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

DEPARTMENT OF THE INTERIOR

Fish and Wildlife Service

50 CFR Part 17

[Docket No. FWS-R8-ES-2011-0013; MO 92210-0-009]

RIN 1018-AX15

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

AGENCY:

Fish and Wildlife Service, Interior.

ACTION:

Proposed rule.

SUMMARY:

We, the U.S. Fish and Wildlife Service (Service), propose to revise the currently designated critical habitat for the Riverside fairy shrimp (

Streptocephalus woottoni

) under the Endangered Species Act of 1973, as amended (Act). The current critical habitat consists of 306 acres (124 hectares) of land in four units in Ventura, Orange, and San Diego Counties, California. We now propose to designate approximately 2,984 acres (1,208 hectares) of land in five units in Ventura, Orange, Riverside, and San Diego Counties, California, which, if finalized as proposed, would result in an increase of approximately 2,678 acres (1,084 hectares) of critical habitat for this species.

DATES:

We will consider comments received or postmarked on or before August 1, 2011. We must receive requests for public hearings, in writing, at the address shown in the

FOR FURTHER INFORMATION CONTACT

section by July 18, 2011.

ADDRESSES:

You may submit comments by one of the following methods:

(1) Federal eRulemaking Portal:

http://www.regulations.gov.

Follow the instructions for submitting comments to Docket Number FWS-R8-ES-2011-0013.

(2) U.S. mail or hand-delivery: Public Comments Processing, Attn: FWS-R8-ES-2011-0013; Division of Policy and Directives Management; U.S. Fish and Wildlife Service; 4401 N. Fairfax Drive, MS2042; Arlington, VA 22203.

We will not accept e-mail or faxes. We will post all comments on

http://www.regulations.gov.

This generally means that we will post any personal information you provide us (see the

Public Comments

section below for more information).

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:

Public Comments

We intend that any final action resulting from this proposed rule will be based on the best scientific and commercial data available and be as accurate and as effective as possible. Therefore, we request comments or information from other concerned government agencies, the scientific community, industry, or other interested party concerning this proposed rule. We particularly seek comments concerning:

(1) The reasons why we should or should not revise the designation of habitat as “critical habitat” under section 4 of the Act (16 U.S.C. 1531

et seq.

), including whether there are threats to the species from human activity, the degree of which can be expected to increase due to the designation, and whether that increase in threat outweighs the benefit of designation such that the designation of critical habitat may not be prudent.

(2) Specific information on:

(a) The amount and distribution of Riverside fairy shrimp habitat;

(b) What areas occupied at the time of listing (or currently occupied) and containing features essential to the conservation of the species, should be included in the designation and why;

(c) What areas not occupied at the time of listing are essential for the conservation of the species and why;

(d) Special management considerations or protection that the features essential for the conservation of the species may require, including management for potential impacts associated with climate change; and

(e) Areas identified in this proposed revised critical habitat rule that should not be proposed as critical habitat and why.

(3) Land-use designations and current or planned activities in the subject areas and their possible impacts on proposed revised critical habitat.

(4) Information that may assist us in identifying or clarifying the physical and biological features essential to the conservation of Riverside fairy shrimp.

(5) Special management considerations or protection that the physical and biological features essential to the conservation of the species may require.

(6) Specific information regarding the occurrence, or non-occurrence, of Riverside fairy shrimp in the Cruzan Mesa vernal pools (in Los Angeles County) and, if the species is present, whether this area is essential to the conservation of the species and if so, whether the area should be considered for exclusion under section 4(b)(2) of the Act and why.

(7) Specific information on the habitat conditions for Riverside fairy shrimp and the presence of physical and biological features essential for the conservation of the species in Subunit 1b (South of Tierra Rejada Valley, which is in Ventura County), and whether this area is essential to the conservation of the species and why.

(8) Specific information regarding the occurrence of Riverside fairy shrimp within proposed Subunit 3h (Santa Rosa Plateau at Mesa de Colorado, which is in western Riverside County), whether this area is essential to the conservation of the species, and if so, whether the area should be considered for exclusion under section 4(b)(2) of the Act and why.

(9) Specific information regarding a potential occurrence of Riverside fairy shrimp at Madrona Marsh (Los Angeles County) and, if the species is present, whether this area is essential to the conservation of the species and why.

(10) Specific information regarding the presence or absence of the physical and biological features essential to the conservation of the species within proposed Subunit 5c, and whether this area is essential to the conservation of the species and why.

(11) Information on the projected and reasonably likely impacts associated with climate change on Riverside fairy shrimp and the areas we are proposing to designate as critical habitat.

(12) How the proposed revised critical habitat boundaries could be refined to more closely circumscribe the landscapes identified as containing the physical and biological features essential to the conservation of the Riverside fairy shrimp.

(13) Any probable economic, national security, or other relevant impacts of designating any area that may be included in the final designation; in particular, any impacts on small entities or families, and the benefits of including or excluding areas that exhibit these impacts.

(14) Whether the potential exclusion under section 4(b)(2) of the Act of Subunits 2c ((MCAS) El Toro) and 2i (Southern California Edison (SCE) Viejo Conservation Bank), which are covered by the Orange County Central-Coastal Natural Community Conservation Plan/Habitat Conservation Plan (Orange County Central-Coastal NCCP/HCP), from final revised critical habitat 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.

(15) Whether the potential exclusion under section 4(b)(2) of the Act of a portion of Subunit 2dA (Saddleback Meadows); portions of Subunit 2dB (O'Neill Regional Park—near Trabuco Canyon) and 2e (O'Neill Regional Park—near Cañada Gobernadora/east of Tijeras Creek); and Subunits 2f (Chiquita Ridge) and 2g (Radio Tower Road), which are covered by the Southern Orange County Natural Community Conservation Plan (NCCP)/Master Streambed Alteration Agreement/Habitat Conservation Plan (HCP), now known as the Orange County Southern Subregion HCP, from final revised critical habitat 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.

(16) Whether the potential exclusion under section 4(b)(2) of the Act of Subunits 3c, 3d, 3e, 3f, 3g, and 3h, which are covered by the Western Riverside County Multiple Species Habitat Conservation Plan (the Western Riverside County MSHCP) from final revised critical habitat 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.

(17) Whether the potential exclusion under section 4(b)(2) of the Act of Subunit 4c (Poinsettia Lane Commuter Station) as critical habitat covered by the Carlsbad Habitat Management Plan (Carlsbad HMP), a subarea plan under the Multiple Habitat Conservation Program (MHCP), from final revised critical habitat 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.

(18) Whether the potential exclusion under section 4(b)(2) of the Act—portions of Subunit 5d, which is covered by the County of San Diego Subarea Plan under the San Diego Multiple Species Conservation Program (MSCP) from final revised critical habitat 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.

(19) Although we are not proposing areas within tribal lands in this proposed rule, we seek specific information regarding the possible species occurrence within two vernal pools on or near tribal land of the Pechanga Band of Luiseño Mission Indians of the Pechanga Reservation, California (Pechanga Band of Luiseño Mission Indians), and, if the species is present, whether this area is essential to the conservation of Riverside fairy shrimp and why.

(20) Although we are not considering for exclusion lands owned by the Department of Homeland Security (DHS) along the U.S.-Mexico border in this proposed rule (Subunit 5b and a portion of land in 5h), we seek comments on whether or not these lands should be considered for exclusion under section 4(b)(2) of the Act of Federal land 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.

(21) Whether our exemption, under section 4(a)(3)(B) of the Act, of land on Department of Defense property at Marine Corps Base (MCB) Camp Pendleton and Marine Corps Air Station (MCAS) Miramar in San Diego County is or is not appropriate, and why.

(22) Whether the benefit of exclusion of any other particular area not specifically identified above outweighs the benefit of inclusion under section 4(b)(2) of the Act.

(23) Information on any quantifiable economic costs or benefits of the proposed revised designation of critical habitat.

(24) Whether we could improve or modify our approach to designating critical habitat in any way to provide for greater public participation and understanding, or to better accommodate concerns and comments.

Our final determination concerning the revision of Riverside fairy shrimp critical habitat will take into consideration all written comments and any additional information we receive during all comment periods. The comments will be included in the public record for this rulemaking, and we will fully consider them in the preparation of our final determination. On the basis of public comments, we may, during the development of our final determination, find that areas within the proposed designation do not meet the definition of critical habitat, that some modifications to the described boundaries are appropriate, or that areas may or may not be appropriate for exclusion under section 4(b)(2) of the Act.

You may submit your comments and materials concerning this proposed rule by one of the methods listed in the

ADDRESSES

section. We will not accept comments sent by e-mail or fax or to an address not listed in the

ADDRESSES

section. We will post your entire comment—including your personal identifying information—on

http://www.regulations.gov.

You may request at the top of your document that we withhold personal information such as your street address, phone number, or e-mail address from public review; however, we cannot guarantee that we will be able to do so.

Comments and materials we receive, as well as supporting documentation we used in preparing this proposed rule, will be available for public inspection on

http://www.regulations.gov,

or by appointment, during normal business hours, at the U.S. Fish and Wildlife Service, Carlsbad Fish and Wildlife Office (see

FOR FURTHER INFORMATION CONTACT

).

Background

It is our intent to discuss only those topics directly relevant to the proposed revision of critical habitat for Riverside fairy shrimp. This proposed rule incorporates new information specific to Riverside fairy shrimp genetics across the species' range that was not available when we completed our 2005 final critical habitat designation (70 FR 19154; April 12, 2005), and new information on the status and distribution of Riverside fairy shrimp that became available since the 2005 final critical habitat designation for this species. A summary of topics that are relevant to this proposed revised critical habitat designation is provided below. 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).

Species Description

The Riverside fairy shrimp is a small (0.56 to 0.92 inch (in)) (14 to 23 millimeter (mm)) aquatic crustacean in the order Anostraca, restricted to

seasonal (vernal) pools, ponds, swales, and other pool-like, ephemeral (lasting a short time) water bodies in southern coastal California, United States, and northern Baja California, Mexico (Eng

et al.

1990, pp. 258-259). Riverside fairy shrimp, like all fairy shrimp in general, have stalked compound eyes, no carapace (hard outer shell), and eleven pairs of phyllopods (swimming legs that also function as gills). They swim or glide upside down by means of complex beating movements of the legs that pass, wave-like, in an anterior to posterior direction. Male and females have red-colored cercopods (anterior appendages) on all of the ninth and 30 to 40 percent of the eighth abdominal segments, which helps to distinguish this species from closely related species (Eng

et al.

1990, p. 259).

First collected in 1979 and described as a new species by Eng

et al.

(1990, pp. 258-259), based on a type specimen collected from an area between Murrieta Golf Course and California Highway 79 in Riverside County (71 FR 14538), Riverside fairy shrimp are currently presumed to occupy 60 or fewer pool complexes throughout southern California (see

Spatial Distribution and Historical Range

below). At the time the species was listed as endangered in 1993, the type locality had been lost to development (Eriksen and Belk 1999, p. 104; Service 2008, p. 5).

Habitat

Typical habitat for fairy shrimp in California includes vernal pools, seasonally ponded areas within vernal swales, and ephemeral freshwater habitats (68 FR 46685). Riverside fairy shrimp are considered habitat specialists, found in moderate to deep (generally ranging from 10 inches (in) (25.4 centimeters (cm)) to 5 to 10 feet (ft) (1.5 to 3 meters (m)) in depth), longer-lived vernal pools and ephemeral wetlands (Eng

et al.

1990, p. 259; Simovich and Fugate 1992, pp. 7-8; Hathaway and Simovich 1996, p. 39) because of specific life-history traits and habitat needs (see

Life History

section below).

Riverside fairy shrimp's known localities are below 2,100 ft (640 m) elevation and are within 50 miles (mi) (80 kilometers (km)) of the Pacific Ocean. Riverside fairy shrimp do not occur in riverine or marine waters or other permanent bodies of water. Water chemistry is an important factor in determining fairy shrimp distribution (Belk 1977, p. 77; Gonzales

et al.

