Endangered and Threatened Wildlife and Plants; Revised Critical Habitat for the Arroyo Toad (Anaxyrus californicus)
Federal RegisterOct 13, 2009
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DEPARTMENT OF THE INTERIOR
Fish and Wildlife Service
50 CFR Part 17
[Docket No. FWS-R8-ES-2009-0069; 92210-1117-0000-B4]
RIN 1018-AV89
Endangered and Threatened Wildlife and Plants; Revised Critical Habitat for the Arroyo Toad (Anaxyrus californicus)
AGENCY:
Fish and Wildlife Service, Interior.
ACTION:
Proposed rule.
SUMMARY:
We, the U.S. Fish and Wildlife Service (Service), propose to revise designated critical habitat for the arroyo toad (
Anaxyrus californicus
), pursuant to the Endangered Species Act of 1973, as amended (Act). The previous final rule designated 11,695 acres (ac) (4,733 hectares (ha)) of critical habitat and was published in the
Federal Register
(FR) on April 13, 2005. We now propose to designate approximately 109,110 ac (44,155 ha) of lands located in Santa Barbara, Ventura, Los Angeles, San Bernardino, Riverside, Orange, and San Diego Counties, California, which, if finalized as proposed, would result in an increase of approximately 97,415 ac (39,422 ha) of critical habitat.
DATES:
We will consider comments we receive on or before December 14, 2009. We must receive requests for public hearings, in writing, at the address shown in the
FOR FURTHER INFORMATION CONTACT
section by November 27, 2009.
ADDRESSES:
You may submit comments by one of the following methods:
•
Federal eRulemaking Portal: http://www.regulations.gov.
Follow the instructions for submitting comments to Docket No. FWS-R8-ES-2009-0069.
•
U.S. mail or hand-delivery:
Public Comments Processing, Attn: FWS-R8-ES-2009-0069, Division of Policy and Directives Management, U.S. Fish and Wildlife Service, 4401 N. Fairfax Drive, Suite 222, Arlington, VA 22203.
We will post all comments on
http://www.regulations.gov.
This generally means that we will post any personal information you provide us (see the Public Comments section below for more information).
FOR FURTHER INFORMATION CONTACT:
For general information on the proposed designation and information about the proposed revised designation in Santa Barbara and Ventura Counties, northern Los Angeles County, and the desert portion of San Bernardino County, contact Diane Noda, Field Supervisor, or Michael McCrary, Listing and Recovery Coordinator, Ventura Fish and Wildlife Office, U.S. Fish and Wildlife Service, 2493 Portola Road, Suite B, Ventura, CA 93003; telephone (805) 644-1766; facsimile (805) 644-3958.
For information about the proposed revised designation in the remaining portions of Los Angeles and San Bernardino Counties, as well as Riverside, Orange, and San Diego Counties, contact Jim Bartel, Field Supervisor, Carlsbad Fish and Wildlife Office, U.S. Fish and Wildlife Service, 6010 Hidden Valley Road, Suite 101, Carlsbad, CA 92011; telephone (760) 431-9440; facsimile (760) 431-9624.
If you use a telecommunications device for the deaf (TDD), call the Federal Information Relay Service (FIRS) at (800) 877-8339.
SUPPLEMENTARY INFORMATION:
Public Comments
We intend any final action resulting from this proposed revised rule to be based on the best scientific and commercial data available and be as accurate and as effective as possible. Therefore, we request comments or information from the public, other government agencies, Tribes, the scientific community, industry, or other interested parties concerning this proposed rule. We particularly seek comments concerning:
1. The reasons why we should or should not revise the designation of habitat as “critical habitat” under section 4 of the Endangered Species Act of 1973, as amended (Act; 16 U.S.C. 1531
et seq.
), including whether there are threats to the species from human activity, the degree of which can be expected to increase due to the designation, and whether that increase in threat outweighs the benefit of designation such that the designation of critical habitat is not prudent;
2. Specific information on:
• The amount and distribution of arroyo toad habitat included in this proposed revised rule,
• What areas within the geographical area occupied by the species at the time of listing contain features essential to the conservation of the species and why, and
• What areas outside the geographical area occupied by the species at the time of listing are essential for the conservation of the species and why;
3. Land-use designations and current or planned activities in the subject areas and their possible effects on proposed revised critical habitat;
4. Any probable economic, national security, or other relevant impacts of designating any area that may be included in the final designation. We are particularly interested in any impacts on small entities, and the benefits of including or excluding areas that exhibit these impacts;
5. Comments or information that may assist us in identifying or clarifying the primary constituent elements and the resulting physical and biological features essential to the conservation of the arroyo toad;
6. How the proposed revised critical habitat boundaries could be refined to more closely circumscribe the landscapes identified as essential;
7. Information regarding Trabuco Creek in Orange County and any special management considerations or protection that any essential physical or biological features in this area may require;
8. Information regarding the San Diego River in San Diego County from just below El Capitan Reservoir downstream to the confluence with San Vicente Creek, and any special management considerations or protection that any essential physical or biological features in this area may require;
9. Whether the potential exclusion under section 4(b)(2) of the Act of non-Federal lands covered by the Western Riverside County Multiple Species Habitat Conservation Plan from final revised critical habitat is or is not appropriate and why;
10. Whether the potential exclusion under section 4(b)(2) of the Act of non-Federal lands covered by the San Diego Multiple Species Conservation Program-City and County of San Diego's Subarea Plans from final revised critical habitat is or is not appropriate and why;
11. Whether the potential exclusion under section 4(b)(2) of the Act of non-Federal lands covered by the Coachella Valley Multiple Species Habitat Conservation Plan from final revised critical habitat is or is not appropriate and why;
12. Whether the potential exclusion under section 4(b)(2) of the Act of non-Federal lands covered by the Orange County Central-Coastal Subregional Habitat Conservation Plan/Natural Community Conservation Plan from final revised critical habitat is or is not appropriate and why;
13. Whether the potential exclusion under section 4(b)(2) of the Act of non-Federal lands covered by the Southern Orange County Natural Community Conservation Plan/Master Streambed Alteration Agreement/Habitat Conservation Plan from final revised critical habitat is or is not appropriate and why;
14. Whether the conservation needs of the arroyo toad can be achieved or not by limiting the designation of final revised critical habitat to non-Tribal lands and why;
15. Whether the potential exclusion under section 4(b)(2) of the Act of Tribal lands of the Rincon Band of Luiseño Mission Indians from final revised critical habitat is or is not appropriate and why;
16. Whether the potential exclusion under section 4(b)(2) of the Act of Tribal lands of the Pala Band of Luiseño Mission Indians from final revised critical habitat is or is not appropriate and why;
17. Whether the potential exclusion under section 4(b)(2) of the Act of Tribal lands of the Sycuan Band of the Kumeyaay Nation from final revised critical habitat is or is not appropriate and why;
18. Whether the potential exclusion under section 4(b)(2) of the Act of Tribal lands of the Capitan Grande Band of Diegueno Mission Indians from final revised critical habitat is or is not appropriate and why;
19. Whether the potential exclusion under section 4(b)(2) of the Act of Tribal lands of the Mesa Grande Band of Diegueno Mission Indians from final revised critical habitat is or is not appropriate and why;
20. Whether our exemption under section 4(a)(3)(B) of the Act of the lands on Department of Defense land at Marine Corps Base, Camp Pendleton, in San Diego County; Fallbrook Naval Weapons Station in San Diego County; and Fort Hunter Liggett Military Reservation in San Luis Obispo County is or is not appropriate, and why;
21. Information on any quantifiable economic costs or benefits of the proposed revised designation of critical habitat;
22. Whether the benefit of exclusion of any other particular area not specifically identified above outweighs the benefit of inclusion under section 4(b)(2) of the Act;
23. Information on the currently predicted effects of climate change on the arroyo toad and its habitat;
24. Any foreseeable impacts on energy supplies, distribution, and use resulting from the proposed revised designation and, in particular, any impacts on electricity production, and the benefits of including or excluding any particular areas that exhibit these impacts; and
25. Whether we could improve or modify our approach to designating critical habitat in any way to provide for greater public participation and understanding, or to better accommodate public concerns and comments.
Our final determination concerning revised critical habitat for the arroyo toad will take into consideration all written comments received during the comment period, including comments requested from peer reviewers, comments received during a public hearing should one be requested, and any additional information we receive during the 60-day comment period. Our final determination will also consider all written comments and any additional information we receive during the comment period for the draft economic analysis. All comments will be included in the public record for this rulemaking. On the basis of peer reviewer and public comments, we may, during the development of our final determination, find that areas within those proposed do not meet the definition of critical habitat, that some modifications to the described boundaries are appropriate, or that areas are or are not appropriate for exclusion under section 4(b)(2) of the Act.
You may submit your comments and materials concerning this proposed rule by one of the methods listed in the
ADDRESSES
section.
We will post your entire comment—including your personal identifying information—on
http://www.regulations.gov.
If you provide personal identifying information, you may request at the top of your document that we withhold this information from public review. However, we cannot guarantee that we will be able to do so. We will post all hardcopy comments on
http://www.regulations.gov.
Please include sufficient information with your comment to allow us to verify any scientific or commercial data you submit.
Comments and materials we receive, as well as supporting documentation we used in preparing this proposed rule, will be available for public inspection on
http://www.regulations.gov,
or by appointment, during normal business hours, at the U.S. Fish and Wildlife Service, Ventura Fish and Wildlife Office (see
FOR FURTHER INFORMATION CONTACT
).
You may obtain copies of the proposed revised rule by mail from the Ventura Fish and Wildlife Office (see
FOR FURTHER INFORMATION CONTACT
) or by visiting the Federal eRulemaking Portal at
http://www.regulations.gov.
Background
It is our intent to discuss only those topics directly relevant to the revised designation of critical habitat in this proposed rule. Additional information on the arroyo toad may also be found in the final listing rule published in the
Federal Register
on December 16, 1994 (59 FR 64859), the “Recovery Plan for the Arroyo Southwestern Toad” (recovery plan; Service 1999), and the designation of critical habitat for the arroyo toad published in the
Federal Register
on April 13, 2005 (70 FR 19562). These documents are available on the Ventura Fish and Wildlife Office and Carlsbad Fish and Wildlife Office Web sites at
http://www.fws.gov/ventura
and
http://www.fws.gov/carlsbad.
However, please note that this proposed rule incorporates new information on the distribution of arroyo toads that became available since the 2005 final critical habitat designation for this species.
Taxonomy and Nomenclature
On December 16, 1994, we published a final rule listing the arroyo southwestern toad (
Bufo microscaphus californicus
) as endangered (59 FR 64859). This animal, originally described as
Bufo cognatus californicus
(Camp 1915, p. 331), has consistently been treated as a distinct taxon. However, its rank as a subspecies or species and taxonomic affiliations with other species has changed several times since it was described. Myers (1930, p. 75) elevated it to species rank as
Bufo californicus
citing morphological, vocalization, and ecological data to distinguish it from
B. cognatus.
Subsequent to Myers' paper, other authors again relegated the animal to subspecies rank aligned with various other species of
Bufo.
The name in use at the time of listing,
Bufo microscaphus californicus,
was published by Stebbins (1951, p. 275).
Since the toad was listed, an analysis of allozyme data (Gergus 1998, p. 322) supports recognition of
Bufo californicus
as separate from
B. microscaphus.
In addition, a phylogenetic analysis of comparative anatomical and molecular genetic data for amphibians (Frost
et al.
2006, p. 363) segregated the Nearctic taxa of
Bufo
as the genus
Anaxyrus
and published the combination
Anaxyrus californicus,
the arroyo toad. This treatment is accepted by the Committee on Standard English and Scientific Names of the American Society of Ichthyologists and Herpetologists, The Herpetologists' League, and the Society for the Study of Amphibians and Reptiles (Frost
et al.
2008, p. 3).
In light of these changes and their acceptance by the above scientific authorities, we are proposing to amend the List of Threatened and Endangered Wildlife at 50 CFR 17.11 to identify the
listed entity as “arroyo toad (
Anaxyrus californicus
).” This change does not alter the description or distribution of the animals.
Species Description
The arroyo toad is a small, dark-spotted toad of the family Bufonidae. Its coloration ranges from light olive green or gray to light brown with a distinctive light-colored, V-shaped stripe across the head and the eyelids. The belly is white or buff and often lacks dark blotches or spots (Stebbins 2003, p. 212). The species is endemic to the coastal plain and mountains of central and southern California, and northwestern Baja California, Mexico, from near sea level to about 8,000 feet (ft) (2,440 meters (m)) in elevation. For a detailed description of the species, see the recovery plan
and references cited within the plan (Service 1999, pp. 1-119), and information in previous
Federal Register
notices, proposed rules, and final rules (59 FR 64859, December 16, 1994; 66 FR 9414, February 7, 2001; 69 FR 23254, April 28, 2004; 70 FR 19562, April 13, 2005). In addition to the recovery plan, important sources for information on the biology of the arroyo toad include: Sweet (1992, pp. 1-198; 1993, pp. 1-73); Campbell
et al.
(1996, pp. 1-46); Griffin
et al.
(1998, pp. 1-66); Griffin and Case (2001, pp. 633-644); Holland and Sisk (2001); and Ramirez (2002a, pp. 1-62; 2002b; 2002c; 2003, pp. 1-101).
Life History
Breeding typically occurs from February to July on streams with persistent water (Griffin
et al.
1999, p. 1). Males may breed with several females in a season; however, female arroyo toads release their entire clutch of eggs as a single breeding effort and probably do not produce a second clutch during the mating season. Eggs are deposited and tadpoles develop in shallow pools with minimal current and little or no emergent vegetation. The substrate in these pools is generally sand or fine gravel overlain with silt. The eggs hatch in 4 to 5 days and the tadpoles are immobile for an additional 5 to 6 days. Tadpoles then begin to disperse from the pool margin into the surrounding shallow water, where they spend an average of 10 weeks. Peak metamorphosis occurs during June and July in the northern part of the arroyo toad's range, and from late April through June farther south, although it could occur later, particularly at higher elevations (Holland 2000,
in litt.
p. 8). After metamorphosis, the juvenile arroyo toads remain on the bordering gravel bars until the pool dries out (usually from 8 to 12 weeks depending on the site and rainfall). Most individuals become sexually mature by the following spring (Sweet 1992, p. 52).
