Endangered and Threatened Wildlife and Plants; Revised Designation of Critical Habitat for the Tidewater Goby (Eucyclogobius newberryi)

DEPARTMENT OF THE INTERIOR

Fish and Wildlife Service

50 CFR Part 17

[FWS-R8-ES-2008-0010; 92210-1117-0000-B4]

RIN 1018-AU81

Endangered and Threatened Wildlife and Plants; Revised Designation of Critical Habitat for the Tidewater Goby (Eucyclogobius newberryi)

AGENCY:

Fish and Wildlife Service, Interior.

ACTION:

Final rule.

SUMMARY:

We, the U.S. Fish and Wildlife Service (Service), are revising the critical habitat designation for the tidewater goby (

Eucyclogobius newberryi

) under the Endangered Species Act of 1973, as amended (Act). In total, approximately 10,003 acres (ac) (4,050 hectares (ha)) fall within the boundaries of the final revised critical habitat designation. The revised critical habitat is located in Del Norte, Humboldt, Mendocino, Sonoma, Marin, San Mateo, Santa Cruz, Monterey, San Luis Obispo, Santa Barbara, Ventura, and Los Angeles Counties, California.

DATES:

This rule becomes effective on March 3, 2008.

ADDRESSES:

The final rule, final economic analysis, and map of critical habitat will be available on the Internet at

http://www.regulations.gov

and

http://www.fws.gov/ventura.

Supporting documentation we used in preparing this final rule will be available for public inspection, by appointment, during normal business hours, at the U.S. Fish and Wildlife Service, Ventura Fish and Wildlife Office, 2493 Portola Road, Suite B, Ventura, California 93003; telephone (805) 644-1766; facsimile (805) 644-3958.

FOR FURTHER INFORMATION CONTACT:

Michael McCrary, Listing and Recovery Coordinator, U.S. Fish and Wildlife Service, Ventura Fish and Wildlife Office, telephone (805) 644-1766 (see

ADDRESSES

section). If you use a telecommunications device for the deaf (TDD), call the Federal Information Relay Service (FIRS) at 800-877-8339.

SUPPLEMENTARY INFORMATION:

Background

It is our intent to discuss only those topics directly relevant to the revised designation of critical habitat in this final rule. For additional information on the tidewater goby, refer to the final listing rule published in the

Federal Register

on February 4, 1994 (59 FR 5494); the original proposed and final critical habitat rules published in the

Federal Register

on August 3, 1999 (64 FR 42250) and November 20, 2000 (65 FR 69693), respectively; and the proposed revised critical habitat designation published in the

Federal Register

on November 28, 2006 (71 FR 68914).

Species Description and Genetic/Morphological Characteristics

The tidewater goby is a small, elongate, grey-brown fish rarely exceeding 2 inches (in) (5 centimeters (cm)) in length. This species possesses large pectoral fins, and the pelvic or ventral fins are joined to each other below the chest and belly from below the gill cover back to just anterior of the anus. Male tidewater gobies are nearly transparent with a mottled brownish upper surface. Female tidewater gobies develop darker colors, often black, on the body and dorsal and anal fins. The tidewater goby is a short-lived species; the lifespan of most individuals appears to be about 1 year (Irwin and Soltz 1984, pg 26; Swift

et al.

1989, pg 4).

Various genetic markers demonstrate that pronounced differences in the genetic structure of tidewater gobies exist, and that tidewater gobies in some locations are genetically distinct. A recent study of mitochondrial DNA and cytochrome b (molecular material used in genetic studies) sequences from tidewater gobies that were collected at 31 locations throughout the species' range identified six major phylogeographic (geographic differences in the evolution of a species) or regional groups (Dawson

et al.

2001, pg 1171). These six regional groups include the following areas: (1) Tillas Slough (Smith River) in Del Norte County to Lagoon Creek in Mendocino County, i.e., the North Coast (NC) Unit; (2) Salmon Creek in Sonoma County to Bennett's Slough in Monterey County, i.e., the Greater Bay (GB) Unit; (3) Arroyo del Oso to Morro Bay in San Luis Obispo County, i.e., the Central Coast (CC) Unit; (4) San Luis Obispo Creek in San Luis Obispo County to Rincon Creek in Santa Barbara County, i.e., the Conception (CO) Unit; (5) Ventura River in Ventura County to Topanga Creek in Los Angeles County, i.e., the Los Angeles-Ventura (LV) Unit; and (6) San Pedro Harbor in Los Angeles County to Los Peñasquitos Lagoon in San Diego County, i.e., the South Coast (SC) Unit.

Metapopulation Dynamics

Local populations of tidewater gobies are best characterized as metapopulations (Lafferty

et al.

1999a, p. 1448). First, local goby populations are frequently isolated from other local populations by extensive areas of unsuitable habitat. Second, gobies occupy coastal lagoons and estuaries that in most cases are separated from each other by the open ocean. Very few tidewater gobies have ever been captured in the marine environment (Swift

et al.

1989, p. 7), which suggests this species rarely occurs in the open ocean. Studies of the tidewater goby suggest that some populations persist on a consistent basis (Lafferty

et al.

1999a, p. 1452), while other tidewater goby populations appear to experience intermittent extirpations. These extirpations may result from one or a series of factors, such as the drying up of some small streams during prolonged droughts (Lafferty

et al.

1999a, p. 1451). Some of the areas where tidewater gobies have been extirpated apparently have been recolonized when extant populations were present within a relatively short distance of the extirpated population (i.e., less than 6 miles (mi) (10 kilometers (km)). These recolonization events suggest that tidewater goby populations exhibit a metapopulation dynamic where some populations survive or remain viable by continually exchanging individuals, and recolonizations may occur after occasional extirpations (Doak and Mills 1994, pg 619).

Lafferty

et al.

(1999b) monitored the post-flood persistence of several tidewater goby populations in Santa Barbara and Los Angeles Counties during and after the heavy winter floods of 1995. All of the monitored populations persisted after the floods, and no significant changes in population sizes were noted (Lafferty

et al.

1999b, p. 621). Tidewater gobies apparently colonized Cañada Honda in Santa Barbara County after one flood event (Lafferty

et al.

1999b, p. 621). This information suggests that flooding may sometimes contribute to recolonization of habitats where a tidewater goby population has become extirpated.

The largest wetland habitats where tidewater gobies have been known to occur are not necessarily the most secure, as evidenced by the fact that the Santa Margarita River in San Diego County and the San Francisco Bay have lost their populations of tidewater goby. Today, the majority of the most stable and largest tidewater goby populations consist of lagoons and estuaries of intermediate sizes, i.e., 5 to 125 ac (2 to 50 ha) that have remained relatively unaffected by human activities (Service 2005, p. 12). Many of the localities where tidewater gobies are consistently present may be “source” populations, and such locations may provide the

colonists for localities that intermittently lose their tidewater goby populations.

Historical records and survey results for several localities occupied by the tidewater goby are available (e.g., Swift

et al.

1989, pp. 18-19; Swift

et al.

1994, pp. 8-16). These documents suggest the persistence of tidewater goby populations is related to habitat size, configuration, location, and proximity to human development. In general, the most stable and persistent tidewater goby populations occur in the lagoons and estuaries that are more than 2.47 ac (1 ha) in size and that have remained relatively unaffected by human activities (Lafferty

et al.

1999a, pp. 1450-1453). We note, however, that some systems that are affected or altered by human activities also have relatively large and stable populations (e.g., Humboldt Bay in Humboldt County, Pismo Creek in San Luis Obispo County, Santa Ynez River in Santa Barbara County, and the Santa Clara River in Ventura County). Also, some habitats less than 2.47 ac (1 ha) in size have tidewater goby populations that persist on a regular basis (Swift

et al.

1997, p. 3; Keegan 2006, p. 8). The best available information suggests that the lagoons and estuaries that have persistent populations are likely the core populations that provide the individuals that colonize adjacent, smaller localities that have ephemeral tidewater goby populations (Lafferty

et al.

1999a, p. 1452).

Distribution

The known geographic range of the tidewater goby is limited to the coast of California (Eschmeyer

et al.

1983, p. 262; Swift

et al.

1989, p. 12). The species historically occurred from localities that extended from 3 mi (5 km) south of the California-Oregon border (i.e., Tillas Slough in Del Norte County) to 44 mi (71 km) north of the United States-Mexico border (i.e., Agua Hedionda Lagoon in San Diego County). The available documentation (e.g., Eschmeyer

et al.

1983, p. 262; Swift

et al.

1989, p. 12) suggests the northernmost locality that forms one end of the historical and current geographic range of the tidewater goby has not changed over time. Tidewater gobies do not currently occur in Agua Hedionda Lagoon, and the species' southernmost known locality currently is located in Cockleburr Canyon 9.2 mi (14.8 km) north of Agua Hedionda Lagoon. Although the northernmost and southernmost extent of the tidewater goby's range has not changed much over time, the tidewater goby's overall population has become patchy and fragmented along the coast.

Tidewater gobies appear to be naturally absent from several large (50 to 135 mi (80 to 217 km)) stretches of coastline where lagoons or estuaries are absent, and steep topography or swift currents may prevent tidewater gobies from dispersing between adjacent localities (Swift

et al.

1989, p. 13). One such gap in lagoons and estuaries occurs between the Eel River in Humboldt County and the Ten Mile River in Mendocino County. A second gap exists between Lagoon Creek in Mendocino County and Salmon Creek in Sonoma County. Another large, natural gap occurs between the Salinas River in Monterey County and Arroyo del Oso in San Luis Obispo County. Habitat loss and other anthropogenic-related factors have resulted in the tidewater goby now being absent from several locations where it historically occurred; their recent disappearance from specific locations has created smaller, artificial gaps in the species' geographic distribution (Capelli 1997, p. 7). Such locations include Buena Vista Lagoon and Agua Hedionda Lagoon in San Diego County, Calleguas Creek/Mugu Lagoon in Ventura County, San Francisco Bay in San Francisco and Alameda Counties, and Redwood Creek and Freshwater Lagoon in Humboldt County.

Swift

et al.

(1989, p. 13) reported that, as of 1984, tidewater gobies occurred, or had been known to occur, at 87 localities; these localities included those at the extreme northern and southern end of the species' historical geographic range. An assessment of the species' distribution in 1993, using records that were limited to the area between the Monterey Peninsula in Monterey County and the United States-Mexico border, found tidewater gobies occurring at four additional localities (Swift

et al.

1993, p. 129). Other goby localities have been identified since 1993, and currently tidewater gobies have been documented at 135 localities within the historical geographic range of the species (Service 2005, p. 6). Of these 135 localities, 23 (17 percent) are no longer known to be occupied by tidewater gobies. Therefore, 112 localities are currently occupied.

Habitat

The lagoons, estuaries, backwater marshes, and freshwater tributaries that tidewater gobies occupy are dynamic environments that are subject to considerable fluctuations on a seasonal and annual basis. In a typical year, the formation of a sandbar occurs in the late spring as flow into a lagoon declines enough to allow the ocean surf to build up the sandbar at the mouth of the lagoon. Winter rains and subsequently increased stream flows may bring in considerable sediment and dramatically affect the bottom profile and substrate composition of a lagoon or estuary. Fine mud and clay either moves through the lagoon or estuary or settles out in backwater marshes, while heavier sand is left in the lagoon or estuary. High flows associated with winter rains can scour out the lagoon bottom to lower levels, with sand building up again after flows decline. These dynamic processes result in wetland habitats that, over time, move both laterally and up-or-down-gradient relative to stationary features that exist outside the flood zone (e.g., roads or buildings).

The horizontal extent of the lentic (pond-like) wetland habitat associated with a particular tidewater goby locality varies on a site-specific basis, and is affected in part by local precipitation patterns and topography. In coastal areas where the topography is steep and precipitation is relatively low (e.g., areas adjacent to the Santa Ynez Mountains in Santa Barbara County), the habitats occupied by tidewater gobies may be a few acres in size, only extend a few hundred feet inland from the ocean, and backwater marshes may be small or absent. In other coastal settings where precipitation is more abundant: (1) Topography is less steep and surface streams are larger; (2) coastal lagoons or estuaries may be hundreds of acres in size and extend many miles inland; and (3) extensive backwater marshes may be present (e.g., Lake Earl in Del Norte County and Ten Mile River in Mendocino County).

Some localities occupied by tidewater gobies receive surface or ground water from upstream areas on a year-round basis. Such localities (e.g., Bennett's Slough in Monterey County) tend to possess wetland habitats that are larger and can extend inland for several hundred feet or even miles. Other occupied locations do not possess stream channels or tributaries that provide a considerable amount of water throughout the summer or fall months. Such locations (e.g., Little Pico Creek in San Luis Obispo County) tend to possess wetland habitats that only extend a short distance inland from the ocean (i.e., 290 ft (88 m)).

Reproduction

Tidewater gobies have been observed spawning in every month of the year except December (Swenson 1999, p. 107). Reproduction tends to peak in late April or May to July, and can continue into November depending on seasonal

temperature and rainfall. Swenson (1995, p. 31) has documented spawning behavior in adult fish and the presence of egg clutches at water temperatures between 48 and 77 degrees Fahrenheit (F) (9 and 25 degrees Celsius (C)). Spawning tidewater gobies have been observed in water salinities between 2 and 27 parts per thousand (ppt) (Swenson 1999, p. 31).

Threats

The final listing rule for the tidewater goby that was published in 1994 (59 FR 5494) states that this species is threatened, or potentially threatened, by: (1) Coastal development projects that result in the loss or alteration of coastal wetland habitat; (2) water diversions and alterations of water flows upstream of coastal lagoons and estuaries that negatively impact the species' breeding and foraging activities; (3) groundwater overdrafting; (4) channelization of the rivers where the species occurs; (5) discharge of agricultural and sewage effluents; (6) cattle grazing and feral pig activity that results in increased sedimentation of coastal lagoons and riparian habitats, removal of vegetative cover, increased ambient water temperatures, and elimination of plunge pools and undercut banks utilized by tidewater gobies; (7) introduced species that prey on the tidewater goby (e.g., bass (

Micropterus

spp.) and crayfish (

Cambaris

spp.)); (8) the inadequacy of existing regulatory mechanisms; (9) drought conditions that result in the deterioration of coastal and riparian habitats; and (10) competition with introduced species such as the yellowfin goby (

Acanthogobius flavimanus

) and chameleon goby (

Tridentiger trigonocephalus

).

Previous Federal Actions

On August 31, 2001, Cabrillo Power L.L.C. (Cabrillo) filed a lawsuit in the U.S. District Court for the Southern District of California challenging a portion of the November 20, 2000, final rule (65 FR 69693) that designated the 10 critical habitat units for the tidewater goby in Orange and San Diego Counties. Specifically, Cabrillo objected to the critical habitat unit involving Agua Hedionda Lagoon and Creek. In a consent decree dated February 27, 2003, the U.S. District Court: (1) Agreed to vacate the critical habitat designation involving Agua Hedionda Lagoon and Creek; (2) stated the nine other critical habitat units should remain in effect; (3) stated the final rule designating critical habitat was remanded in its entirety for reconsideration; and (4) directed the Service to promulgate a revised critical habitat rule that considers the entire geographic range of the tidewater goby and any currently unoccupied tidewater goby habitat. The consent decree requires that the Service submit proposed and final revised rules to the

Federal Register

no later than November 15, 2006, and November 15, 2007, respectively. On November 28, 2006, we published the proposed revised critical habitat designation for the tidewater goby in the

Federal Register

(71 FR 68914). An extension of the due date for the final critical habitat rule was approved by the court on November 19, 2007, and the Service is now required to submit the final rule to the

Federal Register

by January 18, 2008.