1996, p. 319). As previously described in the final listing rule (58 FR 41384; August 3, 1993) and the Background section of the final revised critical habitat rule (70 FR 19154; April 12, 2005), vernal pool habitats that support Riverside fairy shrimp occur in areas with Mediterranean climates (cool, wet winters and hot, dry summers), where shallow depressions become seasonally wet or inundated following winter and spring rains (Keeley and Zedler 1998, p. 2; Smith and Verrill 1998, p. 15). In general, vernal pools occur as poorly drained depressions, perched above an impermeable surface or very slowly permeable soil horizon or bedrock (Cheatham 1976, p. 88; Smith and Verrill 1998, p. 15); restrictive soil layers are typically hardpan or claypan, and bedrock types are volcanic mud or lava flows (Jones and Stokes 1987, p. 70; Zedler 1987, p. 13; Smith and Verrill 1998, p. 15). Other kinds of depressions that hold water of a similar volume, depth, and area, and for a similar duration and seasonality as vernal pools and ponded areas within swales, may also provide potential habitat for Riverside fairy shrimp.

Vernal pools may fill primarily by direct precipitation, or may have contributions from subsurface inflows from surrounding soils, which may help to minimize water level fluctuations during late winter and early spring (Hanes and Stromberg 1998, p. 48; Rains

et al.

2006, p. 1158). Although vernal pools may typically associate with specific types of geological formations, landforms, and soils and within different types of ephemeral wetland landscapes (Zedler 1987, p. 13; Hanes and Stromberg 1998, p. 48; Smith and Verrill 1998, p.15; Rains

et al.

2006, p. 1158), the most common unifying feature to fairy shrimp habitat, in general, is ephemerally wet, flooded, or ponded area that is typically wet during a portion of the year and dry for the remainder of the year.

Throughout this proposed revised critical habitat rule, the term “ephemeral wetlands” refers to vernal pool habitats including vernal lakes, ponds, detention basins, and other natural and manmade depressions that seasonally hold water. While these ephemeral wetlands often occur within landscapes of “mima-mound” topography (Cox 1984, pp. 1397-1398), that is, they form during winter rains as a natural hydrological feature of a gently sloping, undulating landscape, the species can also be found in disturbed vernal pool habitats where basins have been compacted or artificially deepened and therefore hold water for longer periods of time.

Depending on topography, soils, and geographic location, the period of time varies during which these ephemeral wetlands pond (referred to as the “period of inundation”). Basin size and basin shape (Keeley and Zedler 1998, p. 5), soil type, soil consistency, depth of soil to impervious layer (for example, hardpan or claypan), type and thickness of impervious layer, and other local and regional climatic factors (for example, rainfall abundance and timing, rainfall regularity, and evaporation rates) (Keeley and Zedler 1998, p. 2; Helm 1998, p. 136) all are variables that potentially affect the length of ponding in vernal pool landscapes. For southern California's ephemeral wetlands, the wet phase typically occurs between the months of October to May, and the dry phase lasts for a period of time between the months of June to September.

The Riverside fairy shrimp often hatches later in the season than other fairy shrimp species because presumably the deeper pools it inhabits require sufficient rainfall to fill (Simovich and Fugate 1992, p. 8). A minimum period of inundation, or pool duration, that Riverside fairy shrimp need in order to hatch and reach sexual maturity is approximately 8 weeks (48 to 56 days) based on field observations (Hathaway and Simovich 1996, p. 674) (see

Life History

section below for further discussion).

Mounds of soil (mima) (Scheffer 1947, p. 288), or swales (broad, shallow, vegetated, ephemerally wet areas) (Helm 1998, p. 130), that are interconnected with level or low point depressional basins and which contain appropriate impervious clay soils (providing ponding opportunities during winter and spring), are geographically fixed and limited in number. Soils and soil series that underlie vernal pool habitat that supports Riverside fairy shrimp are generally characterized by a high content of coarse sandy grains (marine alluvial sediments), loams, or clay inclusions, or a combination of these, with a subsurface clay or hardpan layer. These are also limited in number and geographically fixed. Riverside fairy shrimp are known to occur in both hardpan and claypan vernal pools in Ventura, San Diego, Los Angeles (now extirpated), Riverside, and Orange Counties, and in addition, in Riverside County on granitic (basaltic) substrate.

Vernal pools and vernal swales are often clustered into pool “complexes” (Bauder 1986a, Appendix 1, 4; Keeler-Wolf

et al.

1998, pp. 60-61, 63-64), and may form dense, interconnected mosaics of small pools, or a sparse scattering of larger pools. Vernal pool complexes that support from one up to many distinct vernal pools are often interconnected by a shared watershed. Both the pool basin and the surrounding watershed are essential for a functioning vernal pool system (Hanes and

Stromberg 1998, p. 48). Loss of upland vegetation, increased overland water flow due to urban runoff, and alteration of the microtopography can modify the function of vernal pool systems, and alter the physiochemical parameters that the Riverside fairy shrimp requires for survival. Because the Riverside fairy shrimp requires ephemerally ponded areas for its conservation (Belk 1998, pp. 147-148), vernal pools are best described from a watershed perspective (see

Physical and Biological Features

section below

,

and Recovery Criteria 1 and 2 in the 1998 Recovery Plan for Vernal Pools of Southern California (Service 1998a, pp. iv-vi)).

The size and number of inundated basins and their associated biota are directly correlated to the amount and timing of precipitation (City of San Diego 2004, p. 6). In southern California, rainfall is erratic within and between years as well as strongly seasonal (Zedler 1987, p. 12). Pool size, location and elevation, upland hydrology, physiochemical processes, and unique species assemblages may all factor into the distribution of vernal pool species (Eng

et al.

1990, p. 273; Branchiopod Research Group 1996, pp. 1-2; Gonzalez

et al.

1996, p. 319). Water chemistry (dissolved solutes, alkalinity, salinity, and temperature) and length of time vernal pools are inundated with water (see

Life History

section below) are important factors that potentially limit and determine the distribution of Riverside fairy shrimp within and among pools complexes.

Water in the pools that typically support Riverside fairy shrimp has low total dissolved solids and alkalinity (means of 77 and 65 milligrams per liter (mg/l) or parts per million (ppm), respectively), corroborated by pH at neutral or just below (6.4-7.1) (Eng

et al.

1990, p. 254; Gonzalez

et al.

1996, p. 317; Eriksen and Belk 1999, p. 104). Riverside fairy shrimp have been shown to tightly regulate their internal body chemistry for pool environments that have low salinity and low alkalinity (Gonzalez

et al.

1996, pp. 317-318). Pools are generally open and unvegetated with turbid water conditions; habitat lies within annual grasslands, which may be interspersed through chaparral or coastal sage scrub vegetation (Lahti

et al.

2010, p. 5). Riverside fairy shrimp are typically found in water temperatures ranging between 50 and 77 degrees Fahrenheit (10 and 25 degrees Celsius) (Hathaway and Simovich 1996, p. 671).

Life History

As discussed in detail in the Background section of the final revised critical habitat rule (70 FR 19154; April 12, 2005), Riverside fairy shrimp feed on algae, bacteria, protozoa, rotifers, and bits of detritus, and constitute a cornerstone in the food web for a wide array of aquatic and terrestrial species.

Because vernal pool ecosystems are highly variable in the length of time pools remain filled, Riverside fairy shrimp have adapted their life-history strategies accordingly. Riverside fairy shrimp populations withstand a seasonal desiccation of their pools by producing resting eggs (herein referred to as reproductive cysts), which when mature can survive environmental conditions such as extremes in temperatures, the digestive tracts of animals, and years of desiccation before hatching under the correct environmental conditions (Pennak 1989, pp. 352-353; Eriksen and Belk 1999, p. 22). Because not all reproductive cysts will hatch with any given refilling of their pool, these reproductive cysts form a “cyst bank” in the soil from which new populations of adults may develop, even in pools that have not had adults for years (Eriksen and Belk 1999, p. 105). Therefore, it is not mandatory for ideal conditions to exist every year for this species to persist.

Adult Riverside fairy shrimp are usually observed from mid-March to April (Eng

et al.

1990, p. 259); however, the hatching periods may be extended in years with early or late rainfall. Unlike San Diego fairy shrimp (

Branchinecta sandiegonensis

), a species that matures quickly (7 to 14 days), Riverside fairy shrimp hatch and mature within 48 to 56 days, depending on water temperature (Hathaway and Simovich 1996, p. 674; Simovich and Hathaway 1997, p. 39; Eriksen and Belk 1999, p. 105). Because of its distinctly longer maturation, Riverside fairy shrimp are typically restricted to relatively deep (greater than 12 in (30 cm)), cool water vernal pools that are inundated for a longer time to complete their reproductive life cycle (Hathaway and Simovich 1996, p. 675) . This longer deve1opment time is thought to account for the species' restriction to deep pools, their rarity, and later appearance (Simovich and Fugate 1992, p. 8).

Spatial Distribution and Historical Range

As discussed in detail in the

Background

section of the final revised critical habitat rule (70 FR 19154; April 12, 2005), Riverside fairy shrimp are considered to have one of the most restricted distributions among fairy shrimps endemic to the West Coast (Eng

et al.

1990; p. 259, Simovich and Fugate 1992, p. 7; Eriksen and Belk 1999, p. 104). Because the Riverside fairy shrimp has a slower developmental rate, the species is limited to fairly deep, and moderate in size, pools that support a longer ponding duration. The Riverside fairy shrimp is, therefore, restricted to a subset of vernal pools and vernal pool complexes in southern California (Ventura, Orange, Riverside, and San Diego Counties) and in northern Mexico (Service 1998a, p. 19; Eriksen & Belk 1999, p. 104). The Riverside fairy shrimp has likely been extirpated from Los Angeles County. With the exception of the Riverside County populations, all populations are within approximately 15 mi (24 km) of the coast. Riverside fairy shrimp range over a north-south distance of approximately 163 mi (262 km) within southern California (excluding Baja, Mexico locations) and occupy pools that range in elevation from 46 to 2,076 ft (14 to 633 m).

For the purposes of this proposed revised critical habitat designation, the word

occurrence

may be a single pool or a pool complex. Keeler-Wolf

et al.

(1998, p. 8) define a vernal pool complex as a set of naturally occurring pools in close proximity. A singular pool—geographically situated such that the pool basin is isolated from adjoining vernal pool topography by distances greater than 10 mi (16 km)—or a network of one or more vernal pool basins in close proximity, that is to say a vernal pool complex, may comprise an occurrence. At the time of listing in 1993, nine historical occurrences for Riverside fairy shrimp were known: Four occurrences in a 37-square-mile (91-square-km) area near Temecula, California (western Riverside County); one occurrence in Orange County, California; two documented occurrences in San Diego County, California; and two occurrences in Baja California, Mexico (58 FR 41384; August 3, 1993).

In our 2008 5-year review of Riverside fairy shrimp, we assembled and reassessed occurrence data for the species (Service 2008, pp. 6-8). Seven of the nine historical occurrences (five in the United States and two in Mexico) were presumed extant at the time Riverside fairy shrimp was listed in 1993 (Service 2008, pp. 7-8). The type locality in western Riverside County (at Murrieta Golf Course) was already extirpated by the time the species was listed, and the single-referenced occurrence from Orange County has never been confirmed. Based on our analysis in the 2008 5-year review for Riverside fairy shrimp, with the discovery of additional occurrences, the regrouping of vernal pool complexes, and the extirpation of nine known occurrences since listing, we concluded

that there were approximately 45 known extant (or presumed extant) occurrences (approximately 200 vernal pools) of Riverside fairy shrimp (Service 2008, p. 5). Discovery of additional occurrences since the time of the 1998 Recovery Plan, include at least four more occurrences, all in western Riverside County: Warm Springs Ranch Pool, Schau Pool, Rancho California Road Pools, and an occurrence (two pools, Pool 4 and Pool 5 in Selheim and Searcy 2010, p. 98) atop Santa Rosa Plateau along Mesa de Colorado. Identification of additional occurrences since listing (1993) has resulted from surveys conducted in locations that were not surveyed prior to 1993. In sum, Riverside fairy shrimp are presently considered to be extant in approximately 49 occurrences (vernal pools and vernal pool complexes), four more than we reported in the 2008 5-year review (Service 2008, pp. 5, 10).

