FWS has designated critical habitat pursuant to section 3 of the Endangered Species Act (ESA) for the federally endangered riverside fairy shrimp that encompasses 306 miles within Ventura, Orange, and San Diego Counties in California.  The riverside fairy shrimp is a freshwater crustacean that is found in vernal pools (a shallow depression that fills with rainwater and does not drain into the lower drainage section) in the coastal California area.  The shrimp is the second most primitive living crustacean and is the most recently discovered crustacean in California.

FWS has designated critical habitat pursuant to section 3 of the Endangered Species Act (ESA) for the federally endangered riverside fairy shrimp that encompasses 306 miles within Ventura, Orange, and San Diego Counties in California.  The riverside fairy shrimp is a freshwater crustacean that is found in vernal pools (a shallow depression that fills with rainwater and does not drain into the lower drainage section) in the coastal California area.  The shrimp is the second most primitive living crustacean and is the most recently discovered crustacean in California.

RULES and REGULATIONS

DEPARTMENT OF THE INTERIOR

Fish and Wildlife Service

50 CFR Part 17

RIN 1018--AT45

Endangered and Threatened Wildlife and Plants; Designation of Critical Habitat
for the Riverside Fairy Shrimp (Streptocephalus woottoni)

Tuesday, April 12, 2005

AGENCY: Fish and Wildlife Service, Interior.

*19154 ACTION: Final rule.

SUMMARY: We, the U.S. Fish and Wildlife Service (Service), designate critical habitat for the federally endangered Riverside fairy shrimp (Streptocephalus woottoni) pursuant to the Endangered Species Act of 1973, as amended (Act). The critical habitat designation encompasses approximately 306 acres (ac) (124 hectares (ha)) of land within Ventura, Orange, and San Diego counties, California.

DATES: This rule becomes effective on May 12, 2005.

ADDRESSES: Comments and materials received, as well as supporting documentation used in the preparation of this final rule, are available for public inspection, by appointment, during normal business hours, at the Carlsbad Fish and Wildlife Office, U.S. Fish and Wildlife Service, 6010 Hidden Valley Road, Carlsbad, California 92009 (telephone 760/431-9440). The final rule, economic analysis, and maps of the designation are also available via the Internet at http://carlsbad.fws.gov.

FOR FURTHER INFORMATION CONTACT: Jim Bartel, Field Supervisor, Carlsbad Fish and Wildlife Office, at the above address (telephone 760/431-9440; facsimile 760/431-9618).

SUPPLEMENTARY INFORMATION:

Designation of Critical Habitat Provides Little Additional Protection to Species

In 30 years of implementing the Act, the Service has found that the designation of statutory critical habitat provides little additional protection to most listed species, while consuming significant amounts of available conservation resources. The Service's present system for designating critical habitat has evolved since its original statutory prescription into a process that provides little real conservation benefit, is driven by litigation and the courts rather than biology, limits our ability to fully evaluate the science involved, consumes enormous agency resources, and imposes huge social and economic costs. The Service believes that additional agency discretion would allow our focus to return to those actions that provide the greatest benefit to the species most in need of protection.

Role of Critical Habitat in Actual Practice of Administering and Implementing the Act

While attention to and protection of habitat are paramount to successful conservation actions, we have consistently found that, in most circumstances, the designation of critical habitat is of little additional value for most listed species, yet it consumes large amounts of conservation resources. Sidle (1987) stated, "Because the Act can protect species with and without critical habitat designation, critical habitat designation may be redundant to the other consultation requirements of section 7." Currently, of the 1,253 listed species in the U.S. under the jurisdiction of the Service, only 470 species (38 percent) have designated critical habitat.
We address the habitat needs of all 1,244 listed species through conservation mechanisms such as listing, section 7 consultations, the section 4 recovery planning process, the section 9 protective prohibitions of unauthorized take, section 6 funding to the States, and the section 10 incidental take permit process. The Service believes that it is these measures that may make the difference between extinction and survival for many species.
We note, however, that the recent 9th Circuit judicial opinion in the case of Gifford Pinchot Task Force v. United States Fish and Wildlife Service has invalidated the Service's regulation defining destruction or adverse modification of critical habitat. We are currently reviewing the decision to determine what effect it may have on the outcome of consultations pursuant to section 7 of the Act.

Procedural and Resource Difficulties in Designating Critical Habitat

We have been inundated with lawsuits for our failure to designate critical habitat, and we face a growing number of lawsuits challenging critical habitat determinations once they are made. These lawsuits have subjected the Service to an ever-increasing series of court orders and court-approved settlement agreements, compliance with which now consumes nearly the entire listing program budget. This leaves the Service with little ability to prioritize its activities to direct scarce listing resources to the listing program actions with the most biologically urgent species conservation needs.
The consequence of the critical habitat litigation activity is that limited listing funds are used to defend active lawsuits, to respond to Notices of Intent (NOIs) to sue relative to critical habitat, and to comply with the growing number of adverse court orders. As a result, listing petition responses, the Service's own proposals to list critically imperiled species and final listing determinations on existing proposals are all significantly delayed.
The accelerated schedules of court ordered designations have left the Service with almost no ability to provide for adequate public participation or to ensure a defect-free rulemaking process before making decisions on listing and critical habitat proposals due to the risks associated with noncompliance with judicially-imposed deadlines. This in turn fosters a second round of litigation in which those who fear adverse impacts from critical habitat designations challenge those designations. The cycle of litigation appears endless, is very expensive, and in the final analysis provides relatively little additional protection to listed species.
The costs resulting from the designation include legal costs, the cost of preparation and publication of the designation, the analysis of the economic effects and the cost of requesting and responding to public comment, and in some cases the costs of compliance with the National Environmental Policy Act (NEPA). None of these costs result in any benefit to the species that is not already afforded by the protections of the Act enumerated earlier, and they directly reduce the funds available for direct and tangible conservation actions.

