neutral (typically in range of 6.4-7.1).

(2) Intermixed wetland and upland habitats that function as the local watershed, including topographic features characterized by mounds, swales, and low-lying depressions within a matrix of upland habitat that result in intermittently flowing surface and subsurface water in swales, drainages, and pools described in PCE 1. Associated watersheds provide water to fill the vernal or ephemeral pools in the winter and spring months. Associated watersheds vary in size and therefore cannot be generalized, and they are affected by factors including surface and underground hydrology, the topography of the area surrounding the pool or pools, the vegetative coverage, and the soil substrates in the area. The size of associated watersheds likely varies from a few acres to greater than 100 ac (40 ha).

(3) Soils that support ponding during winter and spring which are found in areas characterized in PCEs 1 and 2 that have a clay component or other property that creates an impermeable surface or subsurface layer. Soil series with a clay component or an impermeable surface or subsurface layer typically slow percolation, increase water run-off (at

least initially), and contribute to the filling and persistence of ponding of ephemeral wetland habitat where the Riverside fairy shrimp occurs. Soils and soil series known to support vernal pool habitat include, but are not limited to:

(a) The Azule, Calleguas, Cropley, and Linne soils series in Ventura County;

(b) The Alo, Balcom, Bosanko, Calleguas, Cieneba, and Myford soils series in Orange County;

(c) The Cajalco, Claypit, Murrieta, Porterville, Ramona, Traver, and Willows soils series in Riverside County; and

(d) The Diablo, Huerhuero, Linne, Placentia, Olivenhain, Redding, Salinas, and Stockpen soils series in San Diego County.

This final rule identifies the PCEs necessary to support one or more of the life-history functions of Riverside fairy shrimp and those areas containing the PCEs. We conclude that conservation of the Riverside fairy shrimp is dependent upon multiple factors. We consider the criteria for conservation of Riverside fairy shrimp to include: (1) Conservation and management of areas across the species' range that maintain normal hydrological and ecological functions where existing populations survive and reproduce and that are representative of the geographical distribution of the species; (2) conservation of areas representative of the ecological distribution of Riverside fairy shrimp (various combinations of soil types, vernal pool chemistry, geomorphic surfaces, and vegetation community associations), and (3) conservation of areas that allow for the movement of cysts between areas representative of the geographical and ecological distribution of the species (within and between vernal pool complexes).

We are designating most of the known occupied habitat of Riverside fairy shrimp because: (1) Riverside fairy shrimp are not migratory; (2) disjunct populations likely represent unique, locally adapted populations (adapted to unique site-specific or habitat-specific environmental conditions); and (3) gene exchange that should naturally occur between populations or critical habitat units is likely infrequent. Where management units are sufficiently distant (16 to 159 miles (mi) (26 to 256 kilometers (km)) from one another, the likelihood of gene exchange is reduced. All of the areas designated contain all of the PCEs essential for the species that may require special management considerations or protection, and they: (1) Maintain the genetic variability of Riverside fairy shrimp across its known geographical range and allow for a varying nature and expression of the species; (2) allow for natural levels of gene flow and dispersal where possible, in order to accommodate natural processes of local extirpation and colonization over time (and thereby reduce the risk of extinction through random and natural events); and (3) maintain a full range of varying habitat types and characteristics for the species by encompassing the full extent of the physical, biological, and environmental conditions essential for the conservation of Riverside fairy shrimp.

Not all life-history functions require all of the PCEs. For example, Riverside fairy shrimp can persist as cysts for several years when the vernal pools are not filled to the proper depth (note also PCE 1c, which recognizes that vernal pools occupied by Riverside fairy shrimp may not fill every year). Therefore, at any given time and particularly in the dry summer months, not all areas designated as revised critical habitat will demonstrate all aspects of the PCEs. However, over the longer time scale that represents the normal life-history functions of Riverside fairy shrimp, all of the PCEs are present in all of the units. Therefore, in consideration of that longer scale, we confirm that all units in this final critical habitat designation contain all of the PCEs. Further, all units and subunits designated as critical habitat are currently known to be occupied by Riverside fairy shrimp (with the exception of Subunit 1b, which is presumed to be occupied by Riverside fairy shrimp although not every portion of every unit and subunit is occupied by Riverside fairy shrimp. As discussed above, Riverside fairy shrimp require a functioning local watershed that results in intermittently flowing surface and subsurface water to fill the vernal pool basins in which the species occurs (PCE 2). Thus each unit and subunit consists of occupied vernal pool basins and the surrounding local watersheds that intermittently fill those basins. See the Final Critical Habitat Designation section below for more details.

Special Management Considerations or Protection

When designating critical habitat, we first assess whether there are specific areas within the geographical area occupied by the species at the time of listing that contain features essential to the conservation of the species that may require special management considerations or protection before considering whether any areas outside the geographical area occupied by the species at the time of listing may be essential for its conservation. The determination that special management may be required is not a prerequisite to designating critical habitat in areas essential for the conservation of the species that are outside the geographical area occupied at the time of listing. However, all areas (units/subunits) we are designating as revised critical habitat in this final rule, whether or not confirmed occupied or unoccupied at the time of listing, contain essential features that require special management considerations or protection to address current and future threats to Riverside fairy shrimp, maintain or enhance the features, and ensure the recovery and survival of the species.

The physical or biological features in areas designated as revised critical habitat in this final rule all face ongoing threats that require special management considerations or protection. For Riverside fairy shrimp, such threats include vernal pool elimination due to agricultural and urban development, including activities associated with construction of infrastructure (such as highways, utilities, and water storage) (PCEs 1, 2, 3); construction of physical barriers or impervious surfaces around a vernal pool complex (PCEs 1, 2); altered water quality or quantity (PCEs 1, 3) due to channeling water runoff into a vernal pool complex or to the introduction of water, other liquids, or chemicals (including herbicides and pesticides) into the vernal pool basin; physical disturbance to the claypan and hardpan soils within the vernal pool basin (PCEs 1, 3), including discharge of dredged or fill material into vernal pools and erosion of sediments from fill material; disturbance of soil profile by grading, digging, or other earthmoving work within the basin or its upland slopes or by other activities such as OHV use, heavy foot traffic, grazing, vegetation removal, fire management, or road construction within the vernal pool watershed (PCEs 1, 2, 3); invasion of nonnative plant and animal species into the vernal pool basin (PCEs 1, 2), which alters hydrology and soil regimes within the vernal pool; and any activity that permanently alters the function of the underlying claypan or hardpan soil layer (PCE 3), resulting in disturbance or destruction of vernal pool flora or the associated upland watershed (PCEs 2, 3). All of these threats have the potential to permanently reduce or increase the depth of a vernal pool, ponding duration and inundation of the vernal pool, or other vernal pool features beyond the tolerances of Riverside fairy shrimp (PCE 1).