Extant occurrences not identified in the 1993 listing rule (but presumed extant at the time of listing) are located in the following general areas: (1) One occurrence in Ventura County (Tierra Rejada Preserve and South of Tierra Rejada Valley); (2) seven occurrences in Orange County: (MCAS) El Toro, SCE Viejo Conservation Bank, Saddleback Meadows, O'Neill Regional Park—near Trabuco Canyon, O'Neill Regional Park—near Cañada Gobenadora/east of Tijeras Creek, Chiquita Ridge, and Radio Tower Road; (3) nine occurrences in Riverside County at the Australia Pool, the Scott Road Pool, the Warm Springs Ranch Pools, the Schleuniger Pool, the Schau Pool, in the Johnson Ranch area, the Field Pool, the Rancho California Road Pool, and a newly documented occurrence on the Santa Rosa Plateau along Mesa de Colorado; (4) ten occurrences in north San Diego County on MCB Camp Pendleton: San Onofre State Beach, State Park-leased lands, near Christianitos Creek foothills (along the northwest corner of MCB Camp Pendleton); area south of San Onofre State Beach, in Uniform Training Area; Las Pulgas North; Las Pulgas East; Las Pulgas West; Cockleburr North; Cockleburr South; Stuart Mesa; San Mateo; and Wire Mountain; and (5) seven occurrences in central and southern San Diego County, outside of MCB Camp Pendleton: on MCAS Miramar (AA1 pool); City of Carlsbad (Poinsettia Lane Commuter Train Station); and numerous pools on Otay Mesa (southern San Diego County) including what is referred to as the “J series” of vernal pool complexes (J2, J4, J5, J11, J12, J14, J15, J16-18, J29-31, J33).

For the purpose of this proposed revised critical habitat designation, we consider areas where Riverside fairy shrimp have been documented since listing (since 1993) to be within the geographical area occupied by the species at the time of listing (in 1993). As discussed in the 5-year review, most of the additional occurrences identified since listing fall generally within the range of the Riverside fairy shrimp described in the listing rule, although the identification of some occurrences (complexes) broadened the specific range within Ventura, Orange, Riverside, and San Diego Counties (Service 2008, p. 8). As with many species, listing often results in greater efforts to conduct surveys, which may reveal a greater number of occurrences than was initially known.

We believe that these additional occurrences were occupied at the time of listing but had not been identified due to lack of survey effort. We believe occurrences documented since the 1993 listing do not represent an expansion of the species' distribution and range into previously unoccupied areas (with the exception of Johnson Ranch Created Pools), but rather a better understanding of the historical distribution and range of the species (Service 2008, p. 9). Because occurrences documented since listing are within relative proximity to existing, occupied, vernal pool habitat or within similar landscape types (e.g., coastal terraces and mesas, inland valleys, inland mesas, cismontane depressions) supporting ephemeral wetlands with occurrences that were known at the time of listing, it is reasonable to conclude, based on several life-history traits, that Riverside fairy shrimp were present at the time of listing in these unsurveyed habitats.

Riverside fairy shrimp are generally sedentary and are adapted to survive and persist in seasonally ephemeral habitat. Because they are sedentary, possess limited dispersal capabilities (passive dispersal mediated by resistant stages), and exhibit specialized habitat affinities (specific habitat types with fixed landscape features, see

Life History

and

Habitat

sections of this document), we believe it is unlikely that additional occurrences have become established during the relatively short time period since the listing of this species (with the exception of Johnson Ranch Created Pools). With the exception of the land we are proposing to designate under section 3(5)(A)(ii) of the Act—Johnson Ranch Created Pools (in Riverside County), which were created after the species was listed—we consider all known occurrences to be occupied at the time of listing and within the geographical area occupied by the species at the time of listing in this proposed critical habitat designation. Therefore, throughout this proposed rule, we refer to all occurrences (with the exception of Johnson Ranch Created Pools) as being occupied at the time of listing whether the areas were documented before or after the species was listed.

We are designating one area, Johnson Ranch Created Pools, as essential under section 3(5)(A)(ii) of the Act. Although this area falls within the currently occupied geographic range of the species, at the time Riverside fairy shrimp was listed, it was not occupied.

Each area that we are proposing as revised critical habitat contains a currently extant (or in the case of Subunit 1b, considered extant) occurrence of Riverside fairy shrimp; however, Riverside fairy shrimp do not physically occur throughout the entirety of each area. The 2,984 ac (1,208 ha) we are proposing as revised critical habitat contains occurrences of Riverside fairy shrimp as well as surrounding upland areas (the contributing watershed) that contain the physical and biological features essential to support Riverside fairy shrimp where they physically occur within the proposed revised critical habitat subunits (see

Physical and Biological Features

below). For specific information about how this proposed rule compares to the final critical habitat designated for this species in 2005, see the

Summary of Changes From Previously Designated Critical Habitat

section below.

New Information Specific to Riverside Fairy Shrimp

A study to gather genetic distribution data for Riverside fairy shrimp across its range, using mitochondrial DNA (mtDNA) on the cytochrome oxidase I (COI) gene, was conducted in 2010 (Lahti

et al.

2010, pp. 1-47). Sequencing of 179 individuals from 32 pools comprising 20 pool complexes detected low population genetic variability overall at the selected locus, and resulted in detection of five unique haplotypes (Lahti

et al.

2010, p. 17). A haplotype is a combination of alleles (the alternative forms of a gene that is located at a specific position on a specific chromosome) at a single locus or multiple loci that are transmitted together on the same chromosome. This was the first study of its kind to look at genetic composition and variation of Riverside fairy shrimp across its range and, as such, represents preliminary information. Most of the genetic variability was limited to San Diego County (Camp Pendleton, San Diego

north; haplotypes D, E) and Otay Mesa (San Diego south; haplotypes B, C), and all pools in Riverside and Orange Counties were fixed for the most common haplotype, haplotype A (Lahti

et al.

2010, p. 17).

Although the amount of genetic variation was low, haplotype frequencies among complexes varied, showing approximately 60 percent of the genetic variability partitioned among pool complexes and 18 percent partitioned among regions (Lahti

et al.

2010, p. 19). Lahti

et al.

concluded that low variation at the COI gene region does not confer definitive evidence that Riverside fairy shrimp populations are currently connected by high levels of gene flow rangewide; on the contrary in areas where genetic variation was detected, haplotype frequencies varied significantly across even geographically proximate pools, suggesting low gene flow (Lahti

et al.

2010, p. 19). Genetic variability and genetic differentiation between and among populations (and across the species' distribution) may be important to long-term species persistence because it represents the raw material for adaptation to differing local conditions and environmental stochasticity (Frankham 2005, p. 754). The maintenance of genetic variability is crucial to the survival of a species with declining populations and a limited range, such as the Riverside fairy shrimp (Gilpin and Soulé 1986, pp. 32-33; Lesica and Allendorf 1995, p. 756). Loss of genetic connectivity and diversity can hinder a population's ability to adapt to ecological perturbations commonly associated with urbanization, such as habitat degradation, climatic changes, and introduced species (Vandergast

et al.

2007, p. 977). Vernal pool complexes throughout the range of the Riverside fairy shrimp, and within different habitat types, are critical for the conservation of this species.

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 United States 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 Federal 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 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.

United States 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.

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 a 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 any 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 otherwise be relieved, may include regulated taking.

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

For inclusion in a critical habitat designation, the habitat within the geographical area occupied by the species at the time it was listed must contain physical and biological features which are essential to the conservation of the species, and it is included only if those features may require special management considerations or protection. Critical habitat designations identify, to the extent known using the best scientific and commercial data available, habitat areas that provide essential life-history needs of the species, including but not limited to areas which provide for space, food, cover, and protected habitat.

Under the Act, 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. 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. When the best available scientific data do not demonstrate that the conservation needs of the species require such additional areas, we will not designate critical habitat in areas outside the geographical area occupied by the species. An area currently occupied by the species but that was not occupied at the time of listing may, however, be essential to the conservation of the species and may be included in the critical habitat designation.

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 revised critical habitat, our primary source of information is generally the information developed during the listing process for the species. Additional information sources include the 1998 Recovery Plan and the 2008 5-year review for the species, articles in peer-reviewed journals, conservation plans developed by States and counties, scientific status surveys and studies, biological assessments, or other unpublished materials and expert opinion or personal knowledge.

Habitat and species are often dynamic in that both may shift naturally within an area or from one area to another over time. Climate change will be a particular challenge for biodiversity because the interaction of additional stressors associated with climate change and current stressors may push species beyond their ability to survive (Lovejoy 2005, pp. 325-326). The synergistic implications of climate change and habitat fragmentation are the most threatening facet of climate change for biodiversity (Hannah

et al.

2005, p. 4). Current climate change predictions for terrestrial areas in the Northern Hemisphere indicate warmer air temperatures, more intense precipitation events, and increased summer continental drying (Field

et al.

1999, pp. 1-3; Hayhoe

et al.

2004, p. 12422; Cayan

et al.

2005, p. 6; Intergovernmental Panel on Climate Change (IPCC) 2007, p. 1181). Climate change may lead to increased frequency and duration of severe storms and droughts (McLaughlin

et al.

2002, p. 6074; Cook

et al.

2004, p. 1015; Golladay

et al.

2004, p. 504). The southwestern region of the country is predicted to become drier and hotter overall (Hayhoe

et al.

2004, p. 12424; Seager

et al.

2007, p. 1181). Predictions of climatic conditions for smaller subregions such as California are less certain.

Documentation of climate-related changes that have already occurred in California (Croke

et al.

1998, pp. 2128, 2130; Brashears

et al.

2005, p. 15144), and future drought predictions for California (e.g., Field

et al.

1999, pp. 8-10; Lenihen

et al.

2003, p. 1667; Hayhoe

et al.

2004, p. 12422; Brashears

et al.

2005, p. 15144; Seager

et al.

2007, p. 1181) and North America (IPCC 2007, p. 9), indicate prolonged drought and other climate-related changes will continue in the foreseeable 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, p. 41389, August 3, 1993; Service 1998a, p. 34). The magnitude and frequency with which local climate-related changes or drought-induced impacts may negatively affect limited ephemeral wetland habitats, in terms of their seasonal timing, ponding durations, or patterns of inundation and dry down, remains 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 in which 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 if pools dry up before reproduction is complete (Service 1998a, p. 34). Long-term or continuing drought conditions may deplete cyst banks in affected pools as new reproductive cysts are not deposited. Additionally, localized climate-related changes may alter the temporal spatial array of occupied habitat patches (across and between pool complexes) across the species' geographical range. 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

Life History

section above).

The information currently available on the effects of global climate change and increasing temperatures does not adequately predict the location and magnitude of climate change effects to Riverside fairy shrimp; therefore, we are unable to determine if any additional areas may be appropriate to include in this proposed revised critical habitat designation to address the effects of climate change. We specifically request information from the public on the currently predicted effects of climate change on Riverside fairy shrimp and its habitat. Furthermore, we recognize that designation of critical habitat may not include all habitat areas that we may eventually determine are necessary for the recovery of the species, based on scientific data not now available to the Service. For these reasons, a critical habitat designation does not signal that habitat outside the designated area is unimportant or may not promote the recovery of the species.

Areas that support populations of Riverside fairy shrimp, but are outside the critical habitat designation, will continue to be subject to conservation actions we and other Federal agencies

implement under section 7(a)(1) of the Act. They are also subject to the regulatory protections afforded by the section 7(a)(2) jeopardy standard, as determined on the basis of the best available information at the time of the agency action. Federally funded or permitted projects affecting listed species outside their designated critical habitat areas may still result in jeopardy findings in some cases. 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), section 7 consultations, or other species conservation planning efforts if new information available to these planning efforts calls for a different outcome.