Background

Among the rarest animal species endemic (native) to Southern California is a tiny freshwater crustacean known as the Riverside fairy shrimp (Streptocephalus woottoni). Its distribution is highly restricted, with most of the known populations of the endangered Riverside fairy shrimp observed in vernal pools located in portions of a few counties and 50 miles (mi) (24 kilometers (km)) or less from the California coast, and ranging only approximately 125 mi (200 km) from its known northern limit (Ventura and Los Angeles counties) to its southern limit (Mexico border, San Diego County) within the U.S. (Eng et al. 1990; Simovich and Fugate 1992; Eriksen and Belk 1999; Service 2004 (69 FR 23024)). It does not occur in the nearby desert or *19155 mountain areas (Hathaway and Simovich 1996). It is also among the most recently discovered freshwater crustacean species in California, first identified in 1985 as a unique species (Eng et al. 1990) in the genus Streptocephalus (Baird 1852). With 63 species that occur worldwide (retrieved February 22, 2005, from the Integrated Taxonomic Information System on-line database, http://www.itis.usda.gov), Streptocephalus is the most species-rich genus within the aquatic crustacean order Anostraca, which comprises over 258 fairy shrimp species and 7 subspecies worldwide, organized into 21 genera (Belk et al. 1993). The fairy shrimp (Anostraca) are, except for one other group, the most primitive living crustaceans, or members of the sub-phylum Crustacea (Eriksen and Belk 1999). Among the 23 fairy shrimp (Anostracan) species that are found in California, 8 species are found only in this State, giving California the highest level of endemism for any comparable geographic region in North America (Eng et al. 1990), and resulting in the highest number of species occurring in a comparable land area in both North America and worldwide (Eriksen and Belk 1999). Despite this fact, the level of knowledge about many Anastrocans is relatively low due to the relative recentness of their discovery.
The Riverside fairy shrimp and vernal pool crustaceans in general, occupy the first consumer level in the food chain, and thus constitute a cornerstone in the food web. Fairy shrimp form an important food source for an array of aquatic and terrestrial species, from diving beetles, backswimmers (Notonectids), vernal pool tadpole shrimp (Branchinecta species), predaceous aquatic insects and their larvae, to waterfowl and shorebirds, and occasionally even for frogs, toads, and tadpoles (Eriksen and Belk 1999). Humans have also been known to consume fairy shrimp; tribes in California have been known to extensively consume dried Artemia, and Tripos is said to be used as food by some natives in Mexico (Pennak 1989).
The Riverside fairy shrimp, along with numerous sensitive and rare plant species, lives only in vernal pools, vernal ponds, swales, and ephemeral (short-lived) freshwater habitats. A vernal pool (including vernal pond and vernal lake) is defined as an area of shallow depression, usually underlain by some subsurface layer which prohibits drainage into the lower soil profile, thus causing water to collect during the rainy winter season (Holland 1976; Chetham 1976; Weitkamp et al. 1996), i.e., the depression is inundated for portions of the wet season, when temperatures are sufficient for plant growth (Keeley and Zedler 1998). Following a brief waterlogged period during the late wet season or early dry season, a vernal pool will eventually drain and dry out, followed by an extended period of extreme soil-drying conditions (Keeley and Zedler 1998; Rains et al. 2005). Swales are defined as shallow drainages that carry water seasonally. Central to the distinctive ecology of vernal pools is that they are vernal, or ephemeral, i.e., occurring only temporarily, during late winter and spring. The water in vernal pools stands sufficiently long to prohibit zonal vegetation growth (Holland 1976), yet not long enough to allow for colonization by fish species. Vernal pool habitat thus forms a unique type of ecosystem, different in character and species composition from the surrounding habitats (Service 2003; 68 FR46684), and being intermediate between marsh (nearly always wet) and most zonal vegetation communities (nearly always dry) (Holland 1976). In California, where extensive areas of vernal pool habitat have developed over long periods, unique species groups have evolved special adaptations to allow them to survive the unusual conditions of vernal pools. Vernal pools are often defined by their unique, often endemic, flora as well (Smith and Verrill 1998).
The Riverside fairy shrimp occupies, and is thus completely dependent upon, vernal pools to survive. A combination of physical and environmental factors allows for the annual formation and maintenance of their vernal pool habitat. Vernal pools form generally where there is a Mediterranean climate, i.e., a wet season during fall and winter, when rainfall exceeds evaporation and fills the pools, followed by a spring and summer dry season, when evaporation exceeds rainfall and the pools dry up. A typical vernal pool season is characterized by an inundation phase, an aquatic phase, a water-logged drying phase, and a dried-out phase (Keeley and Zedler 1998). Thus, the water regime (hydrologic system) is crucial to the formation and functioning of a healthy vernal pool ecosystem. Some pools fill entirely from direct precipitation (Hanes and Stromberg 1998), while others have a substantial watershed, including both surface, subsurface, and groundwater, flowing through the surrounding bedrock and soils that contributes to their water inputs (Rains et al. 2005).
Vernal pools can be a variety of shapes and sizes, from less than a square yard (0.8 square meters (m [FN2]), to 2.5 ac (1 ha) or more. They occur on gently sloping mesas above the primary drainages, or in valleys at the low end of a watershed (Bauder and McMillan 1998). Vernal pools may be fed or connected by low drainage pathways, or swales. The micro-relief of a vernal pool may be complex, and some are dotted with numerous rounded soil mounds (mima) (Scheffer 1947). Their typical patterning, visible from the air, has allowed a number of vernal pools to be mapped throughout California's Central Valley, on a 10-40 ac unit scale (Holland 1998; 2003, Service 2003). The landscape in which they occur is typically grassland, but vernal pools also occur in a variety of other habitat types (Service 2003).
A critical factor in the development of a vernal pool is the soil conditions of the landscape (an impermeable surface or subsurface layer) and a gently sloping topography (slope of 10 percent or less). Vernal pools form because the soil or sediment layer at or below the surface is nearly or completely impermeable to downward water seepage (Smith and Verrill 1998), and thus rainfall and water from the surrounding watershed becomes trapped above this layer. Soil types of the California vernal pools are volcanic flows, and hardpans and claypans, the latter of which have developed gradually over thousands of years, and can be a yard (1 m) or more thick. The unique assemblage of soils plays a critical role in nutrient cycling in vernal pool ecosystems. The soil types which underlie and surround the vernal pool therefore greatly influence the species composition of both plant and animals, as well as the hydrological functioning of the vernal pool (Hanes and Stromberg 1998; Hobson and Dahlgren 1998; Smith and Verrill 1998). Because water and precipitation flow through the soil to the pool, the chemistry of the soils underlying a vernal pool, and in the surrounding upslope areas, is directly linked to the chemistry of the vernal pool's water, i.e., on its alkalinity, pH, oxidation and reduction processes, dissolved salts and gasses, ion concentrations, mineral richness, and organic material. Thus, soil chemistry likely has a tremendous impact on aquatic invertebrate endemism (cf. Hobson and Dahlgren 1998). The distinct seasonality of vernal pools results in alternating conditions of reduction and oxidation within the soil profile, creating edaphic (soil-influenced) controls that may provide a refuge for competition-sensitive plant and animal species (Hobson and Dahlgren 1998). The length of ponding may also be affected by variables like *19156 consistency of soil, depth of soil to impervious layer (e.g., duripan, claypan), type and thickness of the impervious layer, and local climatic factors (e.g., rainfall abundance and regularity, evaporation rates; Helm 1998).
Because of the transportation of water, soil, minerals and nutrients over the landscape into vernal pools, the upland, or upslope areas associated with vernal pools are an important source of these for vernal pool organisms (Wetzel 1975). Since vernal pools are mostly rain-fed, they tend to have low nutrient levels (Keeley and Zedler 1998). In fact, most of the nutrients that vernal pool crustaceans derive from their vernal pool habitat come from the detritus (decaying organic matter) that washes into pools from the adjacent upslope areas; these nutrients provide the foundation for the food chain in the vernal pool aquatic community (Eriksen and Belk 1999), of which the fairy shrimp fauna constitutes an important component.
Typical to vernal pools are their dramatic fluctuations in local environmental conditions. The water, generally unbuffered, fluctuates greatly on a daily basis in pH, and concentrations of ions and dissolved gasses (oxygen and carbon dioxide), due to varying daily evaporation (Keeley and Zedler 1998). On a larger time-scale, there is extensive monthly and annual variation in the duration and extent of ponding of vernal pools, some pools not filling at all in some years, as the timing and amount of annual rainfall in California varies widely. Because of the unique and ephemeral nature of vernal pool habitat, and the adaptations of its plant and animal species, vernal pools are rich in species composition and contain a large number of highly specialized, native species that are found nowhere else in the region (endemic) (Holland and Jain 1978; Simovich 1998). Vernal pool habitats yield the highest number and species richness of endemics (native species) in comparison to other wetland types (Helm 1998).

Riverside Fairy Shrimp (Streptocephalus woottoni)