Arroyo toad tadpoles feed on loose organic material such as interstitial algae, bacteria, and diatoms. They do not forage on macroscopic vegetation (Sweet 1992, p. 82; Jennings and Hayes 1994, p. 56). Juvenile arroyo toads feed on ants almost exclusively (Service 1999, p. 36). By the time they reach 0.7 to 0.9 inch (in) (1.78 centimeters (cm)) in length, they consume beetles along with ants (Sweet 1992, p. 99; Service 1999, p. 36). Adult arroyo toads probably consume a wide variety of insects and arthropods including (but not limited to) ants, beetles, spiders, larvae, and caterpillars.
Geographic Range
The historical and current range of the arroyo toad extends from the Salinas River Basin southward through the Santa Ynez, Santa Clara, and Los Angeles River basins (Sweet 1992, p. 18), to Orange, Riverside, and San Diego Counties (Jennings and Hayes 1994, p. 54) and southward to the Arroyo San Simeon system, Baja California, Mexico (Service 1999, p. 12; Ramirez 2007, p. 5). Populations also occur on the desert slopes of both the San Gabriel Mountains (in Little Rock Creek in Los Angeles County) and the San Bernardino Mountains (in the Mojave River and in its tributaries, Little Horsethief and Deep Creeks, in San Bernardino County) (Sweet 1992, p. 18; Jennings and Hayes 1994, p. 54).
At the time of listing (59 FR 64859; December 16, 1994), arroyo toads were believed to be extirpated from the Salinas River Basin. In 1996, arroyo toads were found during surveys on the Fort Hunter Liggett Military Reservation approximately 40 miles (mi) (64 kilometers (km)) downstream of the historical Santa Margarita arroyo toad locality (U.S. Army Reserve 2004, pp. 5-10). In 1997, arroyo toads were detected along a 17-mi (27-km) stretch of the San Antonio River. The Army surveyed approximately 6 mi (9.6 km) of the San Antonio River on the Military Reservation in 2002 and estimated there were as many as 7,000 arroyo toad larvae (tadpoles) in the area (U.S. Army Reserve Command 2004, p. 12). We believe this population was present but undetected on Fort Hunter Liggett at the time of listing for the following reasons: (1) Annual surveys (U.S. Army Reserve 2004, p. 38) indicate there is suitable breeding and upland habitats for this large, robust population; and (2) given that the nearest extant population of arroyo toads is 150 mi (240 km) southeast of Fort Hunter Liggett in Santa Barbara County, it is unlikely that arroyo toads could have dispersed and newly colonized the Fort Hunter Liggett area by 1996, just 2 years subsequent to the species being listed in 1994. Therefore, we consider the population on Fort Hunter Liggett to have existed in 1994 and to represent the northernmost limit of the species' range at listing and currently. The geographical area occupied by the species at the time it was listed is the same as the species' current range in the coastal streams extending from Monterey County southward to San Diego County, and extending eastward into the riparian (along the shore of a river, stream, or lake) environments of San Bernardino and Riverside Counties.
Arroyo toads have been extirpated from approximately 75 percent of the habitat they originally occupied (Sweet 1992, p. 189; Jennings and Hayes 1994, p. 57; Campbell
et al.
1996, p. 2). At present, arroyo toads are limited to isolated populations primarily in the headwaters of coastal streams. The species is likely restricted naturally as a result of specific habitat requirements for breeding and development (Service 1999, p. 39). These natural restrictions, coupled with the small sizes of many arroyo toad populations, make them particularly vulnerable to the negative effects of human-induced changes to their habitat (Jennings and Hayes 1994, p. 57).
Habitat
Stream order, elevation, and floodplain width appear to be important factors in determining habitat suitability (Sweet 1992, pp. 24-26; Griffin
et al.
1999, pp. 1-3). Stream order ranks the size and potential power of streams. The smallest channels in a watershed with no tributaries are referred to as first-order streams. When two first-order streams unite, they form a second-order stream; when two second-order streams unite, they form a third-order stream, and so on. Fifth- and sixth-order streams are usually larger rivers, while first- and second-order streams are often small, steep, or intermittent. In the northern portion of the range, arroyo toads are found on third- to sixth-order streams (Sweet 1992, p. 24), while in the central and southern portion of the range, arroyo toads are found in first- to sixth-order streams (Service 1999, p. 32).
Optimal breeding habitat consists of low-gradient sections of slow-moving streams with shallow pools, nearby sandbars, and adjacent stream terraces. Arroyo toads breed and deposit egg masses in the shallow, sandy pools of these streams, which are usually
bordered by sand-gravel flood-terraces. Breeding sites favored by adult arroyo toads have clear water in shallow (less than 12 in (30 cm) deep) pools (Sweet 1992, p. 28). Optimal breeding sites also have flow rates less than 1.97 in (5 cm) per second and bottoms composed of sand or well-sorted, fine gravel, although a significant component of large gravel or cobble may also be present (Sweet 1992, p. 37).
Stream terrace habitat consisting of alluvial bars and terraces that may have established cottonwoods (
Populus
spp.), oaks (
Quercus
spp.), or willows (
Salix
spp.) and almost no grass and herbaceous cover at ground level are extremely important for arroyo toads prior to, during, and after the breeding season (Griffin
et al.
1999, p. 45; Sweet 1992, pp. 28-49). Areas that are used by juveniles consist primarily of sand or fine gravel bars with varying amounts of large gravel or cobble and adjacent stable sandy terraces and oak flats. Juvenile arroyo toads favor areas that are damp and have some vegetation cover (less than 10 percent), which offer refugia and thermal characteristics that are needed for juvenile survival and rapid growth (Campbell
et al.
1996, p. 12). Bare sand and gravel bars may support large numbers of juvenile toads, but survivorship can be reduced due to high levels of predation (Sweet 1992, p. 113).
Adult arroyo toads are often found on sandy alluvial terraces adjacent to the stream that may be sparsely-to-heavily vegetated with brush and trees, such as mulefat (
Baccharis
spp.), California sycamore (
Platanus racemosa
), cottonwoods, coast live oak (
Quercus agrifolia
), and willow (Campbell
et al.
1996,
pp. 12-13). The understory of stream terraces may consist of scattered short grasses, herbs, and leaf litter, with patches of bare or disturbed soil, or have no vegetation at all. When foraging, juvenile and adult arroyo toads are often found around the drip lines of oak trees (Sweet 1992, pp. 45-46; Campbell
et al.
1996, p. 10). When active at night, arroyo toads can often be observed near ant trails feeding on passing ants and other prey.
Upland habitats used by arroyo toads during both the breeding and non-breeding seasons include alluvial scrub, coastal sage scrub, chaparral (shrubby plants adapted to dry summers and moist winters), grassland, and oak woodland. Within terrace and upland habitats, arroyo toads aestivate (a state of dormancy similar to hibernation) in burrows during the non-breeding season, which usually starts in the late summer and extends from August to January (Ramirez 2003, p. 46). In habitat utilization studies conducted by Ramirez (2007, pp. 11-14) from 1999 to 2006 in the West Fork Mojave River and Grass Valley Creek areas, arroyo toads were generally found burrowed within sandy or loamy substrates with no associated canopy cover, or within mulefat scrub or arroyo willow (
Salix lasiolepis
) patches. The majority of individuals tracked in these studies burrowed immediately adjacent to the active channel or on sandy terraces within riparian habitat located within flood-prone areas; however, toads were also found to use upland habitats up to 1,063 ft (324 m) from the active channel (Ramirez 2007, p. 13). In his 2005 study, Ramirez (2007, p. 93) observed several arroyo toad individuals burrowed in stable terrace habitats dominated by Great Basin sage scrub and Utah junipers (
Juniperus osteosperma
)
.
At Little Rock Creek on the desert slopes of the San Gabriel Mountains, arroyo toads burrowed in areas closest to the creek that retained higher soil saturation and were cooler (Ramirez 2002a, p. 50). Griffin
et al.
(1999, p. 45) noted that sands are the preferred burrowing substrate for both male and female arroyo toads, confirming the importance of natural hydrologic regimes that maintain sand and fine sediment deposition across the floodplain.
Dispersal
Arroyo toad movement patterns also vary between watersheds or river reaches in response to different hydrological regimes (Griffin
et al.
1999, p. 11). In broad floodplain river systems, arroyo toads searching for suitable egg-laying sites may have to move across parallel stream channels. Cristianitos Creek, Talega Creek, and the lower San Mateo River are examples of this type of river system because of their wide, sandy floodplains where the river flows into several channels during floods. Despite river depths of 24 in (60 cm) and swift currents, Griffin
et al.
(1999, p. 21) observed numerous toads crossing Talega Creek and the lower San Mateo River, confirming these river systems are not a barrier to arroyo toad dispersal. In their study of arroyo toad movement patterns, Griffin
et al.
(1999, pp. 18-21) tracked 10 female and 3 male arroyo toads in the lower San Mateo River and observed female arroyo toads regularly using riparian and upland habitats far from the river's edge and returning to these areas after traveling far upstream for egg-laying. In one case, a female arroyo toad traveled 919 ft (280 m) across the San Mateo Campground into upland native habitat; in another instance, a female was found 558 ft (170 m) from the San Mateo River under cover of mulefat scrub (Griffin
et al.
1999, p. 20). They also recorded arroyo toads moving in both up- and downstream directions, such as the female arroyo toad that traveled upstream more than 492 ft (150 m) in a single night to a breeding pool. The study found that both male and female arroyo toads moved more into upland habitats after completing individual breeding activity (Griffin
et al.
1999, p. 46).
In contrast, arroyo toads searching for breeding pools in watersheds with relatively narrower, steeper-sided drainages (such as the Piru and Sespe Creek Watersheds in Ventura County) tend to move in both up- and downstream directions along these channels with their structure of alternating riffles and pools (Griffin
et al.
1999, p. 11). In his Mono Creek study, Sweet (1993, pp. 24-65), concluded that female arroyo toads became relatively sedentary as they matured whereas males tended to travel up- and downstream fairly often during the breeding season (Sweet 1993, p. 65). This study also suggested that most juvenile arroyo toads disperse away from their natal pools about a year after metamorphosis (Sweet 1993, p. 65). In fact, numerous juvenile and adult arroyo toads were observed moving up- and downstream as much as 0.5 mi (0.8 km) and over 0.6 mi (1 km) in some cases (Sweet 1993, p. 1). Arroyo toads in these watersheds also travel laterally away from the stream channel into terrace and upland native habitats. On lower Piru Creek, Sweet (1992, pp. 42-45) observed two adult males under oaks that were 200 ft (61 m) away.
Reasons for Decline and Threats
A variety of factors contribute to the decline of arroyo toads but nearly half of historical extirpations prior to listing are attributed to dam building and operation (Sweet 1992, pp. 4-5; Ramirez 2003, p. 7). Suitable habitat is often flooded out by reservoir water, and downstream breeding and non-breeding habitat may be severely altered by reduced flows at some times and sudden excessive flows at others. Sudden excessive releases of water may destroy sand bars used during the breeding season, and reconfigure or destroy suitable breeding pools, thus disrupting clutch and larval development (Ramirez 2003, p. 7). Additionally, dams can interrupt the scouring and deposition processes needed to maintain arroyo toad pool and terrace habitats. Areas below dams can become unsuitable as fine sands are lost and not replaced (Service 1999, pp. 42-43).
In addition to flood control projects, other threats include agriculture; sand and gravel mining; urban development; off-highway vehicle use; urbanization; recreational activities such as camping, fishing, hiking, picnicking; and natural factors, including drought and fire (59 FR 64859; Service 1999, p. 39; Ramirez 2003, p. 7). Conversion of stream terrace habitat for farming, road construction, and residential and commercial uses has eliminated substantial arroyo toad habitat in some areas. Suction dredge mining of sand and gravel causes substantial alteration of habitat by degrading water quality, altering stream morphology, increasing siltation downstream, and creating deep pools that hold water year-round for introduced predators of arroyo toad eggs and larvae (Campbell
et al.
1996, p. 16). Natural disturbances, such as drought and fire, also threaten the arroyo toad (Campbell
et al.
1996, p. 17). Prolonged drought can result in the loss of suitable breeding pools, foraging habitat, and prey availability (Sweet 1992, p. 190). Fire can affect arroyo toads by causing direct mortality and destruction of stream or terrace vegetation.
The introduction of nonnative species that compete for resources or that prey on arroyo toads also poses a serious threat to arroyo toad existence. The introduction of aquatic species not native to southern California watercourses has been facilitated by construction of the California Aqueduct and other sources of inter-basin water transport (Service 1999, p. 48). Currently, the California Aqueduct is linked directly to the Santa Ynez River, Santa Clara River, San Jacinto River, and Mojave River Basins. Predatory species, many of which have used the aqueduct to colonize these river basins, include green sunfish (
Lepomis cyanellus
), largemouth bass (
Micropterous salmoides
), black bullhead (
Ictalurus nebulosus
), prickly sculpin (
Cottus asper
), stocked rainbow trout (
Oncorhynchus mykiss
), oriental gobies (
Tridentiger
spp.), red shiners (
Notropis lutrensis
), bullfrogs (
Rana catesbeiana
), African clawed frogs (
Xenopus laevis
), and crayfish (
Procambarus clarkii)
(Sweet 1992, pp. 118-122; Service 1999, p. 48). All of these species prey on arroyo toad tadpoles.
Of the above introduced-predators, bullfrogs are probably the most serious threat to arroyo toads (Stephenson and Calcarone 1999, p. 82). Bullfrogs are well adapted to deep water conditions in ponded areas above dams, and dam releases can introduce them to downstream habitats (CDFG 2005, p. 178). A broad diet and an extended breeding season give bullfrogs a competitive advantage over native amphibians. Whereas arroyo toad breeding habitat requirements are highly specialized, in that they require shallow, slow-moving streams and riparian habitats that are disturbed on a regular basis, bullfrogs can tolerate elevated water temperatures and make use of standing pools resulting from urban runoff to complete their 2-year life cycle (CDFG 2005, p. 178).