Physical and Biological Features

In accordance with sections 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 at the time of listing to propose as revised critical habitat, we consider those physical and biological features that are essential to the conservation of the species and which may require special management considerations or protection. These include, but are not limited to:

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

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

(3) Cover or shelter;

(4) Sites for breeding, reproduction, and 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 and biological features required for Riverside fairy shrimp from studies of this species' habitat, ecology, and life history as described 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 physical and 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 manmade pools (usually >12 in (30 cm) deep) which support these longer inundation periods; some of

these habitats are artificial pools (cattle tanks and road embankments) which 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 (i.e., water only slowly percolates 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 not all but most years) followed by drying out of the substrate to promote overwintering of cysts, and provide conditions to support a viable cyst bank for the following season. Proper timing of precipitation and the associated hydrological and soil processes in the upland watershed contributes to the provision of space for growth and normal behavior; seasonal filling and persistence of the vernal pool is 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 or complex and its upslope vernal pool watershed (adjacent vegetation and upland habitat) must be available and functional (Hanes and Stromberg 1998, p. 38). Adjacent upland habitat supplies important hydrologic inputs to sustain vernal pool ecosystems. Protection of the upland habitat between vernal pools within the watershed is essential for maintaining space needs for Riverside fairy shrimp (i.e., inundation periods of adequate length to support the entire life-history function and reproductive cycles necessary for Riverside fairy shrimp) and to buffer the vernal pools from edge effects.

Vernal pools generally occur in complexes, which are defined by 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 layer or hardpan, water can also flow and collect below ground, such that the soil remains saturated with water. The result of the movement of the water through vernal pool systems is that pools fill and hold water continuously for a number of days, to weeks, to months, following the initial rainfall (Hanes

et al.

1990, p. 51). Some hydrologic systems have watersheds that cover a large area and that contribute 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 soils or hardpan geology, combined with flat to gently sloping topography, serve to inhibit rapid infiltration of rainwater, resulting in ponded water in vernal pools (Bauder and McMillian 1998, pp. 57-59). These soils also act as a buffer to moderate the water chemistry and rate of water loss to evaporation (Zedler 1987, pp. 17-30). In Ventura County, soils 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 Primary Constituent Elements (PCEs) for Riverside Fairy Shrimp.

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

Riverside fairy shrimp are filter feeders and their diet 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 vernal pools are inundated with water 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 time these habitats are inundated, water plays an important role in providing the necessary aquatic environment (shelter) for the fairy shrimp to complete their life-history requirements. Without protection from desiccation provided by water, 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 period (ponding) excludes species that are exclusively terrestrial, providing a level of shelter from predation and competition for the fairy shrimp that are adapted to short-lived, ephemeral wetland habitats.

The undisturbed soil bank also provides cover and shelter for fairy shrimp cysts during the dry-down period of the vernal pool habitat. The drying phase allows reproductive cysts to overwinter, as the cysts 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 dry period in vernal pools. Cyst dormancy is an important life-history adaptation to 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 dry-down period also 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 shrimp are typically observed from mid-March to 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 presumably restricts Riverside fairy shrimp from occupying shallow pools that often last only several days to a few weeks (Hathaway and Simovich, p. 674).

Because vernal pool ecosystems are highly variable in the length of time pools remain filled, 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 conditions needed for success occur transitorily. 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). Therefore, when the females' eggs are fertilized, they begin to develop; the development of the fertilized eggs stops at an early stage (after a few cell divisions) and the eggs enter diapause (become dormant). Diapausing eggs are often referred to as “cysts” or “resting eggs.” Riverside fairy shrimp cysts are small (finer than a tip of a pencil) and contain a dormant fairy shrimp embryo encased in a hard outer shell. These 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 layer of the vernal pool. 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, see Thorp and Covich, p. 767). Resting eggs of freshwater crustaceans 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 (Belk and Cole 1975, pp. 209, 222; Williams 1985, p. 97).

Researchers have found that only a small portion of the cysts in the cyst bank hatch each time the vernal pool fills. As only small percentages of Riverside fairy shrimp cysts hatch in any given year, 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. The “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 living in variable environments. Allowing conditions within the above physical parameters to occur on a naturally cyclic basis is essential for the survival and conservation of the Riverside fairy shrimp.

As previously discussed in the Background section above, Riverside fairy shrimp are restricted to a small subset of long-lasting vernal pools and ephemeral wetlands in southern California because this species has a relatively longer maturation rate than other fairy shrimp, taking approximately

8 weeks to reach sexual maturity and begin mating (Hathaway and Simovich 1996, p. 673). This distinctly longer maturation rate presumably restricts Riverside fairy shrimp typically to pools that are moderate to deep vernal pools and ephemeral basins (generally ranging from 10 in (25.4 cm) to 5 to 10 feet (1.5 to 3 meters) in depth) (Hathaway and Simovich 1996, p. 675).

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

The majority of complexes and pools that currently support Riverside fairy shrimp have experienced some level of disturbance, some more recently or to a greater extent than others. 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. These areas are more vulnerable to agriculture, cattle, and off-road vehicle 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, there is a possibility of documenting additional occurrences given more intensive survey efforts and reporting. Because Riverside County has not yet been developed and fragmented to the same extent as Los Angeles County, we believe undocumented occurrences of the Riverside fairy shrimp may occur in Riverside County.

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 hydrologic 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 when these species do co-occur, they rarely have been observed to coexist as adults (Hathaway and Simovich 1996, p. 670); given Riverside fairy shrimp's slower rate of development, San Diego fairy shrimp are usually found earlier in the season than Riverside fairy shrimp

(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 (PCEs) for Riverside Fairy Shrimp

Under the Act and its implementing regulations, we are required to identify the physical and 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. We consider primary constituent elements to be the elements of physical and biological features that 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 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, 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 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 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 neutral to alkaline (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. Size of associated watershed 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 Riverside fairy shrimp occur. 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 proposed 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 believe conservation of the Riverside fairy shrimp is dependent upon a multitude of factors. Conservation and management of areas across the species' range that maintain normal hydrologic and ecological functions where existing populations survive and reproduce and that are representative of the geographic distribution of the species, 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 conservation of areas that allow for the movement of cysts between areas representative of the geographic and ecological distribution of the species (within and between vernal pool complexes) are the considered criteria needed for the conservation of Riverside fairy shrimp.

We are proposing to designate most of the known occupied habitat of Riverside fairy shrimp because: (1) Riverside fairy shrimp are non-migratory; (2) disjunct populations likely represent unique, locally adapted populations (adapted to unique, site-specific or habitat-specific environmental conditions); and (3) gene exchange between populations or critical habitat units is likely infrequent. Where management units are sufficiently distant (16 to 159 mi (26 to 256 km)) from one another, the likelihood of gene exchange is reduced. All of the areas proposed contain one or more of the PCEs essential for the species that may require special management considerations or protection. We have also determined that all of the areas we are proposing (including Johnson Ranch Created Pools (Subunit 3h) that was occupied after the time of listing) are essential to the conservation of the species because these areas: (1) Maintain the genetic variability of Riverside fairy shrimp across its known geographic range and allow for a varying nature and expression of the species, (2) allow for gene flow and dispersal, and habitat availability that 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 a species by encompassing a 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. Therefore, not all areas designated as revised critical habitat will contain all of the PCEs. All units and subunits proposed to be designated as critical habitat are currently occupied (with the exception of Subunit 1b, which is considered to be occupied by Riverside fairy shrimp) and contain one or more primary constituent elements that support the life-history needs of the species. In the case of this proposed designation, most of the units contain all of the PCEs.

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 which are essential to the conservation of the species and which may require special management considerations or protection, before considering whether any areas unoccupied at time of listing may be essential to conserve the species. Although 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, all areas (units/subunits) we are proposing as revised critical habitat in this proposed rule, whether occupied or unoccupied at time of listing, require special management considerations or protection of the essential features to address current and future threats to Riverside fairy shrimp, to maintain or enhance the physical and biological features essential to its conservation, and to ensure the recovery and

s

urvival of the species. The areas proposed as revised critical habitat represent our best assessment of the habitat that meets the definition of critical habitat for Riverside fairy shrimp at this time.

A detailed discussion of the threats impacting the physical and biological features essential to the conservation of Riverside fairy shrimp which may require special management considerations or protection can be found in the 1991 proposed listing rule (56 FR 57503; November 12, 1991), the 1993 final listing rule (58 FR 41384; August 3, 1993), the 2001 critical habitat designation (66 FR 29384; May 30, 2001), the 2005 critical habitat designation (70 FR 19154; April 12, 2005), the 2008 5-year review for Riverside fairy shrimp (Service 2008, pp. 12-37), and the 1998 Recovery Plan (Service 1998a, pp. 1-100).

The physical and biological features in areas proposed as revised critical habitat in this proposed critical habitat designation all face ongoing threats that require special management considerations or protection. Threats which may require special management considerations or protection include: vernal pool elimination due to agricultural and urban development, including activities associated with construction of infrastructure (highways, utilities, water storage, etc.) (PCEs 1, 2, 3); the construction of physical barriers or impervious surfaces around a vernal pool complex (PCEs 1, 2); altered water quality/quantity (PCEs 1, 2, 3) due to channeling water runoff into a vernal pool complex or 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 the discharge of dredged or fill material into vernal pools and erosion of sediments from fill material; the disturbance of soil profile by grading, digging, or other earthmoving work within the basin or its upland slopes and/or other activities such as off-road vehicle use, heavy foot traffic, grazing, vegetation removal, fire management, or road construction within the watershed for the vernal pools; the invasion of nonnative plant and animal species into the vernal pool basin (PCEs 1, 2), which alter hydrology and soil regimes within the vernal pool; and any activity which permanently alters the function of the underlying claypan or hardpan soil layer (PCE 3) resulting in the disturbance or destruction of the 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, the 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 and attendant housing, development, and infrastructure needs. Natural areas in these counties are frequently near or bounded by urbanized areas. Grading, discing, and scraping in areas 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, through disruption of soils and removal of the cyst bank, and through the modification of upland hydrology and topography, which may potentially isolate a pool or pools within a pool 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 hydrologic regime is altered (Bauder 1986b), human activities that reduce the extent of the watershed or which alter runoff patterns (i.e., timing, amount, or flow of water) (PCE 2) may also eliminate Riverside fairy shrimp, reduce their population sizes 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 hydrologic patterns due to cattle trampling, off-road vehicle use, human trampling, road development, military activities, and water management activities, impact vernal pools (PCEs 1, 2, 3) (58 FR 41387; August 3, 1993). Due to the species highly fragmented and restricted range, exacerbation of impacts from habitat fragmentation (species isolation) on the species' genetic diversity, patterns of gene flow, and persistence; reductions in air and water quality due to human urbanization; or changes in nutrient availability associated with altered hydrology (Bauder 1986b, pp. 209-211) may further impact vernal pool habitats. Unpredictable natural events, such as drought or fire can be especially devastating due to the fragmented and restricted range of the species (58 FR41390, August 3, 1993). These threats may require special management considerations or protection.

Changes in hydrology that affect the Riverside fairy shrimp's primary constituent elements are caused by activities that alter the surrounding topography or change historical water flow patterns in the watershed (PCEs 2, 3). Even slight alterations of 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 (basin) (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 the pool(s) or of 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 the 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, off-road vehicles, military training activities, repeated or deep agricultural discing, drilling, or creation of berms that obstruct the natural hydrological surface or sub-surface flow of water run-off 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.

Invasive plant species may alter the ponding inundation and water temperature by changing the evaporation rate and shading of standing water in vernal pools (PCEs 1, 2, 3). Invasive plant species, such as brass-buttons (

Cotula coronopifolia

) and Pacific bentgrass

(Agrostis avenaceae

), compete with native vernal plant species and may alter the physiochemical factors of the water (PCE 1), the ponding duration (PCE 1), and the upland habitat (PCE 2), and may modify the soils (PCE 3) in these vernal pools. Impacts due to invasive plants can be managed such that activities needed to remove and manage native vernal pool plants, are conducted 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 facing individual proposed revised critical habitat units is provided in the unit descriptions below. In these proposed 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 shrimp's successful reproduction and growth, adequate feeding habitat, and 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, and areas outside of the geographical area occupied at the time of listing that are essential for the conservation of the Riverside fairy shrimp. We reviewed available information pertaining to the habitat requirements of the species. In accordance with the Act and its implementing regulations at 50 CFR 424.12(e), we considered whether designating additional areas outside those areas occupied at the time of listing are essential to ensure the conservation of the species. We are proposing designation of critical habitat in areas within the geographical area occupied by the species at the time of listing in 1993 with features essential to conservation of the species that may require special management considerations and protection. We are also proposing designation of the the Johnson Ranch Created Pools area. Although this area was not occupied at the time of listing, we believe the area is also essential for the conservation of the the Riverside fairy shrimp, considering the very restricted distribution of the species. We believe the long-term conservation of Riverside fairy shrimp depends upon the ongoing protection and management of these remaining, occupied vernal pools within the known range of the species.