The Riverside fairy shrimp is a small (0.56-0.92 inches (in) (14-23 millimeters (mm))), slender Anostracan that has large stalked compound eyes and a delicate, elongate body with 11 pairs of phyllopods, or swimming appendages, which also function as gills (Eng et al. 1990; Eriksen and Belk 1999). Using their phyllopods in a complex, wavelike motion from front to back, they swim gracefully upside-down. As they swim about, fairy shrimp use these same appendages to filter-feed from the water column, allowing them to non- selectively consume algae, bacteria, protozoa, rotifers and bits of detritus (Eng et al. 1990; Eriksen and Belk 1999). Note that nothing is known specifically about the Riverside fairy shrimp's food resource requirements (Simovich and Ripley, pers. comm., May 25, 2004).
Riverside fairy shrimp are distinguished from other fairy shrimp species primarily by the second pair of antennae on the adult male, which are enlarged for grasping the female during copulation (Pennak 1989; Eriksen and Belk 1999; Service 2003). Both males and females are generally off-white in color, with orange pigment in their tail appendages (cercopods) and sometimes along the edges of the phyllopods (although some females have been observed to be entirely bright red-orange) (Eriksen and Belk 1999). The females, when mature, can be identified by their brood pouch, the elongate, ventral protruding egg sac immediately behind the phyllopods (Eriksen and Belk 1999).
Relative to most other fairy shrimp species, the Riverside fairy shrimp is a rare species with a highly restricted distribution (Hathaway and Simovich 1996). They are found only in a few pools at lower elevations in the Southern California coastal range that are inundated for a longer duration and generally deeper (greater than 12 in or 30 centimeters (cm)) than pools that support San Diego fairy shrimp (Branchinecta sandiegonensis) (Hathaway and Simovich 1996). Some of these pools may have been artificially deepened with berms (i.e., cattle tanks and road embankments) (Hathaway and Simovich 1996). The two species are known to co-occur in a few deep pools; however they generally do not co-exist, as adults of the Riverside fairy shrimp emerge later in the season than San Diego fairy shrimp (Simovich and Fugate 1992; Hathaway and Simovich 1996).
After copulation, the males of some fairy shrimp species die within a few hours (Pennak 1989). When the eggs are fertilized in the female's pouch, they become coated (encysted) with a protein layer that develops into a thick, usually multilayered shell (Eriksen and Belk 1999). When the egg enters the late stage of embryonic development, all growth then ceases, and the egg enters into a dormant stage, or diapause (Drinkwater and Clegg 1991; Eriksen and Belk 1999). The female then either ejects the cysts to fall to the pool bottom, or, if she survives for an extended period, continues to move successive clutches of eggs into her brood pouch. If the vernal pool persists for several weeks to a few months, fairy shrimp may have multiple hatches in a single season (Eriksen and Belk 1999). Cysts can also remain in the brood pouch until the female dies and sinks to the pool bottom (Eriksen and Belk 1999). However, females of some fairy shrimp species can, in the presence of male adults during the wet period, eject thin-shelled cysts that hatch immediately without becoming dormant ("summer eggs"), thus allowing for multiple generations during a single wet season, while the thick-shelled, dormant ("winter") eggs are deposited in the absence of males in the population (Pennak 1989). By the time the pool dries out, the numbers of dormant cysts within each pool basin can reach tens of thousands to millions, depending on pool size, volume, and depth (Belk 1998).
Mature cysts become fully desiccated (dried) after their pool has evaporated, and due to their protective coating, they can withstand extreme environmental conditions (Pennak 1989; Eriksen and Belk 1999). For example, they can survive subjection to physical extremes, such as near-boiling temperatures, months of freezing (Carlisle 1968), fire (Wells et al. 1997), or near-vacuum conditions for 10 years without damage to the embryo (Clegg 1967). These adaptations allow fairy shrimp cysts to survive extreme environmental fluctuations, and hatch only when conditions are favorable, after remaining dormant for as much as decades, possibly centuries (Belk 1998). In one closely related fairy shrimp, Streptocephalus sealii, cysts were brought to hatch after 25 years of storage in the lab (Belk 1998). Further, because the wall of the cyst can even resist damage by stomach enzymes (Horne 1966), the cyst can pass through the digestive tract of animals without harm, thus allowing for one possible mechanism of cyst dispersal. There are several mechanisms for cyst dispersal, and thus fairy shrimp dispersal, to other habitats. Historically, large-scale flooding from heavy winter and spring rains has been a primary dispersal mechanism, but other major mechanisms include dispersal by migratory birds (i.e., wading birds, shorebirds, waterfowl), ungulates (i.e., cattle, buffalo, deer), and possibly amphibians (i.e., salamanders, frogs) and humans (Eriksen and Belk 1999). These animals either carry cyst-containing mud on their bodies incidentally from pool to pool, or the cysts are ingested and are passed through the gut at another location. *19157 Wind, although less probable, may also be a dispersal agent (Eriksen and Belk 1999).
Although cysts can remain dormant within the pool for decades, they can also hatch about a week after a rain-fill, due to their advanced stage of embryonic development (Pennak 1989; Hathaway and Simovich 1996). However, when a dry vernal pool is once again inundated with water, only a fraction of the dormant cysts in the pool will hatch. Simovich and Hathaway (1997) found that when Riverside fairy shrimp cysts were hydrated once, only 0.18 percent hatched, and after three successive hydration periods, the cumulative total increased to only 2.8 percent. This is among the lowest hatching rates, or prolonged diapause, yet recorded among fairy shrimp species (Simovich and Hathaway 1997). They suggested that the prolonged diapause of so many cysts was an adaptation to the variable nature of local rainfall patterns, as pools at times fill only partially and dry quickly--before the fairy shrimp are able to reach maturity and reproduce. Thus, in such an environment with unpredictable filling events, it benefits the individual to have offspring in prolonged diapause, such that not all hatch after just one hydration (Simovich and Hathaway 1997). In San Diego County, only approximately 28 percent of all filling events recorded over 13 years lasted at least a 17-day period, the minimum length of time needed by the San Diego fairy shrimp to develop to first reproduction (and insufficient time for the Riverside fairy shrimp); this period corresponded to the 28-percent hatching rate for their cysts found in the lab (Philippi 2001). This strategy of prolonged diapause is possibly a risk-spreading ("bet-hedging") adaptation to the unpredictability of their environment (Simovich and Hathaway 1997; Philippi 2001).
In addition to their low hatching percentage, the cysts of the Riverside fairy shrimp also take longer to hatch after inundation, relative to other species (Hathaway and Simovich 1996). The time from hydration to the hatching of Riverside fairy shrimp cysts took between 12 to 25 days in the lab at varying temperatures, with the most rapid hatching occurring when temperatures were fluctuating at 41-59 degrees Fahrenheit ((F) 5-15 degrees Celsius (C)). San Diego fairy shrimp, in comparison, can hatch after only 3 days (Hathaway and Simovich 1996). The greatest number of Riverside fairy shrimp cysts hatching in the lab, however, was achieved at 50 degrees F (10 degrees C) (Hathaway and Simovich 1996). Their development or maturation rate is also slow, and individuals are relatively long-lived (Hathaway and Simovich 1996), as is typical of obligate deep pool species. The developmental time to maturity for the Riverside fairy shrimp was found to be 7-8 weeks, far longer than to the 7- 10 day period of the San Diego fairy shrimp.
It is not surprising, therefore, that the Riverside fairy shrimp also lives much longer (2.5 to over 4 months) than the San Diego fairy shrimp (4-6 weeks) (Hathaway and Simovich 1996). Thus, the minimum period of inundation, or pool duration, that the Riverside fairy shrimp need in order to hatch and reach maturity is 9 to 10 weeks (Gonzalez et al. 1996; Hathaway and Simovich 1996). Thus, the association of the Riverside fairy shrimp with large, deep vernal pools that pond continuously for many months may perhaps be explained by its long period of maturity and longevity (cf. Helm 1998). Because of their slow hatch and growth, the Riverside fairy shrimp occur therefore much later in the season than other fairy shrimp species (cf. Hathaway and Simovich 1996).
The vernal pools that Riverside fairy shrimp are found in typically have water with a relatively neutral pH (approximately 7), low to moderate salinity, and low to moderate levels of total dissolved solids (Gonzalez et al. 1996; Eriksen and Belk 1999). One laboratory study conducted on the tolerance of Riverside fairy shrimp to variations in water chemistry found that they tolerate an 8-hour exposure to pH levels ranging from 8 to 10.5, with little effect (Gonzalez et al. 1996). Generally, in vernal pools where Riverside fairy shrimp occur, the external ion concentrations (Na+) averaged 0.73 mmol/l [FN3] (Gonzalez et al. 1996). Although the species was also able to maintain its internal levels of salt concentration fairly constantly over a wide range of external concentrations (0.5-60 mmol/l [FN3]), it was sensitive to the extremes, with 100-percent mortality occurring at 100 mmol/l [FN3] (Gonzalez et al. 1996). Levels of alkalinity in the vernal pool are affected by the surrounding soil type and hydrological regime of the immediate adjacent upland watershed; in four vernal pools, alkalinity averaged 41 mg/l [FN3] (Gonzalez et al. 1996). In the laboratory, Riverside fairy shrimp were found to tolerate a wide range of alkalinities (0-600 mg/l [FN3]), but none could survive levels above 800 mg/l [FN3] (Gonzalez et al. 1996). Importantly, studies show that the Riverside fairy shrimp is sensitive to water temperature; with their hatching occurring a longer time after inundation (25 days) and fewer hatching (1-3 percent) at steady higher temperature of 77 degrees F (25 degrees C), than at cooler temperatures (i.e., 7 days hatching time at 59-77 degrees F (15-25 degrees C); over 10 percent hatching at 50 degrees F (10 degrees C) (Gonzalez et al. 1996).
The upslope areas surrounding vernal pools are critical to the functioning of the vernal pool and thus to the survival of the Riverside fairy shrimp. The surrounding upslope areas provide the vernal pool with the appropriate annual and season temporality and volume of hydrological flow. With that flow follows the necessary nutrients, salts and minerals from the soil and bedrock that all influence the pool's water volume, the duration of ponding, and the complete chemistry, mineral and nutrient contents of the water itself. Therefore, Riverside fairy shrimp, together with its cohabitating vernal pool flora and fauna, is as dependent upon the upland areas for survival and reproduction as it is upon the pool it occupies.
Urban and water development, flood control, and highway and utility projects, as well as conversion of wild lands to agricultural use, have eliminated or degraded vernal pools and/or their watersheds in southern California (Jones and Stokes Associates 1987). Changes in hydrologic patterns, certain military activities, unauthorized fills, overgrazing, and off-road vehicle use also may imperil this aquatic habitat and the Riverside fairy shrimp. The flora and fauna in vernal pools or swales can change if the hydrologic regime is altered (Bauder 1986). Anthropogenic (human-origin) activities that reduce the extent of the watershed or that alter runoff patterns (i.e., amounts and seasonal distribution of water) may eliminate the Riverside fairy shrimp, reduce population sizes or reproductive success, or shift the location of sites inhabited by this species. The introduction of non-native plant species, competition with invading species, trash dumping, fire, and fire suppression activities were some of the reasons for listing the Riverside fairy shrimp as endangered on August 3, 1993 (58 FR 41384). Because of these threats, we anticipate that intensive long-term monitoring and management will be needed to conserve this species. Historically, vernal pool soils covered approximately 500 km [FN2] (200 mi [FN2] of San Diego County (Bauder and McMillan 1998). The greatest recent losses of vernal pool habitat in San Diego County have occurred in Mira Mesa, Rancho Peñasquitos, and Kearny Mesa, which together account for 73 percent of all the pools destroyed in the region during the *19158 7-year period between 1979 and 1986 (Keeler-Wolf et al. 1995). Other substantial losses have occurred in the Otay Mesa area, where over 40 percent of the vernal pools were destroyed between 1979 and 1990. Similar to San Diego County, vernal pool habitat was once extensive on the coastal plain of Los Angeles and Orange counties. Unfortunately, there has been a near-total loss of vernal pool habitat in these areas (Ferren and Pritchett 1988; Keeler-Wolf et al. 1995; Mattoni and Longcore 1997; Service 1998). Significant losses of vernal pools supporting this species have also occurred in Riverside County.
Adequately quantifying occurrence and distribution of the Riverside fairy shrimp can be difficult due to a number of factors. Firstly, Riverside fairy shrimp are restricted to a narrow geographic region, to certain pool types, and also temporally, as they emerge later in the season than other fairy shrimp species (Hathaway and Simovich 1996). Thus, surveys conducted to also encounter earlier-occurring species may actually miss the Riverside fairy shrimp as they may still be so small (in the juvenile stage) that they pass through the mesh of the collecting nets (Eriksen and Belk 1999). Secondly, surveys may also miss collecting adults simply due to their low hatching percent (as few as 0.18 percent; Simovich and Hathaway 1997), which may result in either a very low population level, or to none being detected in a particular year, when viable cysts are actually present. Further, only males can be identified to the species level with certainty (Eriksen and Belk 1999), and cysts can only be identified to the genus level. To add to the difficulty, vernal pools are generally too small to appear on topographic maps (Holland 1976), not all vernal pools fill each year, or fill long enough for hatching (i.e., discovery) of the Riverside fairy shrimp. Some estimates for San Diego County show that over a period of 13 years, only about 28 percent of the pool-filling events lasted 17 days or longer (Philippi 2001).
For a more detailed discussion about the Riverside fairy shrimp's physical description, ecology, range, status and distribution, and a discussion of factors affecting this species, please refer to the following documents from the Federal Register: The final rule listing the species as threatened (58 FR 41384), published on August 3, 1993, the previous final rule to designate critical habitat (66 FR 29384), published on May 30, 2001, and our latest proposed rule to designate critical habitat (69 FR 23024), published on April 27, 2004.