A draft economic analysis (DEA) for the proposed revised designation was completed on August 23, 2007, and a notice of availability for this DEA was published in the

Federal Register

on September 25, 2007 (72 FR 54411). Publication of the notice of availability opened a public comment period for the DEA as well as the proposed revised designation from September 25, 2007, to October 10, 2007. For a discussion of additional Federal actions that occurred prior to the proposed revised designation of critical habitat for this species, please refer to the Previous Federal Actions section of the proposed revised critical habitat rule for the tidewater goby (71 FR 68914).

On September 28, 2007, we completed a 5-year review for the tidewater goby. In the 5-year review we recommended that the tidewater goby be downlisted to threatened because we believe that it is not in imminent danger of extinction. The main reason for this recommendation is that the number of localities known to be occupied has more than doubled since listing (from 48 to 106). We believe this indicates the tidewater goby is more resilient in the face of severe drought events than believed at the time of listing. Furthermore, we believe threats identified at the time of listing have been reduced or are not as serious as thought. One of the main reasons why the tidewater goby was listed was because of habitat destruction and alteration. Current laws and regulations have largely eliminated the major destruction of habitat that occurred in the past along the coast of California. The 5-year review concluded that tidewater goby populations are highly dynamic and will periodically be extirpated or reach such low numbers that they cannot be detected at some localities. This is a natural occurrence within many species exhibiting a metapopulation dynamic including the tidewater goby. Although the rate of extirpation or reduction to low levels is expected to be higher during drought conditions, during wetter periods, we expect that these localities will again be occupied assuming that suitable habitat still exists.

Summary of Comments and Recommendations

We requested written comments from the public on the proposed revised designation of critical habitat for tidewater goby in the proposed rule (71 FR 68914, November 28, 2006) and in the subsequent notice of availability for the DEA (72 FR 54411, September 25, 2007). We also contacted appropriate Federal, State, and local agencies; scientific organizations; and other interested parties and invited them to comment on the proposed revised rule.

During the comment period that opened on November 28, 2006, and closed on January 29, 2007, we received 23 comments directly addressing the proposed revised critical habitat designation: 4 from peer reviewers, 2 from Federal agencies, 1 from the State of California, 2 from local government, and 14 from organizations or individuals. Seventeen commenters generally supported the revised designation of critical habitat for tidewater goby, 4 opposed it, and 2 were neither for nor against it. During the comment period that opened September 25, 2007, and closed on October 10, 2007, we received seven comments addressing the proposed revised critical habitat designation and/or the draft economic analysis: two from local governments and five from organizations or individuals. One commenter supported the revised designation of critical habitat for the tidewater goby, five opposed it and/or the draft economic analysis, and one was neither for nor against it. Comments received were grouped into six general issues and are addressed in the following summary and incorporated into this final rule as appropriate. We did not receive any requests for a public hearing.

Peer Review

In accordance with our policy published on July 1, 1994 (59 FR 34270), we solicited expert opinions from seven knowledgeable individuals with scientific expertise that included familiarity with the species, the geographic region in which the species occurs, and conservation biology principles. We received responses from four of the peer reviewers. The peer reviewers generally concurred with our methods and conclusions, and provided

additional information, clarifications, and suggestions to improve the final revised critical habitat rule. Peer reviewer comments are addressed in the following summary and incorporated into the final rule as appropriate.

Peer Reviewer Comments

1.

Comment:

Four peer reviewers stated that more extant populations need to be designated or new populations established in order to potentially increase connectivity and persistence of present tidewater goby distribution and diversity.

Our Response:

We have not designated all areas currently occupied by tidewater gobies as critical habitat, nor have we designated any areas that were historically occupied but are now unoccupied by the species. However, we believe the 44 critical habitat units we are designating for the tidewater goby, all of which are currently occupied, are the areas that are necessary for the conservation of the tidewater goby and, therefore, meet the definition of critical habitat in the Act. The goal of the recovery plan for the tidewater goby is to preserve the diversity of habitats that occur within the range of the species, the metapopulation structure of the species (see Criteria Used To Identify Critical Habitat section for a definition and additional details on the recovery plan for the tidewater goby), and genetic diversity (Service 2005). The recovery plan identifies 26 subunits throughout the range of the tidewater goby. We designated critical habitat in all 26 subunits included in the recovery plan, except for those on Vandenberg Air Force Base (Santa Barbara County) and Marine Corps Base, Camp Pendleton (San Diego County), which have Integrated National Resource Management Plans (INRMP) that provide protection for the tidewater goby. These areas have been exempted from this final designation of critical habitat (see Application of Section 4(a)(3) of the Act—Approved Integrated Natural Resource Management Plans section). We believe these 44 critical habitat units, in addition to those subunits covered by INRMPs, are sufficient for the conservation of the species throughout its range, as they adequately represent the variation of both the habitat and genetic composition of the species, and they will support the species' recovery. As such, we did not designate any areas that are not currently occupied (see Summary of Changes from Previously Designated Critical Habitat and 2006 Proposed Rule section for more information).

We also agree with the commenters that the introduction of new populations could potentially benefit the tidewater goby. However, we did not include any unoccupied habitat in this designation because we concluded that the 44 units we are designating are the areas essential for conservation.

2.

Comment:

Several peer reviewers stated that all available evidence suggests that the southern tidewater goby is a distinct taxon of, or equivalent to, species rank and given the critical habitat proposed, is very likely to go extinct.

Our Response:

At this time, the tidewater goby is listed as a single species, following the currently accepted taxonomy for the species. If a change in the taxonomy of the tidewater goby is published in a peer-reviewed journal, we will evaluate the listing status of the species at that time. We have not designated any critical habitat in Orange and San Diego Counties because all the areas in these Counties that meet the first part of the definition of critical habitat in section 3(5)(A) of the Act (“the specific areas within the geographical area occupied by the species, at the time it is listed in accordance with the provisions of section 4 of this Act, on which are found those physical or biological features (I) essential to the conservation of the species * * *”) are located on Camp Pendleton Marine Corps Base (Base). The Base has a completed INRMP that provides a conservation benefit to the tidewater goby. Section 4(a)(3) of the Act prohibits the Secretary from designating critical habitat on any lands owned or controlled by the Department of Defense that are subject to an INRMP if the Secretary has determined that such plan provides a benefit to the species for which critical habitat is being proposed for designation. As such, pursuant to section 4(a)(3) of the Act, we have exempted the Base from this final designation of critical habitat (see Application of Section 4(a)(3)—Marine Corps Base Camp Pendleton section). We also did not designate any areas outside the geographical area occupied by the species as critical habitat for the reasons given in our response to comment 1 above and the Summary of Changes from Previously Designated Critical Habitat and 2006 Proposed Rule section.

3.

Comment:

One peer reviewer stated that our identification of tidewater goby populations serving as source populations for other areas is not supported by available information.

Our Response:

We are not aware of any single definition of source population that can be applied to every species. The recovery plan for the tidewater goby defines a source population as a subpopulation of a metapopulation that has an average birth rate that exceeds the average death rate, and therefore produces an excess of juveniles that may disperse to other areas (Service 2005). We do not have information on either tidewater goby population size or productivity for each occupied area. Therefore, for purposes of this rule, we have used the term “source population” to describe those areas that are currently occupied and have been consistently occupied for three or more consecutive years based on presence/absence survey data and published reports. We believe these areas are more likely to be capable of maintaining populations over many years and more likely to be capable of providing individuals to recruit into surrounding subpopulations.

4.

Comment:

Two peer reviewers asserted that coastal lagoon restoration plans that establish tidal salt marshes rather than brackish coastal lagoons should be included as an additional new threat.

Our Response:

We acknowledge that coastal lagoon restoration projects may be a threat to tidewater goby habitat. Although we have not specifically mentioned this type of project in this rule, we consider this as a coastal development project (see Critical Habitat Designation section and the Special Management Considerations or Protection section below).

5.

Comment:

Two peer reviewers stated that critical habitat units should be related to recovery units because the units designated as they are now do not provide for recovery.

Our Response:

We believe that our approach to this designation complies with the definitions in the Act, reflects the intent of the recovery plan for the tidewater goby (Service 2005), and identifies the areas essential to the conservation of the species throughout its range (see our response to comment 1 above). Developing recovery plans and designating critical habitat are not necessarily synonymous under the Act. The Act does not include specific instructions as to the areas that should be included in recovery plans, and often recovery plans include redundant areas. In comparison, critical habitat is defined in section 3(5)(A) of the Act as, “the specific areas within the geographical area occupied by the species, at the time it is listed * * *” Critical habitat is further defined in the Act as those specific areas, “on which are found those physical or biological features (I) essential to the conservation of the

species and (II) which may require special management considerations or protection.” Under section 3(5)(A)(ii) of the Act, areas outside the geographical area occupied by the species at the time it is listed may only be designated as critical habitat, “upon a determination by the Secretary that such areas are essential for the conservation of the species.” Each of these definitions requires us to look at what is essential to the conservation of the species. The word essential means “absolutely necessary, indispensable.” We interpret this as Congressional direction to designate only those areas that are indispensable to conservation, not to designate areas that may be desirable or helpful for conservation. Furthermore, section 3(5)(C) of the Act prohibits us from designating the entire geographical area which can be occupied by a species without the approval of the Secretary. Thus, we considered the 26 subunits in the recovery plan and designated critical habitat units accordingly as discussed in more detail in comment 1 above.

6.

Comment:

One peer reviewer questioned why we did not include the Smith River locality in the critical habitat designation and make it a priority for protection because it is the northernmost population and may be divergent genetically.

Our Response:

We determined that the survey history shows the species to be consistently rare at this location, and within the past 5 years, surveys in this location have only sporadically located a few individuals. Based on this information, we believe this locality does not serve as a source population and does not provide connectivity between localities (see Criteria Used To Identify Critical Habitat section). We also do not have any information that indicates this locality is occupied by a genetically distinct population. Therefore, we do not consider this locality to have the features that are essential to the conservation of the species.

7.

Comment:

One peer reviewer stated that Scott Creek lagoon in Santa Cruz County should be considered for addition to critical habitat because it is substantially isolated and could be genetically distinct and therefore, may be an important potential stepping stone site.

Our Response:

Scott Creek lagoon was not occupied at the time of listing, although it was subsequently colonized (Service 2005). Over the years, survey efforts indicate that occupancy by tidewater gobies at this locality is intermittent and therefore, we do not consider it a source population (Service 2005). We also do not have information that indicates this locality is occupied by a genetically distinct population. Finally, Scott Creek is not likely to provide connectivity between localities because the next locality to the north, Bean Hollow Creek, is 16.1 mi (26 km) from Scott Creek. This distance is well beyond what experts believe to be the dispersal abilities of the tidewater goby (see Background section). Therefore, we do not consider this locality to be essential to the conservation of the species.

8.

Comment:

One peer reviewer stated that Wilder Creek lagoon in Santa Cruz County should be considered for addition to critical habitat because it has a larger late summer population than Baldwin Creek and may be more likely to supply large numbers of dispersing tidewater gobies to other sites in the metapopulation.

Our Response:

As described in the recovery plan for the tidewater goby (Service 2005), the subunit that includes Wilder Creek consists of several small, closely spaced localities. Only small numbers of individuals have been found in many of these localities and occupancy is intermittent in most areas; survey efforts indicate that occupancy by tidewater gobies at Wilder Creek is intermittent (Service 2005). Tidewater gobies are only regularly abundant at one locality in this subunit, Baldwin Creek, which we have designated as critical habitat. We consider Baldwin Creek to be the source population for this subunit. For these reasons, we do not consider the Wilder Creek lagoon to contain the features essential to the conservation of the species.

9.

Comment:

One peer reviewer recognized that, while Marine Corps Base, Camp Pendleton (Base) may be providing some protection to those tidewater goby populations on the Base, the protection of these populations is not sufficient to protect the southern population of the species as a whole and that areas outside the Base that were historically occupied should be designated.

Our Response:

As discussed in the Marine Corps Base, Camp Pendleton section under Application of Section 4(a)(3), occupied tidewater goby habitat occurs on the Base. We have determined that the conservation efforts for estuarine habitat and species identified in the Base's INRMP provide a benefit to the tidewater goby. Section 4(a)(3) of the Act prohibits the Secretary from designating critical habitat on any lands owned or controlled by the Department of Defense that are subject to an INRMP if the Secretary has determined that such plan provides a benefit to the species for which critical habitat is being proposed for designation. As such, pursuant to section 4(a)(3) of the Act, we have exempted the Base from the designation of critical habitat.

Additionally, none of the historically occupied sites in southern California outside of the Base supported tidewater gobies at the time the species was listed in 1994. In fact, tidewater gobies have not been detected at any of the off-Base southern California sites for several decades. As a result, none of these locations meets the first part of the definition of critical habitat.

As noted above, section 3(5)(A)(ii) requires us to determine whether areas outside the geographical area occupied by the species at the time of listing are essential for the conservation of the species. While our final recovery plan for the tidewater goby identifies these off-Base southern California locations as potential reintroduction sites, it also acknowledges that habitat improvements will be needed before these sites can be recolonized. We acknowledge that some of these sites, if restored, may be helpful contributors to the recovery of the species in southern California. However, we did not designate any areas outside the geographical area occupied by the species as critical habitat for the reasons given in our response to comment 1 above and the Summary of Changes from Previously Designated Critical Habitat and 2006 Proposed Rule section.

Public Comments Regarding Site-Specific Areas

10.

Comment:

One commenter stated that we should have included the area around Lake Earl Lagoon above the 4-foot elevation, and we therefore, underestimated the size of the Lake Earl Lagoon critical habitat unit (see DN-1: Lake Earl/Lake Tolowa section).

Our Response:

Lake Earl is artificially breeched, and there are times when water level is well below the 4-foot elevation. We determined that the 4-foot elevation above mean sea level was appropriate for delineating critical habitat for Lake Earl because the portion of Lake Earl below that elevation is wetted during most times of the year, providing consistent habitat for tidewater goby. The area above the 4-foot elevation that is frequently not submerged does not contain the features essential to the conservation of the species.

11.

Comment:

Several commenters wanted additional areas, including unoccupied areas, designated as critical habitat for the tidewater goby.

Our Response:

Please see our response to comment 1 above.

12:

Comment:

One commenter believed that Hathaway Creek in Mendocino County should be included in the critical habitat designation because it is good tidewater goby habitat and is occupied by tidewater gobies.

Our Response:

We have no record that Hathaway Creek is occupied or has ever been occupied by tidewater gobies, and the commenter did not provide specific information that shows it to be occupied. As per our responses to comment 1 and 2 and as discussed in the Summary of Changes from Previously Designated Critical Habitat and 2006 Proposed Rule section, we have determined that unoccupied habitat is not essential for the conservation of the tidewater goby.

13.

Comment:

Two commenters believed that Arroyo Grande Lagoon in San Luis Obispo County should be considered for addition to critical habitat because: it is likely a source population, it possesses all four primary constituents, and it provides connectivity for the Pismo Creek population with the Santa Maria River population.

Our Response:

We agree that Arroyo Grande Lagoon is likely to have some or all of the primary constituent elements (PCEs) for the tidewater goby; however, the mere presence of one or more PCEs does not mean that an area meets the definition of critical habitat. As described in the recovery plan for the tidewater goby (Service 2005), the subunit that includes Arroyo Grande Lagoon consists of five localities, of which four are currently occupied. Tidewater gobies occur only intermittently at San Luis Obispo Creek and Arroyo Grande Lagoon and only in small numbers. Tidewater gobies are only regularly abundant at two localities in this subunit, Pismo Creek and Santa Maria River, which we have designated as critical habitat. We consider Pismo Creek and Santa Maria River to be the source populations for this subunit. Survey efforts indicate that occupancy by tidewater gobies at Arroyo Grande Lagoon is intermittent (Service 2005) and therefore is not likely to be a source population. For these reasons, we do not consider this locality to contain the features essential to the conservation of the species.