Introduced plants have also had a negative effect on arroyo toads and their habitat. Nonnative plant species, particularly tamarisk (
Tamarix
spp.) and giant reed (
Arundo donax
) alter the natural hydrology of stream drainages by eliminating sandbars, breeding pools, and upland habitats. Tamarisk is an aggressive, woody invasive plant species that can tolerate a variety of environmental conditions and has become established over as much as a million acres of floodplains, riparian areas, wetlands, and lake margins in the western United States (Carpenter 2004, pp. 1-30). Tamarisk can replace or displace native woody species such as cottonwood and willow which occupy similar habitats, especially when timing and amount of peak water discharge, salinity, temperature, and substrate texture have been altered by human activities (Carpenter 2004, pp. 1-30). Tamarisk also consumes large quantities of water, possibly more than woody native plant species occupying the same habitat (Carpenter 2004, p. 3). Highly resistant to removal by flooding, tamarisk has the potential to form dense corridors along most large streams. Where this has been allowed to occur, tamarisk has replaced native vegetation, invaded sand bars, and led to channelization by constricting flood flows.
Arundo donax
is a tall, grass-like plant that grows up to 20 ft (6.1 m) in height with jointed stems that resemble corn stalks.
Arundo donax
also invades stream banks and lakeshores, where it can completely displace native vegetation, reduce wildlife habitat, increase fire risks, and alter flow regimes which can cause flooding (Ventura County 2006, pp. 21-23).
In summary, predation from introduced aquatic species and the loss of habitat, coupled with habitat modifications due to the establishment of nonnative plants and the manipulation of water levels in many central and southern California streams and rivers, have caused arroyo toads to disappear from a large portion of their previously occupied habitat in California.
Previous Federal Action
For more information on previous Federal actions concerning the arroyo toad, refer to our final designation of critical habitat published in the
Federal Register
on April 13, 2005 (70 FR 19562). On July 20, 2007 (Service 2007, pp. 1-2), we announced that we would review the April 13, 2005, final rule after questions were raised about the integrity of scientific information used and whether the decision made was consistent with the appropriate legal standards. Based on our review of the previous final critical habitat designation, we determined it was necessary to revise critical habitat and this rule proposes those revisions. On December 19, 2007, the Center for Biological Diversity filed a complaint in the U.S. District Court for the Southern District of California challenging our designation of critical habitat for the arroyo toad (
Center for Biological Diversity
v.
U.S. Fish and Wildlife Service,
Case No. 07-2380-JM-AJB). On June 5, 2008, the court entered a consent decree requiring a proposed revised critical habitat rule to be submitted to the
Federal Register
by October 1, 2009, and a final revised critical habitat designation to be submitted to the
Federal Register
by October 1, 2010.
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) That 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 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. Such methods and procedures include, but are not limited to, all activities associated with scientific resources management such as research, census, law enforcement, habitat acquisition and maintenance, propagation, live trapping and transplantation, and in the extraordinary case where population
pressures within a given ecosystem cannot otherwise be relieved, may include regulated taking.
Critical habitat receives protection under section 7 of the Act through the prohibition against Federal agencies carrying out, funding, or authorizing activities that are likely to result in 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 to access private lands. Such designation does not require implementation of restoration, recovery, or enhancement measures by private landowners. Where a landowner seeks or requests Federal agency funding or authorization of an activity 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 considered for inclusion in a critical habitat designation, habitat within the geographical area occupied by the species at the time it was listed must contain the physical or biological features that are essential to the conservation of the species. Areas supporting the essential physical or biological features are identified, to the extent known using the best scientific data available, as the habitat areas that provide essential life cycle needs of the species; that is, areas on which are found the primary constituent elements laid out in the appropriate quantity and spatial arrangement essential to the conservation of the species. Habitat within the geographical area occupied by the species at the time of listing that contains features essential to the conservation of the species meets the definition of critical habitat only if these features may require special management considerations or protection. Under the Act and the regulations at 50 CFR 424.12, we can designate critical habitat in areas outside the geographical area occupied by the species at the time it is listed only when we determine that the best available scientific data demonstrate that the designation of those areas is 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 our decisions are based on the best scientific data available. They require our biologists, to the extent consistent with the Act and with the use of the best scientific data available, to use primary and original sources of information as the basis for recommendations to designate critical habitat.
When we are determining which areas to propose as revised critical habitat, our primary source of information is generally the information developed during the listing process for the species and any previous designations of critical habitat. Additional information sources may include the recovery plan and 5-year reviews for the species, articles in peer-reviewed journals, conservation plans developed by States and counties, scientific status surveys and studies, biological assessments, or other unpublished materials and expert opinion or personal knowledge.
Habitat is dynamic, and species may move from one area to another over time. In particular, we recognize that climate change may cause changes in the arrangement of occupied habitat patches. Current climate change predictions for terrestrial areas in the Northern Hemisphere indicate warmer air temperatures, more intense precipitation events, and increased summer continental drying (Field
et al.
1999, pp. 1-3; Hayhoe
et al.
2004, p. 12422; Cayan
et al.
2005, p. 6; Intergovernmental Panel on Climate Change 2007, p. 11; Cayan
et al.
2009, p. xi). However, predictions of climatic conditions for smaller sub-regions such as California remain uncertain. It is unknown at this time if climate change in California will result in a warmer trend with localized drying, higher precipitation events, or other effects. Thus, the information currently available on the effects of global climate change and increasing temperatures does not make sufficiently precise estimates of the location and magnitude of the effects. Nor are we currently aware of any climate change information specific to the habitat of the arroyo toad that would indicate what areas may become important to the species in the future. Therefore, we are unable to determine what additional areas, if any, may be appropriate to include in the proposed revised critical habitat for this species; however, we specifically request information from the public on the currently predicted effects of climate change on the arroyo toad and its habitat. Additionally, we recognize that critical habitat designated at a particular point in time may not include all of the habitat areas that we may later determine are necessary for the recovery of the species. For these reasons, a critical habitat designation does not signal that habitat outside the designated critical habitat area is unimportant or may not be required for recovery of the species.
Areas that support populations of the arroyo toad, but are outside the critical habitat designation, may continue to be subject to conservation actions we and other Federal agencies implement under section 7(a)(1) of the Act. They are also subject to the regulatory protections afforded by the section 7(a)(2) jeopardy standard, as determined on the basis of the best available information at the time of the agency action. Federally funded or permitted projects affecting listed species outside their designated critical habitat areas may still result in jeopardy findings in some cases. Similarly, critical habitat designations made on the basis of the best available information at the time of designation will not control the direction and substance of future recovery plans, habitat conservation plans (HCPs), section 7 consultations, or other species conservation planning efforts if new information available to these planning efforts calls for a different outcome.
Methods
As required by section 4(b) of the Act, we used the best scientific and commercial data available in determining which areas within the geographic area occupied by the species at the time of listing contain the features essential to the conservation of the arroyo toad, and which areas outside the geographical area occupied at the time of listing are essential for the conservation of the species. We reviewed information used to prepare the 2004 proposed critical habitat rule (69 FR 23254); the approach to provide conservation for the arroyo toad provided in its recovery plan (Service 1999, pp. 1-119); the 5-year review for the arroyo toad (Service 2009, pp. 1-51); the California Department of Fish and Game's (CDFG) California Natural Diversity Database (CNDDB) records; published peer-reviewed articles;
unpublished papers and reports; academic theses; survey results; Geographic Information System (GIS) data (such as species occurrences, soil data, land use, topography, and ownership maps); and correspondence to the Service from recognized experts. We solicited new information collected since publication of the recovery plan and 2005 final critical habitat designation, including information from State, Federal, and Tribal governments, and from academia and private organizations that have collected scientific data on the arroyo toad. We also based our determination of areas meeting the definition of critical habitat for the arroyo toad in part on the approach in the recovery plan that focuses on protection and management of breeding and non-breeding habitat on a watershed basis for the conservation of the species (Service 1999, pp. 1-119).
Physical and Biological Features
In accordance with section 3(5)(A)(i) of the Act and regulations at 50 CFR 424.12(b), in determining which areas within the geographical area occupied at the time of listing to propose as revised critical habitat, we consider the physical and biological features that are essential to the conservation of the species that may require special management considerations or protection. Those features are the primary constituent elements (PCEs) laid out in the appropriate quantity and spatial arrangement for conservation of the species. The PCEs include, but are not limited to:
(1) Space for individual and population growth, and for normal behavior;
(2) Food, water, air, light, minerals, or other nutritional or physiological requirements;
(3) Cover or shelter;
(4) Sites for breeding, reproduction, and rearing (or development) of offspring; and
(5) Habitats that are protected from disturbance or are representative of the historical, geographical, and ecological distributions of a species.
We derive the specific PCEs required for conservation of the arroyo toad from its biological needs. The areas proposed for designation as revised critical habitat provide aquatic habitat for breeding activities and upland habitat for shelter, foraging, predator avoidance, and dispersal across the arroyo toad's current range. The PCEs and the resulting physical and biological features essential to the conservation of the species are determined based on studies of arroyo toad ecology as described in the “Background” section of this proposed rule and in the final listing rule published in the
Federal Register
on December 16, 1994 (59 FR 64859).
Space for Individual and Population Growth, and for Normal Behavior
The arroyo toad is found along medium-to-large streams in coastal and desert drainages in central and southern California, and Baja California, Mexico. It occupies aquatic, riparian, and upland habitats in a number of the remaining suitable drainages within its range. Suitable habitat for the arroyo toad is created and maintained by the fluctuating hydrological, geological, and ecological processes that naturally occur in riparian ecosystems and adjacent uplands (Campbell
et al.
1996, pp. 13-15; Service 1999, p. 39). Periodic flooding that modifies stream channels, redistributes channel sediments, and alters pool location and form, coupled with upper terrace stabilization by vegetation, is required to keep a stream segment suitable for all life stages of the arroyo toad (Campbell
et al.
1996, p. 13; Service 1999, p. 39). This natural flooding regime helps maintain areas of open, sparsely vegetated, sandy stream channels and terraces.
The substrate in habitats preferred by arroyo toads consists primarily of sand, fine gravel, or pliable soil, with varying amounts of large gravel, cobble, and boulders. Areas that are damp and have less than 10 percent vegetation cover provide the best conditions for juvenile survival and rapid growth (Campbell
et al.
1996, p. 12; Service 1999, pp. 32-34). Arroyo toads breed in the quiet margins of open streams and avoid sites with deep or swift water, tree canopy cover, or steeply incised banks. Larvae occupy shallow areas of open streambeds on substrates ranging from silt to cobble, with preferences for sand or gravel. Newly metamorphosed arroyo toads and juveniles remain on sparsely vegetated sand and gravel bars bordering the natal pool for 3 to 5 weeks (Sweet 1992, p. 52).
Arroyo toads must be able to move between the stream and upland foraging sites, as well as up and down the stream corridor. Juveniles and adult arroyo toads require and spend much of their lives in riparian and upland habitats adjacent to breeding locations (Campbell
et al.
1996, p. 12). Riparian habitats used for foraging and burrowing include sand bars, alluvial terraces, and streamside benches that lack vegetation, or are sparsely to moderately vegetated. Upland habitats used by arroyo toads during both the breeding and non-breeding seasons include alluvial scrub, coastal sage scrub, chaparral, grassland, and oak woodland.
Food, Water, and Physiological Requirements
Arroyo toad tadpoles eat microscopic algae, bacteria, and protozoans consumed from the spaces among pebbles, gravel, and sand, or abraded from stones (Sweet 1992, p. 82). Juveniles and adults eat insects, although ants are preferred. When foraging, arroyo toads are often found around the drip lines of oak trees. These areas often lack vegetation, yet have levels of prey that will support arroyo toads. When active at night, toads often are observed near ant trails feeding on ants, beetles, and other prey.
Cover or Shelter
During the day and other periods of inactivity, arroyo toads seek shelter by burrowing into sand. Thus, areas of sandy or friable (readily crumbled) soils are necessary, but these soils can be interspersed with gravel or cobble deposits. Additionally, arroyo toads may seek temporary shelter under rocks or debris and have been found in mammal burrows on occasion. Upland sites with compact soils can also be used for foraging and dispersal (Holland 2000,
in litt.
).
Sites for Breeding, Reproduction, and Rearing of Offspring
The arroyo toad has specialized breeding habitat requirements. They favor shallow pools (less than 12 in (30 cm) deep) and open sand and gravel channels along low-gradient (typically less than 6 percent) reaches of medium to large streams (Service 1999, pp. 31-32). These streams can have either intermittent or perennial streamflow and typically experience periodic flooding that scours vegetation and replenishes fine sediments. In at least some portions of its range, the species also breeds in smaller streams and canyons where low-gradient breeding sites are more sporadically distributed. Breeding pools must persist long enough for the completion of larval development, which is generally March through June, depending on location and weather. Because the suitability of breeding pools may vary from year to year due to the dynamics of southern California riparian systems and flood regimes, adult arroyo toads may move up or down stream in search of suitable breeding pools, or not breed that year (Campbell
et al.
1996, p. 14).
Arroyo toads breed in rivers with intermittent, seasonal flow, with a breeding period that may range from late February through July. Breeding at
a given site may extend over several months (Griffin and Case 2001, p. 634). Breeding arroyo toads lay their eggs in water over substrates of sand, gravel, or cobble in open sites such as overflow pools, old flood channels, and shallow pools along streams. Such habitats rarely have closed canopies over the lower banks of the stream channel due to periodic flood events. Heavily shaded pools are generally unsuitable for larval and juvenile arroyo toads because of lower water and soil temperatures and poor algal mat development. Pools less than 12 in (30 cm) deep with clear water, flow rates less than 0.2 ft per second (5 cm per second), and bottoms composed of sand or well-sorted fine gravel are favored by adults for breeding and egg deposition (Sweet 1992, pp. 29-37). Although egg strings are laid in very slow-moving water, larvae (tadpoles) can be found in water velocities of up to 1.0 to 1.3 ft per second (30 to 40 cm per second) (Sweet 1992, p. 29). Breeding may occur on several dates at a single site, and eggs may be deposited over a period of 7 to 8 weeks (Campbell
et al.