Previous Federal Actions

For more information on previous Federal actions concerning the Riverside fairy shrimp, please refer to the proposed rule to designate critical habitat for the Riverside fairy shrimp (69 FR 23024) and the notice of availability for the draft economic analysis (DEA) and reopening of the public comment period for the proposed designation of critical habitat for the Riverside fairy shrimp published in the Federal Register (October 19, 2004, 69 FR 61461).

Summary of Comments and Recommendations

We requested written comments from the public on the proposed designation of critical habitat for the Riverside fairy shrimp in the proposed rule (69 FR 23024). We also contacted and invited the appropriate Federal, State, and local agencies, as well as scientific organizations and other interested parties to comment on the proposed rule. In the notice of availability of the draft economic analysis for the proposed designation of critical habitat (69 FR 61461), we again solicited comments from the public on both the draft economic analysis and the proposed rule. All comments and new information received during the two comment periods were incorporated into the final rule as appropriate.
During the first comment period, open from April 27, 2004, to May 27, 2004, we received 21 letters containing 143 comments directly addressing the proposed critical habitat designation from 6 peer reviewers, 5 Federal agencies, 2 county and local agencies, 1 group, 4 businesses, 1 city, 1 water district, 1 individual, and 1 law firm writing on behalf of 2 groups and 2 transportation agencies.
During the second comment period, open from October 19, 2004, to November 18, 2004, we received 11 letters containing 148 comments directly addressing the proposed critical habitat designation and the draft economic analysis. The letters came from 4 Federal agencies, 3 groups, 2 businesses, 1 law firm on behalf of 2 businesses, and 1 law firm on behalf of 2 groups and 2 transportation agencies.
Of a total 32 letters received, 4 supported the designation of critical habitat for the Riverside fairy shrimp, 2 opposed the designation, 18 letters suggested reducing the area of designation, and 4 letters suggested expanding the area. Two letters were requests for an extension of the comment submission period, but did not express support or opposition to the proposed critical habitat designation. Comments received were grouped into six general issues specifically relating to the proposed critical habitat designation for the Riverside fairy shrimp, and are addressed in the following summary and incorporated into the final rule as appropriate. We did not receive any requests for a public hearing. We have reviewed all comments received from the peer reviewers and the public for substantive issues and new information regarding critical habitat for the Riverside fairy shrimp, and have incorporated them into the final rule as appropriate. These are addressed below in the following summary.

Peer Review

In accordance with our policy published on July 1, 1994 (59 FR 34270), to solicit opinions from at least three experts, we solicited the expert opinions of 7 knowledgeable individuals with significant scientific expertise that included familiarity with the Riverside fairy shrimp, the geographic region in which the species occurs, and conservation biology principles. We received responses from six of the peer reviewers. The peer reviewers were generally supportive of the designation of critical habitat, but strongly endorsed the approach that the appropriate management unit was the vernal pool complex (not single pools) together with their immediately surrounding upland watershed. They emphasized the importance of providing conservation protection of pool complexes to ensure the survival of the Riverside fairy shrimp in perpetuity, and of identifying and preserving all remaining populations of Riverside fairy shrimp, including those within conservation-managed areas. Three peer reviewers also gave specific comments on our decision to exclude certain lands from critical habitat based on Habitat Conservation Plans (HCPs) and Integrated Natural Resources Management Plans (INRMPs).