14.

Comment:

One commenter expressed concern over the effects of a proposed multi-lane toll road on tidewater gobies in San Mateo Creek and San Onofre Creek on Marine Corps Base Camp Pendleton (Base). The commenter stated that the Base's INRMP does not address potential impacts to the tidewater goby associated with the proposed toll road, and therefore we should designate habitat along San Mateo Creek and San Onofre on the Base as critical habitat.

Our Response:

The proposed toll road is not a Marine Corps project and therefore is not directly subject to the Base's INRMP. The toll road is a separate Federal action with the U.S. Department of Transportation, Federal Highway Administration as the lead agency; as such, any adverse effects to federally listed species, including tidewater gobies, will be addressed under section 7 of the Act.

However, as described in the Base's INRMP, the Marine Corps agreed that (among other provisos) an on-Base alignment of the toll road could be evaluated provided “that any adverse environmental impacts created as a result of siting this route on the Base * * * must be fully and properly mitigated.” Further, the lower portion of San Mateo Creek and San Onofre Creek is leased to California Department of Parks and Recreation, who is required by the Marine Corps to “conduct its natural resources management consistent with the philosophies and supportive of the objectives” of the Camp Pendleton INRMP. Moreover, the Marine Corps is implementing the INRMP, including actions benefiting the tidewater goby, within the San Mateo Creek and San Onofre watersheds. As stated above, pursuant to section 4(a)(3) of the Act we are required to exempt the Base from critical habitat for the tidewater goby, which includes the lower portion of San Mateo Creek and San Onofre Creek.

15.

Comment:

One commenter stated that unlike Stone or Big Lagoons, Lake Earl is artificially managed and consequently, there is no official monitoring or rescue effort for tidewater gobies, no established population baseline, and a consistent failure to reach the appropriate lagoon level during the summer during tidewater goby breeding season (April to August), making this critical habitat unavailable to tidewater gobies.

Our Response:

The current 10-year Army Corps permit for the breaching of Lake Earl includes the requirement of a monitoring plan. Currently, there are specific post-breach monitoring requirements that include surveying for tidewater gobies in areas suspected to cause stranding. The current permit to breach Lake Earl includes a restriction on breaching after February 15 which is designed to protect tidewater goby habitat during the breeding season, allowing the lagoon sufficient time to close and fill naturally during the spring and summer months, when breeding is thought to peak.

The commenter is correct that there is not enough information available to precisely estimate population baseline. The Service is addressing this issue by looking into innovative methods of obtaining that information in a practical manner.

We believe that the lake levels during most breeding seasons are adequate for tidewater goby breeding to take place if the permit conditions for the artificial breaching are attained.

16.

Comment:

One commenter stated that the proposed revised rule did not provide an analysis of why each individual area with suitable habitat for tidewater gobies, regardless of occupancy, was or was not designated.

Our Response:

To determine which areas to designate as critical habitat for the tidewater goby, we developed a set of rules or criteria (see Criteria Used To Identify Critical Habitat section) specific to tidewater gobies. We believe our criteria identify those areas which meet the definition of critical habitat in the Act and reflect the intent of the recovery plan for the tidewater goby (Service 2005). Based on these criteria, we determined that not all habitat occupied at the time of listing contain the PCEs in the spatial arrangement and quantity essential to the conservation of the species. We also considered localities that we know from surveys, or the lack thereof, were not occupied at the time of listing. We included unoccupied-at-time-of-listing localities in the designation when they met our criteria and were essential to the conservation of the species. See response to Comment 1 for more details.

17.

Comment:

One commenter believed that the proposed critical habitat adjacent to the Mad River Slough Channel should not be designated because they do not include habitat for the tidewater goby.

Our Response:

We believe tidewater goby habitat occurs in these areas adjacent to the Mad River Slough, which are included in Unit Hum-3: Humboldt Bay, because these areas are occupied by tidewater gobies (Goldsmith 2007). We have included these areas in this final revised designation because they form part of the hydrologically interconnected system of estuaries and seasonally flooded backwaters that make up the habitat of the tidewater goby along Humboldt Bay, and these areas have the features that are essential to the conservation of gobies.

Comments Related to Threats to the Species

18.

Comment:

Two commenters stated that illegal breaching of sand bars across

lagoons should be included as an additional new threat.

Our Response:

Untimely breaching of sandbars may be a threat to tidewater gobies in areas where sandbars play a role in the hydrology of estuaries and lagoons. We have provided a discussion of the effects of artificial breaching of sandbars on tidewater gobies, which would include illegal breaching, in the Primary Constituent Elements and Effects of Critical Habitat Designation sections of this rule. We have also more clearly identified artificial breaching of sandbars as a threat to tidewater goby habitat in the Special Management Considerations or Protection section.

19.

Comment:

One commenter stated that disease, particularly since a new species of microsporidian parasite was found in the tidewater goby population at Big Lagoon, should be included as an additional new threat.

Our Response:

The discovery of the parasitic microsporidian referred to by the commenter is a new development. Currently, the parasite has only been identified from Big Lagoon, Humboldt County, with a possible detection from Rodeo Lagoon, Marin County. Surveys evaluating the extent of the parasite, and its role in the decline of the tidewater goby are needed to assess the level of threat to the goby. We have not included this as a threat to the tidewater goby at this time, but will continue to monitor and address new information as it becomes available.

20.

Comment:

One commenter stated we should take in account the potential effects of global warming on tidewater goby habitat and therefore the Service should expand its designation of critical habitat to include unoccupied habitat, particularly upstream of barriers.

Our Response:

The average surface temperature of the Earth is widely recognized by scientists throughout the world to be increasing (IPCC 2007, p. 4). Projected changes in climate include changes in precipitation, sea level rise, and increased frequency and intensity in extreme climatic events leading to increased climate variability (IPCC 2002, p. 4). These changes will have a serious impact on the environment on a global scale. However, it is much more difficult to predict how the climate of a local area will change and how that change will affect the local environment. We are required by section 4(b)(1)(A) of the Act to use the best scientific data available in determining the areas to designate as critical habitat for the tidewater goby. We simply do not have good science at this point that provides local predictions. Therefore, we cannot account for such potential but unknown changes in local climate in our critical habitat designation. However, we do believe this designation does address the potential for climate change by inclusion of critical habitat units over a wide range of latitudes.

Comments Related to Criteria and Methodology

21.

Comment:

One commenter stated that our approach to designating critical habitat could be improved or modified through more public outreach, such as providing information about tidewater goby life history or habitat requirements at some of the critical habitat localities.

Our Response:

We published the Recovery Plan for the Tidewater Goby in 2005. The recovery plan provides detailed information on the biology of the species, reasons for its decline, habitat requirements, the actions needed for recovery of the species, and additional information for each of the localities designated as critical habitat for the species. The recovery plan is available on the Web at

http://ecos.fws.gov/speciesProfile/SpeciesReport.do?spcode=E071.

For future reference, all recovery plans and other documents relating to a species can be found on our Web site at

http://ecos.fws.gov.

22.

Comment:

One commenter stated that critical habitat for tidewater gobies should not be limited to only those areas downstream of barriers.

Our Response:

We consider a barrier, such as sills, dams, and raised culverts, to be impassable by tidewater gobies. Therefore, we consider the areas above the barriers to not contain the features essential to the conservation of the species.

Comments on Other Critical Habitat Related Issues

23.

Comment:

One commenter's opinion was that designation of critical habitat is of little additional value for the tidewater goby.

Our Response:

The process of designating critical habitat as described in the Act requires that the Service identify those lands on which are found the physical or biological features essential to the conservation of the species that may require special management considerations or protection, and the areas outside the current range of the species that are essential for its conservation. In identifying those lands, the Service must consider the recovery needs of the species, such that the habitat that is identified, if managed, could provide for the survival and recovery of the species. Furthermore, once critical habitat has been designated, Federal agencies must consult with the Service under section 7(a)(2) of the Act to ensure that their actions will not adversely modify designated critical habitat or jeopardize the continued existence of the species. As noted in the Ninth Circuit's

Gifford Pinchot

decision, the jeopardy and adverse modification standards are distinct, and adverse modification evaluations require consideration of impacts to the recovery of species. Thus, through the section 7(a)(2) consultation process, critical habitat designations provide recovery benefits to species by ensuring that Federal actions will not destroy or adversely modify designated critical habitat.

Another benefit of including lands in critical habitat is that designation of critical habitat serves to educate landowners, State and local governments, and the public regarding the potential conservation value of an area. Although the designation of critical habitat may not, in and of itself, restrict human activities within an area or mandate any specific management or conservation actions, it does help focus Federal, Tribal, State, and private conservation and management efforts in such areas by clearly delineating areas of high conservation value for the tidewater goby. In general, critical habitat designation always has educational benefits; however, in some cases, they may be redundant with other educational effects.

24.

Comment:

One commenter requested clarification regarding the October 9, 2007, press release noticing the completion of the tidewater goby 5-year review and its recommendation to downlist the species throughout its range. More specifically, the commenter wanted to know how a reclassification to threatened would affect the status of designated critical habitat.

Our Response:

Critical habitat applies equally to both endangered and threatened species. Therefore, reclassifying the tidewater goby from endangered to threatened would have no affect on the designated critical habitat.

25.

Comment:

One commenter expressed concern that designation of critical habitat for the tidewater goby may conflict with management of Aleutian Canada goose (

Branta Canadensis leucopareia

) habitat (Humboldt Bay and Eel River Delta areas) (grazing benefits the goose by improving its habitat), by restricting grazing in upland areas.

Our Response:

The designation of critical habitat does not, in and of itself, restrict human activities within an area or mandate any specific management or conservation actions. However, one of

the benefits of critical habitat is to help focus Federal, Tribal, State, and private conservation and management efforts in such areas. With the knowledge that there is an area that is important to both the Aleutian Canada goose and the tidewater goby, management actions compatible with both species may be undertaken.

Comments Related to Policy Compliance

26.

Comment:

One commenter stated that Federal statutes and regulations require Federal agencies to coordinate their initial planning efforts with local government. Presidential Executive Order 12372 requires Federal agencies to coordinate actions and projects with local governments. To date, the Service has failed to initiate coordination with Del Norte County as required by Federal statute.

Our Response:

Executive Order 12372 (47 FR 30959; July 14, 1982), Intergovernmental Review of Federal Programs pertains to Federal Assistance and is not directly pertinent to this designation of critical habitat. However, we do address the issue of Federal-State Coordination below. Please see the Federalism section for additional information.

Comments Related to the Draft Economic Analysis

27.

Comment:

Several commenters requested that we extend the comment period on the draft economic analysis.

Our Response:

Due to time constraints associated with the consent decree dated February 27, 2003, we were not able to extend or open an additional public comment period.

28.

Comment:

One commenter stated that the economic analysis does not provide grounds for exclusion of any critical habitat because it does not include benefits.

Our Response:

The economic analysis for the tidewater goby did consider economic benefits. Our draft economic analysis predicted an overall net cost savings of $10.2 million to $65.2 million (undiscounted) over the next 20 years.

29.

Comment:

One commenter stated that the economic analysis fails to estimate the benefits of critical habitat designation. This comment includes concerns that the Service: Did not identify the vast majority of benefits from designating critical habitat, including benefits to ecosystem services, wetland protection, and other use and non-use values of habitat; violated the Act by failing to quantify benefits; improperly relied on flawed OMB guidance regarding the estimation of benefits; does not properly qualitatively describe the benefits of designation; improperly establishes the baseline because benefits are not estimated; does not prove the infeasibility of estimating and monetizing benefits in the analysis; could easily quantify the benefits of designating critical habitat; and ignores available information from multiple sources that could have been used to estimate benefits.

Our Response:

The economic analysis for the tidewater goby did include benefits. Our draft economic analysis predicted an overall net cost savings of $10.2 million to $65.2 million (undiscounted) over the next 20 years. The only quantifiable benefit of goby conservation identified through the economic analysis is the saving associated with not constructing a sewage bypass system. While the economic analysis acknowledges the potential for other types of economic benefits, data were not available, for example, to identify where and to what extent property values may be affected by tidewater goby conservation efforts. For example, while property valuation studies may provide estimates of the value to property of being near environmentally pristine area, these studies do not address what changes in property values will result from critical habitat designation.

Section 4(b)(2) of the Act requires the Secretary to designate critical habitat based on the best scientific data available after taking into consideration the economic impact, impact on national security, and any other relevant impact, of specifying any particular area as critical habitat. Where data are available, the economic analyses do attempt to measure the net economic impact.

Most of the other benefit categories submitted by the commenter reflect broader social values, which are not the same as economic impacts. While the Secretary must consider economic and other relevant impacts as part of the final decision-making process under section 4(b)(2) of the Act, the Act explicitly states that it is the government's policy to conserve all threatened and endangered species and the ecosystems upon which they depend. Thus, we believe that explicit consideration of broader social values for the subspecies and its habitat, beyond the more traditionally defined economic impacts, is not necessary as Congress has already clarified the social importance.

30.

Comment:

One commenter stated that the baseline is improperly set because it relies on the Tenth Circuit Court of Appeals instead of the Ninth Circuit, and that the baseline should be compared with the incremental impacts of the designation. Similarly, another commenter expressed concern that the economic analysis improperly measures the impacts of designation by including costs that would have been incurred regardless of critical habitat designation. This commenter stated that impacts such as land acquisition and grazing costs are not properly integrated into the baseline and should not be considered as a consequence of designation, and that the economic analysis does not describe the costs attributable solely to designation.

Our Response:

Appendix B of the Final Economic Analysis (FEA) estimates the potential incremental impacts of critical habitat designation for the goby. It does so by attempting to isolate those direct and indirect impacts that are expected to be triggered specifically by the critical habitat designation. The incremental conservation efforts and associated impacts included in Appendix B would not be expected to occur absent the designation of critical habitat for the tidewater goby. Total present value potential incremental impacts are estimated to be $206,000 discounted at three percent. All other impacts quantified in the FEA are considered baseline impacts and are not expected to be affected by the critical habitat designation.

31.

Comment:

One commenter requested clarification regarding the 50-meter (m) buffer used in the analysis of the study areas for the economic analysis. The commenter was concerned that the term “buffer” indicated that these areas will be barred from use.

Our Response:

The study area analyzed in the draft economic analysis included the critical habitat units, which are primarily lagoons, estuaries, and coastal streams, and a 50-meter (m) wide stream buffer that extended 100 m upstream of the critical habitat units. These buffer areas are not included in the critical habitat units. However, for the purposes of the analysis it was assumed that activities conducted in these areas could indirectly affect the critical habitat units. Therefore, the draft economic analysis took into consideration the potential economic costs that could result from conservation efforts for the tidewater goby within the buffer areas. Also, the term “buffer” as used in Chapter 3 of the FEA has been clarified to indicate that it is for analytical purposes only.

32.

Comment:

Two commenters stated that the land identified as private land within the grazing study area, which the economic analysis determined as

lacking a Federal nexus compelling consultation, should have been addressed in the economic analysis. The commenter is concerned that some combination of Federal, State, and local laws may affect grazing on those private lands.

Our Response:

Review of existing land management documents, section 7 consultations, and State and private grazing practices do not indicate that this private land is likely to be affected. Private grazers have not been affected by goby conservation in the past, there are no known voluntary private grazing restrictions, and, under the Act, the critical habitat designation will not affect grazing on private land absent a Federal nexus. Further, no information is available to suggest that critical habitat designation may trigger additional regulation under other State and local laws concerning grazing. This analysis therefore forecasts that private grazing activity is not likely to be affected by goby conservation.

33.