1996, p. 6). Breeding pools must persist a minimum of 2 months for the completion of larval development because changes in stream level or altering of the stream bed or breeding pool may cause high mortality to eggs and small larvae, sweeping them downstream, stranding and exposing them to desiccation, or burying and asphyxiating them with silt (Campbell
et al.
1996, p. 6). Larvae usually hatch in 4 to 6 days at water temperatures of 54 to 59 degrees Fahrenheit (12 to 16 degrees Celsius). Tadpoles disperse from the pool margin into the surrounding shallow water, where they spend an average of 10 weeks. After metamorphosis, the juvenile arroyo toads remain on the bordering gravel bars until the pool dries out (usually from 8 to 12 weeks depending on the site and rainfall).
Primary Constituent Elements (PCEs) for the Arroyo Toad
Pursuant to the Act and its implementing regulations, when considering the designation of critical habitat, we must focus on the known principal primary constituent elements within the geographical area occupied by the arroyo toad at the time of listing that are essential to the conservation of the species. The essential physical and biological features are those PCEs laid out in an appropriate quantity and spatial arrangement determined to be essential to the conservation of the species. All areas proposed in this rule as revised critical habitat for the arroyo toad are currently occupied, are within the geographical area occupied by the species at the time of listing, and contain sufficient PCEs to support at least one life-history function.
Based on the above needs and our current knowledge of the life history, biology, and ecology of the species, and the habitat requirements for sustaining the essential life-history functions of the species, we have determined that the PCEs specific to the arroyo toad are:
(1) Rivers or streams with hydrologic regimes that supply water to provide space, food, and cover needed to sustain eggs, tadpoles, metamorphosing juveniles, and adult breeding toads. Breeding pools must persist a minimum of 2 months for the completion of larval development. However, due to the dynamic nature of southern California riparian systems and flood regimes, the location of suitable breeding pools may vary from year to year. Specifically, the conditions necessary to allow for successful reproduction of arroyo toads are:
• Breeding pools with areas less than 12 in (30 cm) deep;
• Areas of flowing water with current velocities less than 1.3 ft per second (40 cm per second); and
• Surface water that lasts for a minimum of 2 months during the breeding season (a sufficient wet period in the spring months to allow arroyo toad larvae to hatch, mature, and metamorphose).
(2) Riparian and adjacent upland habitats, particularly low-gradient (typically less than 6 percent) stream segments and alluvial streamside terraces with sandy or fine gravel substrates that support the formation of shallow pools and sparsely vegetated sand and gravel bars for breeding and rearing of tadpoles and juveniles; and adjacent valley bottomlands that include areas of loose soil where toads can burrow underground, to provide foraging and living areas for juvenile and adult arroyo toads.
(3) A natural flooding regime, or one sufficiently corresponding to natural, characterized by intermittent or near perennial flow that contributes to the persistence of shallow pools into at least mid-summer, and that maintains areas of open, sparsely vegetated, sandy stream channels and terraces by periodically scouring riparian vegetation; and also that modifies stream channels and terraces and redistributes sand and sediment, such that breeding pools and terrace habitats with scattered vegetation are maintained.
(4) Stream channels and adjacent upland habitats that allow for movement to breeding pools, foraging areas, overwintering sites, upstream and downstream dispersal, and connectivity to areas that contain suitable habitat.
In summary, the need for space for individual and population growth and normal behavior is met by PCE (1); the need for food, water and physiological requirements is met by PCE (1); cover and shelter requirements are met by PCE (2); areas for breeding reproduction, and rearing of offspring are met by PCEs (1), (2), and (3); and habitats representative of the historical, geographical, and ecological distributions of a species are met by PCE (4).
With this proposed revised designation of critical habitat, we intend to conserve the physical and biological features that are essential to the conservation of the species, through the identification of the appropriate quantity and spatial arrangement of the PCEs sufficient to support the life-history functions of the species. Because not all life-history functions require all the PCEs, not all areas designated as critical habitat will contain all the PCEs. Each of the areas proposed for designation in this rule has been determined to contain sufficient PCEs to provide for one or more of the life-history functions of the arroyo toad.
Special Management Considerations or Protection
In accordance with the definition of critical habitat in section 3(5)(A) of the Act, when designating critical habitat within the geographical area occupied by the species at the time of listing, we assess whether the physical and biological features essential to the conservation of the arroyo toad may require special management considerations or protection. All areas being proposed as critical habitat may require some level of management to address current and future threats to the arroyo toad, to maintain or enhance the physical and biological features essential to its conservation, and to ensure the recovery and survival of the species.
A detailed discussion of threats impacting the physical and biological features essential to the conservation of the arroyo toad which may require special management considerations or protection, can be found in the final listing rule (59 FR 64859; December 16, 1994), the 2001 critical habitat designation (66 FR 9414; February 7, 2001), the 2005 critical habitat designation (70 FR 19561; April 13, 2005), and the recovery plan (Service 1999, pp. 1-119). In summary, these threats include habitat destruction and alteration due to short- and long-term changes in river hydrology, including
construction of dams and water diversions; alteration of riparian wetland habitats by agriculture and urbanization; construction of roads; site-specific damage by off-highway vehicle use and other recreational activities; overgrazing; and mining activities. Arroyo toads and their habitats are also threatened by introduced nonnative predators (such as bullfrogs and predatory fish), drought, periodic fires, unseasonal water releases from dams, livestock grazing, and light and noise pollution from adjacent developments and campgrounds. Activities that may require special management considerations or protection of the features essential to the conservation of the arroyo toad include, but are not limited to: dam construction and operation, river diversion, conversion of riparian wetland habitat by agriculture and urbanization, road construction, off-highway vehicle use, campground development, grazing, and mining. In each proposed critical habitat unit, special management may be needed to ensure that aquatic and terrestrial habitat are able to provide abundant breeding and non-breeding habitat, prey habitat, shelter, and connectivity within the landscape.
In summary, we find that each of the areas we are proposing as revised critical habitat contains features essential to the conservation of the arroyo toad, and that these features may require special management considerations or protection. Special management considerations or protection may be required to eliminate, or reduce to negligible level, the threats affecting each unit and to preserve and maintain the essential features that the proposed critical habitat units provide to the arroyo toad. A more comprehensive discussion of threats facing individual sites is in the individual unit descriptions.
The designation of critical habitat does not imply that lands outside of critical habitat do not play an important role in the conservation of the arroyo toad. Activities with a Federal nexus that may affect those unprotected areas outside of critical habitat, such as development, agricultural activities, and road construction, are still subject to review under section 7 of the Act if they may affect the arroyo toad. The take prohibitions of section 9 of the Act also continue to apply both inside and outside of designated critical habitat. Take is broadly defined in the Act as to harass, harm, pursue, hunt, shoot, wound, kill, trap, capture, or collect a listed species, or to attempt to engage in any such conduct.
Criteria Used To Identify Critical Habitat
Using the best scientific and commercial data available as required by section 4(b)(1)(A) of the Act, we identified those areas to propose for revised designation as critical habitat that, within the geographical area occupied by the species at the time of listing (see “Geographic Range” section), possess those physical and biological features essential to the conservation of the arroyo toad and which may require special management considerations or protection. We also considered the area outside the geographical area occupied by the species at the time of listing for any areas that are essential for the conservation of the arroyo toad. The material we used included the 1994 final listing rule (59 FR 64859), the 2004 proposed critical habitat rule (69 FR 23254), 2008 CNDDB records, the arroyo toad recovery plan, data in reports submitted during section 7 consultations and by biologists holding section 10(a)(1)(A) recovery permits, research published in peer-reviewed articles and presented in academic theses and agency reports, the 5-year review for the arroyo toad (Service 2009, pp. 1-51), and regional GIS coverages. We analyzed this information to develop criteria for identifying areas that contain the PCEs in the appropriate quantity and spatial arrangement essential to the conservation of the arroyo toad that may require special management considerations or protection, or that are essential for the conservation of the arroyo toad.
To begin our analysis, we first examined the CNDDB current and historical records to get an indication of the habitat where arroyo toads are present or absent. The CNDDB is a continually refined and updated inventory of location information gathered during species surveys and observations. We then examined the arroyo toad recovery plan (Service 1999, pp. 1-119), which has a recovery strategy focused on providing sufficient breeding and upland habitat to maintain self-sustaining populations of arroyo toads (defined as populations that require little or no direct human assistance such as captive breeding or rearing, or translocation between sites) throughout the historical range of the species, and on minimizing or eliminating impacts and threats to arroyo toad populations (Service 1999, p. 67). The recovery plan states that in-stream and riparian habitats that support breeding, as well as upland habitats that provide foraging and overwintering habitat, need to be managed to maintain and enhance populations throughout the range of the arroyo toad (Service 1999, p. 68). The recovery plan divides the range of the arroyo toad into three large recovery units—northern, southern, and desert—and we considered the recovery of each of these as well as the species as a whole in our analysis. Using the recovery plan as our guide, we analyzed areas within the geographical area occupied by the arroyo toad at the time of listing to determine which areas contained the PCEs laid out in the appropriate quantity and spatial arrangement essential to the conservation of the species (the physical and biological features).
In determining the specific areas containing the essential physical and biological features, based on the recovery plan, 5-year review, previous critical habitat proposals for the arroyo toad, scientific literature, and results of studies that have been conducted since the species was listed, we made sure that we are proposing critical habitat that will provide for the conservation of the species. Criteria we evaluated to assist our process include units: (1) That are dispersed throughout the current geographical, elevational, and ecological distribution of the species; (2) that would maintain the appropriate population structure across the species' range; (3) that retain or provide the connectivity between breeding sites that allows for the continued existence of essential metapopulations (a population of subpopulations in somewhat geographically isolated patches, interconnected through patterns of gene flow, extinction, and recolonization (Soule 1987, p. 7), despite fluctuations in the status of subpopulations); and (4) that contain upland habitat around each breeding location to allow for survival and recruitment to maintain a breeding population over the long term.
We also evaluated the area outside the geographical area occupied by the species at the time of listing to identify any areas that are essential for the conservation of the arroyo toad. We looked at areas that may have been historically occupied by arroyo toads based on CNDDB records but were no longer occupied at the time of listing. We also considered areas that may have the physical and biological features essential for the conservation of the species but have never been occupied. However, based on the best available scientific information, including the recovery plan which does not identify any such areas as being important to the recovery of the species, we determined that there are no areas outside the
geographical area occupied by the species at the time of listing that are essential for the conservation of the arroyo toad.
To identify and map areas that we determined meet the definition of critical habitat, we used data on known arroyo toad locations and data on movement distances by arroyo toads. The main source for arroyo toad locations was the CNDDB (2008); we also obtained locations that have not yet been entered into the CNDDB directly from the biologists that collected them.
Areas meeting the definition of critical habitat for the arroyo toad include occupied areas on stream reaches containing suitable breeding and upland habitat. To determine the extent of suitable arroyo toad habitat as discussed in the “Habitat” section above, we used spatial data on stream gradients with grades less than 6 percent, aerial photography, surveys of habitat suitability, and site visits. Additionally, we included higher gradient areas between breeding habitat because these areas are used by toads during the non-breeding period and allow toads to disperse between breeding areas. To delineate upland habitat areas, we used a GIS-based modeling procedure to identify alluvial terraces, valley bottomlands, and upland habitats adjacent to stream reaches occupied by the arroyo toad. Lacking spatially explicit data on geomorphology, we used elevation above the stream channel as an indicator of the extent of alluvial and upland foraging habitat. We determined that areas up to 82 ft (25 m) in elevation above the stream channel were most likely to contain the riparian and upland habitat elements essential to arroyo toads. Most arroyo toad activity and movement occurred within these areas; therefore, steeper slopes away from the stream were eliminated. However, we truncated the upland habitat delineation in flat areas at 4,921 ft (1,500 m) from the stream channel (a distance based on known movement of arroyo toads, see below) if the 82-ft (25-m) elevation limit had not yet been reached at that point. The 82-ft (25-m) elevation limit was reached at distances less than 4,921 ft (1,500 m) from the mapped stream channel along the majority of the stream reaches, so the distance limit was often not a factor. These model parameters are based on the best scientific data available and are the same as those used in the 2004 proposed critical habitat designation (69 FR 23254).
To evaluate our critical habitat model, we assessed its effectiveness at capturing documented toad locations from studies that focused specifically on surveying toads in upland habitats and studies involving radio telemetry. Holland and Sisk (2000, pp. 1-28) established extensive pitfall trap arrays at discrete distances from two stream courses and operated these arrays at various periods throughout the year. They had 466 captures of arroyo toads, 35 (7.5 percent) of which were identified as being in upland areas. The low percentage of toads captured in upland areas may be because the vast majority of captures (98.7 percent) were during the months from January to September, when breeding and metamorphosis occurs and when toads would likely be in close proximity to the stream. Nevertheless, toads were captured at distances that ranged from 49 to 3,855 ft (15 to 1,175 m) from the upland-riparian ecotone (boundary) (Holland and Sisk 2000, pp. 1-28). For the two areas sampled in that study (Cristianitos Creek and the upper Santa Margarita River, San Diego County), we found that our critical habitat boundaries encompassed all of the pitfall trapping stations where arroyo toads were detected.
We also assessed studies that involved the tracking of arroyo toads with radio telemetry equipment. For example, in a number of studies by Ramirez (2002a, p. 10; 2002b, p. 50; 2002c, p. 23; 2003, pp. 72-81), arroyo toads were tracked from the end of breeding activity until the commencement of aestivation, generally May through September. Cumulatively, these four studies involved tracking 77 adult arroyo toads in three separate critical habitat units in Orange, San Bernardino, and Los Angeles Counties. All but one of the numerous burrow sites chosen by these arroyo toads fell within our proposed revised critical habitat boundaries.