Comments From Peer Reviewers

1. Peer Reviewer Comment: Most of the reviewers stressed the importance of providing or increasing Federal protection to the Riverside fairy shrimp and their vernal pool habitat, since conservation measures are needed to protect them. Over 95 percent of vernal pools in Southern California have been extirpated (destroyed), and the remaining vernal pools and the species that inhabit them are currently under threat of elimination from both private and public organizations. Additionally, vernal pools are valuable in that they are ecologically unique, while also *19159 providing valuable ecosystem functions. Vernal pool complexes act as hydrologic "sponges," buffering against drought and flooding. Large-scale alterations or developments within the local watershed of vernal pool complexes would affect the local hydrology dramatically and, from an engineering and public works perspective, can lead to increases in the need for management of unnaturally large amounts of runoff following a rainstorm. Thus, vernal pools have not received adequate recognition in the rule for the benefits (ecological services) they provide. For their long-term survival, vernal pools must be adequately protected; the designation of critical habitat does not seem to provide adequate conservation measures to serve this purpose.
Our Response: Section 4 of the Act requires us to designate critical habitat to the maximum extent prudent and determinable, which we have done, based upon the best data available to us at this time. We concur that additional, long-term conservation measures are needed to protect the Riverside fairy shrimp and its habitat, and additional data is needed on locations of their occurrence.
In developing our final designation of critical habitat for the Riverside fairy shrimp, we used the best scientific and commercial data available to identify those areas that contain essential occurrences of Riverside fairy shrimp and/or are defined by the physical and biological features essential to their conservation. We used a number of criteria in defining critical habitat, including but not limited to the known species occurrence (known at the time of listing, as well as discovered subsequently) and distribution data, habitat types, presence of PCE's, degree of habitat fragmentation, soil and landform relationships, connectivity and dispersal factors, and conservation biology principles. We did not include all vernal pool landscapes within the Riverside fairy shrimp's range although surveys in these areas may result in the detection of other occurrences in the future. If significant information becomes available indicating that areas outside of our designation are essential to the conservation of the Riverside fairy shrimp, we can, under the Act, revise critical habitat in the future.
2. Peer Reviewer Comment: While the Service's proposed designation of critical habitat for the Riverside fairy shrimp in southern California was supported, reviewers stated it is questionable whether 5,795 acres in the proposed rule is "enough" critical habitat for the conservation of the remaining Riverside fairy shrimp populations. Firstly, reviewers strongly emphasized the importance of considering the vernal pool complex and the surrounding watershed as the management unit for this species. The unique physiochemical requirements of the Riverside fairy shrimp make it particularly vulnerable to changes in hydrology. Further, other vernal pool species have their own unique ecological requirements in terms of soil, hydrology, etc. Protecting and maintaining entire vernal pool complexes and their surrounding watershed as a functioning unit will benefit the Riverside fairy shrimp and the other endangered species that live in these habitats. If the landscape at a site is changed sufficiently to alter the hydrology of individual vernal pools, then the species in them will eventually go extinct, regardless of whether the pools are disturbed or not. Secondly, some vernal pools excluded from the designation, but set aside for conservation or mitigation, do not have sufficient protection in the surrounding watershed, and thus become ecologically useless. The exclusion of military lands from the final designation is particularly troubling in this regard, because there are no guarantees that the watershed, let alone pools with Riverside fairy shrimp in them, will be adequately protected.
Our Response: Firstly, we note the support of our critical habitat designation, and concur with the reviewers on the importance of considering the vernal pool complexes together with their immediately surrounding upslope areas as the management unit (see Background and Primary Constituent Elements sections below). We have used this approach in our analyses when finalizing our critical habitat designation for the Riverside fairy shrimp, and have, wherever possible, included the upslope areas surrounding the pools. Secondly, for approved, legally operative HCPs that include areas eligible for designation as critical habitat and that specifically address the Riverside fairy shrimp and provide for its long-term conservation, we believe that the benefits of excluding those HCPs will outweigh the benefits of including them. Thirdly, we received requests from three military bases to exclude lands owned or managed by the Department of Defense for military purposes because the designation would increase the costs and regulatory requirements, hamper the military's ability to carry out their national security objectives, or because there is an INRMP in place that provides a benefit to the Riverside fairy shrimp. These installations have either been excluded from final designated critical habitat pursuant to section 4(b)(2) of the Act, or exempted according to section 4(a)(3) of the Act. Please refer to the sections Relationship of Critical Habitat to Approved Habitat Conservation Plans and Relationship of Critical Habitat to Department of Defense Lands below in this final rule for detailed discussions of our rationale for exclusions and exemptions.
3. Peer Reviewer Comment: Any consideration of whether the Riverside fairy shrimp will persist indefinitely (i.e., avoid extinction due to anthropogenic causes) would require a quantification of the Riverside fairy shrimp's (a) dispersal biology, (b) adaptation to local physiochemical conditions, and (c) adaptation to hydrologic uncertainties (via reliance on an egg bank). In terms of the hydrology of the vernal pool habitat, quantifiable data is needed on (d) the historic environmental variation and (e) the predicted future environmental variation. However, only rudimentary data are available on any of these topics, with the possible exception of (d). Therefore, it would be wise to err on the side of caution and offer maximal protection to all remaining populations of this species.
Our Response: We concur that more detailed studies are needed on most aspects of the Riverside fairy shrimp's biology. In this rule, we address the issue of designating critical habitat areas, areas containing the necessary primary constituent elements (PCEs) that are essential to the conservation of the Riverside fairy shrimp. For this purpose, we used the best scientific and commercial information that were available to us and based our analyses upon areas either containing with existing populations of Riverside fairy shrimp or containing features essential for the conservation of the species using the vernal pool complex together with the immediately surrounding upslope areas as our management unit. To assist us in developing this final rule, we also opened two comment periods to obtain as much additional, currently available information as possible.
4. Peer Reviewer Comment: One reviewer suggested that the designation of critical habitat is no longer effective as a means to protect the species and its habitat, as funds that are needed to achieve that goal are spent instead on litigation. Rather, a new method is needed to accomplish this goal, such that the Riverside fairy shrimp and its habitat are actually preserved (rather than designated, then litigated).
*19160 Our Response: We concur that the Service's present system for designating critical habitat has evolved into a process that is often driven by litigation and the courts, and thus consumes enormous agency resources. The Service believes that additional agency discretion would allow our focus to return to those actions that provide the greatest benefit to the species most in need of protection. Pursuant to section 4 of the Act, however, the Secretary shall, to the maximum extent prudent and determinable, designate any habitat which is then considered to be critical habitat for listed endangered or threatened species. Alternative or additional methods for accomplishing more effective conservation of the Riverside fairy shrimp are discussed in the Recovery Plan, Multiple Species Habitat Conservation Plans (MSHCPs), Natural Community Conservation Programs (NCCPs), and other conservation plans. These plans address the survival and recovery of this species, and we expect they will be in a continual process of improvement and increased efficiency with time.
5. Peer Reviewer Comment: Several reviewers disagreed with the Service's statement in the rule (see SUPPLEMENTARY INFORMATION above) that designation of critical habitat provides little additional protection to species, and believed this should be amended or omitted from the rule, as it is self-contradictory. Although designating critical habitat does not in itself protect any habitat, the biggest advantage of critical habitat designation is the ability to address the "cumulative effects" of many small impacts to the habitat. Impacts to a single location are not likely to drive the species to extinction, but the effects of impacts at many individual locations may, in total, create a substantial risk for species extinction. Designating critical habitat establishes a core, reducing the potential for individual small impacts to be allowed to drive the species to extinction.
Our Response: While we concur that critical habitat designation can provide some level of species protection by addressing cumulative effects of numerous impacts to the habitat in certain circumstances, this can only be provided if there is Federal nexus for those agencies planning actions that may impact the designated habitat.
6. Peer Reviewer Comment: The Service's statement in the rule, that the exclusion of HCPs offers "unhindered, continued ability to seek new partnerships with future HCP participants" (see Relationship of Critical Habitat to Approved Habitat Conservation Plans) should be amended in the rule as it is illogical and self-contradictory. Not designating critical habitat within HCPs in order to allow seeking new partnerships implies that the new partnerships would be compromised if they were actually forced to protect Riverside fairy shrimp habitat, which should be one goal of any "partnership."
Our Response: Both HCPs and critical habitat designations are designed to provide conservation measures to protect the Riverside fairy shrimp. The advantage of seeking new conservation partnerships, through HCPs or other means, is that they can offer active management and other conservation measures for the habitat on a full-time and predictable basis, while a critical habitat designation only prevents adverse modification of the habitat where there is a Federal nexus to the modifying activity, a far lesser level of protection. It is our experience that landowners generally react very negatively to having their property designated as critical habitat, and that this is then a strong disincentive for them to cooperate in conservation of the species in question. HCPs offer conservation of covered species whether or not the area is designated as critical habitat (for details see the section Relationship of Critical Habitat to Approved Habitat Conservation Plans).
7. Peer Reviewer Comment: The proposed rule appears to find ways to exclude most of the "potential" critical habitat in Riverside and San Diego counties. Except for areas on March Air Reserve Base, the proposed Map Unit 3 for Riverside County excludes all critical habitat, and specifically that on the Santa Rosa Plateau, based on the speculative assertion that the proposed Western Riverside County Multiple Species Habitat Conservation Plan (MSHCP) will adequately protect the Riverside fairy shrimp. What is the benefit of excluding critical habitat for the Riverside fairy shrimp on the Santa Rosa Plateau? Any scientifically defensible HCP must protect nearly all of the Santa Rosa Plateau.
Our Response: HCPs and their Implementing Agreements include management measures and protections designed to protect, restore, monitor, manage, and enhance the habitat to benefit the conservation of the species covered in the plans. The Western Riverside County MSHCP, which has now been finalized, seeks to accomplish these goals for the Riverside fairy shrimp through the implementation of species-specific conservation objectives.