During preparation of the 1998 Recovery Plan for Vernal Pools in Southern California (see further explanation below), we evaluated the data on known Riverside fairy shrimp occurrences and determined, based on the features associated with vernal pools and vernal pool complexes, those necessary for the stabilization and reclassification of the species (Service 1998a, Appendices F, G). We since have reevaluated those areas based on species occupancy, and their hydrology, watershed, and topographic features, and their current management needs. Lands are proposed for designation (with the exception of Subunit 3g) based on sufficient PCEs being present to support the species' life-history processes.

In determining which areas of habitat occupied at time of listing currently contain the physical and 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 2004 proposed critical habitat designation for Riverside fairy shrimp (69 FR 23024; April 27, 2004); the 2005 final critical habitat designation (70 FR 19154; April 12, 2005); 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 Database (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, 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.

At the time Riverside fairy shrimp was listed in 1993, the geographical area occupied by the species was considered to include Orange, Riverside, and San Diego Counties, as well as Baja, Mexico (58 FR 41384; August 3, 1993). We now have additional records of occurrence for Riverside fairy shrimp extending the species' distribution; we believe these additional areas were occupied at the time of listing but were not identified at the time of listing or in the Recovery Plan.

Although not explicitly detailed, the Recovery Plan identifies areas essential to the recovery of the species as those that are determined necessary to advance at least one of the following conservation criteria: (1) Maintain habitat function and spatial configuration for species viability in the long term; (2) support stable, intact occurrences; (3) represent unique habitat or habitat associations within the species' range; and (4) capture the ecological, biological, edaphic (soils), micro-topography, genetic, and geographical variation within vernal pools and vernal pool complexes throughout the species' range.

Our determination of habitat essential to the conservation of Riverside fairy shrimp takes into consideration this generalized conservation approach and areas identified in the 1998 Recovery Plan as necessary for the species stabilization and reclassification. The 1998 Recovery Plan identifies “management areas” on which the long-term conservation and recovery of Riverside fairy shrimp depends. 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.

The 1998 Recovery Plan uses management areas to define regional conservation objectives. We have used these same management areas and names to assist us in identifying specific areas essential to the conservation of the Riverside fairy shrimp where possible. In cases when new occurrence data identifies occupied vernal pools not identified in the Recovery Plan, we have relied on the best available scientific data to update map coverages (for example, in Orange and Riverside Counties). We believe these new occurrences were in fact occupied at the time of listing, but only have been documented since the publication of the recovery plan. Our 2005 final rule to designate critical habitat used locations identified in Appendices F and G of the 1998 Recovery Plan; however, for this proposed revised critical habitat (due to improvements to the PCEs and 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 1). In some cases, areas within subunits have been reduced because they simply do not contain the PCEs essential to the conservation of the Riverside fairy shrimp. In other cases, we have new distribution information which has led us to remove areas previously determined as essential because the physical and biological features do not support the necessary PCEs, such that we no longer believe that they meet the definition of essential to the conservation of the species (i.e., are areas which have been significantly altered or impacted since the 2005 designation). Specific differences from the 2005 final rule are summarized in the Summary of Changes from Previously Designated Critical Habitat section of this rule.

Table 1—Areas Identified as Necessary for Stabilizing Riverside Fairy Shrimp Populations as Listed in Appendix F of 1998 Recovery Plan, as Identified as Essential in the 2005 Final Critical Habitat Designation, and as Identified as Essential in This 2011 Proposed Revised Critical Habitat Designation

Name/location

Listed in

Appendix F

of 1998

Recovery Plan

2005 Final critical habitat (fCH)

designation (subunit)

2011

Proposed

revised

critical habitat (prCH) (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.

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.

SCE Viejo Conservation Bank

No

No subunit #; 4(b)(2) exclusion

2i.

Saddleback Meadow (*RP: Saddleback Meadow)

Yes

#

2d; 4(b)(2) exclusion

2dA.

O'Neill Regional Park—near Trabuco Canyon

Yes

#

2d; 4(b)(2) exclusion

2dB.

O'Neill Regional Park—near Cañada Gobernadora/east of Tijeras Creek

Yes

#

2

2e.

Chiquita Ridge (*RP: Chiquita Ridge)

Yes

2f; 4(b)(2) exclusion

2f.

“RP: Orange County Foothills (undescribed)”

Yes

#

Proposed as subunits herein (2dB, 2e, 2g, 2h, 2i).

Radio Tower Road

No

2g; 4(b)(2) exclusion

2g.

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

No

2h; 4(a)(3) exemption

2h.

Unit 3: Riverside Inland Valleys (Riverside MA)

March Air Reserve Base

No

3a; Removed

Not proposed.

March Air Reserve Base

No

3b; 4(a)(3) exemption

Not proposed.

Australia Pool

No

No subunit #; 4(b)(2) exclusion

3c.

Scott Road Pool

No

No subunit #; 4(b)(2) exclusion

3d.

Schleuniger Pool

No

No subunit #; 4(b)(2) exclusion

3e.

Skunk Hollow and Field Pool (aka Barry Jones Wetland Mitigation Bank) (*RP: Skunk Hollow/Murrieta)

Yes

No subunit #; 4(b)(2) exclusion

3f.

Johnson Ranch Created Pool

No

No subunit #; 4(b)(2) exclusion

3g.

Santa Rosa Plateau—Mesa de Colorado (*RP: Santa Rosa Plateau)

Yes

Not proposed

3h.

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

Stuart Mesa, Marine Corps Base (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 Mission Critical

4(a)(3)(B) exemption.

San Mateo, MCB Camp Pendleton (*RP: San Mateo)

Yes

No subunit #; 4(a)(3)(B) exemption

Not proposed.

Wire Mountain, MCB Camp Pendleton (*RP: Wire Mountain)

Yes

4(a)(3)(B) exemption

Not proposed.

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 #: Central Sand Diego County, Military Land, Exempted—(San Diego Central Coastal Mesa MA)

AA 1-7, 9-13 East Miramar (Pool 10) (AA1 East)

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: JJ 2 Poinsettia Lane)

Yes

4c

4.

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

J 33 (Sweetwater High School)

No

5a; 4(b)(2) exclusion

5a.

J 15 Arnie's Point (*RP: J2, J5, J7, J11-21, J23-30)

Yes

#

5b; 4(b)(2) exclusion

5b.

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

Proposed as subunits below.

J29-31 (*RP: J2, J5, J7, J11-21, J23-30)

Yes

#

No subunit #; 4(b)(2) exclusion

5d.

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 (aka 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, J16-19 (Goat Mesa) (*RP: J2, J5, J7, J11-21, J23-30)

Yes

No subunit #; 4(b)(2) exclusion

5h.

MA: Management Area as defined in 1998 Recovery Plan.

(*RP): Indicates the 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: indicates the location was identified in the 1998 Recovery Plan.

Yes

#

: indicates the 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 “unlumped” in this 2011 proposed rule.

We consider all areas proposed as revised critical habitat to have been occupied at the time of listing (with the exception of Johnson Ranch Created Pools—Subunit 3g, which was not occupied at the time of listing). As further discussed in the unit descriptions below, all areas proposed as critical habitat for Riverside fairy shrimp are currently occupied by the species (Subunit 1b is considered occupied—see unit description below), are within the species' geographical range, and contain PCEs to support at least one of its life-history functions. If protocol surveys fail to confirm occupancy of Subunit 1b, we are also proposing to designate this area under Section 3(5)(A)(ii) of the Act because we have determined the area is essential for the conservation of the Riverside fairy shrimp (see Subunit 1b unit description below).

As noted above, we also are proposing designation of an area not occupied by the species at the time of listing but which is currently occupied (3g; Johnson Ranch Created Pools), because we have determined the area is essential for the conservation of the species (see unit description below).

We are proposing critical habitat in specific areas that include ephemeral wetland habitat and intermixed wetland and upland habitats of various sizes that possess appropriate soils and topography that support ponding during winter and spring; are within the known geographical and elevation range of Riverside fairy shrimp; are geographically distributed; 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' historical 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)(1)(A) of the Act, we used the best scientific data available in determining areas that contain the features that are essential to the conservation of Riverside fairy shrimp. 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 and biological habitat features that are essential to the conservation of the species (see

Physical and 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, in the 2005 final critical habitat rule for Riverside fairy shrimp, and in the 2008 5-year review for Riverside fairy shrimp; (b) the CNDDB data report for Riverside fairy shrimp and accompanying GIS records (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 MCB Camp Pendleton and MCAS Miramar; (e) the Western Riverside County 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 MSCP and Western Riverside County MHCP, 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 listing rule as well as information that has become available since 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 Pools (Subunit 3g), 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 has limited dispersal capabilities, and because surveys for the species at the time of listing were incomplete. We believe that the documentation of additional occurrences within the range of the

species after the species was listed was due to an increased effort to survey for this species. Therefore, we believe that all of the areas currently extant, excepting Johnson Ranch Created Pools which were created using cysts salvaged from a nearby historic occurrence (at Redhawk development), were occupied prior to the time this species was listed.

(4) We identified which areas contain the PCEs and identified which of those areas may require special management considerations or protection. All areas containing PCEs were mapped and areas not containing PCEs were removed. Units were designated 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, adult). Some units contain only some of the PCEs necessary to support adult Riverside fairy shrimp. Areas that we have identified as having one or more PCEs: (a) Contain large, interconnected ephemeral wetlands; have large numbers of individuals observed; or have habitat areas that allow for connections between existing occurrences of Riverside fairy shrimp; (b) represent important occurrences of this species that are on the geographic edge of this species' 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, and evolutionary time scale); or (d) exist within the distribution of this species and provide connections between occupied areas. The conservation of stable and persistent occurrences throughout the species' range helps to maintain connectivity between occurrences that are in proximity to one another and maintain potential gene flow.

(5) We circumscribed boundaries of potential critical habitat, based on information obtained from the above steps. To map areas proposed as revised critical habitat, we used data on known Riverside fairy shrimp locations and those vernal pools and vernal pool complexes that we identified in the 1998 Recovery Plan as essential for the stabilization and reclassification of the species. For areas identified as essential, we mapped the specific areas that contain the physical and biological features needed to support life-history functions for Riverside fairy shrimp (PCEs). We took the following actions: We first 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, which contribute to the hydrology of the ephemeral wetland habitat. We delineated the border of the proposed 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) Once all areas containing the PCEs were mapped, we removed all areas not containing the physical and biological features essential to the conservation of Riverside fairy shrimp. For example, when determining proposed 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 and 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 proposed rule have been excluded by text in the proposed rule and are not proposed for designation as critical habitat. Therefore, if the critical habitat is finalized as proposed, a Federal action involving these lands would not trigger section 7 consultation with respect to critical habitat and the requirement of no adverse modification unless the specific action would affect the physical and biological features in any adjacent critical habitat.

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

We are proposing for designation as revised critical habitat lands that we have determined were occupied at the time of listing and are currently occupied and contain physical and biological features that are essential to the conservation of the species because they support Riverside fairy shrimp life-history processes, and one area that was not occupied at the time of listing (Johnson Ranch Created Pools) that we have determined is essential for the conservation of Riverside fairy shrimp.

Summary of Changes From Previously Designated Critical Habitat

The areas identified in this proposed rule constitute a proposed revision of the areas we designated as critical habitat for Riverside fairy shrimp on April 12, 2005 (70 FR 19154). In cases where we have new information or information that was not available for the previous designation, we made changes to the critical habitat for Riverside fairy shrimp to ensure that this proposed rule reflects the best scientific data available.

We made a number of changes to this proposed rule compared to the 2005 final critical habitat designation, including the following:

(1) We refined the Primary Constituent Elements (PCEs) to specifically capture those physical and biological features essential to the conservation of Riverside fairy shrimp, and to more accurately describe a range of physiochemical factors (e.g., dissolved solutes, temperature, and other water chemistry attributes) that are necessary for completion of Riverside fairy shrimp's essential life-history processes.

(2) We incorporated information related to the genetics of the species rangewide and new distribution data that have become available to us following the 2005 critical habitat designation.