Loss and degradation of wetland habitat, most directly from conversion

to agriculture and development, was cited in the final listing rule as a cause for the decline of Riverside fairy shrimp (58 FR 41387, August 3, 1993). Most of the populations of this species are located in San Diego, Orange, and Riverside Counties. These counties have had (and continue to have) increasing human populations, development, and infrastructure needs. Natural areas in these counties are frequently near or bounded by urbanized areas. Grading, discing, and scraping for urbanization results in loss of vernal pool topography and soil surface, as well as the subsurface soil layers, to the degree that they will no longer support ponding for Riverside fairy shrimp (PCE 3). Urban development modifies and removes vernal pool topography, compacts or disturbs soils such that basins and upland watershed components are altered, and likely eliminates or fragments populations of Riverside fairy shrimp through direct crushing of cysts, disruption of soils and removal of the cyst bank, and modification of upland hydrology and topography, which may potentially isolate a pool or pools within a complex. Overall, habitat loss continues to be the greatest direct threat to Riverside fairy shrimp.

Because the flora and fauna in vernal pools or swales can change if the hydrological regime is altered (Bauder 1986b), human activities that reduce the extent of the watershed or alter runoff patterns (timing, amount, or flow of water) (PCE 2) may also eliminate Riverside fairy shrimp, reduce their population size or reproductive success, or alter the duration or filling of basins such that the location of sites inhabited by this species may shift. Changes to hydrological patterns due to cattle trampling, OHV use, human trampling, road development, military activities, and water management activities impact vernal pools (PCEs 1, 2, 3) (58 FR 41387, August 3, 1993). Impacts to Riverside fairy shrimp such as the species' genetic diversity and patterns of gene flow, persistence from reductions in air and water quality due to human urbanization, or changes in nutrient availability associated with altered hydrology may be exacerbated by the species' highly fragmented and restricted range (Bauder 1986b, pp. 209-211).

Unpredictable natural events, such as fire, can be especially devastating due to the fragmented and restricted range of the species (58 FR 41390, August 3, 1993). Vernal pool habitat is naturally subject to wildfires, and cysts of other fairy shrimp species are known to survive fire events (Zedler 1987, p. 96; Wells
et al.
1997, p. 200). However, fire can have detrimental impacts on vernal pools from direct burning of dense surrounding vegetation (Bauder and Wier 1991, p. 5-10). Fire suppression can also damage vernal pools due to grading activities, suppression activities, crushing from vehicles associated with fire control, or from sediment runoff following fire (Bauder 1986a, p. 21; Bauder and Wier 1991, pp. 5-10-5-11; Hecht
et al.
1998, p. 33). These threats may require special management considerations or protection.

Changes in hydrology that affect the Riverside fairy shrimp's PCEs are caused by activities that alter the surrounding topography or change historical water flow patterns in the watershed (PCEs 2, 3). Even slight alterations in the hydrology can change the depth, volume, and duration of ponding inundation; water temperature; soil; mineral and organic matter transport to the pool; and water quality and chemistry, which in turn can make the ephemeral wetland habitat (PCE 1) unsuitable for Riverside fairy shrimp. Activities that impact the hydrology include, but are not limited to, road building, grading and earth moving, impounding natural water flows, and draining of pools or their immediately surrounding upland watershed. Impacts to the hydrology of vernal pools can be managed through avoidance of such activities in and around the pools and the associated surrounding upland areas.

Disturbance to the impermeable substrate layer of claypan and hardpan soils within vernal pools occupied by Riverside fairy shrimp (PCE 3) may alter the depth, ponding inundation, water temperature, and water chemistry. Physical disturbances to claypan and hardpan soils may be caused by excavation of borrow material (soil or sediments), OHV use, military training activities, repeated or deep agricultural discing, drilling during construction activities, or creation of berms that obstruct the natural hydrological surface or subsurface flow of water runoff and precipitation. Impacts to the soils of vernal pools can be managed through avoidance of these activities in and around the pools and the associated surrounding upland areas.

Nonnative plant species may alter ponding inundation and water temperature by changing the evaporation rate and shading of standing water in vernal pools (PCEs 1, 2). Invasive plant species, such as
Cotula coronopifolia
(brass-buttons) and
Agrostis avenacea
(Pacific bentgrass), compete with native vernal pool plant species and may alter the physiochemical factors of the water (PCE 1), the ponding duration (PCE 1), and the upland habitat (PCE 2) in these vernal pools. Impacts from nonnative plants can be managed to maintain the appropriate hydrology and physiochemical nature of the vernal pools required by the life-history processes of Riverside fairy shrimp.

Further discussion of specific threats to the PCEs in individual critical habitat units is provided in the unit descriptions below. In these revised critical habitat units, special management considerations or protection may be needed to ensure the long-term existence and management of ephemeral and upland habitat sufficient for the Riverside fairy shrimp's successful reproduction and growth, adequate feeding habitat, proper physiochemical and environmental regimes, linked hydrology, and connectivity within the landscape.

Criteria Used To Identify Critical Habitat

As required by section 4(b)(1)(A) 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 the Riverside fairy shrimp. In accordance with the Act and its implementing regulations at 50 CFR 424.12(e), we considered whether designating additional areas outside the geographical area occupied at the time of listing are essential to ensure the conservation of the species. At the time of listing, Riverside fairy shrimp were known to occupy nine vernal pool complexes within Orange, Riverside, and San Diego Counties, California, and Baja California, Mexico. Occupied complexes included four vernal pools in Riverside County, one population in Orange County, two complexes in San Diego County, and two locations in Baja California, Mexico (58 FR 41384; August 3, 1993).

In determining which areas within the geographical area occupied at the time of listing currently contain the physical or biological features essential to the conservation of Riverside fairy shrimp, we used all available scientific and commercial data, including information from the 1991 proposed listing rule (56 FR 57503, November 12, 1991), the 1993 final listing rule (58 FR 41384, August 3, 1993), the 1998 Recovery Plan (Service 1998a, pp. 1-113), the 2008 5-year review for Riverside fairy shrimp (Service 2008, pp. 1-57), the California Department of Fish and Game's (CDFG) California Natural Diversity Data Base

(CNDDB) records, published peer-reviewed articles, unpublished papers and reports, academic theses, survey results, geographic information system (GIS) data (such as species occurrences, soil data, land use, topography, and ownership maps), and correspondence to the Service from recognized experts. We solicited new information collected since publication of the 1998 Recovery Plan and 2005 final critical habitat designation (70 FR 19154), including information from State, Federal, and tribal governments; scientific data on Riverside fairy shrimp collected by academia and private organizations; information in reports submitted during consultations under section 7 of the Act; information contained in analyses for individual and regional HCPs where Riverside fairy shrimp is a covered species; and data collected from reports submitted by researchers holding recovery permits under section 10(a)(1)(A) of the Act.