In our analyses, the benefits of excluding critical habitat areas covered by the Western Riverside County MSHCP outweigh the benefits of inclusion. Of the conservation measures this plan identifies for the Riverside fairy shrimp, the first objective is to include within its Conservation Area at least five Core Areas of vernal pools (or vernal pool complexes) and their watersheds; these areas contain five known key Riverside fairy shrimp populations. Core Areas include the Santa Rosa Plateau Ecological Reserve (17,188 acres), Skunk Hollow (156 acres), Murrieta (1,292 acres) and Lake Elsinore back basin (3,180 acres). Within the key population areas, approximately 5,868 acres (33 percent) of potential vernal pool and playa habitat and suitable soils habitat land coverages would be located outside the MSHCP Conservation Area. Any Riverside fairy shrimp present within this area would be subject to incidental take under the guidelines implemented as part of this Plan. Each Reserve Manager responsible for a Core Area containing soils identified as supporting the Riverside fairy shrimp (e.g., the Santa Rosa Plateau Ecological Reserve) shall evaluate their Core Area for the presence of historic or vestigial vernal pools. A program to enhance these areas will be undertaken. Within the MSHCP Conservation Area, that pond water seasonally will be identified and monitored for the presence of fairy shrimp. Reserve managers will ensure habitat support functions within the MSHCP Conservation Area by maintaining and/or preserving watersheds of conserved known or future vernal pools or depressions. Particular management emphasis will be given to disking, illegal dumping and maintaining hydrology (MSHCP Final Documents, Vol. 1--The Plan, June 17, 2003). See Western Riverside County Multiple Species Habitat Conservation Plan in the section Relationship of Critical Habitat to Approved Habitat Conservation Plans below for more details.
8. Peer Reviewer Comment: The Service's assumption that the existence of an HCP automatically affords protection to the Riverside fairy shrimp within the covered area is questionable. In the development of the San Diego Multiple Species Conservation Plan (MSCP)/HCP, vernal pools were explicitly excluded from its intended coverage, because at the time, those areas covered by the conservation plans were regulated as wetlands by the Environmental Protection Agency. As San Diego County does not have a good record of enduring protection of vernal pools, it is important, from a scientific and land-management perspective, to *19161 have an explicit analysis of what (if any) Riverside fairy shrimp populations and their habitats are actually covered in the designated protected areas of the HCP, before exclusion of any areas are made.
Our Response: Vernal pool habitats that support the Riverside fairy shrimp that were considered essential but excluded from critical habitat were included on our website for public review and comment. Of the 1,183 ac (479 ha) of mapped vernal pool habitat within the MSCP planning area, over 847 ac (343 ha) occur within the planning area. The Service has completed a Biological Opinion (June 1997) on the San Diego MSCP, and found that the Plan meets the standards set forth in 50 CFR 17.32(b)(2), and has issued an incidental take permit to the City of San Diego for the 85 species covered in the plan, including the Riverside fairy shrimp. The permit action does not, however, authorize impacts to wetlands or wetland communities; the MSCP assumes a policy of "no net loss" of vernal pools. The permit requires that impacts to vernal pools be avoided; unavoidable impacts will be minimized to the maximum extent practicable and mitigated at a 2:1 or 4:1 ratio to prevent any net loss of vernal pool function and value. In addition to conserving existing vernal pool habitat, the Multiple Habitat Planning Area is expected to conserve 7,745 ac (3,134 ha) of undeveloped areas with clay soils and clay hardpan, and implement management and monitoring measures for vernal pools within the area. In the Biological Opinion issues, the Service has specifically addressed the Riverside fairy shrimp, and emphasized the conservation of the hydrological processes needed for vernal pool functioning. Pursuant to section 4(b)(2), we have excluded lands within legally operative HCPs, including the San Diego MSCP, that address the conservation needs of the Riverside fairy shrimp, if the plans provide assurances that the conservation measures outlined will be implemented and effective. Please see Relationship of Critical Habitat to Approved Habitat Conservation Plans section of the rule below.
9. Peer Reviewer Comment: Several reviewers stated that the proposed critical habitat designation does not go far enough to provide for the protection of the Riverside fairy shrimp, because significant portions of the species' range were excluded from critical habitat protection. These areas include Department of Defense lands and MSCP/HCP lands. The Riverside fairy shrimp populations in these areas, particularly those on Department of Defense land, are not protected and are either being lost at present, or vulnerable to loss due to a number of sources and activities, including military maneuvers, crushing by vehicles and toxic poisoning from vehicles or ordnances. In fact, lands under the jurisdiction of HCPs, MSCPs, and the Department of Defense have continued to lose populations of San Diego fairy shrimp (e.g., Cousin's pool, Marine Corps Air Station Miramar) and restoration/creation efforts have thus far not succeeded, and this will likely happen with the Riverside fairy shrimp unless adequate protection is provided for the existing populations. For example, in San Diego County, 66 of 67 vernal pools occupied by the federally endangered San Diego fairy shrimp (Branchinecta sandiegonensis) have been recently lost in Mira Mesa, an area covered by the San Diego County MSCP. Thus, the benefits of exclusion do not outweigh the benefits of inclusion due to the significantly increased threat to the species survival that exclusion of critical habitat poses to the species.
Our Response: We do not agree with the peer reviewer that excluding critical habitat on lands covered by an HCP or INRMP poses a "significantly increased threat to the species survival." Please refer to the responses to Peer Reviewer Comments 7 and 8 above, and the sections Relationship of Critical Habitat to Department of Defense Lands and Relationship of Critical Habitat to Approved Habitat Conservation Plans below.
10. Peer Reviewer Comment: The small amounts of habitat designated as critical habitat may be questionable. The strip along the international border in the proposed rule (Map Sub-unit 5B, southwestern Otay Mesa) appears to be mitigation or restoration from the Border Infrastructure System. It is not clear that the current hydroperiods are comparable to the pre-impact hydroperiods. Further, it appears that the Department of Homeland Defense drives vehicles through the pools with impunity, without the need for permitted take from the Service. Habitat of such dubious condition is not a suitable substitute for the excluded (but intact) habitat surrounding the proposed areas on western Otay Mesa (critical habitat Map Sub-units 5A, 5B).
Our Response: Please refer to the response to Comment 4-1 below.
11. Peer Reviewer Comment: Areas of critical habitat that have been excluded in the proposed rule are under a high level of threat, and local populations of Riverside fairy shrimp in those areas thus face considerable risk of being extirpated, as has happened with populations of the San Diego fairy shrimp. Currently, there is not enough scientific information on the population genetic structure or life history of the Riverside fairy shrimp to be able to predict the consequences of population losses. Without such data, it is not possible to identify the areas of highest genetic variability, population sources and sinks, levels of gene flow, gene flow distances, evolutionarily significant units or population viability requirements. Loss of critical populations or connections between populations could increase the probability of extinction and put the species as a whole in jeopardy. Thus, it is important that all populations of the Riverside fairy shrimp be included in the critical habitat designation to provide adequate protection of the species as required by the Act.
Our Response: We recognize the current threats facing the Riverside fairy shrimp, the need to minimize fragmentation effects, and to provide adequate conservation protection. However, we did not designate critical habitat for all populations of the Riverside fairy shrimp. Some areas in our proposed designation were not designated as critical habitat for the following reasons: (1) The area did not meet the definition of critical habitat under section 3(5)(A) of the Act, (2) the area is now included within legally operative HCPs, (3) the area was necessary for national security measures, or (4) economic impact costs. However, for some areas which were excluded from critical habitat under section 4(b)(2) of the Act, or exempted under section 4(a)(3) of the Act, the Riverside fairy shrimp still receives protection under conservation plans such as HCPs or INRMPs.
12. Peer Reviewer Comment: According to the proposed rule, critical habitat is identified for the Riverside fairy shrimp in six separate units, each of which correspond to the larger Management Areas that support Riverside fairy shrimp occurrences as outlined in the Recovery Plan (Service 1998; 2004). However, the management areas specified in the Recovery Plan for Vernal Pools of Southern California are based on simple geographical locations, not the biology of the species considered, and the Recovery Plan does not include a population viability analysis. Genetic information on the San Diego fairy shrimp has shown that these management areas do not coincide with the species' evolutionarily significant units based on the population genetic structure of the species. The identification of populations essential to the species requires genetic analysis and *19162 life history analysis to determine "source/sink" status and to evaluation the viability of the population and probability of persistence. Simple geographic location is not sufficient, especially considering the amount of loss of intervening habitat. The management areas are therefore not relevant to the species' conservation, a fact which likely also applies for the Riverside fairy shrimp (Bohonak et al. 2003).
Our Response: We agree that no scientific information is available on the genetic diversity of the Riverside fairy shrimp, as is the case for the San Diego fairy shrimp. Thus, we used geographical descriptions to identify critical habitat units. These geographical descriptions are not meant to suggest any evolutionary divergence or population genetic structure. At the same time, we also based our analyses on what areas constituted critical habitat upon the best available scientific and commercial data available to us at the time, and made available public comment periods to allow for submission of any new information.
13. Peer Reviewer Comment: The proposed rule stated that an artificial vernal pool complex had been created to offset the impacts to a population of Riverside fairy shrimp by the Redhawk Development, and that another artificial vernal pool creation was planned in order to offset the taking of Riverside fairy shrimp at the Clayton Ranch Pool. Two reviewers questioned whether these artificial pools have produced viable, reproducing populations with positive rates of increase, rather than simply hatching shrimp from the transplanted cysts. To the reviewers' knowledge, no such successes have been recorded in the primary literature; i.e., see Ripley et al. (2004). Furthermore, the proposed rule stated that on Otay Mesa in San Diego County, significant work had been done to restore and enhance vernal pools for listed species, including the Riverside fairy shrimp. However, the reviewers noted that due to failure to check the transplanted cysts, the Otay pools have become "infected" with a "weedy" species, the winter fairy shrimp (Branchinecta lindahli), which can hybridize with the San Diego fairy shrimp (Fugate 1998); its effect on the Riverside fairy shrimp is yet unknown. Thus, the restoration or creation efforts have not been verified as successful (producing viable populations and a growing cyst bank) for either San Diego fairy shrimp or Riverside fairy shrimp, and have in fact, introduced new potential threats.
Our Response: We did not designate any artificial vernal pools as critical habitat for the Riverside fairy shrimp.