(3) We renamed unit and subunit numbers, and when appropriate redefined (redrew) boundaries to improve and better delineate those areas containing features essential to the survival and conservation of Riverside fairy shrimp. Boundaries more precisely capture the underlying physical and biological features associated with vernal pools and vernal pool complexes throughout the species' range. In the 2005 rule, we used 330-ft (100-m) Universal Transverse Mercator (UTM) (North American Datum 1927 (NAD 27)) grid cells overlaid on top of those vernal pool complexes and their associated watershed. In this proposed revision, because we have improved our mapping methodology and our selection criteria, areas containing upland habitat not directly contributing to the hydrology of the vernal pools have not been included in this proposal.

(4) We re-evaluated areas considered for exclusion from critical habitat designation under section 4(b)(2) of the Act for which we are seeking public comment (see Public Comments section of this rule).

(5) We added, subtracted, and revised areas that do or do not meet the definition of critical habitat. Certain areas identified as previously meeting the definition of critical habitat were determined—based on a review of the best available scientific and commercial information—to no longer meet the definition of critical habitat. In these cases, we removed areas that no longer meet the definition of critical habitat due to significant alterations in drainage or development within the watershed. The revised criteria resulted in inclusion of areas essential to the conservation of the species and removal of areas (since the 2004 proposed rule or the 2005 final rule) that no longer meet the definition of critical habitat.

In this proposed revised critical habitat, we have identified 33 areas that we believe meet the definition of critical habitat. One of the areas being proposed was unoccupied at the time of listing (Johnson Ranch Created Pools). Each of the 33 areas contains the physical and biological features essential to the conservation of Riverside fairy shrimp. Table 2 shows a comparison of the locations, units, and acreage between the 2005 final critical habitat designation and this proposed revised critical habitat designation. Eight of the 33 areas determined to be essential are in north San Diego County on MCB Camp Pendleton and are exempt from this proposed rule under section 4(a)(3)(B)(i) of the Act: San Onofre State Beach, State Park-leased lands, near Christianitos Creek foothills (along the northwest corner of MCB Camp Pendleton); area south of San Onofre State Beach, in Uniform Training Area; Las Pulgas North; Las Pulgas East; Las Pulgas West; Cockleburr North; Cockleburr South; and Stuart Mesa; One area is on MCAS Miramar (AA1) and is also exempt from this proposed rule under section 4(a)(3)(B) of the Act. The remaining 25 areas (5 units consisting of 25 subunits) that meet the definition of critical habitat are mapped as proposed revised critical habitat for Riverside fairy shrimp, are presented in Table 2, and are described in the unit descriptions below.

Table 2—Evaluation of Units and Subunits for Areas Containing Essential Features Between 2005 Final Critical Habitat (fCH) and 2011 Proposed Revised Critical Habitat (prCH Considered To Meet the Definition of Critical Habitat

[Note: If amount in 2005 final critical habitat is bracketed, the unit/subunit and its acreage were proposed in 2004 but removed in 2005.]

Location*

2005 Final critical habitat [or prCH 2004]

Subunit

Area containing essential features 2005

2011 Proposed revised critical habitat

Subunit

Area containing essential features 2011

Unit 1: Ventura County Management Area

Tierra Rejada Preserve

1a

47 ac (19 ha)

1a

18 ac (7 ha).

South of Tierra Rejada Valley

1b

185 ac (75 ha)

1b

448 ac (182 ha).

Cruzan Mesa

[1c; 534 ac (216 ha)]; Removed

0 ac (0 ha)

1c; no longer meets definition of essential; no confirmed species occupancy data

0 ac (0 ha).

Unit 2: Los Angeles Basin-Orange County Foothills Management Area

LAX

[2a; 49 ac (20 ha)]; Removed

0 ac (0 ha)

2a; no longer meets definition of essential; PCEs no longer present

0 ac (0 ha).

LAX

[2b; 54 ac (22 ha)]; Removed

0 ac (0 ha)

2b; no longer meets definition of essential; PCEs no longer present

0 ac (0 ha).

(MCAS) El Toro

[2c; Excluded under section 4(b)(2)]

14 ac (6 ha)

2c

26 ac (11 ha).

SCE Viejo Conservation Bank

Excluded under section 4(b)(2)

84 ac (34 ha)

2i

63 ac (25 ha).

Saddleback Meadows and O'Neill Regional Park—near Trabuco Canyon

Unit 2 combined; portion excluded under section 4(b)(2)

57 ac (23 ha) Excluded

2dA

256 ac (104 ha).

49 ac (20 ha)

2dB

91 ac (37 ha).

O'Neill Regional Park—near Can

ada Gobernadora/east of Tijeras Creek

Excluded under section 4(b)(2)

101 ac (41 ha)

2e

70 ac (28 ha).

Chiquita Ridge

Excluded under section 4(b)(2)

262 ac (106 ha)

2f

56 ac (23 ha).

Radio Tower Road

Excluded under section 4(b)(2)

417 ac (169 ha)

2g

51 ac (21 ha).

San Onofre State Beach, State Park-leased lands

Excluded under section 4(b)(2)

47 ac (19 ha)

2h

107ac (43 ha).

Unit 3: Riverside Inland Valleys Management Area

March Air Reserve Base

[3a; 44 ac (18 ha)];

Removed

0 ac (0 ha)

3a; no longer meets definition of essential; PCEs no longer present

0 ac (0 ha).

March Air Reserve Base

3b; Excluded under section 4(b)(2)

101 ac (41 ha)

3b; no longer meets definition of essential; PCEs no longer present

0 ac (0 ha).

Australia Pool

Excluded under section 4(b)(2)

529 ac (214 ha)

3c

19 ac (8 ha).

Scott Road Pools

Excluded under section 4(b)(2)

15 ac (6 ha)

3d

9 ac (4 ha).

Schleuniger Pool

Excluded under section 4(b)(2)

136 ac (55 ha)

3e

23 ac (9 ha).

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

Excluded under section 4(b)(2)

230 ac (93 ha)

3f

163 ac (66 ha).

Johnson Ranch Created Pools

Excluded under section 4(b)(2)

82 ac (33 ha)

3g

54 ac (22 ha).

Santa Rosa Plateau—Mesa de Colorado

Excluded under section 4(b)(2)

4,394 ac (1,778 ha)

3h

597ac

(242 ha).

Unit 4: San Diego North and Central Coastal Mesas Management Area

MCB Camp Pendleton

4(a)(3) exemption

2,936 ac (1,188 ha)

4(a)(3) exemption

1,929 ac (780 ha).

Poinsettia Lane Commuter Station

2c; partially excluded under section 4(b)(2)

22 ac (9 ha)

4c

9 ac (4 ha).

Miramar (AA1 East)

4(a)(3) exemption

117 ac (47 ha)

4(a)(3) exemption

59 ac (24 ha).

Unit 5: San Diego: Southern Coastal Mesas Management Area

Sweetwater (J33)

Proposed 5a; partially excluded under section 4(b)(2)

3 ac (1 ha)

5a

2 ac (1 ha).

Arnie's Point (J15)

Proposed 5a

122 ac (49 ha)

5b

29 ac (12 ha).

Otay Mesa (including J2, J4, J5, J11, J14, J15, J16-18, J33)

Excluded under section 4(b)(2)

2,004 ac (811 ha)

1

Now includes 5a, 5b, 5e, 5f, 5g, 5h

East Otay Mesa (undescribed)

5c; partially excluded under section 4(b)(2)

111 ac (45 ha)

5c

57 ac (23 ha).

J23-J25, formerly part of east Otay Mesa

Excluded under section 4(b)(2)

301 ac (122 ha)

Not proposed, determined not essential

0 ac (0 ha).

J19, J21, J27-28

Excluded under section 4(b)(2)

524 ac (212 ha)

Not proposed, determined not essential

0 ac (0 ha).

J29-J31, J2 N, J4, J5 (includes Robinhood Ridge)

Excluded under section 4(b)(2)

645 ac (261 ha)

5d

370 ac (150 ha).

Excluded under section 4(b)(2)

portion of 2,004 ac (811 ha)

1

5e

44 ac (18 ha).

J2 S, J2 W (includes Hidden Valley, Cal Terraces, and Otay Mesa Road)

Excluded under section 4(b)(2)

portion of 2,004 ac (811 ha)

1

5f

33 ac (13 ha).

J14

Excluded under section 4(b)(2)

ortion of 2,004 ac (811 ha)

1

5g

136 ac (55 ha).

J11E, J11 W, J12, J16-19

Excluded under section 4(b)(2)

portion of 2,004 ac (811 ha)

1

5h

255 ac (103 ha).

Total Area Essential for the Conservation of Riverside fairy shrimp**

13,535 ac (5,477 ha)

5 units, 25 subunits

4,974 ac (2,013 ha).

**

Note:

Column may not add due to rounding.

*Location is based on vernal complex names used in 1998 Recovery Plan; unit names are based on Management Areas as identified in the 1998 Recovery Plan.

**Values in this table may not sum due to rounding.

1

2,004 ac (811 ha) formerly “lumped sum” under Otay Mesa vernal pool complexes—these are now identified as individual subunits: 5a, 5b, 5e, 5f, 5g, 5h.

The following section provides detailed descriptions of the changes made in this proposed rule and points to new information that precipitated each change.

The PCEs in this proposed rule describe the ephemeral wetland habitat where Riverside fairy shrimp occur along with associated hydrological attributes (ponding, water chemistry, dry down) (PCE 1), the upland habitat (watershed and underlying hydrology) characteristics that support the ephemeral wetlands and their function (PCE 2), and the soils and topography (PCE 3) that allow water to pond during winter and spring months. Compared to the 2005 PCE regarding the vernal pools where Riverside fairy shrimp occur (ephemeral wetland habitats), we have added information about the necessary timing and duration of ponding and broadened the range of physiochemical parameters that may occur in order to more clearly characterize the breadth of conditions in which this species occurs (PCE 1). For the 2005 PCE involving the local watershed and filling of the ephemeral wetland habitat (intermixed wetland and upland habitats that act as a local watershed), we now discuss the land features (topography) that contribute to a functional hydrologic regime (i.e., local watershed) (PCE 2). For the 2005 PCE that related to soil types associated with habitat for Riverside fairy shrimp (soils that support ponding during winter and spring), we now state that hardpan or claypan soil series types (including a partial list) create an impermeable surface or subsurface and facilitate the slow percolation and minimal run-off of water necessary for the ephemeral wetland habitat where Riverside fairy shrimp occur (PCE 3).

Similar to the 2005 critical habitat, we used the 1998 Recovery Plan as a guide; however, in this proposed revised critical habitat we conducted additional analyses of all the Riverside fairy shrimp data currently available which are substantially more complete than what was known at the time the 1998 Recovery Plan was approved. The result of our additional analysis is that some areas identified as essential in the 2005 designation were removed, and other areas that were not identified as essential in the 2005 rule, such as areas in existence at the time of listing but not evaluated or included due to lack of surveys for Riverside fairy shrimp, are included in this proposed rule.

In this proposed revised critical habitat designation, we have described the steps used to identify and delineate the areas we are proposing as revised critical habitat in better detail compared to the 2005 critical habitat designation, to ensure that the public better understands why the areas are being proposed as critical habitat. In improving our explanation and intent, we have discontinued the use of the “core” and “satellite” population areas, as further discussed below.

In the 2004 proposed critical habitat designation (69 FR 23024; April 27, 2004), we discussed the areas that represent “core population areas” and “isolated population areas” for Riverside fairy shrimp. Core population areas are defined in the 2004 proposed rule (69 FR 23027; April 27, 2004) as multiple pools or pool complexes containing Riverside fairy shrimp that are within close proximity (approximately 5 mi (8 km)) of other occupied pools and pool complexes and that contain the necessary PCEs to support one or more life-history functions essential to the conservation of Riverside fairy shrimp. Isolated populations are defined in the 2004 proposed rule (69 FR 23027; April 27, 2004) as single pools or pool complexes that are known to contain Riverside fairy shrimp, are separated from other known locations by greater than 10 mi (16 km), and which contain the necessary PCEs to support one or more life-history functions essential to the conservation of Riverside fairy shrimp.