Comment:

One commenter stated that the draft economic analysis does not address municipal land ownership of grazing land, but counts it as privately-owned land instead. The commenter expressed concern that the economic analysis should predict future conservation efforts on municipal land.

Our Response:

Review of existing land management documents, consultations, and State and private grazing practices do not indicate that municipal land is likely to be affected differently than private land. Grazing on municipal land has not been affected by goby conservation in the past, and information gathered in the development of the analysis did not suggest that it was likely to be affected in the future. Under the Act, the critical habitat designation will not affect grazing on municipal land absent a Federal nexus, and there is no information to suggest that State or local regulation may be tightened because of the designation of critical habitat. This analysis therefore forecasts that grazing on municipal lands is unlikely to be affected by goby conservation.

34.

Comment:

One commenter expressed concern about impacts of potential changes in grazing restrictions and management practices on the state lands due to critical habitat.

Our Response:

Information received during the comment period concerning the California Department of Fish and Game's (CDFG) grazing management practices on State lands in the study area has prompted changes in Chapter 3 of the economic analysis. The FEA estimates foregone forage values and construction costs as part of the baseline impacts of CDFG management. These ongoing, co-extensive impacts are expected to continue into the future. There are no anticipated changes for grazing practices in the study area that will result from the critical habitat designation. Further, no additional impacts to grazing activities are expected to result from this rulemaking as described in Chapter 3 of the FEA.

35.

Comment:

One commenter stated that there are alternative ways to manage grazing other than exclusion.

Our Response:

The commenter is correct; there are alternative ways to manage grazing other than exclusion. However, CDFG currently manages grazing in tidewater goby habitat through exclusion. As noted in Chapter 3 of the FEA, the practice of excluding livestock from tidewater goby habitat is unlikely to change after critical habitat designation as CDFG does not anticipate that there will be any future changes to grazing management practices. Chapter 3 provides post-designation cost estimates for current CDFG management practices that CDFG has validated and indicates are unlikely to change. Total impacts to grazing are estimated to be $1.53 million, undiscounted (20 percent lost grazing value and 80 percent fencing maintenance and construction costs).

36.

Comment:

Two commenters stated that the undiscounted impacts to grazing of $1,430,000 are understated. The commenters pointed out that the number of Animal Unit Months (AUMs) should be multiplied by the number of months grazed.

Our Response:

New information received during the comment period from the CDFG has been incorporated into the FEA regarding grazing impacts. As described in Chapter 3, the estimates of foregone grazing values incorporate the number of months in the grazing season. The information received during the comment period provided better data on both grazing and fencing construction and maintenance impacts. The FEA estimates foregone forage values and construction costs as part of the baseline impacts of CDFG management. These ongoing, co-extensive impacts are expected to continue into the future. The draft economic analysis estimated $1.43 million in undiscounted total impacts (4 percent lost grazing value and 95 percent fence construction and maintenance costs). Based upon the information received during the comment period, total impacts to grazing are estimated to be $1.53 million, undiscounted (20 percent lost grazing value and 80 percent fencing maintenance and construction costs).

37.

Comment:

Three commenters stated that potential grazing land should be valued not at its rental rate, but at the opportunity cost in terms of the amount of livestock that could not be produced. These commenters stated that reducing grazing acreage has additional effects beyond the market value of the land.

Our Response:

As discussed in Section 3.1.3 of the FEA, the analysis applies a well-accepted method of assigning value to grazing land using the forage value available on that land, expressed in AUMs, as a proxy. The grazing rental rate is the opportunity cost of the forage that is given up. This price is the amount that would have to be paid to purchase an equivalent amount of grazing forage somewhere else.

38.

Comment:

Two commenters stated that some of the land that will be removed from grazing may be organic, which has a higher rental value.

Our Response:

While the FEA quantifies ongoing, co-extensive impacts of foregone grazing associated with goby conservation, it does not forecast further limitations on grazing activity as a result of critical habitat designation. While organic grazing rental rates are likely to be higher, consultation with CDFG has indicated that the rental estimates provided in Chapter 3 closely approximate the total impacts of the existing grazing management program.

39.

Comment:

One commenter stated that the economic analysis does not explain the presence of the pre-designation impacts.

Our Response:

As discussed in the introduction to Chapter 1 and in Section 1.4.6 of the FEA, pre-designation impacts are provided as context for the ongoing goby conservation efforts in the post-designation period. The continuation of existing policies and practices post-designation is evident when comparing the pre- and post-designation impact exhibits in Chapters 2 through 6.

40.

Comment:

One commenter said that the cost of constructing exclosure fencing would be a huge burden on the ranching community.

Our Response:

The question of who is affected by exclosure costs has been clarified in Section 3.1.2 of the FEA. Following conversations with CDFG, the costs of building fencing quantified in the analysis are forecast to be paid by CDFG and not by the ranching community.

41.

Comment:

One commenter stated that the economic analysis did not address potential critical habitat designation impacts on recreation and recreation dependent businesses.

Our Response:

Review of management documents and consultations, and interviews with the National Park Service, counties, municipalities, and local park officials did not indicate that goby conservation efforts would be undertaken that may affect recreational activities. A sentence clarifying this point has been added to Section 1.1 of the FEA.

42.

Comment:

One commenter stated that the economic analysis does not consider secondary effects on resource conservation districts that currently sub-contract to provide grazing management services.

Our Response:

As described in Chapter 3, the economic analysis does not predict any changes in grazing policy as a result of critical habitat designation.

43.

Comment:

One commenter stated that the economic analysis failed to address what could happen if sandbar breaching at Lake Earl is no longer permitted. The commenter cited excerpts from breaching consultations and says that the consultation appears to favor not breaching, which would cause substantial economic impacts to property.

Our Response:

As indicated in Section 2.2 of the FEA, a review of the consultation history and discussions with the Service, CDFG, and the U.S. Army Corps of Engineers, indicate that the cessation of sandbar breaching permitting in Lake Earl is improbable.

Comments From the State

44.

Comment:

The California Department of Fish and Game stated that our critical habitat designations are premature and we should wait until our current data gathering and genetic analyses for Del Norte, Humboldt, and Mendocino Counties are completed and disclosed.

Our Response:

As required by section 4(b)(1)(A) of the Act, we used the best scientific data available in determining the areas to designate as critical habitat for the tidewater goby. Further, under a consent decree, we are restricted to a specific deadline for finalizing the critical habitat designation. As such, we must use the best scientific data available to us at this time and cannot delay our designation to allow for possible additional data. Within the area mentioned, the commenter suggests that the presence of tidewater gobies within Humboldt Bay does not indicate that the population sites are persistent. On the contrary, there are several sites where surveys indicate alternating presence and absence of gobies. We believe that the significance of detecting tidewater gobies within Humboldt Bay as a unit should be emphasized, and due to their potential ability to move within the bay, we believe that we designated the area with features essential to the species within Humboldt Bay.

45.

Comment:

The California Department of Fish and Game asserted that we have a lack of understanding regarding the processes that drive and maintain metapopulation dynamics (e.g., hydrology, hydrological connections, source population identification, persistence of sink populations) used in determining the PCEs and identifying whether critical habitat exists at certain locations in the absence of tidewater goby presence.

Our Response:

The process we use to identify the features that are essential to the conservation of the tidewater goby reflects a complete assessment of the current, best scientific data available. We also solicited information from knowledgeable biologists that have worked with the tidewater goby. We did not find any locations that are currently unoccupied to be essential to the conservation of the species.

Summary of Changes From Previously Designated Critical Habitat and 2006 Proposed Rule

On November 20, 2000, we designated critical habitat for the tidewater goby at 10 coastal stream segments in Orange and San Diego Counties, California, totaling approximately 1,581 acres (ac) (642 hectares (ha)) (65 FR 69693). We proposed to revise this designation to a total of approximately 10,003 ac (4,050 ha) on November 28, 2006 (71 FR 68914). This is an increase of approximately 8,422 ac (3,408 ha) from the previously designated critical habitat. In this section we present the differences between what was designated in 2000 and what is included in this revised final designation.

The 2000 final critical habitat designation (65 FR 69693, November 20, 2000) consisted of 10 units totaling 1,581 ac (642 ha). In the 2000 rule, critical habitat was only designated in Orange and San Diego Counties due to uncertainty over the future listing status of tidewater goby populations to the north. The Service had published a proposed rule on June 24, 1999, to: (1) Delist populations of the tidewater goby in areas north of Orange and San Diego Counties, and (2) retain the tidewater goby populations in Orange and San Diego Counties as an endangered distinct population segment based on our re-evaluation of the species' status throughout its range (64 FR 33816). Subsequently, the Service determined that the tidewater goby should remain listed as endangered throughout its range and withdrew the June 24, 1999, proposal (67 FR 67803, November 7, 2002). In this revised final critical habitat designation we have designated critical habitat for the tidewater goby throughout its range. We considered but did not include the 10 units that were previously designated in Orange and San Diego Counties. We exempted 8 of the 10 units, all of which are located on U.S. Marine Corps Base, Camp Pendleton (Base), under section 4(a)(3) of the Act because these areas are subject to the Base's INRMP and we determined that the INRMP provides a benefit to the tidewater goby and its habitat (see Application of Section 4(a)(3) of the Act—Approved Integrated Natural Resource Management Plans section). We also considered but did not include the remaining 2 units out of the 10 from the 2000 rule (65 FR 69693), Aliso Creek in Orange County and Agua Hedionda Lagoon in northern San Diego County. For several reasons, we have now determined that these two localities are not essential for the conservation of the species. The 2000 designation found that the eight occupied localities on the Base were not sufficient for the conservation of the species. However, at that time, the Base did not have an approved INRMP and therefore, the future of the tidewater goby on the Base was not assured. Subsequent to the 2000 designation, the Base completed its INRMP, which includes protections for the tidewater goby. Specific measures in the INRMP that benefit the tidewater goby include: (1) General avoidance of estuarine wetlands by all military activities, (2) maintenance of currently and historically occupied tidewater goby habitat, (3) compensation for unavoidable impacts, (4) regular monitoring of tidewater goby populations, and (5) controlling and removing exotic plants and fish.

Second, more information is now available on the status of both the tidewater goby throughout its range and on the Base. We now know that there are many more occupied localities than when the species was listed in 1994. In our recently completed 5-year review for the tidewater goby, we found that the number of occupied localities has more than doubled since the species was listed (106 versus 48) and concluded that the species was more resilient to perturbations such as drought than was believed when it was listed. As a result we recommended in the 5-year review that the tidewater goby be downlisted to threatened. We also now have a longer record of the continued occupancy of those localities

on the Base, which supports our view that they make up 1-2 viable metapopulations. Therefore, we have now determined that the occupied habitat in Orange and San Diego Counties is sufficient to support the natural pattern of local extinctions and recolonizations (Swift et al. 1989, Moyle et al. 1995, Lafferty et al. 1999b, Swenson 1999) that characterize the tidewater goby's population biology. Thus, the unoccupied areas designated in 2000 (i.e., Aliso Creek and Agua Hedionda Lagoon) are no longer considered essential for the conservation of the tidewater goby.

We also made changes to our proposed designation in preparing this final critical habitat designation for the tidewater goby. We reviewed and considered comments from the public and peer reviewers on the proposed revised designation of critical habitat published on November 28, 2006 (71 FR 68914). We also received comments from the public on the draft economic analysis published on September 25, 2007 (72 FR 54411). As a result of comments received, we made changes to our proposed designation, as follows:

(1) Based on peer review comments, we further refined our definition of source populations (see response to comment 3). However, this did not result in any change in the designation.

(2) We made minor adjustments to the number of areas historically and currently occupied by tidewater gobies because in some cases we have combined two adjacent areas into one, and a few areas have recently become occupied. However, these changes did not affect the number or acreage of the units proposed for designation.

Critical Habitat

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

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

(a) Essential to the conservation of the species and

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

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

Conservation, as defined under section 3 of the Act, means to use and the use of all methods and procedures that are necessary to bring any endangered species or threatened species to the point at which the measures provided under the Act are no longer necessary.

Critical habitat receives protection under section 7 of the Act through the prohibition against Federal agencies carrying out, funding, or authorizing the destruction or adverse modification of critical habitat. Section 7(a)(2) of the Act requires consultation on Federal actions that may affect critical habitat. The designation of critical habitat does not affect land ownership or establish a refuge, wilderness, reserve, preserve, or other conservation area. Such designation does not allow the government or public access to private lands. Such designation does not require implementation of restoration, recovery, or enhancement measures by non-federal landowners. Where a non-federal landowner seeks or requests federal agency funding or authorization for an action that may affect a listed species or critical habitat, the consultation requirements of Section 7(a)(2) would apply, but even in the event of a destruction or adverse modification finding, the Federal action agency's and the applicant's obligation is not to restore or recover the species, but to implement reasonable and prudent alternatives to avoid destruction or adverse modification of critical habitat.

To be included in a critical habitat designation, habitat within the geographical area occupied by the species at the time it was listed must contain features that are essential to the conservation of the species. The Service must identify, to the extent known using the best scientific data available, habitat areas that provide essential life cycle needs of the species (areas on which are found the PCEs, as defined at 50 CFR 424.12(b)). The features at issue must also be ones that may require special management considerations or protection.

Under the Act, we can designate areas outside the geographical area occupied by the species at the time it is listed as critical habitat only when we determine that those areas are essential for the conservation of the species.

Section 4 of the Act requires that we designate critical habitat on the basis of the best scientific and commercial data available. Further, our Policy on Information Standards Under the Endangered Species Act, published in the

Federal Register

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

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

Habitat is often dynamic, and species may move from one area to another over time. Furthermore, we recognize that critical habitat designated at a particular point in time may not include all of the habitat areas that we may later determine are necessary for the recovery of the species. For these reasons, critical habitat designation does not signal that habitat outside the designation is unimportant or may not be required for recovery of the species.

Areas that are important to the conservation of the tidewater goby, but are outside the critical habitat designation, will continue to be subject to conservation actions implemented by Federal agencies under section 7(a)(1) of the Act. Areas that support populations are also subject to the regulatory protections afforded by the section 7(a)(2) jeopardy standard, as determined on the basis of the best available scientific information at the time of the agency action. Federally funded or permitted projects affecting listed species outside their designated critical habitat areas may still result in jeopardy findings in some cases. Similarly, critical habitat designations made on the basis of the best available information at the time of designation will not control the direction and substance of future recovery plans, habitat conservation plans (HCPs), or other species conservation planning efforts, if information available at the time of these planning efforts calls for a different outcome.

Primary Constituent Elements

In accordance with section 3(5)(A)(i) of the Act and the regulations at 50 CFR 424.12, in determining which areas within the geographical area occupied at

the time of listing to designate as critical habitat, we consider those physical and biological features that are essential to the conservation of the species to be the primary constituent elements (PCEs) laid out in the appropriate quantity and spatial arrangement for conservation of the species. These include, but are not limited to:

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

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

(3) Cover or shelter;

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

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

The specific PCEs required for the tidewater goby are derived from the biological needs of the tidewater goby as described in the final listing rule, the proposed revised critical habitat rule (71 FR 68914), and information contained in this final rule.

Space for Individual and Population Growth and Normal Behavior

Saline Aquatic Habitat

Tidewater gobies occur in lagoons, estuaries, and backwater marshes that are adjacent to the Pacific Ocean (Wang 1982, p. 14; Irwin and Soltz 1984, p. 27; Swift

et al

. 1989, p. 1; Swenson 1993, p. 3; Moyle 2002, p. 431). Tidewater gobies are most commonly found in waters with relatively low salinities, i.e., less than 10 to 12 parts per thousand (ppt) (Swift

et al

. 1989, p. 7). This species can, however, tolerate a wide range of salinities and is frequently found in coastal habitats with higher salinity levels (Swift

et al

. 1989, p. 7; Worcester 1992, p. 106; Swift

et al

. 1997, pp. 15-22). The species has been collected in salinities as high as 42 ppt (Swift

et al

. 1989, p. 7). The species' tolerance of high salinities likely enables it to withstand some exposure to the marine environment, allowing it to recolonize nearby lagoons and estuaries following flood events. However, tidewater gobies have only rarely been captured in the marine environment (Swift

et al

. 1989, p. 7), and they appear to enter the ocean only when flushed out of lagoons, estuaries, and river mouths by storm events or human-caused breaches of sand bars.