We acknowledge the geographical area known to be occupied by the species in the United States as presented in the listing rule (58 FR 41384; August 3, 1993) is that area bounded by the coastline to the west, east to an area near tribal land of the Pechanga Band of Luiseño Mission Indians of the Pechanga Reservation, California, in western Riverside County, north into the central foothills of Orange County near the former Marine Corps Air Station (MCAS) El Toro, and south to coastal mesa tops along the United States-Mexico Border in San Diego County. However, as with many species, listing often results in greater efforts to conduct surveys that may reveal more information related to specific occurrences across a greater geographical area than were initially known (76 FR 31690; June 1, 2011). The current known range of Riverside fairy shrimp is from Ventura County to the United States-Mexico Border in San Diego County, a north-south distance of approximately 163 miles (mi) (262 kilometers (km)) within southern California and inland from the Pacific Coast 50 mi (80 km), based on all available species occurrence data pre- and post-listing. Two additional records documented Riverside fairy shrimp in northwestern Baja California, Mexico, at the time the species was listed (58 FR 41384). Extant occurrences are located within four counties in southern California: Ventura, Orange, Riverside, and San Diego.

When we developed our proposed critical habitat, we considered areas where Riverside fairy shrimp have been documented since listing (1993), including areas outside the geographical range of the species as presented in the listing rule, to be “within the geographical area occupied by the species at the time of listing [in 1993]” (see proposed rule at 76 FR 31689, June 1, 2011, and discussion below). Based on our review of the species' biology and life-history traits, we conclude that occurrences documented since the 1993 listing do not represent an expansion of the species' distribution and range, but rather reflect our better understanding of the distribution and range of the species at the time of listing (Service 2008, p. 9).

The life history of Riverside fairy shrimp supports the conclusion that many of the pools surveyed after publication of the listing rule were, in fact, occupied at the time of listing. Riverside fairy shrimp are relatively sedentary and possess limited dispersal capabilities (Davies
et al.
1997, p. 157). Dispersal is assumed to be through passive means, including movement of diapausing cysts by rain and overponding of water (Zedler 2003, p. 602) and wind (Brendonck and Riddoch 1999, p. 67; Vanschoenwinkel 2008, pp.130-133), or through active means, such as animal-mediated transport (Keeler-Wolf
et al.
1998, p. 11; Bohonak and Jenkins 2003, p. 784; Green and Figuerola 2005, p. 150). However, evidence of passive dispersal remains limited, and the relative role of vertebrate vectors requires additional studies (see Bohonak and Jenkins 2003, p. 786).

Riverside fairy shrimp have a relatively long maturation time (Simovich 1998, p. 111), which limits the species to deeper pools with longer ponding durations (Hathaway and Simovich 1996, p. 675). Riverside fairy shrimp exhibit a diversified bet-hedging reproductive strategy (Simovich and Hathaway 1997, p. 42). In other words, the species spreads reproductive effort over more than one ponding event through diapause of eggs (production of a cyst bank) and the hatching of a fraction of the cyst bank (Simovich and Hathaway 1997, p. 42; Philippi
et al.
2001, p. 392; Ripley
et al.
2004, p. 222).

Riverside fairy shrimp are restricted to certain pool types (deep, long-ponding, along coastal mesas or in valley depressions) with certain underlying soils (Bauder and McMillian 1998, p. 57), which have variable but specific water chemistry (Gonzalez
et al.
1996, p. 317) and temperature regimes (Hathaway and Simovich 1996, p. 672). Suitable pools are geographically fixed and limited in number, and influenced by position, distance from coast, and elevation (Bauder and McMillian 1998, pp. 62, 64). Typically, mima mound topography (landscapes consisting of mounds of soil) and impervious soils with a subsurface clay or hardpan layer provide the necessary ponding opportunities during winter and spring (Zedler 1987, pp. 13, 17). Underlying soil types and pool size influence the wetland habitat physiochemical parameters, associated vegetation, and faunal communities; those latter three factors are also affected by regional climate (rainfall, temperature, evaporation rate) and elevational differences (Keeler-Wolf
et al.
1998, p. 9). Vernal pools are discontinuously distributed in several regions in southern California, and Riverside fairy shrimp are well adapted to the ephemeral nature of their habitat and to the localized climate, topography, and soil conditions (Bauder and McMillian 1998, p. 56; Keeley and Zedler 1998, p. 6). These statements are supported by careful review of the species' habitat, ecology, and life-history requirements.

Based on these habitat and life-history traits, we conclude that the additional occurrences detected since listing, both within and to the north of the species' known geographical area at the time of listing, were likely present in those areas prior to listing, but the presence of the species was not known because protocol surveys had not been conducted prior to listing. Occurrences documented since the 1993 listing should not be construed to represent an expansion of the species' distribution and range, but rather to reflect our current and better understanding of the distribution and range of the species at the time of listing based on the best information available to us at this time (Service 2008, p. 9).

After publication of the June 1, 2011, proposed rule but before the March 1, 2012, publication, the Federal Circuit Court of Appeals for the District of Columbia invalidated a portion of the final rule designating critical habitat for the San Diego fairy shrimp under section 3(5)(A)(i) of the Act. The court concluded that the Service lacked adequate information to support its conclusion that the area in question was occupied at the time of listing and qualified as critical habitat under section 3(5)(A)(i) (
Otay Mesa Property, L.P. et al.
v.
U.S. Dept. of the Interior,
646 F.3d 914 (D.C. Cir. 2011) (
Otay Mesa
)). The court noted, however, that its ruling was narrow and directed only at the Service's reliance on section 3(5)(A)(i) of the Act. The court pointed out that the Service could choose to designate the area in question under section 3(5)(A)(ii) of the Act as long as we provide adequate justification for designation under that provision (

Otay

Mesa,

646 F.3d at 914). Because habitat containing the physical or biological features essential for the conservation of Riverside fairy shrimp overlaps with essential habitat for the San Diego fairy shrimp at issue in
Otay Mesa,
and because the species have similar life-history and habitat requirements, we applied the circuit court's reasoning in our March 1, 2012, publication (77 FR 12543), and apply it in this final designation of revised critical habitat for the Riverside fairy shrimp.