Four “core” population areas—Orange County Foothills, Western Riverside County, the southern coastal portion of Camp Pendleton in San Diego County, and Otay Mesa in San Diego County—and seven isolated (“satellite”) populations—the City of Moorpark in Ventura County; Cruzan Mesa and Los Angeles International Airport in Los Angeles County; March Air Reserve Base and near the City of Banning in Riverside County; and in the City of Carlsbad and on MCAS Miramar in San Diego County—were identified as essential for Riverside fairy shrimp in the 2004 proposed critical habitat designation (69 FR 23024; April 27, 2004). We have discontinued the use of this “core” and “satellite” terminology for labeling areas essential to the conservation of the species and have focused on the habitat characteristics of essential areas.

Large, interconnected ephemeral wetland areas supporting vernal pools or vernal pool complexes in areas with potential for more species complexity and associations are essential to, and will serve as anchors for, the overall conservation of this species. As discussed in the 1998 Recovery Plan, conserving larger, interconnected wetland areas with representative habitat heterogeneity (consisting of dissimilar elements or parts) adjacent to lands with compatible uses are generally preferable to smaller, more isolated pools (Service 1998a, p. 61). Conservation of these areas will sustain the largest populations of Riverside fairy shrimp, allowing the species to persist where it will be less constrained by the threats that negatively impact its essential habitat features (PCEs). However, more isolated (i.e., separated from other known locations by greater than 10 mi (16 km)) habitat areas also support stable, intact occurrences of Riverside fairy shrimp and are also essential to the conservation of the species. Preservation of remaining habitat, including the more isolated pools, serves a fundamental role in the survival and recovery of Riverside fairy shrimp because these areas may represent unique habitat and assemblages within this species' range. A full array of vernal pools and their constituent species, including a range of physical attributes that characterize various occurrences and associations (e.g., pool soils and topography) may be as rare as the individual species associated with them. The more isolated habitat areas occur over a wide range of soils and at various elevations such that, over a range of environmental variables, the preservation of these pools will help maintain the genetic diversity and adaptive potential of Riverside fairy shrimp and may enable them to survive and potentially respond to future environmental changes and threats. In summary, we believe the areas proposed in this revised critical habitat would provide for the conservation of Riverside fairy shrimp by: (1) Maintaining the physical and biological features essential to the conservation of the species in areas where Riverside fairy shrimp are known to occur; (2) maintaining the current distribution of Riverside fairy shrimp, and thus preserving an array of unique habitat and assemblages within this species' range, preserving genetic variation and adaptive potential of Riverside fairy shrimp throughout its range, and minimizing the potential effects of local extinction; and (3) including an area that was not occupied at the time of listing but that is essential to conserve the species.

In the 2005 final critical habitat designation, both larger, interconnected ephemeral wetland areas and isolated, small basins and pools were identified as essential to the conservation of the species due largely in part to the species' limited numbers and distribution (Service 2005, p. 19178). Given the historical loss of vernal pool

habitat in southern California (Mattoni and Longcore 1997; Bauder and McMillian 1998; Keeler-Wolf

et al.

1998), the conservation of the few remaining occurrences of Riverside fairy shrimp was considered essential for its conservation (Service 1998a). Further, given that Riverside fairy shrimp have a narrow geographic distribution and unique and specialized habitat requirements within that range, we concluded in the 2004 proposed critical habitat designation that all known occupied locations of Riverside fairy shrimp were essential to the conservation of the species (Service 2004, p. 23027). In this proposed revised designation, we have concluded that the conservation of the remaining occupied locations of Riverside fairy shrimp within the geographical range known at the time of listing, and the one created pool area outside the known geographical location at the time of listing capture those areas essential to the conservation of the species. We used the following criteria in the selection of areas that contain the essential features for the Riverside fairy shrimp and focused on designating units and subunits in: (1) Areas throughout the current geographic, elevation, and ecological distribution of the species; (2) areas that maintain the current population structure across the species' range; (3) areas that retain or provide for connectivity within occupied sites such that they would allow for water or wind dispersal to adjacent ephemeral wetland habitat; (4) areas that possess large continuous blocks of occupied habitat, representing source populations and/or unique ecological characteristics; and (5) areas that contain sufficient upland habitat around each occupied location to allow for sufficient survival and recruitment to maintain a self-sustaining population over the long term.

By improving our mapping methodology, we more accurately define the critical habitat boundaries and better represent those areas that possess the physical and biological features essential to the conservation of Riverside fairy shrimp. In the 2005 final rule, we used a 100-meter grid resolution to delineate critical habitat, which resulted in more poorly defined and larger critical habitat areas. In this proposed rule, we accurately mapped areas that contain the PCEs by directly approximating the delineation of essential features rather than using a 100-meter grid. We believe the result is a more precise mapping of the habitat features and the areas which contain features essential to the conservation of the species. In this proposed revised critical habitat, upland areas (located immediately surrounding the vernal pool basins) and ephemeral wetlands (areas that contain one or more of the PCEs for the Riverside fairy shrimp) were mapped based on topographic features such as ridges, mounded micro-topography (mima mounds), and elevation gradients or slopes. Boundaries for these areas were further refined and delineated by mapping those areas that slope toward the pools, from highest point to highest point in the immediate surrounding upland areas, following the map's topographic elevation gradient around the high points (peaks), to the sides and the lowest part of the basin that encompass the complex of vernal pools. Those areas that the topographic maps show sloping steeply away from the pools, or that are developed or altered, such that necessary PCEs (for example, water, soil, and minerals) cannot be transported toward the vernal pools over such areas, are left outside of the refined delineation. This method was used for vernal pools in both basin and mesa-type topographic settings. Although our mapping methodology results in fewer described acres captured, it is a more accurate depiction of critical habitat boundaries that possess the physical and biological features essential to the conservation of the species.

The 2005 final critical habitat designation (70 FR 19154; April 12, 2005) included 4 units, one of which consisted of two subunits (1A and 1B), comprising a total of 306 ac (124 ha). We identified an additional 13,607 ac (5,506 ha) of land containing features essential to the conservation of Riverside fairy shrimp that were exempted from the 2005 critical habitat designation pursuant to section 4(a)(3)(B)(i) of the Act, or excluded under section 4(b)(2) of the Act (70 FR 19180; April 12, 2005). This proposed rule identifies 4,972 ac (2,012 ha) considered to contain the physical and biological features essential to the conservation of Riverside fairy shrimp (including military land exempt under section 4(a)(3) of the Act (see Table 1, above, and Table 3, below)). The essential habitat identified in this proposed revision is 9,504 ac (3,846 ha) less than we identified as essential, inclusive of what was excluded or exempted, in the 2005 rule. The acreage reduction is primarily due to our attempt to more accurately delineate the areas that contain the physical and biological features essential to the conservation of Riverside fairy shrimp. We acknowledge the possibility that, due to mapping, data, and resource constraints, there may be some undeveloped areas mapped as critical habitat that do not contain the PCEs. We made every effort to exclude all developed areas, and other land unlikely to contain primary constituent elements essential for Riverside fairy shrimp conservation. Any such structures remaining inside the proposed revised critical habitat are not considered part of the units. This also applies to the land on which the structure lies. A brief discussion of each area designated as critical habitat is provided in the unit descriptions below.

We identified several areas that are exempt under section 4(a)(3)(B)(i) of the Act or will be considered for exclusion under section 4(b)(2) of the Act (see Table 3). In this proposed rule, eight areas (seven areas on MCB Camp Pendleton (1,929 ac (781 ha)) and one area on MCAS Miramar (59 ac (24 ha)) are determined exempt under section 4(a)(3)(B)(i) of the Act. These lands are on land owned, managed, or under the control of the Department of Defense and are addressed in an approved integrated natural resources management plan (INRMP) (in the case of San Onofre State Beach, State Park-leased lands under the Real Estate Agreements and Leases section of the INRMP; see Exclusions section below). Military lands exempt from proposed designation under section 4(a)(3)(B) of the Act are not assigned subunit identifiers; however, MCB Camp Pendleton falls within Unit 4 as discussed in the unit descriptions below. We will consider certain areas for exclusion from final designation under section 4(b)(2) of the Act. Any exclusion in the final revised critical habitat designation could differ from the exclusions we made in the 2005 final critical habitat designation.

Table 3—(1) Proposed Habitat Determined To Be Essential, (2) Proposed Habitat Exempted Pursuant to 4(

a

)(3)(B)(

i

) of the Act, (3) Proposed Habitat Being Considered for Exclusion Pursuant to Section 4(

b

)(2) of the Act Under HCP, (4) Proposed Habitat Being Considered for Exclusion Pursuant to Section 4(

b

)(2) for National Security Reasons, (5) Total Proposed Habitat Considered for Exclusion, (6) Total Proposed Habitat Considered for Exemption and Exclusion, and (7) Total Habitat Proposed as Revised Critical Habitat in This 2011 Rule

(1) Habitat determined to be essential to the conservation of the Riverside fairy shrimp

4,972 ac (2,012 ha).

(2) Proposed habitat exempted pursuant to section 4(a)(3)(B)(i) of the Act (MCAS Miramar and MCB Camp Pendleton)

1,988 ac (805 ha).

(3) Proposed habitat being considered for exclusion pursuant to section 4(b)(2) of the Act under approved habitat conservation plan (HCP)

1,219 ac (493 ha).

(4) Proposed habitat being considered for exclusion pursuant to section 4(b)(2) for national security reasons

0 ac (0 ha).

(5) Total proposed habitat considered for exclusion

1,219 ac (493 ha).

(6) Total proposed habitat exempted or considered for exclusion

3,207 ac (1,298 ha).

(7) Total habitat proposed in 2011 as revised critical habitat (total proposed minus total exempted)

2,984 ac (1,208 ha).

We have identified several areas that are being considered for exclusion under section 4(b)(2) of the Act (see Table 3). In the 2005 rule, we excluded several subunits under section 4(b)(2) of the Act within the planning boundaries of: (a) The Orange County Southern Subregion HCP, (b) the draft City of Oceanside Subarea Plan and the City of Carlsbad's HMP under the MHCP, (c) the Western Riverside County MSHCP, and (d) the City and County of San Diego Subarea Plans under the MSCP. In this proposed revised critical habitat rule, we identified several areas we are considering for exclusion under section 4(b)(2) of the Act within the planning boundaries of, as follows: (a) The Orange County Central-Coastal subregional NCCP/HCP, (b) The Orange County Southern Subregion HCP, (c) the City of Carlsbad's HMP under the MHCP, (d) the Western Riverside County MSHCP, and (e) the County of San Diego Subarea Plan under the MSCP (see the Exclusions section).

We are requesting public comment on the potential exclusion of 89 ac (36 ha) covered by the Orange County Central-Coastal subregional 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 Carlsbad HMP under the MHCP; and 23 ac (9 ha) covered by the County of San Diego Subarea Plan under the MSCP. Any exclusions we make in the final revised critical habitat designation may differ from the exclusions we made in the 2005 final critical habitat designation.

Areas designated as critical habitat units in this proposed rule are divided into five separate units (Units 1 through 5) which follow the six Management Areas presented in the 1998 Recovery Plan (Service 1998a, p. 38). We have combined two management areas identified in the 1998 Recovery Plan, the San Diego: North Coastal Mesas Management Area and the San Diego: Central Coastal Mesas Management Area into one, single unit (Unit 4) for this proposed rule. The management areas are based primarily on geographical locations, although we have considered these locations in terms of underlying soil types and geomorphic processes, size and type of associated watershed, and topographic position (i.e., coastal mesa, inland valley, on granitic soils, etc.). Where possible, unit and subunit labels in this proposed rule follow previous naming conventions found in the 2005 critical habitat. We have retained original names associated with management areas, units, subunits, or pool complex names, where possible, to reduce confusion and promote consistency between previous rules and this proposed revision. Changes from the 2005 final critical habitat rule, however, include the following unit name reassignments: Unit 3 now includes land in Riverside County (land previously excluded from the 2005 designation of critical habitat and which, therefore, had no unit or subunit numbers assigned), and Unit 5 now incorporates Otay Mesa in southern San Diego County, previously labeled as Unit 4 in the 2005 rule. As with the 2005 final critical habitat rule, some land within the San Diego North and Central Coastal Mesa Management Areas (Service 1998a, p. 46) has not been proposed because these lands have been determined to be exempt under 4(a)(3)(B)(i) of the Act (MCAS Miramar and MCB Camp Pendleton) (see Tables 1 and 2 above; and Exemptions section below).