The goal of the recovery plan for the tidewater goby is to preserve the diversity of habitats that occur within the range of the species, the metapopulation structure of the species, and genetic diversity (Service 2005). The recovery plan identifies 26 subunits throughout the range of the tidewater goby. We designated critical habitat in all 26 subunits included in the recovery plan, except for those on Vandenberg Air Force Base (Santa Barbara County) and Marine Corps Base, Camp Pendleton (San Diego County), which have Integrated National Resource Management Plans (INRMP) that provide protection for the tidewater goby. These areas have been exempted from this final designation of critical habitat (see Application of Section 4(a)(3) of the Act—Approved Integrated Natural Resource Management Plans section). We believe these 44 critical habitat units, in addition to those subunits covered by INRMP's, are the areas essential to the conservation of the species throughout its range, as they adequately represent the variation of both the habitat and genetic composition of the species, and they will support the species’ recovery. As such, we did not designate any other areas, including areas outside the geographical area occupied by the species, as critical habitat. For a further discussion of how we determined how much space was essential to the conservation of the species, please see the Criteria Used To Identify Critical Habitat section below.

Water Depth, Velocity, and Temperature

Tidewater gobies are most commonly collected in water less than 6 feet (ft) (2 meters (m)) deep (Wang 1982, pp. 4-5; Worchester 1992, p. 53). However, recently tidewater gobies were collected in Big Lagoon in Humboldt County during the breeding season at a water depth of 15 ft (4.6 m) (Goldsmith 2006a, p. 1). Whether use of these deeper waters is confined to this locality or is more widespread will require additional sampling at various depths at various locations.

Tidewater gobies tend to avoid currents and concentrate in slack-water areas; this suggests they are less likely to occur in areas with a steep gradient or microhabitats that have a substantial current. At Pescadero Creek in San Mateo County, tidewater gobies were absent from portions of the flowing creek that had a surface velocity of 0.15 m per second (0.49 ft per second), and the species was instead more densely concentrated in nearby eddies with lower water velocities (Swenson 1993, p. 3).

Backwater marshes, including lateral sloughs, are likely to be important to tidewater gobies for multiple reasons. Flood waters with increased water velocities can have a negative effect on tidewater gobies (Irwin and Soltz 1984, p. 27), and backwater marshes may provide important refuges that reduce the likelihood that tidewater gobies will be flushed out of the lagoons or estuaries and into the marine environment during heavy winter floods (Lafferty

et al.

1999a, p. 619). Evidence that increased flows can eliminate tidewater gobies from a locality is suggested by the elimination of tidewater gobies from Waddell Creek in Santa Cruz County following a flood event in the winter of 1972-73 (Nelson as cited in Swift 1990, p. 2); this creek had been channelized and no longer afforded protection from high flows during flood events. Likewise, the channelization and elimination of habitat lateral to the main stream channel upstream of San Onofre Lagoon in San Diego County probably led to the flushing and extirpation of tidewater gobies from this locality during a storm in 1993 (Swift

et al.

1994, p. 22-23). The importance of backwater marshes is also highlighted by the fact that tidewater gobies in these habitats can achieve a greater size than in adjacent lagoons and creeks (Swenson 1993, pp. 6-7).

Freshwater Habitat

Tidewater gobies also occur in freshwater streams up gradient and tributary to brackish habitats; the salinity of these freshwater streams is typically less than 0.5 ppt. The available documentation demonstrates that in some areas, tidewater gobies can occur 1.6 to 7.3 miles (mi) (2.6 to 11.7 kilometers (km)) upstream from the ocean environment (Irwin and Soltz 1984, p. 27; Swift

et al.

1997, p. 20; Chamberlain and Goldsmith 2006, p. 1).

Within a 2-hour period, hundreds of tidewater gobies have been observed to move upstream of a fixed location into areas in the Santa Ynez River 3.2 mi (5.1 km) from the ocean in Santa Barbara County (Swift

et al.

1997, p. 20). The fact that this many individuals were observed to move through an area suggests that freshwater tributaries in some riverine systems provide important habitat for individual and population growth.

We have reviewed a variety of documents to determine how far tidewater gobies have been detected upstream from the ocean. Chamberlain and Goldsmith (2006, p. 1) found tidewater gobies 1.6 to 2.0 mi (2.6 to 3.3 km) upstream from the ocean in the Ten Mile River in Mendocino County; Swift

et al.

(1997, p. 18) found tidewater gobies 4.6 mi (7.3 km) upstream from the ocean in the San Antonio River in Santa Barbara County; Swift

et al.

(1997,

p. 20) found tidewater gobies at various distances from 3.9 to 7.3 mi (6.2 to 11.7 km) upstream from the ocean in the Santa Ynez River in Santa Barbara County; and Holland (1992, p. 9) found tidewater gobies 3 mi (5 km) upstream from the ocean in the Santa Margarita River in San Diego County. Collectively, these data suggest the average distance tidewater gobies have been detected upstream from the ocean in medium to large rivers is approximately 3.8 mi (6.1 km). Other than high stream gradient, the reasons for the variation in up-stream movement between one locality and another have not been determined; salinity could be an important factor. Upstream salinity levels may vary with time of year, tidal cycles, storm events, and topography. However, Swift

et al.

(1997, p. 26) indicate that gradient and lack of barriers (e.g., beaver dams, sills) are more important factors than salinity to upstream dispersal.

Sandbars

Many of the locations occupied by the tidewater goby closely correspond to stream drainages. Under natural conditions, these stream drainages and the marine environment collectively act to produce sandbars that form a barrier between the ocean and the lagoon, estuary, backwater marsh, and freshwater stream system (Habel and Armstrong 1977, p. 39). These sandbars tend to be present during the late spring, summer, and fall seasons. The presence of a sandbar can create a lower salinity level (i.e., 5 to 10 ppt) in the area up gradient from the sandbar (Carpelan 1967, p. 324) than would otherwise exist if there were no sandbar.

Tidewater gobies are more commonly associated with these lower salinity levels than with the salinity levels that occur in the ocean or an estuary without a sandbar, i.e., about 35 ppt. The formation of a sandbar also creates a larger area for aquatic organisms because water becomes ponded behind the sandbar. Artificial breaching of a sandbar tends to result in a rapid decrease in water levels and increases the likelihood that adult tidewater gobies, their nests, and their fry could become stranded and die, or become concentrated and subject to greater levels of predation pressure by birds or other predators.

In Humboldt Bay and the Eel River estuary in Humboldt County, a large amount of salt and brackish marsh habitat was eliminated through the construction of levees and drainage channels. As a result, several of the localities occupied by the tidewater goby do not contain natural sandbars between the ocean and habitat where the species is present. Instead, manmade water control structures, such as tidegates and culverts, exist between tidal waters and the locations where tidewater gobies occur. These tidegates have been in place for decades, and in some cases, they provide habitat conditions similar to those created by the presence of a seasonal sandbar. In fact, most of the occupied tidewater goby habitats in the Humboldt Bay-Eel River estuaries are above tidegates.

Food

Tidewater gobies feed mainly on macro-invertebrates such as mysid shrimp, gamarid amphipods, ostracods, and aquatic insects such as chironomid midge larvae (Irwin and Soltz 1984, p. 21-23; Swift

et al.

1989, p. 6; Swenson 1995, p. 87). The diets of adult and juvenile tidewater gobies tend to include the same relative abundance of different invertebrate species (Swenson and McCray 1996, p. 962).

Cover or Shelter

A variety of native and nonnative fish species and fish-eating bird species such as egrets (

Egretta

spp.) and herons (e.g., great blue herons (

Ardea herodias

)) prey on tidewater gobies, and escape cover or shelter is necessary to reduce the likelihood that tidewater gobies will be preyed upon.

A species' ability to persist when it is subject to predation pressure frequently depends on the presence of features that provide cover from predators, or the presence of a heterogeneous habitat that provides a greater level of structure which makes it more likely a prey species will avoid predation (Crowder and Cooper 1982, p. 1802; Gilinsky 1984, p. 455).

At locations where tidewater gobies occur, submerged and emergent aquatic vegetation has the potential to provide cover from predators, and provide a greater degree of habitat heterogeneity or structure that would not otherwise exist if the aquatic vegetation was absent. Stable lagoons often possess dense aquatic vegetation that frequently consists of sago pondweed (

Potamogeton pectinatus

) or widgeon grass (e.g.,

Ruppia maritima

and

R. cirrhosa

). At some locations, juvenile tidewater gobies are more prevalent in areas with at least some submergent vegetation as compared to other areas with no or little vegetation (Wang 1984, p. 16; Swenson 1994, p. 6; Trihey & Associates, Inc. 1996, p. 11). We believe it is reasonable to assume that the presence of submerged or emergent vegetation reduces the likelihood that tidewater gobies will be preyed upon by native and nonnative species because this vegetation provides cover and increases the level of habitat heterogeneity in a way that makes it more likely that tidewater gobies will persist where they co-occur with predators.

Aquatic vegetation may provide some degree of shelter or refuge during flash flood events (Lafferty

et al.

1999b, p. 621). These refuges presumably would result because the presence of vegetation would create lower water velocities than might otherwise occur in unvegetated areas. Such refuges would be especially important to fish species that are not strong swimmers, such as the tidewater goby.

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

The eggs of the tidewater goby are laid in burrows that are excavated by male fish. The available literature suggests that burrows most commonly occur in areas with relatively unconsolidated, clean, coarse sand (Swift

et al.

1989, p. 8), while other documents demonstrate that burrows also occur in silt or mud (Wang 1982, p. 6). Swenson (1995, p. 148) demonstrated that tidewater gobies prefer a sandy substrate in the laboratory. Male tidewater gobies remain in the burrow to guard the eggs attached to the burrow ceiling and walls. Male tidewater gobies care for the embryos for approximately 9 to 11 days until they hatch, rarely if ever emerging from the burrow to feed (Swift

et al.

1989, p. 4). Tidewater goby larvae occupy the water column after the eggs hatch (Wang 1982, p. 15). As they mature, they occupy the bottom substrate. Worcester (1992, pp. 77-79) found that larval tidewater gobies in Pico Creek Lagoon in San Luis Obispo County tended to use the deeper portion of the lagoon, i.e., 29 inches (in) (73 centimeters (cm)) deep water versus 17 in (42 cm) deep water.

Primary Constituents for the Tidewater Goby

Under the Act and its implementing regulations, we are required to identify the known primary constituent elements (PCEs) within the geographical area occupied by the species that in the appropriate spatial arrangement and quantity comprise the physical or biological features essential to the conservation of the species which may require special management considerations or protection.

Based on our current knowledge of the life history, biology, and ecology of the species and the requirements of the habitat to sustain the essential life history functions of the species, we have

determined that the tidewater goby's PCEs are:

(1) Persistent, shallow (in the range of about 0.1 to 2 m), still-to-slow-moving, aquatic habitat most commonly ranging in salinity from 0.5 ppt to about 10 to 12 ppt, which provides adequate space for normal behavior and individual and population growth;

(2) Substrates (e.g., sand, silt, mud) suitable for the construction of burrows for reproduction;

(3) Submerged and emergent aquatic vegetation, such as

Potamogeton pectinatus

,

Ruppia maritima

,

Typha latifolia

, and

Scirpus

spp. that provides protection from predators; and

(4) Presence of a sandbar(s) across the mouth of a lagoon or estuary during the late spring, summer, and fall that closes or partially closes the lagoon or estuary, thereby providing relatively stable water levels and salinity.

This designation of critical habitat for the tidewater goby is designed for the conservation of PCEs necessary to support the life history functions of the species comprising the physical or biological features essential to the conservation of the species, and the areas supporting these features. We propose units for designation based on sufficient PCEs being present to support at least one of the species' life history functions. Some units contain all of these PCEs and support multiple life processes, while some units contain only a portion of these PCEs, those necessary to support the species' particular use of that habitat.

Special Management Considerations or Protection

When designating critical habitat, we assess whether the areas within the geographical area occupied by the species at the time of listing contain the features essential to the conservation of the species that may require special management considerations or protection. Special management considerations or protection may be necessary to eliminate or reduce the magnitude of threats that affect the tidewater goby. Threats that were identified in the final rule listing the tidewater goby include: (1) Coastal development projects that result in the loss or alteration of coastal wetland habitat; (2) water diversions and alterations of water flows upstream of coastal lagoons and estuaries that negatively impact the species' breeding and foraging activities; (3) groundwater overdrafting that results in reduction of flows and negatively impacts the species' breeding and forging activities; (4) channelization of habitats where the species occurs that removes or reduces quality of habitat; (5) discharge of agricultural and sewage effluents; (6) cattle grazing and feral pig activity that results in increased sedimentation of coastal lagoons and riparian habitats, removes vegetative cover, increases ambient water temperatures, and eliminates plunge pools and collapsed undercut banks utilized by tidewater gobies; (7) introduced species that prey on the tidewater goby (e.g., bass, crayfish (

Cambaris

spp.)); (8) the inadequacy of existing regulatory mechanisms; (9) drought conditions that result in the deterioration of coastal and riparian habitats; and (10) competition with introduced species such as the yellowfin goby and chameleon goby.

For the purposes of this rule, we have combined the “water diversions and alterations of water flows upstream of coastal lagoons and estuaries that negatively impact the species' breeding and foraging activities” threats category with “drought conditions” and “groundwater overdrafting,” along with the addition of artificial breaching of sandbars, into one threat category called “water diversions, alterations of water flows, artificial sandbar breaching, and groundwater overdrafting that negatively impact the species' breeding and foraging activities.” Similarly, we have combined the two threat categories of “introduced species that prey on the tidewater goby (e.g., bass, crayfish, (

Cambaris

spp.))” and “competition with introduced species such as the yellowfin goby and chameleon goby” into one category called “Introduced species that prey on, or compete with, the tidewater goby (e.g., yellowfin gobies, bass, and crayfish).” Where special management may be necessary, regulatory mechanisms may need to be added or amended by local, State or Federal governmental entities if sufficient management is not achievable through voluntary mechanisms.

We find that the PCEs present within all the areas we are designating may require special management considerations or protection due to threats to the tidewater goby or its habitat. Using current information provided in the tidewater goby recovery plan (Service 2005, Appendix E) and other information in our files, we have identified the PCEs, which may require special management considerations or protection from known threats within each of the critical habitat units (see Critical Habitat Designation and Table 2 below for a unit-by-unit description).

Criteria Used To Identify Critical Habitat

As required by section 4(b)(1)(A) of the Act, we use the best scientific and commercial data available in determining the specific areas within the geographical area occupied by the species at the time of listing that contain features essential to the conservation of species which may require special management considerations or protection. We also use the best scientific and commercial data available when determining if any specific areas outside the geographical area occupied by the species at the time of listing are essential for the conservation of the species. We only designate areas outside the geographical area presently occupied by a species when a designation limited to its present range would be inadequate to ensure the conservation of the species (50 CFR 424.12e). Such data used included research published in peer-reviewed articles and presented in academic theses and agency reports; information submitted during section 7 consultations and by biologists holding section 10(a)(1)(A) recovery permits; information that is contained within the recently completed recovery plan for the tidewater goby (Service 2005); the final rule listing the tidewater goby (59 FR 5494); and regional Geographic Information System (GIS) coverage. We also solicited information from knowledgeable biologists that have worked with the tidewater goby.