Upon completion of our analyses with our GIS modeling, we identified six tribes that own lands within areas identified as meeting the definition of critical habitat: Rincon Band of Luiseño Mission Indians; Pala Band of Luiseño Mission Indians; Sycuan Band of the Kumeyaay Nation; the Barona Group of Capitan Grande Band of Mission Indians and the Viejas (Baron Long) Group of Capitan Grande Band of Mission Indians, which jointly manage the Capitan Grande Band of Diegueno Mission Indians Reservation (Capitan Grande Reservation); and Mesa Grande Band of Diegueno Mission Indians. These areas are included in this proposed revised critical habitat, although we are requesting public comment on whether the conservation needs of the arroyo toad can be achieved or not by limiting the designation of final revised critical habitat to non-Tribal lands, and are otherwise considering these Tribal lands for exclusion from the final critical habitat under section 4(b)(2) of the Act based on partnerships and habitat management plans and practices. We will evaluate any submitted plans in consideration of Secretarial Order 3206, “American Indian Tribal Rights, Federal Tribal Trust Responsibilities, and the Endangered Species Act” (June 5, 1997); the President's memorandum of April 29, 1994, “Government-to-Government Relations with Native American Tribal Governments” (59 FR 22951); Executive Order 13175; and the relevant provision of the Departmental Manual of the Department of the Interior (512 DM 2) in relation to the conservation benefits to the arroyo toad, the features essential to the conservation of the species, and the appropriateness of excluding Tribal lands under section 4(b)(2) of the Act. Please see the “Tribal Lands—Exclusions Under Section 4(b)(2) of the Act” section for additional discussion.
To provide legal boundaries for the critical habitat areas, critical habitat boundaries for all drainages were mapped as contiguous blocks of 98-ft by 98-ft (30-m by 30-m) cells that conform to a Universal Transverse Mercator (UTM) grid. Due to the conversion of GIS data from two different geographic projections (UTM zone 10 and zone 11) and conversion of the data to acres and hectares, some rounding adjustments may be reflected in the total acreage of the units designated as critical habitat that are shown in the acreage tables and unit descriptions.
After determining the criteria used to identify critical habitat, 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 arroyo toad. We also avoided fragmented areas such as those surrounded by development. Agricultural lands may have been included if they were within areas identified as necessary for dispersal or connectivity between known occurrences. However, we avoided known areas of intensive agriculture that lacked the PCEs for the arroyo toad. The scale of the maps we prepared under the parameters for publication within the Code of Federal Regulations may not reflect the exclusion of such developed lands. Any such lands inadvertently left inside critical habitat boundaries shown on the maps of this proposed revised critical habitat are excluded by text in this rule and are not proposed for critical habitat designation. Therefore, if the critical habitat is
finalized as proposed, a Federal action involving these lands would not trigger section 7 consultation with respect to critical habitat and the requirement of no adverse modification, unless the specific action may affect adjacent critical habitat.
We propose to designate 22 critical habitat units within the geographic area occupied by the species at the time of listing based on the criteria presented above. A brief discussion of each area proposed for designation 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.
Summary of Changes From Previously Designated Critical Habitat
In this proposal to revise critical habitat for the arroyo toad, we determined that it would be appropriate to begin our analysis of critical habitat using the previous proposed critical habitat designation (69 FR 23254; April 28, 2004) as a base from which to make changes. We are not using the previous final critical habitat designation (70 FR 19562, April 13, 2005) after questions were raised about the integrity of the scientific information used and whether the decision made was consistent with appropriate legal standards. This new analysis based on the best scientific information currently available has resulted in an overall decrease in the amount and distribution of habitat identified as meeting the definition of critical habitat, as compared to the previous 2004 proposed designation (69 FR 23254). In this revised rule, we are proposing to designate 109,110 ac (44,155 ha) of land in Los Angeles, Orange, Riverside, San Bernardino, San Diego, Santa Barbara, and Ventura Counties, California, as critical habitat, which is a decrease of approximately 29,603 ac (11,978 ha) as proposed in 2004 (69 FR 23254). However, it should be noted that this does not reflect a decrease in every proposed unit compared to the previous proposal. In fact, the area included in some proposed revised critical habitat units is larger than it was in the 2004 proposed critical habitat designation (69 FR 23254) because in some cases new information has identified additional arroyo toad areas that meet the definition of critical habitat and these areas are now included.
The main differences between the 2004 proposed critical habitat rule (69 FR 23254) and this 2009 proposed revised critical habitat rule for the arroyo toad include the following:
(1) Our analysis of new and updated information received since the 2004 proposed critical habitat designation (69 FR 23254) resulted in the identification of areas meeting the definition of critical habitat that differs from the areas identified in 2004.
(2) We modified the mapping methodology from our previous proposed critical habitat designation (69 FR 23254). For the 2004 proposed designation, unit boundaries were snapped to points on a grid conforming to the Universal Transverse Mercator (UTM) projection. The reason for using a grid, which consisted of 100-meter by 100-meter cells, was to decrease the number of coordinate pairs and thereby simplify the description of unit boundaries. However, for this revised proposed designation, we use a more detailed description of unit boundaries. Although the change in area resulting from this modification is relatively minor (about 5 percent), this change affects all units.
(3) We did not exclude any areas in this proposed rule pursuant to section 4(b)(2) of the Act. In accordance with 50 CFR 424.19, in making our final determination regarding the revised designation, we will consider the impacts of designating lands (such as tribal and HCP lands) as critical habitat and may exclude such lands in the final rule pursuant to section 4(b)(2) of the Act.
The following paragraphs provide explanations of how the proposed revised critical habitat units differ from those in the 2004 proposed critical habitat designation (69 FR 23254), except for those units where the only change was from the modification in mapping methodology described above (units 2, 3, 4, 5, 6, 14, and 21). The unit names used in the subsection headings refer to the unit names as proposed in 2004.
Unit 1: San Antonio River
In the current proposal, we are now exempting areas within the Department of Defense's Fort Hunter Liggett Military Reservation from designation as revised critical habitat under section 4(a)(3)(B) of the Act. This unit is within the geographical area occupied at the time of listing (see “Geographical Range” section) and contains the physical or biological features essential to the conservation of the species which may require special management considerations or protection. In the previous 2004 proposed designation (69 FR 23254), Fort Hunter Liggett had not yet completed its Integrated Natural Resources Management Plan (INRMP) and, therefore, was not exempted under section 4(a)(3)(B) of the Act. However, Fort Hunter Liggett was excluded under section 4(b)(2) of the Act for reasons of national security and because existing management plans provided a benefit to the arroyo toad. Fort Hunter Liggett's first INRMP was approved in 2005, and an updated version was approved in 2007, which includes management actions that benefit the arroyo toad. Unit 1 as proposed in 2004 (69 FR 23254) encompassed approximately 6,546 ac (2,649 ha). For this proposed revised critical habitat designation, the modified mapping methodology we used resulted in a 1.4 percent decrease in acres in Unit 1, for a total of 6,453 ac (2,612 ha). With our current exemption of all areas within Fort Hunter Liggett (see “Application of Section 4(a)(3) of the Act” section), the entire unit has been exempted from designation as revised critical habitat.
Unit 7: Upper Los Angeles River Basin
We have removed Subunit 7a (approximately 2,262 ac (915 ha)) within Unit 7 from our proposed revision of critical habitat. Subunit 7a is within the geographical area occupied at the time of listing; however, this subunit was erroneously included in the previous proposed rule (69 FR 23254). Although we were not aware of this issue when we published the previous proposed rule, high-flow water releases from the Big Tujunga Dam upstream of this subunit have likely altered the hydrology such that arroyo toad breeding habitat is not maintained (that is, lack of PCEs 1 and 3) (Hitchcock
et al.
2004, p. 8; Backlin 2009, pers. comm.). The loss of the PCEs from this area has resulted in the extirpation of arroyo toads (Backlin
et al.
2002, pp. 6, 12; Hitchcock
et al.
2004, pp. 8-9, 29). Furthermore, the presence of the Big Tujunga Dam blocks dispersal from occupied areas upstream. Therefore, we have determined that the area does not contain the physical and biological features essential to the conservation of the arroyo toad and therefore does not meet the definition of critical habitat for the arroyo toad.
Unit 8: Lower Santa Ana River Basin
Areas meeting the definition of critical habitat that were excluded in the 2004 proposed critical habitat designation (69 FR 23254) within the Orange County Central-Coastal NCCP/HCP are now being proposed in this rule, and we are considering them for exclusion in the final rule (see “Habitat Conservation Plans—Exclusions Under Section 4(b)(2) of the Act” section). These areas include: (1) Black Star Creek from the NCCP/HCP boundary
downstream to the confluence with Santiago Creek, (2) Baker Canyon from the NCCP/HCP boundary downstream to the confluence with Santiago Creek, and (3) Santiago Creek from the confluence with Silverado Creek downstream to Irvine Lake. Information received since our previous 2004 proposed critical habitat designation (69 FR 23254) indicates that areas within Santiago Creek upstream of the confluence with Silverado Creek contain occupied suitable habitat on which are found the physical and biological features essential to the conservation of the species. Therefore, we also added areas to Unit 8 encompassing approximately 6.6 mi (11 km) of Santiago Creek from just below the town of Modjeska downstream to Irvine Lake. Additionally, new information indicates that Silverado Creek contains occupied suitable habitat on which are found the features essential to the conservation of the species (Haase 2005, p. 2; Haase
2008, pp. 2-3; Thomas 2009, pers. comm.). Therefore, we added areas to Unit 8 encompassing approximately 7.3 mi (12 km) of Silverado Creek from the eastern edge of section 11 (T05S, R07W) in the Cleveland National Forest downstream to the confluence with Santiago Creek. With the exception of areas that were excluded within the Orange County Central-Coastal NCCP/HCP, this unit encompassed approximately 172 ac (69 ha) in the 2004 proposed critical habitat designation (69 FR 23254). With the proposed addition of areas within the Orange County Central-Coastal NCCP/HCP and other areas described above, it now encompasses approximately 2,182 ac (883 ha).
Unit 9: San Jacinto River Basin
Areas meeting the definition of critical habitat that were excluded in the 2004 proposed critical habitat designation (69 FR 23254) within the Western Riverside County MSHCP are now being proposed in this rule, and we are considering them for exclusion in the final rule (see “Habitat Conservation Plans—Exclusions Under Section 4(b)(2) of the Act” section). These areas include: (1) The San Jacinto River from the Sand Canyon confluence downstream to the Soboba Indian Reservation border, and (2) Bautista Creek from areas outside of the San Bernardino National Forest downstream to near the middle of Section 27 (T5S, R1E) where the stream enters a debris basin. Unit 9 encompassed approximately 683 ac (277 ha) along Bautista Creek in the 2004 proposed critical habitat designation (69 FR 23254); with the addition of the areas described above, areas along the San Jacinto River and Bautista Creek are now proposed as separate subunits. Subunit 9a along the San Jacinto River encompasses approximately 1,226 ac (496 ha)) and Subunit 9b along Bautista Creek encompasses approximately 1,180 ac (478 ha).
Unit 10: San Juan Creek Basin
Information received since our previous 2004 proposed critical habitat designation (69 FR 23254) indicates that areas upstream of Subunit 10a in Bell Canyon, up to the southern half of section 8 (T06S, R06W) in the Cleveland National Forest, contain occupied suitable habitat on which are found the physical and biological features essential to the conservation of the species (Haase 2009a,
in litt.
). In the previous 2004 proposed critical habitat designation (69 FR 23254), Subunit 10a encompassed approximately 5,143 ac (2,076 ha) of Bell Canyon from just below Crow Canyon downstream to the confluence with San Juan Creek, in addition to areas along San Juan Creek. We added these upstream areas to Subunit 10a, which now totals 4,728 ac (1,913 ha). Although we added upstream areas to Subunit 10a, the total area of this subunit decreases from the 2004 proposed critical habitat designation (69 FR 23254) because of our change in mapping methodology.
Unit 11: San Mateo Creek and San Onofre Creek Basins
In the 2004 proposed critical habitat designation (69 FR 23254), areas in Subunits 11a and 11c within Marine Corps Base (MCB) Camp Pendleton were exempted from critical habitat under section 4(a)(3)(B) of the Act, except areas leased to outside parties for other land uses (such as San Onofre State Park and private agricultural lands). We are now exempting all lands within MCB Camp Pendleton from designation as revised critical habitat, including the leased lands (which are subject to the approved Integrated Natural Resources Management Plan (INRMP) for MCB Camp Pendleton), due to the benefits afforded to the arroyo toad by the management described in the approved INRMP for MCB Camp Pendleton (see “Application of Section 4(a)(3) of the Act” section). Subunit 11a encompassed approximately 4,112 ac (1,664 ha) in the 2004 proposed critical habitat designation (69 FR 23254); with the exemption of all areas within MCB Camp Pendleton, it now encompasses approximately 1,034 ac (418 ha). Subunit 11c encompassed approximately 399 ac (161 ha) as proposed in 2004; with the exemption of all areas within MCB Camp Pendleton (including the lands leased to other parties), the entire subunit is removed.
Unit 12: Lower Santa Margarita River Basin
In the 2004 proposed critical habitat designation (69 FR 23254), we exempted a portion of Unit 12 within MCB Camp Pendleton under section 4(a)(3)(B) of the Act. In this proposed rule, we are exempting all lands within both MCB Camp Pendleton and the Fallbrook Naval Weapons Station from designation as revised critical habitat (see “Application of Section 4(a)(3) of the Act” section). Unit 12 encompassed approximately 1,840 ac (744 ha) in the 2004 proposed critical habitat designation (69 FR 23254); with the exemption of all areas within MCB Camp Pendleton and the Fallbrook Naval Weapons Station, it now encompasses approximately 1,009 ac (408 ha).