In light of that ruling, we reiterate that Unit 1 (1a, 1b), Unit 2 (2dA, 2dB, 2e, 2f, 2g, 2h, 2i), Unit 3 (3c, 3d, 3e, 3h), Unit 4 (4c), and Unit 5 (5a, 5b, 5c, 5e, 5f, 5g, 5h) meet the definition of critical habitat under section 3(5)(A)(i) of the Act (i.e., are areas within the geographical area occupied by the Riverside fairy shrimp at the time of listing) for the reasons explained in our March 1, 2012, publication (77 FR 12543) despite the absence of proof of occupancy at the time of listing. However, assuming such areas would not meet the definition of critical habitat under section 3(5)(A)(i) of the Act under the
Otay Mesa
court's application of “occupancy” under that provision due to the absence of prelisting surveys confirming the presence of Riverside fairy shrimp, we conclude that the areas alternatively meet the definition of critical habitat under section 3(5)(A)(ii) of the Act. These areas are essential for the conservation of the species, and a designation limited to areas documented to have been occupied at the time of listing would be inadequate to ensure the conservation of Riverside fairy shrimp. Nine occurrences of Riverside fairy shrimp were identified in the listing rule (58 FR 41384). One of those occurrences, located in Riverside County, has been lost due to development activities (Service 1998a, Appendix 1); a further two are in Baja California, Mexico, and therefore not subject to critical habitat designation (50 C.F.R. 424.12(h)). Based on a review of the best available scientific and commercial information, only five of those remaining six occurrences known at the time of listing currently contain the physical or biological features essential to the conservation of the species (see further details on identification of critical habitat units below). Those five occurrences are MCAS El Toro (Subunit 2c), Skunk Hollow Pool (Subunit 3f), Field Pool (Subunit 3f), complex J29-31 (Subunit 5d), and East Miramar (AA1 South+ Group)(Pool 4786; previously Pool 12). The latter occurrence is on MCAS Miramar and exempt from this final critical habitat rule. The sixth occurrence identified at the time of listing was a vernal pool partially within the Pechanga Band of Luiseño Mission Indians reservation and partially on private land abutting the reservation. That occurrence has been lost as a result of agricultural activities and construction of a gravel pit. In the proposed revised critical habitat rule published in 2011 (76 FR 31686; June 1, 2011), we requested comments from the public about these vernal pools, but received no information pertaining to them. Therefore, due to insufficient occurrence information and evidence of severely modified and impacted pools from years of discing and plowing, we are not proposing to designate critical habitat on tribal lands of the Pechanga Band of Luiseño Mission Indians.

These remaining five occurrences (representing three subunits) alone are not sufficient to conserve Riverside fairy shrimp. In addition, all of the areas that support extant occurrences of Riverside fairy shrimp face threats including development, habitat fragmentation, altered hydrology, livestock grazing, nonnative vegetation, military activities, pollution, dumping, human disturbance, and climate change (Service 2008, pp. 12-37; see also the
Climate Change
section above). Protecting a wide variety of habitat will provide a buffer against these threats and provide for the conservation of the species. Therefore, given the endangered status and the small number of extant Riverside fairy shrimp populations, and the need to protect the species' genetic and habitat variability to minimize the likelihood of a stochastic event eliminating most or all of the surviving populations, a critical habitat designation limited to areas known to be occupied at the time of listing would be inadequate to provide for the conservation of the species.

We identify three subunits (Subunit 2c, 3f, and 5d) as meeting the definition of critical habitat under section 3(5)(A)(i) of the Act because the areas were known to be occupied at the time of listing. We identify Subunit 3g as meeting the definition of critical habitat under section 3(5)(A)(ii) of the Act because the pool was created after the time of listing and because we consider it to be essential for the conservation of the species. We consider the remaining 21 subunits (Subunits 1a, 1b; Subunits 2dA, 2dB, 2e, 2f, 2g, 2h, 2i; Subunits 3c, 3d, 3e, 3h; Subunit 4c; Subunits 5a, 5b, 5c, 5e, 5f, 5g, 5h) to meet the definition of critical habitat under section 3(5)(A)(i) of the Act. However, because we lack definitive evidence of their occupancy at the time of listing, which under
Otay Mesa
could disqualify the areas from designation under section 3(5)(A)(i) of the Act, we alternatively identify these areas as meeting the definition of critical habitat under section 3(5)(A)(ii) of the Act. We identify them as such to make clear that we consider these specific areas to be essential for the conservation of Riverside fairy shrimp, notwithstanding the absence of surveys confirming the presence of Riverside fairy shrimp at the time of listing. Although we consider the available evidence sufficient to conclude that these subunits were occupied by Riverside fairy shrimp at the time the species was listed, due to the lack of documentation of occupancy, such as survey results prior to 1993, for the purposes of this rulemaking we determine that these subunits also alternatively meet the definition of critical habitat in section 3(5)(A)(ii) of the Act.

Our identification of these units and of habitat essential to the conservation of Riverside fairy shrimp takes into consideration the conservation approach described in the 1998 Recovery Plan and considers areas identified therein as necessary for the species' stabilization and recovery. The 1998 Recovery Plan identifies management areas on which the long-term conservation and recovery of Riverside fairy shrimp depend. Appendices F and G in the 1998 Recovery Plan defined known vernal pool complexes essential to the conservation of several vernal pool species, including Riverside fairy shrimp (Service 1998a, pp. F1-G3). Eight distinct management areas were identified based on plant and animal distribution, soil types, and climatic variables (Service 1998a, pp. 38-39). Management areas include vernal pools and complexes known to be occupied and essential to the conservation of Riverside fairy shrimp.

We have used these same eight management areas and names, where possible, to assist us in identifying specific areas essential to the conservation of the Riverside fairy shrimp. In cases where new occurrence data identify occupied vernal pools not identified in the 1998 Recovery Plan, we have relied on the best available scientific data to update map coverage (for example, in Orange and Riverside Counties). Our 2005 final rule (70 FR 19154) used locations identified in Appendices F and G of the 1998 Recovery Plan; however, for this final revised critical habitat rule (due to revisions to the PCEs and improvements in mapping methodologies), some additions and subtractions have

occurred in areas previously identified as essential either in the 1998 Recovery Plan or in the 2005 final critical habitat designation (Table 2). In some cases, areas within subunits have been removed because, based on new information, they no longer contain the physical or biological features or PCEs that are essential to the conservation of Riverside fairy shrimp. Specific differences from the 2005 final rule are summarized in the Summary of Changes from Previously Designated Critical Habitat section of the proposed rule published on June 1, 2011 (76 FR 31686).

We are designating critical habitat in specific areas that include ephemeral wetland habitat and intermixed wetland and upland habitats of various sizes; possess appropriate soils and topography that support ponding during winter and spring; are within the known geographical and elevational range of Riverside fairy shrimp; are geographically distributed throughout the range of the species; represent unique ecological or biological features and associations; and will help protect against stochastic extirpation, allow for local adaptation, and provide connectivity to facilitate dispersal and genetic exchange. By protecting a variety of habitats throughout the species' range, we increase the probability that the species can adjust in the future to various limiting factors that may affect the population, such as changes in abundance and timing of precipitation.