The process we use to identify the features that are essential to the conservation of the tidewater goby reflects a complete assessment of the current, best scientific data available. Much of the available information on the tidewater goby is summarized in the Recovery Plan for the Tidewater Goby (Service 2005). The emphasis of the recovery plan is to preserve the diversity of habitats that occur within the range of the tidewater goby, the metapopulation structure of the species, and genetic diversity. The recovery plan identifies 26 subunits (i.e., groups) of tidewater goby localities and describes them as being metapopulations. A metapopulation is generally considered a group of genetically related subpopulations (i.e., localities as used elsewhere in this rule) that are linked by the dispersal of individuals between subpopulations. Some subunits consist of a single occupied locality. Others consist of multiple populations that make up a source-sink type metapopulation where some subpopulations produce such an abundance of young that they are available to disperse to other localities (i.e., source), while others (sinks) may sometimes be extirpated until they are recolonized. These subunits identified

in the recovery plan were based on the most up-to-date scientific information on tidewater goby morphology and genetics available. Based on the goals of the recovery plan and the scientific literature that was used in the preparation of the plan, we developed criteria for identifying critical habitat units (see below). In this rule, we have also attempted to describe, in a more explicit manner, the criteria we use to determine the lateral and upstream extent of the critical habitat unit boundaries.

The criteria for identifying which areas meet the definition of critical habitat include:

(a) Areas occupied at the time of listing and that possess one or more PCEs such that the area supports one or more of the tidewater goby's life processes. We determined which areas were occupied at the time of listing from information in the recovery plan (Service 2005) and in two papers on tidewater goby occurrence (Swift

et al.

1989, p. 13; Swift

et al.

1993, p. 129), both of which were used in the preparation of the final listing rule for the tidewater goby;

(b) Areas that are currently occupied but were not occupied at the time of listing, which are determined to be essential to the conservation of the species;

(c) Areas that are representative of the distribution of the tidewater goby throughout the entire geographic range occupied at the time of listing, including those with unique ecological characteristics (e.g., large, open bays in Humboldt County versus small, routinely closed lagoons in Santa Barbara County), with the goal of maintaining the full range of the habitat variability and genetic and morphological adaptation in the species; and

(d) Areas that allow for the conservation of viable metapopulations (as defined in the Background section above) under varying environmental conditions (e.g., drought). These areas include those that presumably serve as source populations or those that provide important connectivity between source populations.

For the purposes of this designation, we define source populations as those that are currently occupied and have been consistently occupied for three or more consecutive years based on survey data and published reports. Based on the source-sink metapopulation type structure of many tidewater goby localities, we believe these areas are more likely to be capable of maintaining populations over many years and therefore capable of providing individuals to recruit into surrounding subpopulations.

Locations that provide connectivity between source populations are those locations that exist between source populations that are likely to act as “stepping stones” between more isolated populations, and contribute to metapopulation persistence. Locations that possess unique ecological characteristics are those that represent the full range of environmental variability where the tidewater goby has evolved, and therefore are likely to promote the adaptation of the species to different environmental conditions. For example, some of these habitats would include locations that reflect different environmental conditions in southern and northern California (e.g. smaller habitats that occur in a more arid environment versus large habitats that occur in areas with abundant rainfall). Morphological and genetic variability was used to support the inclusion of locations where we assume that this variability may play a role in positively affecting the species' conservation over time.

The conservation of a broad range of environmental, morphological, and genetic diversity that is present at the various locations is an important consideration in determining localities that have the features essential for the conservation of the species. For example, a population's ability to successfully adapt to changing environmental conditions is a function of the heterozygosity, population size, and genetic variation of the individuals at a given location (Reed and Frankham 2003, p. 233). Local adaptations to different environmental conditions and morphological differences are likely linked to genetic variations among populations. These features may in turn be best protected by: (a) Identifying areas that represent the species and genetic diversity, and (b) maximizing within these areas the protection of contiguous environmental gradients across which selection and migration can interact to maintain population viability and (adaptive) genetic diversity (Moritz 2002, p. 238).

By applying these criteria to the 26 subunits described in the recovery plan, we identified 44 critical habitat units that we have determined to be essential to the conservation of the tidewater goby. In general, we are designating these 44 units as critical habitat because: (1) They are representative of the distribution of the tidewater goby; (2) some units are occupied by source populations such that they support other habitats with tidewater gobies; (3) some units, although not considered sources, provide connectivity between populations; and, (4) other units reflect the diversity of the species and its currently occupied habitats. Although all 44 units are currently occupied by tidewater gobies, 3 of the units were not occupied at the time of listing (HUM-4, SB-8, and LA-2). We have included these three units because they meet our criterion “b,” “c,” and “d” above and we determined that they are essential for the conservation of the species (please see the Critical Habitat Designation section below for more information). Critical habitat units in this final designation are located in all 26 subunits in the recovery plan, except for those on Vandenberg Air Force Base (Santa Barbara County) and Marine Corps Base, Camp Pendleton (San Diego County), which have completed INRMPs that provide protection for the tidewater goby (see Application of Section 4(a)(3) of the Act—Approved Integrated Natural Resource Management Plans section). In some cases, several critical habitat units are included within a recovery plan subunit. In these instances we believe either that there is likely more than one source population and/or the inclusion of additional localities increases the chance for dispersal of individuals between localities.

Finally, we considered but did not include any currently unoccupied habitat in this designation because we concluded that the 44 units we are designating are sufficient for the conservation of the species. Many changes have occurred to the coastal wetlands of California, including the complete destruction of some. Many of these changes can not be reversed to the point where tidewater gobies are likely to be able to survive in these unoccupied areas. Additionally, our recently completed 5-year review evaluating the status of the species has recommended downlisting the species. This is in part due to an increase in the number of occupied locations since listing, which indicates the threats, or levels thereof, are not as seriously impacting tidewater goby populations as previously believed. Therefore, we believe the designation of the 44 currently occupied units which meet the criteria listed above provides for the conservation of the species, and we are not designating any habitat outside the geographical area presently occupied by the species.

After determining the areas that meet the definition of critical habitat by applying criteria “a” through “d” above, the boundary of each critical habitat unit was mapped. Unit boundaries were based on several factors including

species occurrence data that demonstrated where tidewater gobies have been observed, the presence of barriers and stream gradients that limit tidewater goby movements, and the presence and extent of the aquatic habitat required by tidewater gobies.

The lateral extent of each critical habitat unit was delineated, in part, using existing digital data. To determine the lateral boundaries of each critical habitat unit, we most frequently relied on National Wetland Inventory (NWI) maps that were prepared by the Service in 2006. The NWI maps are based on the Cowardin classification system (Cowardin

et al.

1979); the Service has adopted this classification system as its official standard to describe wetland and deepwater habitats. Specifically, the following wetland types based on Cowardin (1979) were used to delineate unit boundaries: Lake, Estuarine and Marine Deepwater, Estuarine and Marine Wetland, Freshwater Pond, Freshwater Emergent Wetland, Freshwater Forested/Shrub Wetland, and Riverine. These wetland types have or are likely to have the PCEs at various times throughout the year depending on the season and environmental factors such as storm or drought events. In some cases, we used existing anthropogenic structures, such as concrete or riprap channel linings, that occur within wetland habitat types to delineate the lateral boundaries of units. To a lesser extent, we also used aerial imagery from the National Agricultural Imagery Program (NAIP) to delineate the lateral boundaries of a critical habitat unit where insufficient NWI data was available.

The precise location where tidewater goby habitat occurs at a particular locality may vary on a daily, seasonal, and annual basis, i.e., the habitats occupied by tidewater gobies exist in a dynamic environment that varies over time. For example, the size and lateral extent of a coastal lagoon or estuary varies with daily tide cycles. Flood events may also change the precise location where surface water exists within a given lagoon, estuary, backwater marsh, or freshwater tributary. Therefore, it is appropriate to delineate each critical habitat unit to encompass the entire area occupied by tidewater gobies on a daily, seasonal, and annual basis. To accomplish this, we used the boundaries delineated on the NWI maps to determine the lateral extent of each unit.

The delineation of the upstream-most extent of a particular critical habitat unit was determined using one of four features that include: (a) The average distance that tidewater gobies are known to move upstream from the ocean (3.8 mi (6.1 km)), (b) the presence of barriers (e.g., culverts) that may prevent tidewater gobies from moving upstream, (c) the presence of a gradient that precludes tidewater gobies from swimming upstream (vertical drops of more than 4 to 8 in (10 to 20 cm) high can act as barriers that make it less likely tidewater gobies will be able to swim upstream (Swift

et al.

1997, p. 20)), or (d) limited surface water in the tributary up gradient from the lagoon or estuary. Each of the above features describes a barrier to upstream movement; therefore the upstream extent of a particular unit was determined by whichever barrier was identified first through the mapping process regardless of whether or not PCEs were still present above it.

When determining critical habitat boundaries, we made every effort to avoid developed areas such as lands covered by buildings, pavement, and other structures because such lands lack PCEs for the tidewater goby. The scale of the critical habitat maps prepared under the parameters for publication within the

Code of Federal Regulations

may not reflect the exclusion of such developed lands. Any such lands inadvertently left inside critical habitat boundaries shown on the maps of this final rule were excluded in the text of the proposed rule and are excluded in this final rule. Therefore, a Federal action involving these lands would not trigger section 7 consultation with respect to critical habitat and the requirement of no adverse modification, unless the specific action may affect adjacent critical habitat.

A brief discussion of each area designated as critical habitat is provided in the unit descriptions below. Additional detailed documentation concerning the essential nature of these areas is contained in our supporting record for this rulemaking.

Critical Habitat Designation

We are designating 44 units as critical habitat for the tidewater goby. All areas are currently occupied by the tidewater goby and constitute our best assessment of areas that meet the definition of critical habitat for the species. The 44 areas designated as critical habitat occur in: Del Norte, Humboldt, Mendocino, Sonoma, Marin, San Mateo, Santa Cruz, Monterey, San Luis Obispo, Santa Barbara, Ventura, and Los Angeles Counties, California.

Table 1 identifies the geographic areas that meet the definition of critical habitat for tidewater goby but are being exempted from critical habitat pursuant to section 4(a)(3) of the Act. Table 2 shows the approximate area, by unit and landownership, designated as critical habitat for the tidewater goby.

Table 1.—Approximate Size of Occupied Areas Containing Features Essential to the Conservation of the Tidewater Goby (Definitional Area) and the Areas Determined To Be Exempt From the Critical Habitat Designation Under Section 4(a)(3) of the Act

Geographic area

Definitional area

(acres/

hectares)

Exempted area

(acres/

hectares)

Total

Camp Pendleton Marine Corps Base

838/340

838/340

838/340

Vandenberg Air Force Base

775/314

775/314

775/314

Table 2.—Critical Habitat Units Designated for the Tidewater Goby. Area Estimates (Acres/Hectares) Reflect All Land Within the Critical Habitat Unit Boundaries. Area Estimates Are Rounded to the Nearest Whole Integer That Is Equal to or Greater Than 1. Units Are Arranged North to South

Unit name

Federal

State

Local

Private

Total

Threats requiring special management of PCEs

1

DN-1: Lake Earl/Lake Tolowa

0/0

2,682/1,085

0/0

0/0

2,682/1,085

1,4

HUM-1: Stone Lagoon

0/0

586/237

0/0

0/0

586/237

4

HUM-2: Big Lagoon

0/0

1,505/609

0/0

0/0

1,505/609

4

HUM-3: Humboldt Bay

879/356

296/120

90/36

213/86

1,478/598

1,3,4,5

HUM-4: Eel River

0/0

32/13

0/0

236/96

268/109

4,5

MEN-1: Ten Mile River

0/0

218/88

0/0

0/0

218/88

4

MEN-2: Virgin Creek

0/0

11/4

0/0

0/0

11/4

1,4

MEN-3: Pudding Creek

0/0

23/9

0/0

0/0

23/9

1,4

MEN-4: Davis Lake and Manchester State Park Ponds

0/0

24/10

0/0

0/0

24/10

4

SON-1: Salmon Creek

0/0

41/17

0/0

59/24

100/41

1,2,4,5

MAR-1: Estero Americano

1/1

6/2

0/0

288/117

295/120

1,4,5

MAR-2: Estero De San Antonio

0/0

60/24

0/0

118/48

178/72

1,2,4,5

MAR-3: Lagunitas (Papermill) Creek

176/71

666/270

0/0

7/3

849/344

1,3,4,5

MAR-4: Rodeo Lagoon

40/16

0/0

0/0

0/0

40/16

1

SM-1: San Gregorio Creek

0/0

39/16

0/0

0/0

39/16

1,3

SM-2: Pescadero-Butano Creek

0/0

218/88

0/0

0/0

218/88

1,3,4

SM-3: Bean Hollow Creek (Arroyo de Los Frijoles)

0/0

3/1

0/0

7/3

10/4

1,2

SC-1: Laguna Creek

0/0

26/11

0/0

0/0

26/11

2,4

SC-2: Baldwin Creek

0/0

17/7

0/0

0/0

17/7

2,4

SC-3: Corcoran Lagoon

0/0

5/2

6/2

21/8

32/12

1,4

SC-4: Aptos Creek

0/0

3/1

0/0

0/0

3/1

1,3,4

SC-5: Pajaro River

0/0

158/64

10/4

8/3

176/71

1,3,4

MN-1: Bennett Slough

0/0

82/33

5/2

68/28

155/63

1,2,3,4

SLO-1: Arroyo del Corral

0/0

5/2

0/0

0/0

5/2

1,5

SLO-2: Oak Knoll Creek (Arroyo Laguna)

0/0

3/1

0/0

0/0

3/1

1,3

SLO-3: Little Pico Creek

0/0

2/1

0/0

0/0

2/1

5

SLO-4: San Simeon Creek

0/0

16/7

0/0

0/0

16/7

2,4,5

SLO-5: Villa Creek

0/0

5/2

0/0

0/0

5/2

1,2,4,5

SLO-6: San Geronimo Creek

0/0

1/1

0/0

0/0

1/1

5

SLO-7: Pismo Creek

0/0

12/5

1/1

5/2

18/8

1,3,4

SB-1: Santa Maria River

0/0

149/60

33/13

286/116

468/189

1,2,4,5

SB-2: Cañada de las Agujas

0/0

0/0

0/0

1/1

1/1

1,4

SB-3: Cañada de Santa Anita

0/0

0/0

0/0

3/1

3/1

4

SB-4: Cañada de Alegria

0/0

0/0

0/0

1/1

1/1

1,2,4,5

SB-5: Cañada de Agua Caliente

0/0

0/0

0/0

1/1

1/1

1,4

SB-6: Gaviota Creek

0/0

8/3

0/0

1/1

9/4

1,3,4,5

SB-7: Winchester/Bell Canyon

0/0

0/0

1/1

5/2

6/3

4

SB-8: Arroyo Burro

0/0

0/0

2/1

0/0

2/1

1,3,4

SB-9: Mission Creek-Laguna Channel

0/0

9/4

5/2

0/0

14/6

1,3,4

VEN-1: Ventura River

0/0

26/10

16/6

9/4

51/20

1,2,3,4

VEN-2: Santa Clara River

0/0

218/88

22/9

110/45

350/142

1,2,3,4

VEN-3: J Street Drain-Ormond Lagoon

0/0

5/2

40/16

0/0

45/18

1,3,4

LA-1: Malibu Lagoon

0/0

58/24

0/0

6/3

64/27

1,2,3,4

LA-2: Topanga Creek

0/0

5/2

0/0

0/0

5/2

1,2,3,4

Total

1,096/444

7,223/2,923

231/93

1,453/593

10,003/4,053

1

Codes of known threats to tidewater goby habitat that may require special management considerations or protection of the PCEs are as follows:

1. Coastal development projects that result in the loss or alteration of coastal wetland habitat affecting PCEs 1, 2, 3, and 4.