Unit 13: Upper Santa Margarita River Basin
Areas meeting the definition of critical habitat that were excluded in the 2004 proposed critical habitat designation within the Western Riverside County MSHCP are now being proposed in this rule, and we are considering them for exclusion in the final rule (see “Habitat Conservation Plans—Exclusions Under Section 4(b)(2) of the Act” section). These areas include: (1) Areas around Subunit 13a along Arroyo Seco Creek, (2) areas downstream of Subunit 13b along Temecula Creek to Vail Lake, and (3) Wilson Creek from Lancaster Valley downstream to Vail Lake. Subunit 13a encompassed approximately 704 ac (285 ha) in the 2004 proposed critical habitat designation (69 FR 23254); with the addition of surrounding areas in Arroyo Seco Creek, it now encompasses approximately 1,155 ac (467 ha). Subunit 13b encompassed approximately 2,924 ac (1,183 ha) as proposed in 2004; with the addition of downstream areas of Temecula Creek, it now encompasses approximately 4,756 ac (1,925 ha). Information received since our previous critical habitat designation indicates that areas upstream of Lancaster Valley along Wilson Creek (included in this proposed rule as Subunit 13c) to the confluence with Cahuilla Creek contain occupied suitable habitat on which are found the physical and biological features essential to the conservation of the species (Haase 2009a,
in litt.
). This new subunit encompasses approximately 2,226 ac (901 ha).
Unit 15: Upper San Luis Rey River Basin
Information received since our previous 2004 proposed critical habitat designation (69 FR 23254) indicates that the area downstream of Barker Valley (formerly Subunit 15b) along the West Fork of the San Luis Rey River, which is within the geographical area occupied by the species at the time of listing, contains suitable habitat on which are found the physical and biological features essential to the conservation of the species, and provides for dispersal between populations in this area and populations in Lake Henshaw (formerly Subunit 15a) (Haase 2009, pers. comm.). In the 2004 proposed critical habitat designation (69 FR 23254), Subunits 15a and 15b together encompassed approximately 11,725 ac (4,745 ha). We are including the area between Barker Valley and Lake Henshaw in this proposed revised designation and have merged the two subunits into a single unit (Unit 15), which now totals 12,026 ac (4,867 ha).
Unit 16: Santa Ysabel Creek Basin
Areas meeting the definition of critical habitat that were excluded in the 2004 proposed critical habitat designation (69 FR 23254) within the San Diego MSCP-City and County of San Diego Subarea Plans are now being proposed in this rule, and we are considering them for exclusion in the final rule (see “Habitat Conservation Plans—Exclusions Under Section 4(b)(2) of the Act” section). In the previous 2004 proposed critical habitat designation (69 FR 23254), Subunits 16a, 16b, and 16c were three separate areas due to our exclusion in the 2004 proposed rule of downstream habitat along Santa Ysabel Creek. Subunit 16a encompassed approximately 2,758 ac (1,116 ha) along Santa Ysabel Creek from just below Sutherland Reservoir, Temescal Creek, and Boden Canyon; Subunit 16b encompassed approximately 2,727 ac (1,104 ha) along Guejito Creek; and Subunit 16c encompassed approximately 3,749 ac (1,517 ha) along Santa Maria Creek. We merged these three subunits into a single subunit (16a) in this proposed revised critical habitat rule; thus, Subunit 16a now totals 12,136 ac (4,911 ha).
In this proposed revised critical habitat designation, we removed areas within Subunit 16a that encompass Santa Ysabel Creek from just below Sutherland Reservoir downstream to the confluence with Temescal Creek. When we published our previous 2004 proposed critical habitat designation (69 FR 23254), we believed this area, which is within the geographical area occupied at the time of listing, met the definition of critical habitat. However, information we received since then indicates that breeding habitat is not available due to the absence of a natural flooding regime downstream of Sutherland Dam and the steepness of the stream corridor (lack of PCEs 1, 2, and 3). Furthermore, this area does not provide connectivity to upstream areas occupied by the species due to the presence of the dam. Survey information indicates arroyo toads have been extirpated from this area as a result of the loss of PCEs (Service 2006, p. 2). Therefore, we determined that this area, which is within the geographical area occupied by the species at the time of listing, does not contain features essential to the conservation of the species and therefore does not meet the definition of critical habitat for the arroyo toad.
Unit 17: San Diego River Basin/San Vicente Creek
Information received since our previous 2004 proposed critical habitat designation (69 FR 23254) indicates that areas upstream of Subunit 17a along the San Diego River to Temescal Creek, which are within the geographical area occupied by the species at the time of listing, contain occupied suitable habitat on which are found the physical and biological features essential to the conservation of the species (HELIX 2008, pp. 2, 7; Brown and Rochester 2009, pers. comm.). Subunit 17a as proposed in 2004 encompassed approximately 1,003 ac (406 ha) along the San Diego River from Ritchie Creek downstream to the upper edge of El Capitan Reservoir. In this proposed rule, we added these upstream areas to Subunit 17a, which now totals 1,241 ac (502 ha).
Areas meeting the definition of critical habitat that were excluded in the 2004 proposed critical habitat designation within the San Diego MSCP-City and County of San Diego Subarea Plans are now being proposed in this rule, and we are considering them for exclusion in the final rule (see “Habitat Conservation Plans—Exclusions Under Section 4(b)(2) of the Act” section). In the previous 2004 proposed critical habitat designation (69 FR 23254), Subunits 17b and 17c were two separate areas due to our exclusion in the 2004 proposed rule of downstream habitat along the San Diego River. Subunit 17b encompassed approximately 174 ac (70 ha) and Subunit 17c approximately 707 ac (286 ha) along the San Diego River as proposed in 2004. We merged the two subunits into a single subunit (17b) in this proposed revised critical habitat rule; thus Subunit 17b now totals 1,865 ac (755 ha).
Unit 18: Sweetwater River Basin
Areas meeting the definition of critical habitat that were excluded in the 2004 proposed critical habitat designation (69 FR 23254) within the San Diego MSCP-City and County of San Diego Subarea Plans are now being proposed in this rule, and we are considering them for exclusion in the final rule (see “Habitat Conservation Plans—Exclusions Under Section 4(b)(2) of the Act” section). In the previous 2004 proposed critical habitat designation (69 FR 23254), Subunits 18a, 18b, and 18d were three separate areas due to our exclusion in the 2004 proposed rule of downstream habitat along the Sweetwater River. As proposed in 2004, Subunit 18a encompassed approximately 4,196 ac (1,698 ha) along the Sweetwater River from the top of Upper Green Valley in Cuyamaca Rancho State Park, Subunit 18b encompassed approximately 583 ac (236 ha) along Peterson Canyon, and Subunit 18d encompassed approximately 474 ac (192 ha) along Viejas Creek. In this proposed rule, we merged these three subunits into a single subunit (18a), which now totals 4,156 ac (1,682 ha). Although we added areas that were excluded from the 2004 proposed critical habitat designation (69 FR 23254), the total area of the new Subunit 18a is smaller than the areas proposed in Subunits 18a, 18b, and 18d in the 2004 proposed rule because of our change in mapping methodology.
In this proposed revised critical habitat designation, we removed areas within Subunit 18c that encompass the Sweetwater River from just above Sycuan Resort downstream to the upper edge of Sweetwater Reservoir. These areas were erroneously included in the previous 2004 proposed rule. We now know that sand mining operations and channelization of the river through two golf courses have likely altered the hydrology in this area such that breeding habitat is not maintained (that is, lack of PCEs 1 and 3) (Brown and Rochester 2009, pers. comm.). Furthermore, information received since our previous 2004 proposed critical habitat designation (69 FR 23254) indicates that this area is no longer occupied by arroyo toads (Madden-Smith
et al.
2005, p. 22; Brown and Rochester 2009, pers. comm.; Martin 2009, pers. comm.) because of the loss of PCEs. Therefore, we have determined that this area does not contain features essential to the conservation of the species and therefore does not meet the
definition of critical habitat for the arroyo toad. As proposed in 2004, Subunit 18c encompassed approximately 3,982 ac (1,611 ha) along the Sweetwater River from immediately below Loveland Dam downstream to the upper edge of Sweetwater Reservoir; with the proposed removal of the areas described above, Subunit 18c now totals 627 ac (254 ha).
Unit 19: Cottonwood Creek Basin
In this proposed revised critical habitat designation, we removed areas within Subunit 19b that encompass 9.9 mi (16 km) of Cottonwood Creek from approximately 2.5 mi (4 km) below Morena Reservoir downstream to Barrett Reservoir. These areas were erroneously included in the previous 2004 proposed rule. Information received since our previous 2004 proposed critical habitat designation (69 FR 23254) indicates that the hydrology in this area was altered since the construction of the Morena Dam in the early 1900s such that breeding habitat is not maintained (lack of PCEs 1 and 3), and therefore this area is no longer occupied by arroyo toads (Jennings 2009, pers. comm.). Moreover, the presence of Morena and Barrett reservoirs block arroyo toad dispersal from occupied areas upstream and downstream along Cottonwood Creek (lack of PCE 5). Therefore, we determined that this area, which is within the geographical area occupied by the toad at the time of listing, does not contain features essential to the conservation of the species and therefore does not meet the definition of critical habitat for the arroyo toad.
Areas meeting the definition of critical habitat downstream of Subunit 19b to the U.S.-Mexico border that were excluded in the 2004 proposed rule within the San Diego MSCP-City and County of San Diego Subarea Plans are now being proposed in this rule, and we are considering them for exclusion in the final rule (see “Habitat Conservation Plans—Exclusions Under Section 4(b)(2) of the Act” section). Subunit 19b, which encompassed approximately 5,564 ac (2,252 ha) in the 2004 proposed critical habitat designation (69 FR 23254), now encompasses approximately 5,129 ac (2,076 ha). Additionally, data received since our previous 2004 proposed critical habitat designation (69 FR 23254) indicate that Campo Creek, which is within the geographical area occupied by the species at the time of listing, has occupied suitable habitat on which are found the physical and biological features essential to the conservation of the species (LEI 2008, pp. 5, 8). Therefore, we added areas encompassing approximately 4.4 mi (7 km) of Campo Creek from Campo Lake downstream to the U.S.-Mexico border as part of Subunit 19e.
Unit 20: Upper Santa Ana River Basin/Cajon Wash
Information received since our previous 2004 proposed critical habitat designation (69 FR 23254) indicates that areas upstream of Unit 20 to just below Cajon Junction are within the geographical area occupied by the arroyo toad at the time of listing and contain the physical and biological features essential to the conservation of the species (Rathbun 2007,
in litt.;
Meyer 2009,
in litt.
). In the previous 2004 proposed critical habitat designation (69 FR 23254), Unit 20 encompassed approximately 1,262 ac (511 ha) of Cajon Wash from just south of Cajon campground. We added these upstream areas to Unit 20, which now totals 1,775 ac (718 ha).
Unit 22: Upper Mojave River Basin
We have removed Subunit 22b (approximately 8,631 ac (3,493 ha)) within Unit 22 from our proposed revision of critical habitat. Subunit 22b is within the geographical area occupied at the time of listing. However, new information received since our previous 2004 proposed critical habitat designation (69 FR 23254) indicates that this area was erroneously proposed as critical habitat in 2004. Habitat in this area for the arroyo toad has been altered by steadily declining groundwater levels along the Upper Narrows to Lower Narrows reach of the Mojave River (Webb
et al.
2001, p. 1) to such an extent that it does not contain features essential to the conservation of the species and therefore does not meet the definition of critical habitat for the arroyo toad.
Unit 23: Whitewater River Basin
In this proposed revised critical habitat designation, we removed areas within Unit 23 that encompass Whitewater River from the Colorado River Aqueduct downstream to Interstate Highway 10. When we published our previous 2004 proposed critical habitat designation (69 FR 23254), we believed this area, which is within the geographical area occupied at the time of listing, met the definition of critical habitat. However, information received since our previous 2004 proposed critical habitat designation (69 FR 23254) indicates that high-flow water releases and channelization of the river downstream of the aqueduct has likely altered the habitat such that it no longer supports the physical and biological features essential to the conservation of the arroyo toad (Roberts 2009, pers. comm.). We have determined that this area does not meet the definition of critical habitat for the arroyo toad and should not have been proposed in 2004. As proposed in 2004, Unit 23 encompassed approximately 1,997 ac (808 ha) along the Whitewater River from near Red Dome downstream to Interstate 10; with the removal of the areas described above, Unit 23 now totals 1,355 ac (548 ha).
Proposed Revisions to Critical Habitat Designation
We are proposing to designate 22 units (Units 2 through 23) as critical habitat for the arroyo toad. The total area identified as Unit 1 is exempted from critical habitat designation under section 4(a)(3)(B) of the Act, and therefore is not proposed. All proposed units are within the geographical area occupied by the species at the time of listing and contain the physical and biological features essential to the conservation of the arroyo toad which may require special management considerations or protection. Although not a prerequisite for designation as critical habitat, all units are currently occupied. The proposed revised critical habitat areas described below constitute our best assessment at this time of areas that meet the definition of critical habitat for the arroyo toad. Approximate area encompassing the proposed revised critical habitat by county and land ownership is shown in Table 1, and the overall area of proposed revised critical habitat units for the arroyo toad are shown by unit in Table 2. The designation of these units, if finalized, would replace the existing critical habitat designation for the arroyo toad in 50 CFR 17.95(d).
Table 1—Approximate Proposed Revised Critical Habitat for the Arroyo Toad, in Acres (ac) (Hectares (ha)) by County (Ordered From North to South) and Land Ownership
County
Federal
State/local
Tribal
Private
Total
Santa Barbara
3,914
0
0
2,892
6,806
(1,584)
(1,171)
(2,755)
Ventura
4,392
0
0
639
5,031
(1,778)
(259)
(2,036)
Los Angeles
2,382
0
0
3,453
5,835
(964)
(1,398)
(2,362)
San Bernardino
3,964
132
0
3,599
7,695
(1,604)
(53)
(1,456)
(3,113)
Riverside
1,789
210
0
7,504
9,503
(724)
(85)
(3,037)
(3,846)
Orange
434
1,909
0
6,362
8,705
(176)
(773)
(2,575)
(3,524)
San Diego
6,843
3,481
4,046
51,165
65,535
(2,769)
(1,409)
(1,636)
(20,707)
(26,521)
Total
23,718
5,732
4,046
76,951
109,110
(9,598)
(2,320)
(1,636)
(31,141)
(44,155)
Values in table may not sum due to rounding.