Public Comments

Issue 1: Policy and Regulations

1-1. Comment: It was suggested that all essential Riverside fairy shrimp habitat areas within the boundaries covered by the Western Riverside County Habitat Conservation Plan (HCP), Central/Coastal Orange County Natural Community Conservation Program (NCCP), and San Diego Multiple Species Conservation Plan (MSCP) should be included in the final critical habitat designation because (a) areas within those plans meet the definition of critical habitat; the Service has identified those areas as essential to the conservation of the species, and the plans provide special management for the species, (b) the benefits of inclusion far outweigh the harm wrongly perceived by others, (c) the critical habitat designation provides greater conservation benefits than those contained in the plans, which are inadequate to conserve the Riverside fairy shrimp, (d) because the educational benefits of HCPs are much less than those provided by critical habitat designation, and (e) the critical habitat designation has greater specificity, addressing the needs of specific species, than HCPs. Another commenter suggested that the critical habitat designation should be expanded to include all Riverside fairy shrimp populations, including those in excluded Department of Defense lands or HCP areas. In contrast, one commenter suggested that lands within the Western Riverside County MSHCP do not require additional special management considerations or protection, and thus do not meet definition of "critical habitat."
Our Response: Although the habitat within the boundaries of these conservation plans contains one or more of the physical and biological characteristics essential to the conservation of the Riverside fairy shrimp, we have determined that these conservation plans provide special management and/or protection for the Riverside fairy shrimp, and we have concluded that the benefits of excluding the lands covered by these plans from the final critical habitat designation outweigh the benefits of including these areas. Thus, we have excluded these areas from critical habitat designation under 4(b)(2) of the Act.
We recognize that critical habitat is only one of many conservation tools for federally listed species. HCPs are one of the most important tools for reconciling land use with the conservation of listed species on non-Federal lands. Section 4(b)(2) of the Act allows us to exclude from critical habitat designation areas where the benefits of exclusion outweigh the benefits of designation, provided the exclusion will not result in the extinction of the species. We believe that in most instances, the benefits of excluding HCPs from critical habitat designations will outweigh the benefits of including them. For this designation, we find that the benefits of exclusion outweigh the benefits of designation for all approved and legally operative HCPs which address the Riverside fairy shrimp and provide for its long-term conservation. These include the San Diego MSCP in San Diego County, the Western Riverside County MSHCP and the Rancho Bella Vista HCP and Assessment District 161 Sub-regional HCP in Riverside County.
HCPs must meet issuance criteria, according to section 10(a)(1)(B) of the Act, including minimizing and mitigating any take of the listed species covered by the permit to the maximum extent practicable, and that the taking must not appreciably reduce the likelihood of the survival and recovery of the species in the wild. The take minimization and mitigation measures provided under the above-mentioned HCPs are expected to adequately protect the essential habitat lands designated as critical habitat in this rule, such that the value of these lands for the survival and recovery of the Riverside fairy shrimp is not appreciably diminished through direct or indirect alterations. We expect that HCPs undertaken by local jurisdictions (e.g., counties and cities) and other parties will identify, protect, and provide appropriate management for those specific lands within the boundaries of the plans that are essential for the long-term conservation of the species. We discuss these standards in detail in the section 7 Consultation and Relationship of Critical Habitat to Approved Habitat Conservation Plans portions of this document below).
1-2. Comment: It was suggested that the essential Riverside fairy shrimp habitat areas within the boundaries covered by the Western Riverside County HCP should not be excluded as critical habitat because the plan was only recently approved and the protection benefits the plan provided to the species were thus unproven and speculative. According to the Act, the Service cannot base its decisions to exclude areas from its critical habitat designation on unproven conservation activities.
*19163 Our Response: Under section 4(b)(2), we may exclude any area from critical habitat if we determine that the benefits of such an exclusion outweigh the benefits of including the area in the critical habitat designation, unless, based on the best scientific and commercial data available, we determine that failure to designate the area as critical habitat will result in the extinction of the species. We have excluded the areas within the Western Riverside County MSHCP from the final critical habitat designation under section 4(b)(2) of the Act because the benefits of exclusion outweigh the benefits of inclusion. (For a detailed discussion please see the section Relationship of Critical Habitat to Approved Habitat Conservation Plans below).
1-3. Comment: Several comments were made that the Service inaccurately overstates the benefits of conservation plans while overemphasizing possible harm of critical habitat designation within plans' boundaries, that the Service cannot rest any claim of harm on mere perceptions; possible complaints by plan participants would suggest intention of significantly reduced conservation compared to those in a designated critical habitat. Critical habitat designation of an area after the approval of an HCP there will not serve as disincentive, but actually encourage HCP preparation.
In an opposing view, one commenter supported the exclusion of critical habitat within the Western Riverside County MSHCP, asserting that if it were included, it would undermine cooperative conservation partnerships. Two commenters stated, in general, that all lands covered by an HCP (e.g., NCCPs/ special area management plans) should be automatically excluded from critical habitat designation upon approval of the respective conservation or management plan.
Our Response: It is our experience that most landowners strongly object to inclusion of their lands within critical habitat; thus while proposing a designation may in some cases provide an incentive to participate in developing an HCP, we have no indication that designating private lands as critical habitat encourages the owners to engage in conservation activities. We do recognize that the designation of critical habitat does not provide the same set of conservation conditions that an HCP does, and an HCP may well provide more benefits to the species than critical habitat designation. We recognize that critical habitat is only one of many conservation tools for federally listed species, but HCPs are one of the most important tools for reconciling land use with the conservation of listed species on non-Federal lands. Furthermore, the benefits of including HCPs or NCCP/HCPs in the critical habitat designation are normally small; i.e., any federally funded or authorized activities in such habitat that may affect critical habitat would require consultation under section 7 of the Act. Such consultation would ensure that adequate protection is provided to avoid adverse modification of critical habitat. Where HCPs are in place, we believe that this benefit is small or non-existent. Although conservation plans are important tools to ensure the species survival and recovery, our actions regarding newly implemented plans are not automatic; it is our policy is to carefully review each plan, and only exclude areas from critical habitat designations consistent with section 4(b)(2) of the Act.
1-4. Comment: All essential habitats within the boundaries of the Central/Coastal Orange County NCCP/HCP should be included in the critical habitat designation because the Riverside fairy shrimp in natural vernal pools is not covered by these plans, and therefore cannot benefit from the conservation measures in the plan.
Our Response: The Riverside fairy shrimp is known to occur in only two areas within the Central-Coastal Orange County NCCP/HCP, which provides for the establishment of approximately 38,738 ac (15,677 ha) of reserve lands for 39 Federal or State listed, unlisted, and sensitive species. Within this NCCP/HCP, we proposed critical habitat at the former Marine Corps Air Station (MCAS) El Toro but we excluded this area pursuant to section 4(b)(2) for economic impacts. We excluded an area within the Edison Viejo Conservation Bank, as their management plan meets our criteria for conservation measure for the species. The Riverside fairy shrimp is also known to occur in the North Ranch Policy Plan area which was originally not included within the Central-Coastal NCCP/HCP. However, in 2002, the Irvine Company, owner of lands within the North Ranch Policy Plan area, granted a conservation easement to The Nature Conservancy over the portion of the land where this vernal pool is located, and provided a $10 million management endowment. The conservation easement and management endowment ensure conservation of the Riverside fairy shrimp at this site. (For details, see Relationship of Critical Habitat to Approved Habitat Conservation Plans below).
1-5. Comment: The critical habitat designation does not give landowners effective notice as to whether their property contains critical habitat, causing a burden to landowners who must determine which portions of their land contain critical habitat.
Our Response: We identified, as critical habitat, specific areas in the proposed determination that are referenced by UTM coordinates found on standard topographic maps. Note that areas delineated as critical habitat on the maps do not include developed areas within the boundaries that do not contain more than one of the primary constituent elements for the species. During the public comment periods, we also made available the proposed critical habitat units, superimposed on 7.5 minute topographic maps and spot imagery, for inspection by the public at the Carlsbad Fish and Wildlife Office. Furthermore, we distributed geographic data and maps of the proposed critical habitat to all individuals, organizations, local jurisdictions and State and Federal agencies that requested them. We believe the information made available to the public is sufficiently detailed to allow for determination of critical habitat boundaries. This final rule contains the legal descriptions of areas designated as critical habitat required under 50 CFR 424.12(c). The accompanying maps are for illustration purposes only. If additional clarification is necessary, contact the Carlsbad Fish and Wildlife Office, 6010 Hidden Valley Road, Carlsbad, California 92009 (telephone 760/431-9440).
1-6. Comment: Essential Riverside fairy shrimp habitat within MCAS Miramar should be included as critical habitat because the habitat under their Integrated Natural Resource Management Plan (INRMP) meets the definition of critical habitat, as the Service has identified those areas as essential to conservation of species and the plan provides special management for the species. Further, the current INRMP (a) does not provide details for any existing or future exotic control project and thus does not provide adequate protection against current threats posed by the spread of exotic plants, (b) contains mainly future plans and few active measures addressing current conservation needs, and little information on when and where the actions will be accomplished, (c) does not include the Navy's past Miramar Vernal Pool Management Plan, i.e., treatment of vernal pools is not mandated, (d) its protection measures are not permanent, i.e., its reference to "political developments" could be seen as future decision to convert base to a *19164 regional airport or other development; (e) identifies the NEPA and the Clean Water Act as primary mechanisms for reconciling land uses with conservation, but these do not provide effective conservation of vernal pools, and (f) the INRMP provides few benefits, as the INRMP and past consultations will not ensure conservation or protection of Riverside fairy shrimp and its essential habitat.
Our Response: Under section 4(a)(3) of the Act, we must exempt military lands subject to an INRMP from critical habitat if that plan provides a benefit to Riverside fairy shrimp. The lands at MCAS Miramar are covered by an approved INRMP that identifies sensitive natural resources within management areas that have various resource conservation requirements and management concerns. These areas have been assigned five levels of conservation priority corresponding with their sensitivity, with e.g., Level I management areas receiving the highest proactive measures. MCAS Miramar continues to monitor, restore and manage its vernal pool resources, including studies in progress, and has indicated it has no plans for changes in future land use. MCAS Miramar has completed an INRMP which we have reviewed and determined that it provides benefits to the Riverside fairy shrimp. Therefore, lands at MCAS Miramar have not been included in the proposed or final designation in accordance with 4(a)(3) of the Act (for more details, see benefits analysis in proposed rule (69 FR 23024) under Relation of Critical Habitat to Department of Defense Lands; Marine Corps Air Station Miramar).
1-7. Comment: The Service did not provide for adequate public notice of the proposed rule and sufficient opportunity for public comment. Additionally, requests for extension of the comment period were denied, while previous comments have not been acted upon. The 30-day comment period on the draft economic analysis lacks compliance with the required 60-day comment period per the Service's own regulations, the Act and the Regulatory Flexibility Act; with a shorter comment period.
Our Response: Pursuant to our implementing regulations at 50 CFR 424.16, we are required to provide for at least 60-days for public comment following the publication of a proposed rule in the Federal Register. We published the proposed rule to designate critical habitat for the Riverside fairy shrimp in the Federal Register on April 27, 2004 (69 FR 23024), and accepted comments from the public for 30 days, to May 27, 2004. We contacted all appropriate State and Federal agencies, county governments, elected officials, and other interested parties and invited them to comment on the proposed rule. In addition, we published notices in the San Diego Union Tribune, the Orange County Register, and the Los Angeles Times, all on May 6, 2004. We published a second notice in the Federal Register on October 19, 2004 (69 FR 61461), announcing the availability of the draft economic analysis and opening a 30-day public comment period until November 18, 2004, to allow for comments on the draft economic analysis and additional comments on the proposed determination. We provided notification of the draft economic analysis through telephone calls, letters, and news releases faxed and/or mailed to relevant elected officials, local jurisdictions, and interest groups. Following its release, we also published the draft economic analysis and associated material on our Web site (http://carlsbad.fws.gov). We believe these two public comment periods provided adequate opportunity for public comment and constitute compliance with our implementing regulations at 50 CFR 424.16. Because of the court-ordered time frame, we were not able to extend the second comment period or open an additional public comment period.
1-8. Comment: Would the designation of critical habitat for the Riverside fairy shrimp be considered a changed or unforeseen circumstance with respect to the various sub-area HCPs presently approved or pending?
Our Response: In this rule, no critical habitat was designated within lands covered by any pending or un-approved HCP.
1-9. Comment: One commenter stated that the proposal to designate critical habitat violates the Act because of (a) failure to use the best available science to exclude non-essential lands from the critical habitat designation, (b) failure to determine whether any specific areas may require special management considerations or protection, (c) it does not contain an economic impact analysis; Congress intended that the Service consider economic and other impacts of the critical habitat designation concurrently with the formulation of critical habitat proposals, (d) certification pursuant to the Regulatory Flexibility Act impermissibly relies on the as-yet unavailable economic analysis, reducing ability of public to provide meaningful comment, and because (e) the Service has failed to comply with NEPA prior to designating critical habitat.
Our Response: We are directed by the Act to use the best commercial and scientific information available to us at the time we conduct our analyses. In response to part (a), we relied on the best scientific resources when determining to either designate areas essential to the conservation of the Riverside fairy shrimp and to exclude other areas from our final critical habitat designation. Our final delineation of critical habitat is based on the best available scientific and commercial data regarding the species, including a compilation of data from peer-reviewed published scientific literature, unpublished or non-peer-reviewed survey or research reports, and statements from expert biologists knowledgeable about the Riverside fairy shrimp and its habitat. In addition to the above information available to us, we also requested additional information from the public and from peer reviewers to further assist us in our analyses. All new information that was provided during the public comment periods was considered in this final designation, as appropriate. The areas designated as critical habitat represents our best estimate of what areas are essential and critical for the conservation of the species. In response to part (b), please refer to our section Relationship of Critical Habitat to Approved Habitat Conservation Plans for details on our analyses of approved conservation plans. In response to comments (c) and (d), we have provided a draft economic analysis, available for public review during the second comment period, giving individuals opportunity to submit comments on its contents, which we have reviewed and addressed in this rule. In response to comment (e), we are not required to prepare environmental analyses as defined by the NEPA in connection with designating critical habitat under the Endangered Species Act of 1973, as amended. (For more details, see National Environmental Policy Act (NEPA) below).
1-10. Comment: Would on-going activities (such as routine inspections, road grading, construction, etc.) that occur adjacent to designated critical habitat be considered to appreciably decrease habitat values or quality through indirect effects?
Our Response: The Federal agency planning to conduct such activities must determine if their proposed action may affect critical habitat designated for the Riverside fairy shrimp. The action agency determines whether their action(s) "may affect" the Riverside fairy shrimp or its primary constituent elements within the adjacent critical habitat based on their analyses. If so, the *19165 action agency would enter into consultation with the Service under section 7.
1-11. Comment: Can the Service exclude all areas addressed under existing section 7 permits in a manner similar to the exclusions for areas covered under existing section 10 permits? Specifically, can an existing section 7 permit based on a biological opinion for the California gnatcatcher be amended to cover the Riverside fairy shrimp critical habitat in the Otay Mesa area? Specifically, this would be necessary for ongoing operations and maintenance by the San Diego County Water Authority of the Mexico Emergency Connection Pipeline on the western portion of Otay Mesa (final Map Unit 4).
Our Response: Consultation under section 7 of the Act does not result in the issuance of a section 7 "permit" per se. Federal actions that we conclude are not likely to jeopardize the continued existence of a listed species are exempted from the prohibition against take of listed animal species under section 9 of the Act so long as the Federal agency and any permittee comply with the terms and conditions of the incidental take statement accompanying the Service's biological opinion. Assuming the Federal agency that was subject to consultation under section 7 of the Act for a listed species still retains discretionary jurisdiction over the action, the Federal agency must re-initiate section 7 consultation if its action "may affect" designated critical habitat for the Riverside fairy shrimp. See Section 7 Consultation below.
1-12. Comment: One commenter requested that the Major and Minor Amendment areas of the eastern portion of Otay Mesa, southern San Diego region (Map Unit 5C), be excluded from the critical habitat designation because these areas must conform to the MSCP, sub-area plans, and the resource protection ordinance, and a critical habitat designation would result in additional section 7 requirements, economic burdens on HCP participants, discourage HCP development, cause additional regulatory review that could jeopardize ongoing conservation efforts, possibly encourage legal challenges to the HCPs because of the uncertainty of the "adverse modification" threshold, and afford no additional benefit to the species because HCPs provide better long-term conservation measures.
Our Response: Although the Major/Minor Amendment areas are within the boundaries of the San Diego MSCP, these areas are not covered by completed plans that address the conservation of the Riverside fairy shrimp. While we have excluded lands covered by approved sub-area plans under the MSCP, the plans for the Major/Minor Amendment areas are incomplete and thus do not provide adequate conservation measures addressing the Riverside fairy shrimp. However, we have excluded all of Sub-unit 5C in private ownership within the Otay Mesa Major/Minor Amendment areas, under section 4(b)(2) of the Act, in order to avoid some or all of the additional costs incurred by affected landowners.
1-13. Comment: One commenter suggested that the areas proposed as Riverside Fairy Shrimp critical habitat (a) do not need special protection or satisfy the definition of critical habitat because they receive substantial protections under new regulations (i.e., Clean Water Act, Porter-Cologne Water Quality Control Act, California Environmental Quality Act, California Department of Fish and Game permitting codes, State Water Board regulations; and (b) must be re-evaluated to determine whether the habitat requires special protection in light of new regulations governing such areas, i.e., the California Porter-Cologne Water Quality Control Act.
Our Response: While the statutes listed above may provide some regulatory protection for the Riverside fairy shrimp and its associated essential habitat, they do not provide assured management for the species.
Therefore, exclusion of essential habitat from this designation on the basis of the regulatory protections potentially afforded by these statutes is not warranted.
1-14. Comment: One commenter asserted that Service has unlawfully pre- determined that exclusion from the final critical habitat designation of essential Riverside fairy shrimp habitat that lies within other conservation plan areas outweighs any benefits of inclusion because the acknowledged essential habitat was excluded prior to the public's review of the Service's analyses of benefits and harm.
Our Response: Notice of our intent to exclude lands within approved and/or pending HCPs was provided to the public, and maps showing the lands proposed for exclusion were readily available to the public for inspection during the two public comment periods. We solicited comments from the public for 30 days about the areas which we proposed to include or exclude from the proposed rule to designate critical habitat for the Riverside fairy shrimp on April 27, 2004 (69 FR 23024). In the Federal Register notice, we notified the public that we may revise the critical habitat designation if additional information becomes available that changes our assessment of the relative benefits of including or excluding these areas from critical habitat. We also contacted appropriate State and Federal agencies, county governments, elected officials, and other interested parties and invited them to comment on the proposed rule, and published notices in the San Diego Union Tribune, Orange County Register, and Los Angeles Times on May 6, 2004. We published a second notice on October 19, 2004 (69 FR 61461), announcing the availability of the draft economic analysis and opening a 30-day public comment period until November 18, 2004, and also published the draft economic analysis and associated material on our Web site (http://carlsbad.fws.gov). In making our final critical habitat determination, we considered every comment submitted.