As required by section 4(b)(2) of the Act, we used the best scientific data available to designate critical habitat. The steps we followed in identifying critical habitat are described in detail below.

(1) We determined, in accordance with section 3(5)(A)(i) of the Act and regulations at 50 CFR 424.12, the physical or biological features that are essential to the conservation of the species (see the
Physical or Biological Features
section above).

(2) We compiled all available observational data on Riverside fairy shrimp into a GIS database. Data on locations of Riverside fairy shrimp occurrences are based on collections and observations made by biologists, biological consultants, and academic researchers. We compiled data from the following sources to create our GIS database for Riverside fairy shrimp: (a) Data used in the 1998 Recovery Plan, 2005 final critical habitat rule for Riverside fairy shrimp, and 2008 5-year review for Riverside fairy shrimp; (b) the CNDDB data report and accompanying GIS records for Riverside fairy shrimp (CNDDB 2010, pp. 1-9); (c) data presented in the City of San Diego's Vernal Pool Inventory for 2002-2003 (City of San Diego 2004, pp. 1-125); (d) monitoring reports for Riverside fairy shrimp from Marine Corps Base (MCB) Camp Pendleton and MCAS Miramar; (e) the Western Riverside County Multiple Species Habitat Conservation Plan (MSHCP) species GIS database; and (f) the Carlsbad Fish and Wildlife Office's (CFWO) internal species GIS database, which includes the species data used for the County of San Diego Multiple Species Conservation Plan (MSCP) and Western Riverside County MSHCP, reports from section 7 consultations, and Service observations of Riverside fairy shrimp (CFWO internal species GIS database). Compiled data were reviewed to ensure accuracy. Each data point in our database was checked to ensure that it represented an original collection or observation of Riverside fairy shrimp and that it was mapped in the correct location. Data points that did not match the description for the original collection or observation were remapped in the correct location or removed from our database.

(3) We determined which occurrences were extant at the time of listing, based on the 1993 listing rule, as well as information that has become available since the time of listing. We considered several sources in compiling the best available data on Riverside fairy shrimp vernal pool distribution and species' occurrence. We have concluded that, with the exception of Johnson Ranch Created Pool (Subunit 3g, which was created using cysts salvaged from a nearby historical occurrence at Redhawk development), all currently occupied vernal pools were also occupied and extant at the time of listing (see Background section and the specific unit descriptions below). We have drawn this conclusion because Riverside fairy shrimp have limited dispersal capabilities, and because surveys for the species at the time of listing were incomplete. We conclude that the documentation of additional occurrences within the range of Riverside fairy shrimp after it was listed was due to an increased survey effort for this species. However, as described above, we also find these areas are essential for the conservation of the species.

(4) We identified which areas contain the PCEs for Riverside fairy shrimp, and identified those areas that may require special management considerations or protection. Units were identified based on sufficient PCEs being present to support Riverside fairy shrimp life-history processes. Some units contain all of the identified PCEs and support multiple life stages (resting cyst, nauplii (recently hatched larvae), and adult). Areas that we have identified as having one or more PCEs: (a) Contain large interconnected ephemeral wetlands, large numbers of individuals, or habitat areas that allow for connections between existing occurrences of Riverside fairy shrimp; (b) represent important occurrences of this species on the geographic edge of its distribution; (c) contain occurrences that are more isolated from other occurrences by geographic features, but may represent unique adaptations to local features (biogeochemistry, hydrology, microclimate, soil mineralogy, soil fertility, soil formation processes, evolutionary time scale); or (d) exist within the distribution of the species and provide connections between occupied areas. The conservation of stable and persistent occurrences throughout the species' range helps to maintain connectivity and gene flow between occurrences that are in proximity to one another, as well as by preserving unique genetic assemblages in vernal pools across the range, including those pools not within close proximity to one another.

(5) We circumscribed boundaries of potential critical habitat, based on information obtained from the above steps. For areas containing the physical or biological features essential to the conservation of the species, we mapped the specific areas that contain the PCEs for Riverside fairy shrimp. First, we mapped the ephemeral wetland habitat in the occupied area using occurrence data, aerial imagery, and 1:24,000 topographic maps. We then mapped the intermixed wetland and upland habitats that function as the local watersheds and the topography and soils that support the occupied ephemeral wetland habitat. We mapped these areas to identify the gently sloping area associated with ephemeral wetland habitat and any adjacent areas that slope directly into the ephemeral wetland habitat, and that contribute to the hydrology of the ephemeral wetland habitat. We delineated the border of the revised critical habitat around the occupied ephemeral wetlands and associated local watershed areas to follow natural breaks in the terrain such as ridgelines, mesa edges, and steep canyon slopes.

(6) We removed all areas not containing the physical or biological features essential to the conservation of Riverside fairy shrimp. For example, 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 for Riverside fairy shrimp. 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 final rule have been excluded by text in the final rule and are not designated as critical habitat. Therefore, in this final revised critical habitat rule, a Federal action involving these lands would not trigger section 7 consultation with respect to critical habitat and the requirement of no adverse modification unless the specific action would affect any adjacent critical habitat.

(7) We exempted areas within the boundaries of MCB Camp Pendleton and MCAS Miramar in this final rule because we determined that these areas are exempt under section 4(a)(3)(B)(i) of the Act from critical habitat designation (see Exemptions section below).

The critical habitat designation is defined by the map or maps, as modified by any accompanying regulatory text, presented at the end of this document in the rule portion. We include more detailed information on the boundaries of the critical habitat designation in the preamble of this document. The coordinates or plot points or both on which each map is based are available to the public on
http://www.regulations.gov
at Docket No. FWS-ES-R8-2011-0013, on our Internet site (
http://www.fws.gov/carlsbad/
), and at the field office responsible for the designation (see
FOR FURTHER INFORMATION CONTACT
above).

Table 2—Areas Identified as Necessary for Stabilizing Riverside Fairy Shrimp Populations
[As listed in Appendix F of 1998 Recovery Plan, and as identified as essential and as containing the PCEs in the 2005 final critical habitat designation and this 2012 final revised critical habitat designation]

Name/Location
Listed in Appendix F of 1998 Recovery Plan

2005 final critical habitat designation
(subunit)

2012 final revised critical habitat
(subunit)

Unit 1: Ventura County (Goleta and Transverse MA)

Tierra Rejada Preserve (*RP: Carlsberg (Ranch))
Yes
1a
1a.

South of Tierra Rejada Valley (east of Hwy 23)
No
1b
1b.

Cruzan Mesa (*RP: Cruzan Mesa)
Yes
1c; Removed
Not proposed; not designated.

Unit 2: Los Angeles Basin—Orange County Foothills (Los Angeles Basin—Orange MA)

(MCAS) El Toro (*RP: El Toro)
Yes
2c; 4(b)(2) exclusion
2c; 4(b)(2) exclusion.