2. Water diversions, alterations of water flows, artificial breaching of sandbars, and groundwater overdrafting that negatively impact the species' breeding and foraging activities and PCEs 1, 2, 3, and 4.

3. Channelization of habitats where the species occurs, affecting PCEs 1, 2, 3, and 4.

4. Non-point and point source pollution or discharge of agricultural and sewage effluents that are likely to impact the species health or breeding and foraging activities and PCE 1.

5. Cattle grazing that results in increased sedimentation of coastal lagoons and riparian habitats, removes vegetative cover, increases ambient water temperatures, and eliminates plunge pools and undercut banks utilized by tidewater gobies affecting PCE 1.

Below, we present brief descriptions of all units, and reasons why they meet the definition of critical habitat for the tidewater goby. The first two or three letters in the code for each critical habitat unit description reflects the county where the unit occurs: DN = Del Norte, HUM = Humboldt, LA = Los Angeles, MAR = Marin, MEN = Mendocino, MN = Monterey, SLO = San Luis Obispo, SM = San Mateo, SB = Santa Barbara, SC = Santa Cruz, SON = Sonoma, and VEN = Ventura. In Table 2 above, these units are listed in sequential order from north to south,

with the most northerly unit being described first and the most southerly unit being described last.

DN-1: Lake Earl/Lake Tolowa

Unit DN-1 consists of 2,682 ac (1,085 ha) located approximately 3 mi (4.8 km) north of the town of Crescent City and approximately 10 mi (16 km) south of the California-Oregon border. On an intermittent basis, DN-1 possesses a sandbar across the mouth of the lagoon or estuary during the majority of the late spring, summer, and fall that closes or partially closes the lagoon or estuary and thereby provides relatively stable conditions (PCE 4). This unit includes two contiguous lagoons (Lake Tolowa and Lake Earl), referred to collectively as Lake Earl. DN-1 includes State-owned land within the California Department of Fish and Game's (CDFG) Lake Earl Wildlife Area, and a portion of Tolowa Dunes State Park. DN-1 was occupied at the time of listing and is currently occupied. This critical habitat unit is the largest occupied locality in Del Norte County. Tidewater gobies have regularly been found throughout the lagoon in large numbers during surveys and intensive studies (Tetra Tech 2000, pp. 8-9 and Tables G-1 through G-12). The unit is separated from the nearest extant population to the north, in Tilla Slough/Smith River (not designated as critical habitat), by 7.3 mi (11.8 km). Because DN-has been consistently occupied over time, it is likely a source population for this region. It likely provides demographic and connectivity for other intermittent localities such as Tillas Slough, and provides a source population for reestablishment of the species at historically occupied, but currently extirpated, localities at Redwood Creek estuary and Freshwater Lagoon.

Furthermore, Lake Earl/Lake Tolowa are representative of extensive coastal lagoons and bays north of Cape Mendocino formed over uplifting Holocene sediments on broad flat coastal benches. These coastal benches include an intricate network of estuaries and other channels that are features essential to the conservation of the tidewater goby because they provide refugia during seasonal floods and breeding habitat through the full range of climatic cycles. The water level and salinity within the lagoon varies seasonally and annually in response to (a) periods of high precipitation or drought within its watershed; (b) the timing, duration, and frequency of breaching events; (c) the water level in the lagoon at the time of breaching; and (d) ocean tidal cycles during and immediately following a breach. As a result of natural and human-induced environmental changes, maximum water depth within Lake Earl varies during an annual cycle from less than 5 ft (1.5 meters) deep to more than 10 ft (3 meters) deep. The distribution of tidewater gobies and PCEs within Lake Earl changes in response to these dynamic, short-term habitat conditions; over a multi-year cycle, tidewater gobies may persist and breed anywhere within the lagoon. PCEs 1, 2, and 3 are found throughout DN-1, on a short term but variable time scale in response to the dynamic variability of the habitat itself. This unit and the essential features contained therein are also important to the conservation of the species because the goby population that it supports is considered a source population and will support the recovery of the tidewater goby population along this important coastal range, help conserve genetic diversity within the species, and facilitate colonization of currently unoccupied locations. Known threats to tidewater goby habitat that may require special management considerations or protection of the PCEs in this unit are described in Table 2.

HUM-1: Stone Lagoon

Unit HUM-1 consists of 586 ac (237 ha) located approximately 11 mi (18 km) north of the city of Trinidad. HUM-1 (Stone Lagoon) is a moderately large, natural, coastal lagoon with a narrows and spit separating it from the ocean. The lagoon includes fresh water input from two streams on the east and southern sides of the unit. Similar to DN-1, HUM-1 is typical of large north coast lagoons, characterized by a seasonal sandbar that results in relatively stable habitat within a naturally variable range of seasonal and annual climate conditions. HUM-1 possesses a sandbar across the mouth of the lagoon or estuary during the majority of the late spring, summer, and fall that closes or partially closes the lagoon or estuary and thereby provides relatively stable conditions (PCE 4). Tidewater goby distribution within this overall large lagoon varies in response to annual and seasonal climatic conditions. The other three PCEs occur throughout the unit, and the species likely alters its distribution within the lagoon in response to seasonal and annual habitat variability. HUM-1 is entirely State-owned and is part of Humboldt Lagoons State Park. Management of the lagoon does not include goals or tasks specific to the tidewater goby. HUM-1 was occupied at the time of listing, is currently occupied and is likely a source population for this region. HUM-1 is the northernmost of the four Humboldt County units and is located 40.8 mi (65.6 km) south of Lake Earl/Lake Tolowa (DN-1). The unit is separated from the nearest extant population to the north, in Freshwater Lagoon (not designated as critical habitat), by 30.7 mi (49.4 km). HUM-1 is the closest source population to reestablish the tidewater goby within formerly suitable but known extirpated localities at Redwood Creek and Freshwater Lagoon. HUM-1 will also support the recovery of tidewater goby populations along this portion of the coast and help facilitate colonization of currently unoccupied locations. Known threats to tidewater goby habitat that may require special management considerations or protection of the PCEs in this unit are described in Table 2.

HUM-2: Big Lagoon

Unit HUM-2 consists of 1,505 ac (609 ha) located approximately 7 mi (11 km) north of the city of Trinidad. Big Lagoon is a large coastal lagoon with a narrow sand spit separating it from the ocean, and receives the majority of its fresh water input from one stream in the southeast portion of the unit. Similar to DN-1, HUM-2 is typical of large north coast lagoons and estuaries, characterized by a seasonal sandbar that results in relatively stable habitat within a naturally variable range of seasonal and annual climate conditions. HUM-2 possesses a sandbar across the mouth of the lagoon or estuary during the majority of the late spring, summer, and fall that closes or partially closes the lagoon or estuary and thereby provides relatively stable conditions (PCE 4). Tidewater goby distribution within this overall large lagoon varies in response to annual and seasonal climatic conditions. The other three PCEs occur throughout the unit, and the species likely alters its distribution within the lagoon in response to seasonal and annual habitat variability. HUM-2 consists entirely of State lands that are part of Humboldt Lagoons State Park; however, the CDFG currently holds a lease from State lands for all lands to the mean high tide line of the lagoon. Furthermore, the landward areas are managed as Humboldt Lagoons State Park administered by the California Department of Parks and Recreation. HUM-2 was occupied at the time of listing, is currently occupied, and is likely a source population for this region. HUM-2 is located 4.6 mi (7.3 km) south of Stone Lagoon (HUM-1), which is also the nearest extant population. Conservation of this unit will support the recovery of tidewater goby populations along this portion of the coast, help conserve diversity within

the species, and facilitate colonization of currently unoccupied locations. Known threats to tidewater goby habitat that may require special management considerations or protection of the PCEs in this unit are described in Table 2.

HUM-3: Humboldt Bay

Unit HUM-3 consists of 1,478 ac (598 ha) located within an 8 mi (13 km) radius to the north, south, and east of the city of Eureka. This area was occupied at the time of listing and is currently occupied. Humboldt Bay and its adjacent marshes and estuaries are a complex mixture of natural and human-made aquatic features that have experienced many decades of human-induced changes. These changes include the construction of levees, tidegates, culverts, and other water control structures, and extensive dredging of sandbars. Surrounding the bay itself is a generally broad bench historically dominated by mudflats, tidal marshes, estuarine channels, and brackish marshes. Substantial portions of those habitats were converted to agricultural, urban, and industrial uses in recent history, resulting in the loss of as much as 10,000 ac (4,047 ha) of potentially suitable habitat. This critical habitat unit consists of a complex of interconnected estuary channels and human-made structures along the eastern edge of Humboldt Bay which collectively mimic, on a much reduced scale, habitats largely lost through past management practices. Many of these channels and marshes are themselves the result of changes to historical habitats, and depend on specific yet generally undocumented management activities for their continued function. To address the dynamic variability of these habitats resulting from seasonal and inter-annual precipitation differences, we have included both the actual known locations where tidewater gobies have been documented, as well as portions of those channels contiguous to but upchannel or downchannel from the known localities. We have not included Humboldt Bay proper in critical habitat, nor have we included major channels substantially subject to daily tidal fluctuations, as we have no evidence suggesting tidewater gobies may breed there. Similarly, we have not included channels that are not contiguous with occupied habitat, nor have we included intervening marsh or agricultural lands that may occasionally be flooded during severe winter storm events.

Based on several recent surveys, we have found that the precise locations of tidewater goby use within the channel complex during any particular year may change in response to annual variation in precipitation and channel hydrology. PCEs 1, 2, and 3 occur throughout the unit, although their precise location during any particular time period may change in response to seasonal fluctuations in precipitation and tidal inundation. Only PCE 4 (a sandbar(s) across the mouth of a lagoon or estuary) is not likely to occur within this unit because a navigable, dredged channel with a permanent open connection to the ocean is maintained on a regular basis. We anticipate that the persistence of the tidewater goby source population within this unit may require protection of localities that are not occupied every year, but collectively form a source population through an interconnected complex of channels and shallow water habitats. That is, any of the several known occupied localities within a channel complex may be used by tidewater gobies during various years in response to dynamic habitat conditions during seasonal, annual, and longer term climatic cycles (e.g., drought).

Recently, significant restoration efforts directed primarily at salmonid recovery have occurred or are anticipated to occur within areas designated as critical habitat. The outcome of these salmonid restoration efforts to tidewater gobies is unknown, and will likely vary with their design features and their location. This unit consists of Federal, State, local government, and private lands. HUM-3 is located 21.0 mi (33.9 km) south of Big Lagoon (HUM-2). The unit is separated from the nearest extant population to the south, in the Eel River (HUM-4), by 18.4 mi (29.7 km). This source population may provide essential demographic and genetic support to HUM-4, especially during periods of extreme floods (e.g., the 1964 “Christmas Flood”), when the population of tidewater gobies at the Eel River estuary may have been extirpated. Conservation of this unit will support the recovery of tidewater goby populations along this portion of the coast and help facilitate colonization of currently unoccupied locations. Known threats to tidewater goby habitat that may require special management considerations or protection of the PCEs in this unit are described in Table 2.

HUM-4: Eel River

Unit HUM-4 consists of 268 ac (109 ha) located approximately 4 mi (6.5 km) north of the town of Ferndale. The Eel River delta includes a large, complex estuary with a network of diked and natural slough channels which contain suitable tidewater goby habitat. The Eel River delta contains many small, un-surveyed slough channels and other backwater areas that provide suitable habitat for tidewater gobies, but it also contains larger channels open to direct tidal influence that do not provide suitable habitat and are not included in this unit. This unit consists of backwater channels and immediately adjacent marsh contiguous to the known occupied habitat. Although no tidewater goby surveys are known to have occurred in the Eel River estuary prior to the listing, we considered this area to be unoccupied by the species until the Service discovered a new population of tidewater gobies in the Eel River estuary during surveys in 2004 (Goldsmith 2006b, p. 1). Although not occupied at the time of listing, we consider this locality to be essential to the conservation of the species because this unit possesses ecological characteristics which are important in maintaining the species' ability to adapt to changing environments, including the ability to disperse into higher channels and marsh habitat during severe flood events. This unit will also support the recovery of the tidewater goby population along this portion of the coast and help facilitate colonization of currently unoccupied locations. This unit consists of State lands, local government lands, and private lands. Similar to HUM-3, this unit includes portions of the contiguous channel upstream from the known locality, expected to function as habitat in response to seasonal and inter-annual fluctuations of water level and salinity. On an intermittent basis, HUM-4 possesses a sandbar across the mouth of the lagoon or estuary during the late spring, summer, and fall that closes or partially closes the lagoon or estuary and thereby provides relatively stable conditions (PCE 4). The other three PCEs occur throughout the unit in a dynamic and seasonally variable distribution.

As described earlier in HUM-3, we anticipate that tidewater gobies use various locations throughout this unit as a moving source population in response to the naturally changing habitat conditions. This unit is subject to infrequent yet severe flooding from the nearby Eel River proper. The major flood event of 1964 (“Christmas Flood”), and other major floods during the past century, may have severely altered habitat in most channels, including those currently occupied. Tidewater gobies may have survived the flood and the resulting loss of habitat in the refugia provided in upper channels and swales. Alternatively, the species may have been extirpated at the Eel River delta during those severe events,

and reestablished itself through demographic and genetic support from HUM-3, located approximately 18.4 mi (29.7 km) to the north. Of particular importance, the Eel River location is at the north end of one of the largest natural geographic gaps in the tidewater goby's geographic range. The gap extends to the Ten Mile River (Mendocino County) to the south, representing a coastline distance in excess of 135 mi (217 km). This gap, with its rocky coastline, strong currents, and long distance, remains a formidable barrier to the dispersal of tidewater gobies. Thus, an additional reason why this unit is essential to the conservation of the species is because it is at the boundary of a large, natural gap in the geographic range of the species.

MEN-1: Ten Mile River

Unit MEN-1 consists of 218 ac (88 ha) located 9 mi (14.5 km) north of the town of Fort Bragg. Ten Mile River includes a moderately large estuary with a long, low-gradient profile that contains many beneficial characteristics for supporting tidewater gobies, including part-time tidal exchange, brackish water, complex cover, suitable substrate types, and areas of off-channel refugia. Suitable habitat in this estuary extends to at least 3 mi (5 km) from the ocean, where a gradual increase in gradient and freshwater conditions dominates. On an intermittent basis, MEN-1 possesses a sandbar across the mouth of the lagoon or estuary during the late spring, summer, and fall that closes or partially closes the lagoon or estuary and thereby provides relatively stable conditions (PCE 4). Persistent, shallow water extends in the estuary for more than 3 mi (5 km) upstream from the ocean. Through this long estuary, salinity and water depth vary by season, amount of precipitation, and tidal cycle. Thus, PCEs 1, 2, and 3 occur throughout the unit, although their precise location during any particular time period may change in response to seasonal and longer term fluctuations in precipitation and tidal inundation.

This unit consists entirely of State lands. Ten Mile River was occupied by tidewater gobies at the time of listing and is currently occupied. MEN-1 is located 135.0 mi (217.0 km) south of Eel River (HUM-4). The unit is separated from the nearest extant population to the south, in Virgin Creek (MEN-2), by 5.6 mi (8.9 km). This unit is considered a source population, and will support the recovery of the tidewater goby population along this portion of the coast and help facilitate colonization of currently unoccupied locations. Furthermore, this unit is the largest block of habitat along the coast of Mendocino County, and is the last location on the southern end of one of the longest stretches of unsuitable habitat in the species range (previously described under HUM-4). Thus, this unit is important to connect populations within Mendocino County. South of Ten Mile River, only three other small, isolated localities occupied by tidewater gobies are known to exist across the more than 100 miles of rugged coastline between MEN-1 and SON-1 in south-coastal Sonoma County. Known threats to tidewater goby habitat that may require special management considerations or protection of the PCEs in this unit are described in Table 2.