Table 2—Approximate Proposed Revised Critical Habitat Units for the Arroyo Toad
Unit
Critical habitat units and subunits
County
Acres
Hectares
Northern Recovery Unit
1
San Antonio River—exempt
Monterey
0
0
2
Sisquoc River
Santa Barbara
3,775
1,528
3
Upper Santa Ynez River
Santa Barbara
3,032
1,227
4
Sespe Creek
Ventura
2,760
1,117
5
Piru Creek
Ventura
2,507
1,015
5a
1,358
550
5b
1,149
465
6
Upper Santa Clara River
Los Angeles
3,795
1,537
6a
520
210
6b
1,995
807
6c
1,279
518
7
Upper Los Angeles River Basin
Los Angeles
1,190
482
Subtotal
17,059
6,904
Southern Recovery Unit
8
Lower Santa Ana River Basin
Orange
2,182
883
9
San Jacinto River Basin
Riverside
2,406
974
9a
1,226
496
9b
1,180
478
10
San Juan Creek Basin
Orange, Riverside
5,667
2,293
10a
4,728
1,913
10b
939
380
11
San Mateo Basin
Orange, San Diego
1,068
432
11a
1,034
418
11b
34
14
12
Lower Santa Margarita, Basin
San Diego
1,009
408
12a
394
159
12b
615
248
13
Upper Santa Margarita Basin
Riverside, San Diego
8,137
3,293
13a
1,155
467
13b
4,756
1,925
13c
2,226
901
14
Lower and Middle San Luis Rey Basin
San Diego
12,906
5,223
15
Upper San Luis Rey Basin
San Diego
12,026
4,867
16
Santa Ysabel Creek
San Diego
13,567
5,490
16a
12,136
4,911
16d
1,431
579
17
San Diego River Basin
San Diego
4,263
1,725
17a
1,241
502
17b
1,865
755
17d
1,158
469
18
Sweetwater River Basin
San Diego
4,783
1,936
18a
4,156
1,682
18c
627
254
19
Cottonwood Creek Basin
San Diego
14,375
5,817
19a
5,847
2,366
19b
5,129
2,076
19c
1,511
611
19d
938
380
19e
950
384
Subtotal
82,389
33,342
Desert Recovery Unit
20
Upper Santa Ana River Basin/Cajon Wash
San Bernardino
1,775
718
21
Little Rock Creek Basin
Los Angeles
612
248
22
Upper Mojave River Basin
San Bernardino
5,919
2,395
22a
5,684
2,300
22c
235
95
23
Whitewater River Basin
Riverside
1,355
548
Subtotal
9,661
3,909
Total
109,110
44,155
Values in table may not sum due to rounding.
Presented below are brief descriptions of all units. The units are grouped by recovery unit as described in the recovery plan (Service 1999) and listed in order geographically north to south and west to east within each recovery unit. A brief description of each unit and the reasons it meets the definition of critical habitat are presented below.
Northern Recovery Unit
As described in the recovery plan (Service 1999, pp. 1-119), maintaining arroyo toad populations in the areas described by the following 7 unit descriptions is necessary to conserve the species in the northern recovery unit. Because the toad populations in this recovery unit have been reduced in size and their habitat fragmented by road construction, dams, agriculture, and urbanization, it is important to protect all of them and safeguard against the loss of any one population due to random natural or human-caused events. The U.S. Forest Service is the primary landowner of proposed revised critical habitat within the northern recovery unit.
Unit 1: San Antonio River
Although the lands in this unit are exempt from critical habitat designation under section 4(a)(3)(B) of the Act, we provide the following information to explain why these lands meet the definition of critical habitat. This unit is located in Monterey County and encompasses: (1) San Antonio River and adjacent uplands from about 2 mi (3 km) upstream of the confluence with Mission Creek downstream to San Antonio Reservoir, a distance of about 17 mi (27 km); and (2) small portions of Mission Creek and other tributaries. The unit consists of 6,453 ac (2,612 ha) of Federal (Department of Defense) land and is entirely contained within Fort Hunter Liggett Military Reservation boundaries. Arroyo toads can be found along the entire length of this segment of the San Antonio River, which is still in a relatively natural state, consists of high-quality arroyo toad habitat, and supports probably one of the largest populations within the northern recovery unit (U.S. Army Reserve Command 2004, p. 38). The northernmost known population of arroyo toads is located here and is approximately 100 mi (160 km) north of the nearest documented extant population. Arroyo toads in this unit may experience climatic conditions not faced by toads farther south. Unit 1 contains the physical and biological features that are essential to the conservation of the species, including breeding pools in low-gradient stream segments with sandy or fine gravel substrates (PCEs 1 and 2), seasonal flood flows (PCE 3), and relatively undisturbed riparian and upland habitat for foraging and dispersal (PCE 4). The physical and biological features essential to the conservation of the species in this unit may require special management considerations or protection to address threats from nonnative vertebrate predators such as bullfrogs and beavers (
Castor canadensis
). These lands on Fort Hunter Liggett are exempt from critical habitat designation under section 4(a)(3)(B) of the Act because they are subject to the 2007 Integrated Natural Resources Management Plan (INRMP) for Fort Hunter Liggett, and the INRMP provides a benefit to the arroyo toad (see the “Application of Section 4(a)(3) of the Act” section of this proposed rule for a detailed discussion).
Unit 2: Sisquoc River (3,775 ac (1,528 ha))
This unit is located in Santa Barbara County and encompasses approximately 33 mi (54 km) of the Sisquoc River and adjacent uplands from Sycamore Campground downstream to just below the confluence with La Brea Creek. Upper stretches of the river are within the Los Padres National Forest and mostly within the San Rafael Wilderness Area. Below the National Forest boundary, the river and adjacent uplands are on rural private lands. The unit consists of 1,700 ac (688 ha) of Federal land and 2,073 ac (839 ha) of private land. This long, undammed river is one of the few remaining major rivers in southern California with a natural flow regime, and supports a core population of arroyo toad that is important for maintaining the genetic diversity of the species. Unit 2 contains the physical and biological features that are essential to the conservation of the species, including breeding pools in low-gradient stream segments with sandy or fine gravel substrates (PCEs 1 and 2), seasonal flood flows (PCE 3), and relatively undisturbed riparian and upland habitat for foraging and dispersal (PCE 4). The physical and biological features essential to the
conservation of the species in this unit may require special management considerations or protection to address threats from the removal and alteration of habitat due to sand and gravel mining, livestock overgrazing of riparian habitats, and limited recreational activities. Please see the “Special Management Considerations or Protection” section of this proposed rule for a discussion of the threats to arroyo toad habitat and potential management considerations.
Unit 3: Upper Santa Ynez River Basin (3,032 ac (1,227 ha))
This unit is located in Santa Barbara County upstream of Gibraltar Reservoir and encompasses approximately 27 mi (43 km) of the upper Santa Ynez River, Indian Creek, Mono Creek, and adjacent uplands. The unit consists of 2,214 ac (896 ha) of Federal land and 818 ac (331 ha) of private land within the Los Padres National Forest, and supports a large and well-studied arroyo toad population (Sweet 1992, pp. 1-198; 1993, pp. 1-73) that likely experiences precipitation and soil moisture conditions not faced by toads at drier sites. Potential adaptations to these conditions make this unit important for maintaining the genetic diversity of the species. Unit 3 contains the physical and biological features that are essential to the conservation of the species, including breeding pools in low-gradient stream segments with sandy or fine gravel substrates (PCEs 1 and 2), seasonal flood flows (PCE 3), and relatively undisturbed riparian and upland habitat for foraging and dispersal (PCE 4). The physical and biological features essential to the conservation of the species in this unit may require special management considerations or protection to address threats, primarily along the lower Santa Ynez River and lower Mono Creek, from nonnative species, recreation, and problems associated with an upstream dam (such as sediment trapping, altered hydrological regime, and temperature changes). Please see the “Special Management Considerations or Protection” section of this proposed rule for a discussion of the threats to arroyo toad habitat and potential management considerations.
Unit 4: Sespe Creek (2,760 ac (1,117 ha))
This unit is located in Ventura County and encompasses approximately 27 mi (43 km) of Sespe Creek and adjacent uplands, from the lower end of Sespe Gorge (elevation approximately 3,530 ft (1,076 m)) downstream to the confluence with Alder Creek. The unit consists of 2,498 ac (1,011 ha) of Federal land and 262 ac (106 ha) of private land. This unit supports one of the largest arroyo toad populations on the Los Padres National Forest along Sespe Creek, which is undammed and retains its natural flooding regime. Up to several hundred adult arroyo toads inhabit this reach of the Sespe River (Sweet 1992, p. 192), and during years of successful reproduction, such as 2003, thousands of juveniles can be found as well (Murphy 2008, pers. comm.). Arroyo toads have been found up to 3,300 ft (1,000 m) in elevation in this area, which is one of the highest known occurrences in the northern recovery unit. The arroyo toads in this unit likely experience temperature extremes or other environmental conditions not faced by toads at lower elevations so that potential adaptations to these conditions make this unit important for maintaining the genetic diversity of the species. Unit 4 contains the physical and biological features that are essential to the conservation of the species, including numerous suitable breeding pools (shallow, sand- or gravel-based pools with a minimum of vegetation along one or both margins during the breeding season from late March to June (Sweet 1992, p. 28)) and an abundance of sandy substrates (PCEs 1 and 2), unimpeded seasonal flood flows (PCE 3), and relatively undisturbed riparian habitat and upland benches for foraging and dispersal (PCE 4). The physical and biological features essential to the conservation of the species in this unit may require special management considerations or protection to address threats from recreational activities and nonnative predators. Please see the “Special Management Considerations or Protection” section of this proposed rule for a discussion of the threats to arroyo toad habitat and potential management considerations.
Unit 5: Piru Creek (2,507 ac (1,015 ha))
This unit is located in Ventura and Los Angeles Counties and consists of two subunits totaling 2,105 ac (852 ha) of Federal land and 402 ac (163 ha) of private inholdings.
Subunit 5a
Subunit 5a encompasses approximately 17 mi (27 km) of Piru Creek and adjacent uplands from the confluence with Lockwood Creek downstream to Pyramid Reservoir. The subunit consists of 1,277 ac (517 ha) of Federal land and 81 ac (33 ha) of private land. The upper portion of Subunit 5a is free of nonnative vertebrate predators, and the substantial arroyo toad population supported by this subunit has been increasing and expanding in this area over the past several years (Uyehara 2003, pers. comm.). Subunit 5a contains the physical and biological features that are essential to the conservation of the species, including breeding pools in low-gradient stream segments with sandy substrates (PCEs 1 and 2), seasonal flood flows (PCE 3), and riparian habitat and upland benches for foraging and dispersal (PCE 4). The physical and biological features essential to the conservation of the species in this subunit may require special management considerations or protection to address threats from horse and cattle grazing and recreational activities. Please see the “Special Management Considerations or Protection” section of this proposed rule for a discussion of the threats to arroyo toad habitat and potential management considerations.
Subunit 5b
Subunit 5b is primarily within the Sespe Wilderness and encompasses approximately 15 mi (24 km) of Piru Creek from the confluence with Fish Creek downstream to Lake Piru, as well as Agua Blanca Creek from Devil's Gateway downstream to the confluence with Piru Creek. The subunit supports a substantial arroyo toad population and consists of 828 ac (335 ha) of Federal land and 321 ac (130 ha) of private land. Subunit 5b contains the physical and biological features that are essential to the conservation of the species, including breeding pools in low-gradient stream segments with sandy substrates (PCEs 1 and 2), seasonal flood flows (modified to some extent below Pyramid Dam) (PCE 3), and riparian habitat and upland benches for foraging and dispersal (PCE 4). Because lower Piru Creek in Subunit 5b is downstream of a large dam, the habitat there has experienced some degradation over the years from perennial water releases, rapid changes in flow volume, excessive flows during the breeding season, and an increased presence of nonnative predators. However, Pyramid Dam has permanently changed the water release schedule to one that will more closely mimic natural flows and will benefit the arroyo toad (State Water Board 2008, p. 3). The physical and biological features essential to the conservation of the species in this subunit may require special management considerations or protection to address threats from nonnative predators and recreational activities. Please see the “Special Management Considerations or Protection” section of this proposed rule for a discussion of the threats to arroyo
toad habitat and potential management considerations.
Unit 6: Upper Santa Clara River Basin (3,795 ac (1,537 ha))
This unit is located in northwestern Los Angeles County and consists of three subunits totaling 443 ac (179 ha) of Federal land and 3,351 ac (1,356 ha) of private land.
Subunit 6a
Subunit 6a encompasses approximately 7 mi (12 km) of Castaic Creek from Bear Canyon downstream to Castaic Lake, and 0.7 mi (1.2 km) of Fish Creek from Cienaga Spring to the confluence with Castaic Creek. Subunit 6a encompasses approximately 11 mi (18 km) of upper Santa Clara River from Arrastre Canyon downstream to the confluence with Bee Canyon Creek. The subunit consists of 284 ac (115 ha) of Federal land and 236 ac (96 ha) of private land. Subunit 6a contains the physical and biological features that are essential to the conservation of the species, including breeding pools in low-gradient stream segments with sandy substrates (PCEs 1 and 2), seasonal flood flows (PCE 3), and riparian habitat and upland benches for foraging and dispersal (PCE 4). The physical and biological features essential to the conservation of the species in this subunit may require special management considerations or protection to address threats from urban development, agriculture, recreation, mining, and nonnative predators. Please see the “Special Management Considerations or Protection” section of this proposed rule for a discussion of the threats to arroyo toad habitat and potential management considerations.