SCE Viejo Conservation Bank
No
No subunit #; 4(b)(2) exclusion
2i; 4(b)(2) exclusion.

Saddleback Meadow (*RP: Saddleback Meadow)
Yes **
2d; 4(b)(2) exclusion
2dA; partial 4(b)(2) exclusion.

O'Neill Regional Park (near Trabuco Canyon)
Yes **
2d; 4(b)(2) exclusion
2dB; partial 4(b)(2) exclusion.

O'Neill Regional Park (near Cañada Gobernadora)
Yes **
2
2e; partial 4(b)(2) exclusion.

Chiquita Ridge (*RP: Chiquita Ridge)
Yes
2f; 4(b)(2) exclusion
2f; 4(b)(2) exclusion.

RP: “Orange County Foothills (undescribed)”
Yes **
Not proposed
2h; partial designation 2dB, 2e, 2g, 2h, 2i; 4(b)(2) exclusion.

Radio Tower Road
No
2g; 4(b)(2) exclusion
2g; 4(b)(2) exclusion.

San Onofre State Beach, State Park-leased land (near Christianitos Creek foothills)
No
2h; 4(a)(3)(B) exemption
2h; partial 4(a)(3)(B) exemption.

Unit 3: Riverside Inland Valleys (Riverside MA)

March Air Reserve Base
No
3a; Removed
Not proposed; not designated.

March Air Reserve Base
No
3b; 4(a)(3)(B) exemption
Not proposed; not designated.

Australia Pool
No
No subunit #; 4(b)(2) exclusion
3c; 4(b)(2) exclusion.

Scott Road Pool
No
No subunit #; 4(b)(2) exclusion
3d; 4(b)(2) exclusion.

Schleuniger Pool
No
No subunit #; 4(b)(2) exclusion
3e; 4(b)(2) exclusion.

Skunk Hollow and Field Pool (Barry Jones Wetland Mitigation Bank) (*RP: Skunk Hollow/Murrieta)
Yes
No subunit #; 4(b)(2) exclusion
3f; 4(b)(2) exclusion.

Johnson Ranch Created Pool
No
No subunit #; 4(b)(2) exclusion
3g; 4(b)(2) exclusion.

Santa Rosa Plateau—Mesa de Colorado (*RP: Santa Rosa Plateau)
Yes
Not proposed
3h; 4(b)(2) exclusion.

No Unit #: Northern San Diego County Military Land, Exempted (San Diego North Coastal Mesa MA)

Stuart Mesa, MCB Camp Pendleton (*RP: Stuart Mesa)
Yes
No subunit #; 4(a)(3)(B) exemption
4(a)(3)(B) exemption.

Cockleburr, MCB Camp Pendleton (*RP: Cockleburr )
Yes
No subunit #; 4(a)(3)(B) exemption
4(a)(3)(B) exemption.

Las Pulgas, MCB Camp Pendleton (*RP: Las Pulgas)
Yes
No subunit #; 4(a)(3)(B) exemption
4(a)(3)(B) exemption.

Land south of San Onofre State Park
Yes
No subunit #; 4(b)(2) exclusion for National Security
4(a)(3)(B) exemption.

San Mateo, MCB Camp Pendleton (*RP: San Mateo)
Yes
No subunit #; 4(a)(3)(B) exemption
Not proposed; not designated.

Wire Mountain, MCB Camp Pendleton (*RP: Wire Mountain)
Yes
4(a)(3)(B) exemption
Not proposed; not designated.

Portion of San Onofre State Beach, State Park-leased land (near Christianitos Creek foothills) (*RP: State Park Lease Area)
No
No subunit #; 4(b)(2) exclusion for National Security
4(a)(3)(B) exemption.

No Unit Number: Central Sand Diego County, Military Land, Exempted (San Diego Central Coastal Mesa MA)

East Miramar (AA1 South+ Group)(Pool 4786; previously Pool 12)
Yes
4(a)(3)(B) exemption
4(a)(3)(B) exemption.

Unit 4: San Diego North Coastal Mesas (San Diego: North Coastal MA)

Poinsettia Lane Commuter Train Station (JJ 2) (*RP: JJ2 Poinsettia Lane)
Yes
4c
4c; 4(b)(2) exclusion.

Unit 5: San Diego Southern Coastal Mesas (San Diego: South Coastal MA)

J33 (Sweetwater High School)
No
5a; 4(b)(2) exclusion
5a.

J15 (Arnie's Point) (*RP: J2, J5, J7, J11-21, J23-30)
Yes **
5b; 4(b)(2) exclusion
5b; 4(b)(2) exclusion.

East Otay Mesa (*RP: Otay Mesa undescribed)
Yes
5c; partial 4(b)(2) exclusion
5c.

“Otay Mesa vernal pool complexes” (*RP: J2, J5, J7, J11-21, J23-30)
Yes **
No subunit #; 4(b)(2) exclusion
Designated as subunits below.

J29-31 (*RP: J2, J5, J7, J11-21, J23-30)
Yes **
No subunit #; 4(b)(2) exclusion
5d; partial 4(b)(2) exclusion.

J2 N, J4, J5 (Robinhood Ridge-J2) (*RP: J2, J5, J7, J11-21, J23-30)
Yes
No subunit #; 4(b)(2) exclusion
5e.

J2 S and J2 W (Hidden Valley, Cal Terraces, Otay Mesa Road) (*RP: J2, J5, J7, J11-21, J23-30)
Yes
No subunit #; 4(b)(2) exclusion
5f.

J14
No
No subunit #; 4(b)(2) exclusion
5g.

J11-12, J16-18 (Goat Mesa) (*RP: J2, J5, J7, J11-21, J23-30)
Yes
No subunit #; 4(b)(2) exclusion
5h; partial 4(b)(2) exclusion.

MA:
Management Area as defined in 1998 Recovery Plan.

(*RP):
name of pool (or pool complex) as stated in the 1998 Recovery Plan.

No:
not in 1998 Recovery Plan; occurrence not identified until after 1998.

Yes:
location was identified in the 1998 Recovery Plan.

Yes **:
location was considered in the 1998 Recovery Plan, but at that time was grouped (lumped) as multiple vernal pool complexes. These locations have now been separated in this 2012 final rule.

Final Critical Habitat Designation

We are designating 3 units, containing 13 subunits, as critical habitat for Riverside fairy shrimp. The three units are: Unit 1 (Ventura County), Unit 2 (Los Angeles Basin—Orange County Foothills), and Unit 5 (San Diego Southern Coastal Mesas). All of Unit 3 (Riverside County) and Unit 4 (San Diego North and Central Coastal Mesas) are excluded in this final rule. Table 3 shows all of the critical habitat units, including excluded acreages.