Following a new analysis of the best available scientific information, proposed habitat areas have been added or subtracted based on new information received. In Table 2 above, we have provided a comparison between the 2005 final critical habitat designation and this proposed revised critical habitat rule and identify the change in area (by subunit) between the 2005 critical habitat designation and this proposed revised critical habitat designation. As already stated, some areas designated in the 2005 rule are not being proposed for designation because they do not meet the criteria used to identify areas essential to the conservation of Riverside fairy shrimp (see

Criteria Used to Identify Critical Habitat

for additional discussion). Further we are proposing to designate as revised critical habitat areas not considered in the 2005 final designation (Johnson Ranch Created Pools).

Two areas identified as meeting the definition of critical habitat in the 2004 proposed rule, but removed from the 2005 final critical habitat designation, are not proposed in this revision of critical habitat (Los Angeles Airport and March Air Reserve Base). The best available scientific and commercial data indicate these two areas no longer contain the physical and biological features essential to the conservation of the species and that the species has been extirpated. Further, we are not proposing three areas (Cruzan Mesa in Los Angeles, Banning in western Riverside County, and Wire Mountain in San Diego County) in this proposed rule, because we believe that these areas do not meet the definition of critical habitat, and because we do not possess sufficient data to substantiate Riverside fairy shrimp occurrence (we have conflicting accounts of positive species identification). San Mateo Pool (MCB Camp Pendleton, San Diego County) has been removed from our proposed designation because we possess insufficient data to evaluate its current status or condition, need for special management, or persistence of the occurrence and we, therefore, do not consider it to meet the definition of critical habitat. In the 2005 final critical habitat designation for Riverside fairy shrimp, we mentioned evidence of two vernal pools on or near tribal land

within the Pechanga Band of Luiseño Mission Indians reservation (6 ac (2 ha)) near the City of Temecula with possible historical occurrences, but, based on information available from 2004, we were unable to confirm these occurrences (70 FR 19199). 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 (see Public Comments section above).

For three areas in this rule (portions of proposed Subunits 5b, 5c, and 5h), we have removed portions of the areas previously defined as essential in 2005 because, due to their proximity to the border and ongoing impacts from border patrol activities, we believe they no longer contribute to the long-term viability of Riverside fairy shrimp. More information about the units and subunits that contain the physical and biological features essential to the conservation of Riverside fairy shrimp and an explanation of how the added or removed areas do or do not contribute to the conservation of Riverside fairy shrimp is provided below in the Proposed Revised Critical Habitat Designation section.

In summary, on April 27, 2004, we proposed revised critical habitat of 5,795 ac (2,345 ha) in 5 units, including 19 subunits, located in Los Angeles, Orange, Riverside, San Diego and Ventura Counties. In response to information received during the public comment periods for our 2004 proposed critical habitat, refined mapping methodology, and re-evaluation of essential habitat, we removed 4,822 ac (1,951 ha) of non-essential habitat from the designation (Cruzan Mesa and Los Angeles Airport (Los Angeles County), March Air Reserve Base (Riverside County), and portions within southwestern and southeastern Otay Mesa (San Diego County)). In 2005, we designated approximately 306 ac (124 ha) as critical habitat for Riverside fairy shrimp in 4 units, one of which consisted of two subunits (1A and 1B) (70 FR 19154; April 12, 2005). For this proposed revision, we have included 5 units, including 25 subunits, comprising a total of 2,984 ac (1,208 ha) of land determined to be essential to the conservation of Riverside fairy shrimp.

Proposed Revised Critical Habitat Designation

We propose to designate 2,984 ac (1,208 ha) in 5 units, containing 25 subunits, as critical habitat for Riverside fairy shrimp. The critical habitat areas we describe below constitute our current best assessment of areas that meet the definition of critical habitat for Riverside fairy shrimp. The proposed revised critical habitat includes Riverside fairy shrimp habitat throughout the species' range in the United States. Proposed units generally correspond to the geographic areas identified as “Management Areas” in the 1998 Recovery Plan (Service 1998a, pp. 35-44). This proposed rule, when finalized, will supersede the 2005 critical habitat designation for Riverside fairy shrimp in 50 CFR 17.95(h).

The five map units proposed for designation as critical habitat are referred to by the following geographical names: (Map Unit 1) Ventura County (Transverse Range); (Map Unit 2) Los Angeles Basin—Orange County Foothills; (Map Unit 3) Riverside County Inland Valleys; (Map Unit 4) San Diego Northern and Central Coastal Mesas; and (Map Unit 5) San Diego Southern Coastal Mesas. Areas proposed as revised critical habitat are under Federal, State, local, and private ownership. The approximate area of proposed revised critical habitat by county and land ownership is shown in Table 4.

Table 4—Proposed Revised Critical Habitat for Riverside Fairy Shrimp

[Not including exempted land]

Critical habitat unit

Federal land

State land

Local land

Private land

Total area

Unit 1: Ventura County

31 ac (13 ha)

435 ac (176 ha)

466 ac (189 ha).

1a. Tierra Rejada Preserve

18 ac (7 ha)

18 ac (7 ac).

1b. South of Tierra Rejada

Valley

31 ac (13 ha)

417 ac (169 ha)

448 ac (182 ha).

Unit 2: Los Angeles Basin—Orange County Foothills

142 ac (58 ha)

576 ac (233 ha)

718 ac (291 ha).

2c. (MCAS) El Toro

18 ac (7 ha)

8 ac (3 ha)

26 ac (11 ac).

2dA. Saddleback Meadows

4 ac (2 ha)

252 ac (102 ha)

256 ac (104 ha).

2dB. O'Neill Regional Park—near Trabuco Canyon

75 ac (30 ha)

15 ac (6 ha)

90 ac (37 ha).

2e. O'Neill Regional Park—near Cañada Gobernadora

45 ac (18)

24 ac (10 ha)

69 ac (28 ha).

2f. Chiquita Ridge

56 ac (23 ha)

56 ac (23 ha).

2g. Radio Tower Road

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).

2i. SCE Viejo Conservation Bank

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).

3c. Australia Pool

19 ac (8 ha)

19 ac (8 ha).

3d. Scott Road Pool

9 ac (4 ha)

9 ac (4 ha).

3e. Schleuniger Pool

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).

3g. Johnson Ranch Created Pools

54 ac (22 ha)

54 ac (22 ha).

3h. Santa Rosa Plateau—Mesa de Colorado

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).

4c. Poinsettia Lane Train Station

6 ac (3 ha)

3 ac (1 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).

5a. Sweetwater (J33)

2 ac (less than 1 ha)

less than 1 ac (0 ha)

2 ac (less than 1 ha).

5b. Arnie's Point (J15)

29 ac (12 ha)

29 ac (12 ha).

5c. East Otay Mesa

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).

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

32 ac (13 ha)

12 ac (5 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).

5g. J14

45 ac (18 ha)

18 ac (7 ha)

72 ac (29 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).

Totals

40 ac (16 ha)

316 ac (128 ha)

330 ac (135 ha)

2,297 ac (929 ha)

2,984 ac (1,208 ha).

Note:

Sums of land areas may not total due to rounding.

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 31 ac (13 ha) of local land and 435 ac (176 ha) of private land. This proposed unit includes the vernal pools near the city of Moorpark in Ventura County, at Tierra Rejada Preserve (formerly called Carlsberg Ranch) on the west side of State Highway 23, and a basin to the southeast of Carlsberg Ranch site, east of State Highway 23 called South of Tierra Rejada Valley. 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 (i.e., 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, 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.

This subunit is occupied at the time of listing and remains occupied. Resting cysts were detected in recent soil analyses (Chris Dellith 2010, pers. comm.) and adult fairy shrimp were observed on April 7, 2011 (Judi Tamasi 2010, 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 Orcutt's grass (

Orcuttia californica

), which is an indicator of longer ponding duration. 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); it was formed primarily by tilting and subsidence along the Santa Rosa fault (Hecht

et al.

1998, p. 5). Given its geologic and hydrologic features and the associated wetland vegetation occurring 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 through “substantial disturbance and change in general area of the vernal pool” given 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.

(2011) did not survey this pool during their completion of a rangewide genetic analysis, this occurrence does represent 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 and biological features that are essential to the conservation of Riverside fairy shrimp, including appropriate soil series (Azule, Calleguas, and Linne soil series; 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 slopes) with scrub vegetation yielding substantial amounts of sediment that provide nutrients, minerals, and hydrology (Hecht

et al.

1998, p. 6). Additionally, because of adjacent urban development, altered hydrology, and potential for runoff, this vernal pool 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 regards 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 and may provide an important opportunity for colonization or re-colonization of unoccupied vernal pools and, thus, contribute to long-term conservation (and recovery) of the species (Gilpin and Soulé 1986, pp. 32-33; Lande 1999, p. 6). Research on genetic differentiation among fairy shrimp species across their known distributions have demonstrated that geographically distinct populations may or may not be genetically distinct, but that they have unique genetic characteristics allowing for 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). For these reasons, subunit 1a is uniquely situated and considered essential for recovery of the Riverside fairy shrimp.

The physical and 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 hydrologic 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. 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 proposed 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 proposed subunit is approximately 1.5 km (1 mi) southeast of Subunit 1a and east of State Highway 23. Subunit 1b consists of 31 ac (13 ha) of locally owned land and 417 ac (169 ha) of private land. We assume that Subunit 1b was not identified in the 1998 Recovery Plan (Appendix F) because at that time we were unable to confirm occupancy. To the best of our knowledge, this subunit has never been protocol surveyed to confirm presence or absence of Riverside fairy shrimp (Chris Dellith 2010, pers. comm.). This subunit, however, was proposed and designated as essential habitat in the previous 2005 proposed revised critical habitat rule because we considered it occupied (see discussion below) and because the necessary PCEs were present. Although we continue to presume Subunit 1b is occupied despite the absence of protocol survey results and have determined that the subunit contains the PCEs and therefore meets the definition of critical habitat under Section 3(5)(A)(i) of the Act, we are also proposing to designate Subunit 1b under Section 3(5)(A)(ii) of the Act. Even if Subunit 1b was not occupied at the time of listing, the subunit is essential for the conservation of the species due to its suitable habitat conditions, proximity to subunit 1a, and location at the northernmost extent of the species' range.

Subunit 1b is located approximately one mile to the south of Tierra Rejada Preserve (Subunit 1a), within the Tierra Rejada Valley watershed. Like Subunit 1a, this pool is one of the last representatives of what is believed to be a historic distribution of coastal terrace vernal pools common to the marine terraces and inland area of Ventura County prior to the 1950s. This subunit is considered occupied based on several factors which strongly suggest the likelihood of Riverside fairy shrimp occurrence. As discussed in the 2005 proposed rule (70 FR 19154, p. 19181) these are: (1) The important biotic and abiotic conditions (soil type, geology, morphology, local climate, topography, and plant associations, e.g. California Orcutt's grass) suggesting the presence of vernal pool ponding at appropriate season and for appropriate duration; (2) topographic features and ponding evidence based on aerial surveys confirming a ponding pool basin; (3) several large permanent and semi-permanent pools observed within the Subunit's local watershed; (4) proximity (less than 1 mi (1500 m)) to a known Riverside fairy shrimp occurrence and likely within the known dispersal distance expected for an invertebrate species with a resistant cyst stage; and (5) the determination that Subunit 1a and Subunit 1b are adjoined, based on fluvial and geomorphic evidence suggesting that the Tierra Rejada Valley river system once likely connected the two pools and would have provided the connectivity to disperse cysts between the two subunits.

Subunit 1b is proposed as revised critical habitat because we have determined it to be essential for the conservation of the species as it includes one or more pools capable of maintaining habitat function, genetic diversity, and species viability (Service 1998a, p. 65) for Riverside fairy shrimp at the northern limit of its current distribution, and it is near, and likely has connectivity with, a known occupied location of ecological and distributional significance. It is also identified as essential because best supporting evidence indicates the basin contains appropriate depth and ponding duration

This text is long and has been trimmed here. Open the source document for the complete record.