Issue 2: Adequacy and Extent of Critical Habitat Designation

2-1. Comment: One commenter stated that there is no substantiation for an increase in area designated as critical habitat from the previous critical habitat rule issued on May 30, 2001 (66 FR 29384).
Our Response: In the May 30, 2001, final critical habitat rule for the Riverside fairy shrimp (66 FR 29384), we designated approximately 6,870 ac (2,790 ha) as critical habitat. Since then, additional, new information on vernal pools and the occurrences of the little-studied Riverside fairy shrimp has become available, while on the other hand, numerous of the discovered essential areas have been included in several regional HCPs or INRMPs. Thus, on April 27, 2004, we proposed to designate approximately 5,795 ac (2,345 ha) of vernal pools and their adjacent watersheds essential to the conservation of the species as critical habitat for the Riverside fairy shrimp (69 FR 23024). This final determination designates 306 ac (124 ha) as critical habitat, which represents less than five percent of the area originally designated as critical habitat in the previous rule of 2001.
2-2. Comment: One commenter stated that the Service did not use an appropriate mapping scale for this species, and since the species' range is well known in San Diego County, the Service should have been able to delineate critical habitat boundaries with extreme precision. The current 100 m [FN2] blocks include areas that do not have the PCEs for the Riverside fairy shrimp, and those areas should be excluded. Another commenter asked whether the Service intends to exclude from the designated critical habitat all existing *19166 roads, aqueducts, etc. regardless of the state of these features.
Our Response: We are required to define and delimit critical habitat by specific limits using reference points and lines as found on standard topographic maps of the area" (50 CFR 424.12(c)). We have delimited the boundaries of critical habitat boundaries in this rule based on a minimum mapping scale of 100 m. This mapping scale was based on the availability and accuracy of aerial photography and GIS data layers used to develop the designation. In drawing our critical habitat boundaries for the proposed and final rules, we have attempted to exclude all areas that do not contain essential habitat for the Riverside fairy shrimp as defined by its PCEs. Based on information obtained through public comments and updated imagery and GIS data layers, we have been able to further refine the boundaries of critical habitat during the development of this final rule. Within the limitations of our mapping scale, we have been able to exclude most, but not all areas, that do not contain the PCEs, including some man-made features. Note, however, that we have determined that existing man-made features and structures, such as buildings, roads, railroads, airports, runways, other paved areas, lawns, and other urban landscaped areas are not likely to contain one or more of the PCEs and thus do not constitute critical habitat and the lands on which they are found. Activities in these areas are unlikely to affect PCEs (i.e., essential habitat for the Riverside fairy shrimp), and therefore, consultation under section 7 of the Act would not be required unless such activities would affect the species or adjacent critical habitat. In making the critical habitat designation, we used the best scientific and commercial information available to us, including information obtained during the two public comment periods
2-3. Comment: The proposed critical habitat designation violates the Act because of the Service's failure to limit the designation to areas essential to the conservation of the Riverside fairy shrimp.
Our Response: In proposing critical habitat designation, we used the best scientific and commercial information available to determine those areas essential for the conservation of the Riverside fairy shrimp. We used additional information available to us, including a more detailed aerial imagery, a finer mapping grid (changed from 250 m [FN2] to 100 m [FN2]), as well as information provided by commenters to refine our mapping of all essential habitat included in the final designation. Please see the sections Background, Criteria Used to Identify Critical Habitat, and Critical Habitat Designation of this rule for further discussions on how we determined habitat that is essential to the conservation of the species. The areas designated by this final rule are limited to lands essential for the conservation of the Riverside fairy shrimp.
2-4. Comment: Rancho Mission Viejo stated that in the proposed rule: (a) The Service used a "recovery standard" which resulted in an overly broad critical habitat designation, (b) the Service did not provide scientific data to indicate how it determined the ex