Table 3—Final Critical Habitat for Riverside Fairy Shrimp Is Shown in the Last Column of the Table.
[This table does not include habitat exempted under Section 4(a)(3) of the Act but does identify habitat excluded under Section 4(b)(2) in column 6.]

Critical habitat unit
Federal land
State land

Local land
1

Private land

Total area
containing essential features

Area excluded

Final critical
habitat

Unit 1: Ventura County

31 ac (13 ha)
435 ac (176 ha)
466 ac (189 ha)

466 ac (189 ha).

1a. Tierra Rejada Preserve

18 ac (7 ha)
18 ac (7 ac)

18 ac (7 ac).

1b. South of Tierra Rejada Valley

31 ac (13 ha)
417 ac (169 ha)
448 ac (182 ha)

448 ac (182 ha).

Unit 2: Los Angeles Basin—Orange County Foothills

142 ac (58 ha)
576 ac (233 ha)
718ac (291 ha)
322 ac (130 ha)
396 ac (160 ha).

2c. (MCAS) El Toro

18 ac (7 ha)
8 ac (3 ha)
26 ac (11 ac)
26 ac (11 ha)

2dA. Saddleback Meadow

4 ac (2 ha)
252 ac (102 ha)
256 ac (104 ha)
4 ac (2 ha)
252 ac (102 ha).

2dB. O'Neill Regional Park (near Trabuco Canyon)

75 ac (30 ha)
15 ac (6 ha)
90 ac (37 ha)
75 ac (30 ha)
15 ac (6 ha).

2e. O'Neill Regional Park (near Cañada Gobernadora)

45 ac (18 ha)
24 ac (10 ha)
69 ac (28 ha)
47 ac (19 ha)
22 ac (9 ha)

2f. Chiquita Ridge

56 ac (23 ha)
56 ac (23 ha)
56 ac (23 ha)

2g. Radio Tower Road

51 ac (21 ha)
51 ac (21 ha)
51 ac (21 ha)

2h. San Onofre State Beach, State Park-leased land (near Christianitos Creek foothills)

107 ac (43 ha)
107 ac (43 ha)

107ac (43 ha).

2i. SCE Viejo Conservation Bank

63 ac (25 ha)
63 ac (25 ha)
63 ac (25 ha)

Unit 3: Riverside Inland Valleys

54 ac (22 ha)

811 ac (328 ha)
865 ac (350 ha)
865 ac (350 ha)

3c. Australia Pool

19 ac (8 ha)
19 ac (8 ha)
19 ac (8 ha)

3d. Scott Road Pool

9 ac (4 ha)
9 ac (4 ha)
9 ac (4 ha)

3e. Schleuniger Pool

23 ac (9 ha)
23 ac (9 ha)
23 ac (9 ha)

3f. Skunk Hollow and Field Pool (Barry Jones Wetland Mitigation Bank)

163 ac (66 ha)
163 ac (66 ha)
163 ac (66 ha)

3g. Johnson Ranch Created Pool

54 ac (22 ha)

54 ac (22 ha)
54 ac (22 ac)

3h. Santa Rosa Plateau—Mesa de Colorado

597 ac (242 ha)
597 ac (242 ha)
597 ac (242 ha)

Unit 4: San Diego North and Central Coastal Mesas

6 ac (3 ha)
3 ac (1 ha)
9 ac (4 ha)
9 ac (4 ha)

4c. Poinsettia Lane Commuter Train Station

6 ac (3 ha)
3 ac (1 ha)
9 ac (4 ha)
9 ac (4 ha)

Unit 5: San Diego Southern Coastal Mesas
40 ac (16 ha)
256 ac (104 ha)
157 ac (64 ha)
472 ac (191 ha)
925 ac (375 ha)
63 ac (25 ha)
862 ac (348 ha).

5a. Sweetwater (J33)

2 ac (less than 1 ha)
less than 1 ac (0 ha)
2 ac (less than 1 ha)

2 ac (less than 1 ha).

5b. Arnie's Point (J15)
29 ac (12 ha)

29 ac (12 ha)
29 ac (12 ha)

5c. East Otay Mesa

57 ac (23 ha)
57 ac (23 ha)

57 ac (23 ha).

5d. J29-31
less than 1 ac (0 ha)
211 ac (85 ha)

159 ac (64 ha)
370 ac (149 ha)
23 ac (9 ha)
347 ac (140 ha).

5e. J2 N, J4, J5 (Robinhood Ridge)

32 ac (13 ha)
12 ac (5 ha)
44 ac (18 ha)

44 ac (18 ha).

5f. J2 W and J2 S: (Hidden Trails, Cal Terraces, Otay Mesa Road)

22 ac (9 ha)
11 ac (4 ha)
33 ac (13 ha)

33 ac (13 ha).

5g. J14

45 ac (18 ha)
18 ac (7 ha)
72 ac (29 ha)
135 ac (55 ha)

135 ac (55 ha).

5h. J11 E and J11 W, J12, J16-18 (Goat Mesa)
11 ac (4 ha)

83 ac (34 ha)
161 ac (65 ha)
255 ac (103 ha)
11 ac (4 ha)
244 ac (99 ha).

Totals
40 ac (16 ha)
310 ac (126 ha)
336 ac (138 ha)
2,297 ac (929 ha)
2,984 ac (1,208 ha)
1,259 ac (510 ha)
1,724 ac (698 ha).

Note: Sums of land areas may not total due to rounding.
Details on excluded acres and HCPs are given in Table 5.

1
Local land includes land owned by local government agencies.

We present brief descriptions of all units, and reasons why they meet the definition of critical habitat for Riverside fairy shrimp, below.

Unit 1: Ventura County Unit (Transverse Range)

Unit 1 is located in central Ventura County and consists of two occupied subunits totaling approximately 466 ac (189 ha), with 31 ac (13 ha) of local land and 435 ac (176 ha) of private land. Unit 1 is within the geographical area occupied by the species at the time of listing. This unit includes vernal pools near the City of Moorpark in Ventura County at Tierra Rejada Preserve (formerly Carlsberg Ranch) on the west side of State Highway 23, and a basin to the southeast of the Carlsberg Ranch site called South of Tierra Rejada Valley, east of State Highway 23. This unit occurs within the larger Santa Clara-Calleguas/Calleguas-Conejo Tierra Rejada Valley watershed, within the east-west trending Transverse (mountain) Range. The Transverse Range system was formed by the interaction of an east-west oceanic fault zone with the San Andreas Fault. Because the interaction of the two fault systems has been extensive and continues with rapid local uplift, Riverside fairy shrimp habitat within the Transverse Range reflects past activities of tectonic processes and their effects on watershed development. Accelerated erosion, sedimentation, and debris processes, such as mud and rock flows, landslides, wind flows, and debris flows (soil development processes), contribute to a unique set of physiochemical and geomorphic features for pools occupied by Riverside fairy shrimp.