MEN-2: Virgin Creek

Unit MEN-2 consists of 11 ac (4 ha) located 3.5 mi (5.6 km) north of the town of Fort Bragg and includes the small estuary of Virgin Creek. On an intermittent basis, MEN-2 possesses a sandbar across the mouth of the estuary during the late spring, summer, and fall that closes or partially closes the estuary and thereby provides relatively stable conditions (PCE 4). PCEs 1, 2, and 3 occur throughout the unit, although their precise location during any particular time period may change in response to seasonal fluctuations in precipitation and tidal inundation. This unit consists entirely of State lands that are part of McKerricher State Park, but is influenced by factors, such as upstream water quality, not under the jurisdiction of the Park. The tidewater goby occupied this locality at the time of listing and the unit is currently occupied. MEN-2 is located 5.6 mi (8.9 km) south of Ten Mile River (MEN-1). The unit is separated from the nearest extant population to the south, in Pudding Creek (MEN-3), by 1.2 mi (2.0 km). This unit is considered a source population, and it will support the recovery of the tidewater goby population along this portion of the coast and help facilitate colonization of currently unoccupied locations. As described above, this unit is one of only three small estuaries occupied by tidewater gobies between MEN-1 and SON-1. It forms an important intermediate locality for movement within Mendocino County. Known threats to tidewater goby habitat that may require special management considerations or protection of the PCEs in this unit are described in Table 2.

MEN-3: Pudding Creek

Unit MEN-3 consists of 23 ac (9 ha) located 2.5 mi (4.0 km) north of the town of Fort Bragg. Pudding Creek, is a moderately small estuary controlled at the upstream end by a low-head, municipal water storage dam. On an intermittent basis, MEN-3 possesses a sandbar across the mouth of the lagoon or estuary during the late spring, summer, and fall that closes or partially closes the estuary, and thereby provides relatively stable conditions (PCE 4). PCEs 1, 2, and 3 occur throughout the unit, although their precise location during any particular time period may change in response to seasonal fluctuations in precipitation and tidal inundation. This unit consists entirely of State lands that are part of McKerricher State Park, but is influenced by factors, such as upstream water quality, not under the jurisdiction of the Park. Tidewater gobies have been known from this location for at least the last 30 years, including the time of listing, and it is currently occupied. MEN-3 is located 1.2 mi (2.0 km) south of Virgin Creek (MEN-2), which is also the nearest extant population. This unit allows for connectivity between tidewater goby source populations, and thereby supports gene flow and metapopulation dynamics in this region. As described above, this unit is one of only three small estuaries likely to be occupied by tidewater gobies between MEN-1 and SON-1. It forms an important intermediate locality for long-term connectivity within Mendocino County. Known threats to tidewater goby habitat in this unit that may require special management considerations or protection of the PCEs are described in Table 2.

MEN-4: Davis Lake and Manchester State Park Ponds

Unit MEN-4 consists of 24 ac (10 ha) located 3.3 mi (5.2 km) northeast of Point Arena, and includes an area with ponds fed by a small, unnamed, low-elevation, coastal stream in Manchester State Park. On an intermittent basis, MEN-4 possesses a sandbar across the mouth of the lagoon or estuary during the late spring, summer, and fall that closes or partially closes the lagoon or estuary and thereby provides relatively stable conditions (PCE 4). PCEs 1, 2, and 3 occur throughout the unit, although their precise location during any particular time period may change in response to seasonal fluctuations in precipitation and tidal inundation. This unit consists entirely of State lands that are part of Manchester State Park. Tidewater gobies have been known from this location for at least the last 30 years, including the time of listing, and it is currently occupied. MEN-4 is located 32.4 mi (52.2 km) south of Pudding Creek (MEN-3), which is also the nearest extant population. This unit

is considered a source population, and it will support the recovery of the tidewater goby population along this portion of the coast and help facilitate colonization of currently unoccupied locations. As described above, this unit is one of only three small estuaries likely to be occupied by tidewater gobies between MEN-1 and SON-1. It forms an important intermediate locality for long-term connectivity within Mendocino County. There are other potential areas of suitable habitat in neighboring wetlands. However, tidewater gobies have not been documented from these locations, and they are not included in this unit. Known threats to tidewater goby habitat that may require special management considerations or protection of the PCEs in this unit are described in Table 2.

SON-1: Salmon Creek

Unit SON-1 consists of 100 ac (41 ha) located about 7 mi (11.3 km) south of the community of Jenner at the mouth of the Russian River. On an intermittent basis, SON-1 possesses a sandbar across the mouth of the lagoon or estuary during the late spring, summer, and fall that closes or partially closes the lagoon or estuary and thereby provides relatively stable conditions (PCE 4). PCEs 1, 2, and 3 occur throughout the unit, although their precise location during any particular time period may change in response to seasonal fluctuations in precipitation and tidal inundation. Within the unit, the beach, estuary downstream of the State Route (SR) 1 bridge, and the floodplain north of Salmon Creek and upstream (east) of SR 1 are State lands under the jurisdiction of the CDPR. The area and wetlands south of the creek and east of SR 1 in the unit are privately owned. This unit was occupied by tidewater gobies at the time of listing, is currently occupied, and is likely a source population for this region. The closest known existing population of tidewater gobies to Salmon Creek is located at Estero Americano 5.3 mi (8.5 km) to the south. The geological feature known as Bodega Head separates Salmon Creek and Estero Americano, and is likely to reduce the exchange of tidewater gobies between these two locations. This unit will support the recovery of the tidewater goby population along this portion of the coast and help facilitate colonization of currently unoccupied locations. Known threats to tidewater goby habitat that may require special management considerations or protection of the PCEs in this unit are described in Table 2.

MAR-1: Estero Americano

Unit MAR-1 consists of 295 ac (120 ha) located south of the Bodega Head, about 3.5 mi (5.7 km) south of Bodega Bay. Estero Americano is approximately 750 to 1,000 ac (300 to 400 ha) in size and is a large lagoon relative to other known extant and historical tidewater goby locations. On an intermittent basis, MAR-1 possesses a sandbar across the mouth of the lagoon or estuary during the late spring, summer, and fall that closes or partially closes the lagoon or estuary and thereby provides relatively stable conditions (PCE 4). PCEs 1, 2, and 3 occur throughout the unit, although their precise location during any particular time period may change in response to seasonal fluctuations in precipitation and tidal inundation. The majority of this unit consists of privately-owned lands. A small portion of the unit also consists of Federal and State lands. Although the abundance of tidewater goby in Estero Americano seems to vary, it was occupied by tidewater gobies at the time of listing and is currently occupied. MAR-1 is likely a source population for this region. The unit is one of two known locations of tidewater goby in this area, the other being Estero de San Antonio (MAR-2) approximately 2.2 mi (3.5 km) to the south. The closest known existing locations of tidewater goby to the north is the Salmon Creek estuary (SON-1), but this location is upcoast from the Bodega Head, which likely limits interactions with tidewater gobies from this unit. This unit will support the recovery of the tidewater goby population along this portion of the coast and help facilitate colonization of currently unoccupied locations. Known threats to tidewater goby habitat that may require special management considerations or protection of the PCEs in this unit are described in Table 2.

MAR-2: Estero de San Antonio

Unit MAR-2 consists of 178 ac (72 ha) located about 5.6 mi (9 km) south of Bodega Bay. Estero de San Antonio provides approximately 500 to 750 ac (200 to 300 ha) of fish habitat and is a large lagoon relative to other known extant and historical tidewater goby locations. On an intermittent basis, MAR-2 possesses a sandbar across the mouth of the lagoon or estuary during the late spring, summer, and fall that closes or partially closes the lagoon or estuary and thereby provides relatively stable conditions (PCE 4). PCEs 1, 2, and 3 occur throughout the unit, although their precise location during any particular time period may change in response to seasonal fluctuations in precipitation and tidal inundation. The majority of this unit consists of private lands, and the rest are State lands. Tidewater gobies are abundant within Estero de San Antonio, and it was occupied by tidewater gobies at the time of listing and is currently occupied. MAR-2 is one of two known locations of tidewater gobies to remain within the local area. This critical habitat unit includes a source population of tidewater gobies that likely provides individuals that are recruited into surrounding subpopulations. The closest known existing locations of tidewater goby are Estero Americano (i.e., MAR-1) approximately 2.2 mi (3.5 km) to the north and Lagunitas (Papermill) Creek (i.e., MAR-3) approximately 15.5 mi (25 km) to the south. Given the proximity between the MAR-1 and MAR-2 units, it is possible they have exchanged individuals in the past and that they continue to exchange individuals. Exchange between these populations bolsters the continued sustainable existence of the two populations which will, together with SON-1 and MAR-3 units, provide for natural and introduced colonization of available but unoccupied estuaries within the region south of the Russian River and north of Point Reyes. This unit will support the recovery of the tidewater goby population along this portion of the coast and help facilitate colonization of currently unoccupied locations. Known threats to tidewater goby habitat that may require special management considerations or protection of the PCEs in this unit are described in Table 2.

MAR-3: Lagunitas (Papermill) Creek

Unit MAR-3 consists of 849 ac (344 ha) located in Tomales Bay 20.5 mi (33 km) south of Bodega Bay. We do not have information that confirms that PCE 4 (a sandbar(s) across the mouth of the lagoon or estuary) is present within this unit on at least an intermittent basis. PCEs 1, 2, and 3 occur throughout the unit, although their precise location during any particular time period may change in response to seasonal fluctuations in precipitation and tidal inundation. The bayward portion of the unit consists of State lands. A portion of the unit consists of Federal lands under the jurisdiction of the National Park Service. The remaining portion of the unit is privately owned. This unit was occupied prior to listing and is currently occupied; therefore we consider it to have been occupied at the time of listing. It is the only known location of the tidewater goby to remain within the greater Tomales Bay area. Thus, if allowed to establish a robust population

the unit could act as an important source population for future colonization or introductions to other habitats within Tomales Bay. The closest known location with an extant tidewater goby population is Estero de San Antonio approximately 15.5 mi (25 km) to the north. Known threats to tidewater goby habitat that may require special management considerations or protection of the PCEs in this unit are described in Table 2.

MAR-4: Rodeo Lagoon

Unit MAR-4 consists of 40 ac (16 ha) located at the tip of the Marin Peninsula, approximately 3.8 mi (6 km) north of San Francisco. MAR-4 possesses a sandbar across the mouth of the lagoon or estuary during the late spring, summer, and fall that closes or partially closes the lagoon or estuary and thereby provides relatively stable conditions (PCE 4). PCEs 1, 2, and 3 occur throughout the unit, although their precise location during any particular time period may change in response to seasonal fluctuations in precipitation and tidal inundation. This unit consists of Federal lands under the jurisdiction of the National Park Service's Golden Gate National Recreation Area. Tidewater gobies are abundant within Rodeo Lagoon, and the lagoon was occupied by tidewater gobies at the time of listing and is currently occupied. MAR-5 is the only known location where the tidewater goby remains within the greater Bay Area. It also provides habitat for a population of tidewater gobies that could disperse to other adjoining habitats. The closest known existing locations of tidewater goby are Lagunitas Creek in Tomales Bay 23.6 mi (38 km) to the north, and San Gregorio Creek 36 mi (58 km) to the south. This unit will support the recovery of the tidewater goby population along this portion of the coast and help facilitate colonization of currently unoccupied locations. Known threats to tidewater goby habitat that may require special management considerations or protection of the PCEs in this unit are described in Table 2.

SM-1: San Gregorio Creek

Unit SM-1 consists of 39 ac (16 ha) located about 28 mi (45 km) south of the San Francisco-San Mateo County line. On an intermittent basis, SM-1 possesses a sandbar across the mouth of the lagoon or estuary during the late spring, summer, and fall that closes or partially closes the lagoon or estuary and thereby provides relatively stable conditions (PCE 4). PCEs 1, 2, and 3 occur throughout the unit, although their precise location during any particular time period may change in response to seasonal fluctuations in precipitation and tidal inundation. This unit consists entirely of State lands that are part of San Gregorio State Beach. This unit was occupied at the time of listing, and it is currently occupied. SM-1 is the northernmost of the only three extant populations in San Mateo County. This unit is noted for high densities of tidewater gobies (Swenson 1993, p. 3). The closest extant population of tidewater gobies north of San Gregorio Creek is 36 mi (58 km) at Rodeo Lagoon and the closest historical location to the north is Lake Merced approximately 28 mi (45 km) to the north. The lack of nearby populations to the north reduces the likelihood that the existing SM-1 population would be naturally reestablished if it were lost. SM-1's position as the northernmost of the only extant tidewater locations remaining in San Mateo County and its proximity to potential reintroduction sites, the lack of other nearby locations to the north, and the presence of a stable population makes this unit an important source population for this region of the California coast. Known threats to tidewater goby habitat that may require special management considerations or protection of the PCEs in this unit are described in Table 2.

SM-2: Pescadero-Butano Creek

Unit SM-2 consists of 218 ac (88 ha) located approximately 32 mi (51 km) south of the San Francisco-San Mateo County line. The unit consists of a lagoon, marshes, and creek channels. Unit SM-2 is located between two extant tidewater goby populations; namely the populations in San Gregorio Creek (SM-1) about 3.7 mi (6 km) to the north and in Bean Hollow Creek (SM-3) about 2.9 mi (4.7 km) to the south. On an intermittent basis, SM-2 possesses a sandbar across the mouth of the lagoon or estuary during the late spring, summer, and fall that closes or partially closes the lagoon or estuary and thereby provides relatively stable conditions (PCE 4). However, since the early 1990s the timing of the sandbar formation seems to have changed from spring/ summer to late summer or fall. PCEs 1, 2, and 3 occur throughout the unit, although their precise location during any particular time period may change in response to seasonal fluctuations in precipitation and tidal inundation. This unit consists entirely of State lands that are part of Pescadero State Beach and Pescadero Marsh Natural Preserve. This unit was occupied by tidewater gobies at the time of listing and is currently occupied. This unit is unusual in that some tidewater gobies from this location possess a parasite that appears to occasionally affect their health; these parasites, or the environmental factors that increase the prevalence of the parasites, may represent a threat to this population not identified in Table 2. This unit allows for connectivity between tidewater goby source populations, and thereby supports gene flow and metapopulation dynamics in this region. Known threats to tidewater goby habitat that may require special management considerations or protection of the PCEs in this unit are described in Table 2.

SM-3: Bean Hollow Creek (Arroyo de Los Frijoles)

Unit SM-3 consists of 10 ac (4 ha) located approximately 34.8 mi (56 km) south of the San Francisco-San Mateo County line. On an intermittent basis, SM-3 possesses a sandbar across the mouth of the lagoon or estuary during the late spring, summer, and fall that closes or partially closes the lagoon or estuary and thereby provides relatively stable conditions (PCE 4). PCEs 1, 2, and 3 occur throughout the unit, although their precise location during any particular time period may change in response to seasonal fluctuations in precipitation and tidal inundation. The area east of State Highway 1 is privately owned and the portion of the lagoon west of the highway consists of State lands, which are part of Bean Hollow State Beach. This unit was occupied by tidewater gobies at the time of listing and it is currently occupied. SM-3 is the southernmost of the three San Mateo County units and is located 2.9 mi (4.7 km) south of Pescadero Creek. The unit is separated from the nearest extant population to the sou

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