Subunit 1a: Tierra Rejada Preserve

Subunit 1a is located near the City of Moorpark in southeastern Ventura County, California. This subunit is located on what was formerly known as the Carlsberg Ranch, at the north end of the Tierra Rejada Valley and just west of State Highway 23. It is near the northeast intersection of Moorpark Road and Tierra Rejada Road in a residential housing development. Subunit 1a consists of 18 ac (7 ha) of privately owned land. The vernal pool (pond), 4.6 acres (1.7 ha) in size, is located in the Tierra Rejada Vernal Pool Preserve, owned and managed by Mountains Recreation and Conservation Authority (MCRA). Subunit 1a contains areas identified in the 1998 Recovery Plan (Appendix F) as necessary to stabilize and protect (conserve) existing populations of Riverside fairy shrimp.

We consider this subunit to have been occupied at the time of listing, and it is currently occupied. Subunit 1a is within the geographical area occupied by the species at the time of listing. Resting cysts were detected in recent soil analyses (C. Dellith 2010, pers. comm.) and adult fairy shrimp were observed on April 7, 2011 (J. Tamasi 2011, pers. comm.), the first observation of adults since the 2000-2001 ponding season. This area is essential to the conservation of this species for several reasons. The pool supports endangered
Orcuttia californica
(Orcutt's grass), which is an indicator of the longer ponding duration necessary to support the life-history needs of Riverside fairy shrimp. This pool is fundamentally different in terms of size, origin, depth, and duration of ponding, contributing areas (watershed), and the thickness of the underlying sediments compared to flat areas of older soils with highly developed claypans and hardpans throughout the State (Hecht
et al.
1998, p. 47). This pool was formed primarily by tilting and subsidence along the Santa Rosa fault (Hecht
et al.
1998, p. 5). Given its geological and hydrological features and associated wetland vegetation within the subunit, this pool possesses a set of physical and biological factors unique to this occurrence to which the Riverside fairy shrimp has likely become adapted. The present biological resources and value of the pool have been sustained despite “substantial disturbance and change [in] the general area of the vernal pool” and given the history of land and water use and analysis of 60 years of aerial photography (Hecht
et al.
1998, p. 6 and Appendix A). Although Lahti
et al.
(2010) did not survey this pool during their completion of a rangewide genetic analysis, this occurrence represents the northernmost extension of the species' occupied range within a notably unique vernal wetland type (Hecht
et al.
1998, p. 5, and see discussion below).

Subunit 1a contains the physical or biological features essential to the conservation of Riverside fairy shrimp, including appropriate soil series (Azule, Calleguas, Linne; PCE 3) situated on a saturated fault between rocks of different permeability (“tectonogenic”; Hecht
et al.
1998, p. 5), and it is “sediment-tolerant” given that it possesses a watershed with reasonably steep slopes (10-50 percent) that yield substantial amounts of sediment that provide nutrients and minerals (Hecht
et al.
1998, p. 6). The fine clay sediment deposited in the basin settles and allows the pool to fill; this is in contrast to most other vernal pools, where hydrology is maintained through clay soils created by soil forming processes (Hecht
et al.
1998, p. 5). Additionally, because of adjacent urban development, altered hydrology, and potential for runoff, the PCEs in this subunit may require special management considerations or protection for the recovery of Riverside fairy shrimp. This subunit has one large ponding feature, and is essential to maintain habitat function, genetic diversity, and species viability (Service 1998a, p. 65) at the species' northernmost geographical distribution.

Due to its unique geographic location and other features stated above, Subunit 1a is essential to the conservation of Riverside fairy shrimp. Although preliminary genetic studies are not definitive with regard to gene flow and genetic variability across the range of this species, populations at the edge of a species' distribution have been demonstrated to be important sources of genetic variation, may provide an important opportunity for colonization or recolonization of unoccupied vernal pools, and, thus, contribute to long-term conservation (and recovery) of the species (Gilpin and Soule´ 1986, pp. 32-33; Lande 1999, p. 6). Research on genetic differentiation among fairy shrimp species across their known distributions has demonstrated that geographically distinct populations may or may not be genetically distinct, but that they have unique genetic characteristics that may allow for adaption to environmental changes (Bohonak 2003, p. 3; Lahti
et al.
2010, p. 17). These characteristics may not be present in other parts of a species' range (Lesica and Allendorf 1995, p. 756), making preservation of this subunit and the unique genetic diversity it contains essential for the recovery of the species.

We are lacking specific documentation of Riverside fairy shrimp occupancy in Subunit 1a at the time of listing. However, Subunit 1a contains the physical or biological features necessary to the conservation of the species, and these features support life-history characteristics of Riverside fairy shrimp (such as the presence of cyst banks that indicate long-term occupancy of a vernal pool). The presence of these traits makes it likely that the subunit was occupied at the time of listing, and that it meets the definition of critical habitat under section 3(5)(A)(i) of the Act because it is within the geographical area occupied by the species at the time of listing. However, as discussed in the
Criteria Used To Identify Critical Habitat
section above, we alternatively designate Subunit 1a under section 3(5)(A)(ii) of the Act because the subunit is essential for the conservation

of Riverside fairy shrimp, regardless of occupancy data at the time of listing. Thus, for the purposes of this rulemaking, we determine that Subunit 1a meets the definition of critical habitat in section 3(5)(A)(i) or, alternatively, under section 3(5)(A)(ii) of the Act.

The physical or biological features essential to the conservation of the species in this subunit may require special management considerations or protection to address threats from nonnative plant species (nonnative grasses and
Schinus molle
(Peruvian pepper) groves) and alterations to the hydrological cycle, including type conversion of habitat; activities that remove or destroy the habitat assemblage of the pools, such as creation of fuel breaks, mowing, and grading; and human encroachment that occurs in the area. These threats could impact the water chemistry characteristics that support Riverside fairy shrimp (PCE 1) and disrupt the surrounding watershed that provides water to fill the pool in the winter and spring (PCE 2). For example, inundation from artificial water sources can cause pools to stay inundated longer than normal or even convert vernal pools into perennial pools that are not suitable for Riverside fairy shrimp (Service 2008, p. 16). Please see
Special Management Considerations or Protection
section of this final rule for a discussion of the threats to Riverside fairy shrimp habitat and potential management considerations.

Subunit 1b: South of Tierra Rejada Valley

Subunit 1b is located near the City of Moorpark in Ventura County, California. This subunit is approximately 1 mi (1.5 km) southeast of

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Source: Frix Law Library, https://www.frixlaw.com/law-library/documents/fr%3A2012-28250. Public record. Not legal advice.