Subunit 6b
Subunit 6b encompasses: (1) Approximately 2.6 mi (4.2 km) of Castaic Creek from the downstream edge of The Old Road right-of-way (adjacent to Interstate 5) down to the confluence with the Santa Clara River, (2) 6 mi (10 km) of the Santa Clara River from the confluence with Bouquet Creek down to the confluence with Castaic Creek, and (3) 1.1 mi (2 km) of San Francisquito Creek from Newhall Ranch Road downstream to the confluence with the Santa Clara River. The subunit consists of 159 ac (65 ha) of Federal land and 1,995 ac (807 ha) of private land. This subunit allows for natural population expansion and fluctuation of the Santa Clara River population by connecting arroyo toad habitat in Castaic Creek with San Francisquito Creek and the occupied reach of the Santa Clara River. Subunit 6b contains the physical and biological features that are essential to the conservation of the species, including breeding pools in low-gradient stream segments with sandy substrates (PCEs 1 and 2), seasonal flood flows (PCE 3), and riparian habitat and upland benches for foraging and dispersal (PCE 4). The physical and biological features essential to the conservation of the species in this subunit may require special management considerations or protection to address threats from urban development, agriculture, recreation, mining, and nonnative predators. Please see the “Special Management Considerations or Protection” section of this proposed rule for a discussion of the threats to arroyo toad habitat and potential management considerations.
Subunit 6c
Subunit 6c encompasses approximately 11 mi (18 km) of upper Santa Clara River from Arrastre Canyon downstream to the confluence with Bee Canyon Creek. The subunit consists of 159 ac (64 ha) of Federal land and 1,120 ac (453 ha) of private land. This subunit is important for maintaining the arroyo toad metapopulation in the upper Santa Clara River Basin. Additionally, the upper portion of the Santa Clara River in this subunit supports a breeding population of arroyo toads (Sandburg 2001,
in litt.;
Farris 2001, pers. comm.; Hovore 2001,
in litt.
) that has the potential to greatly increase in size. Subunit 6c contains the physical and biological features that are essential to the conservation of the species, including breeding pools in low-gradient stream segments with sandy substrates (PCEs 1 and 2), seasonal flood flows (PCE 3), and riparian habitat and upland benches for foraging and dispersal (PCE 4). The physical and biological features essential to the conservation of the species in this subunit may require special management considerations or protection to address threats from urban development, agriculture, recreation, mining, and nonnative predators. Please see the “Special Management Considerations or Protection” section of this proposed rule for a discussion of the threats to arroyo toad habitat and potential management considerations.
Unit 7: Upper Los Angeles River Basin (1,190 ac (482 ha))
This unit is located in central Los Angeles County and encompasses: (1) Approximately 8 mi (13 km) of upper Big Tujunga Creek from immediately above Big Tujunga Reservoir upstream to approximately 1.2 mi (2 km) above the confluence with Alder Creek, (2) almost 3.7 mi (6 km) of Mill Creek from the Monte Cristo Creek confluence downstream to Big Tujunga Creek, and (3) approximately 1.9 mi (3 km) of Alder Creek from the Mule Fork confluence downstream to Big Tujunga Creek. The unit consists of 1,113 ac (451 ha) of Forest Service land and 77 ac (31 ha) of private land. This unit supports an important high-elevation arroyo toad population in the Big Tujunga Canyon watershed in the Upper Los Angeles River Basin within the Angeles National Forest, which is atypical for arroyo toads, and supports the only significant known population remaining in the coastal foothills of the San Gabriel Mountains. Unit 7 contains the physical and biological features that are essential to the conservation of the species, including aquatic habitat for breeding and non-breeding activities (PCEs 1, 2, and 3) and upland habitat for foraging and dispersal activities (PCE 4). The physical and biological features essential to the conservation of the species in this unit may require special management considerations or protection to address threats from nonnative predators, such as crayfish, bullfrogs, and nonnative plants such as
Arundo donax.
Please see the “Special Management Considerations or Protection” section of this proposed rule for a discussion of the threats to arroyo toad habitat and potential management considerations.
Southern Recovery Unit
As described in the recovery plan (Service 1999, pp. 1-119), maintaining arroyo toad populations in the following 12 critical habitat units is necessary to conserve the species in the southern recovery unit. The units consist of a range of geographic locations from coastal regions to interior mountains. Arroyo toads likely occurred throughout each of these river and creek basins, but are now found only in segments of the rivers and creeks due to loss or change of habitat and nonnative predators. Conserving arroyo toad populations in these river basins is necessary for preserving the species' full range of genetic and phenotypic (observable characteristics produced by the interaction of the genotype and the environment) variation.
Unit 8: Lower Santa Ana River Basin (2,182 ac (883 ha))
This unit is located in east-central Orange County and encompasses: (1) Approximately 6.6 mi (11 km) of Santiago Creek from just below the town of Modjeska downstream to Irvine Lake, (2) approximately 2 mi (3 km) of Black Star Creek downstream to the
confluence with Santiago Creek, (3) an approximately 2.4 mi (4 km) stretch of lower Baker Canyon downstream to the confluence with Santiago Creek, and (4) approximately 7.3 mi (12 km) of Silverado Creek from the eastern edge of section 11 (T05S, R07W) in the Cleveland National Forest downstream to the confluence with Santiago Creek. The unit consists of 54 ac (22 ha) of Forest Service land and 2,128 ac (861 ha) of private land. This unit contains a vital arroyo toad population in central Orange County that may represent one of the last remnants of a greater historical population from the Santa Ana River Basin that was mostly extirpated due to urbanization of the greater Los Angeles metropolitan area. It is also possible that this population belongs to a larger metapopulation that extends across the lower coastal mountain slopes of the Santa Ana Mountains from Santiago Creek to San Mateo Creek (including Units 10 and 11 discussed below). Unit 8 contains the physical and biological features that are essential to the conservation of the species, including aquatic habitat for breeding and non-breeding activities (PCEs 1, 2, and 3) and upland habitat for foraging and dispersal activities (PCE 4). The physical and biological features essential to the conservation of the species in this unit may require special management considerations or protection to address threats from nearby residential activities and degrading habitat conditions due to past commercial sand and gravel removal operations. Please see the “Special Management Considerations or Protection” section of this proposed rule for a discussion of the threats to arroyo toad habitat and potential management considerations. We are considering the exclusion of approximately 1,497 ac (606 ha) of lands in Unit 8 within the Orange County Central-Coastal NCCP/HCP from the final revised critical habitat designation under section 4(b)(2) of the Act (see “Application of Section 4(b)(2) of the Act” section of this proposed revised rule for a detailed discussion).
Unit 9: San Jacinto River Basin (2,406 ac (974 ha))
This unit is located in west-central Riverside County and consists of two subunits totaling 13 ac (5 ha) of Bureau of Land Management land, 492 ac (199 ha) of Forest Service land, 210 ac (85 ha) of State land, and 1,691 ac (684 ha) of private land. This unit supports the most northeastern arroyo toad populations within the coastal region of the species' range and is effectively isolated from other known toad populations to the south in the Santa Margarita Watershed, to the west in the San Juan Watershed, and from residual populations to the north in the Santa Ana Watershed due to geographic features. It is likely that this isolation occurred over a long geologic time period; therefore, toads in the San Jacinto Watershed may have evolved unique genetic, phenotypic, or behavioral characteristics that are important for the conservation of the species.
Subunit 9a
Subunit 9a encompasses approximately 6.3 mi (10 km) of the San Jacinto River from the Sand Canyon confluence downstream to the Soboba Indian Reservation border. The subunit consists of 64 ac (26 ha) of Forest Service land, 8 ac (3 ha) of Bureau of Land Management land, and 1,154 ac (467 ha) of private land. Subunit 9a contains the physical and biological features that are essential to the conservation of the species, including aquatic habitat for breeding and non-breeding activities (PCEs 1, 2, and 3) and upland habitat for foraging and dispersal activities (PCE 4). The physical and biological features essential to the conservation of the species in this subunit may require special management considerations or protection to address threats from cumulative impacts from human activities, including direct mortality from vehicular traffic, trampling, trash dumping, and collection (Ortega 2009,
in litt.
p. 1; Wilcox 2009, pers. comm.). Please see the “Special Management Considerations or Protection” section of this proposed rule for a discussion of the threats to arroyo toad habitat and potential management considerations. We are considering the exclusion of approximately 678 ac (274 ha) of private lands in Subunit 9a within the Western Riverside County MSHCP from the final revised critical habitat designation under section 4(b)(2) of the Act (see “Application of Section 4(b)(2) of the Act” section of this proposed revised rule for a detailed discussion).
Subunit 9b
Subunit 9b encompasses approximately 7.4 mi (12 km) of Bautista Creek from near the eastern edge of Section 20 (T6S, R2E) downstream to approximately the middle of Section 27 (T5S, R1E), where the stream enters a debris basin. The subunit consists of 428 ac (173 ha) of Forest Service land, 5 ac (2 ha) of Bureau of Land Management land, 210 ac (85 ha) of State land, and 537 ac (217 ha) of private land. Subunit 9b contains the physical and biological features that are essential to the conservation of the species, including aquatic habitat for breeding and non-breeding activities (PCEs 1, 2, and 3) and upland habitat for foraging and dispersal activities (PCE 4). The physical and biological features essential to the conservation of the species in this subunit may require special management considerations or protection to address threats from recreation and vehicular traffic (USGS 2001, p. 8). Please see the “Special Management Considerations or Protection” section of this proposed rule for a discussion of the threats to arroyo toad habitat and potential management considerations. We are considering the exclusion of approximately 475 ac (192 ha) of private lands in Subunit 9b within the Western Riverside County MSHCP from the final revised critical habitat designation under section 4(b)(2) of the Act (see “Application of Section 4(b)(2) of the Act” section of this proposed revised rule for a detailed discussion).
Unit 10: San Juan Creek Basin (5,667 ac (2,293 ha))
This unit is located in southern Orange County and southwestern Riverside County and consists of two subunits totaling 558 ac (225 ha) of Forest Service land, 1,909 ac (773 ha) of local government land, and 3,200 ac (1,295 ha) of private land. This unit supports a vital arroyo toad population in the San Juan Creek Basin, and arroyo toad populations in this unit may function as an important linkage between toads in Santiago Creek (Unit 8) to the north and the San Mateo Creek Basin (Unit 11) to the south.
Subunit 10a
This subunit is located in southern Orange County and southwestern Riverside County. Subunit 10a encompasses: (1) Approximately 5 mi (8 km) of San Juan Creek from immediately above the Upper San Juan Campground downstream to Interstate 5, (2) approximately 9.9 mi (16 km) of Bell Canyon from the southern half of section 8 (T06S, R06W) in the Cleveland National Forest downstream to the confluence with San Juan Creek, and (3) approximately 1.2 mi (2 km) of an unnamed tributary to the west of Bell Canyon in sections 8 and 18 (T06S, R06W) downstream to the confluence with Bell Creek. The subunit consists of 547 ac (221 ha) of Forest Service land, 1,406 ac (569 ha) of local government land, and 2,775 ac (1,123 ha) of private land. Subunit 10a contains the physical and biological features that are essential to the conservation of the species,
including aquatic habitat for breeding and non-breeding activities (PCEs 1, 2, and 3) and upland habitat for foraging and dispersal activities (PCE 4). The physical and biological features essential to the conservation of the species in this subunit may require special management considerations or protection to address threats from nonnative predators (bullfrogs), increased water diversions, and residual effects of recent gravel mining operations (Bloom 1998, p. 2). Please see the “Special Management Considerations or Protection” section of this proposed rule for a discussion of the threats to arroyo toad habitat and potential management considerations. We are considering the exclusion of approximately 3,405 ac (1,378 ha) of permittee-owned or controlled lands in Subunit 10a within the Southern Orange County NCCP/Master Streambed Alteration Agreement/HCP from the final revised critical habitat designation under section 4(b)(2) of the Act (see “Application of Section 4(b)(2) of the Act” section of this proposed revised rule for a detailed discussion).
Subunit 10b
This subunit is located in southern Orange County. Subunit 10b encompasses 5.2 mi (8 km) of Trabuco Creek downstream from approximately the middle of section 6 (T06S, R06W) in the Cleveland National Forest. The subunit consists of 11 ac (4 ha) of Forest Service land, 503 ac (204 ha) of local government land, and 425 ac (172 ha) of private land. Subunit 10b contains the physical and biological features that are essential to the conservation of the species, including aquatic habitat for breeding and non-breeding activities (PCEs 1, 2, and 3) and upland habitat for foraging and dispersal activities (PCE 4). The physical and biological features essential to the conservation of the species in this subunit may require special management considerations or protection to address threats from nonnative predators (bullfrogs), increased water diversions, and residual effects of recent gravel mining operations (Bloom 1998, p. 2). Please see the “Special Management Considerations or Protection” section of this proposed rule for a discussion of the threats to arroyo toad habitat and potential management considerations.
Unit 11: San Mateo Creek Basin (1,068 ac (432 ha))
This unit is located in northwestern San Diego County, southern Orange County, and southwestern Riverside County and consists of two subunits totaling 34 ac (14 ha) of Forest Service land and 1,034 ac (418 ha) of private land. This unit supports large arroyo toad populations in close proximity to the coast. Nearly all of the other near-coastal, historical populations of arroyo toad were extirpated due to extensive urbanization and river channelization along the coastal regions of southern California. Distinctive climatic conditions near the coast may provide different selective pressures on toads in this area, and favor specific genetic characteristics that help maintain the genetic diversity of the species. We are exempting from designation approximately 5,994 ac (2,426 ha) of military land that fall within the boundaries of this proposed revised critical habitat unit under section 4(a)(3)(B) of the Act because the lands are subject to the 2007 INRMP for MCB Camp Pendleton, and the INRMP provides a benefit to the arroyo toad (see the “Application of Section 4(a)(3) of the Act” section of this proposed revised rule for a detailed discussion).
Subunit 11a
Subunit 11a encompasses: (1) Approximately 1.7 mi (3 km) of Cristianitos Creek from just above Gabino Creek downstream to the MCB Camp Pendleton boundary; (2) approximately 3.1 mi (5 km) of Gabino Creek upstream from its confluence with Cristianitos Creek, including about 0.6 mi (1 km) of La Paz Creek; and (3) approximately 4 mi (6 km) of Talega Creek upstream from its confluence with Cristianitos Creek and beyond the boundaries of MCB Camp Pendleton. The subunit consists of 1,034 ac (418 ha) of private land. Subunit 11a contains the physical and biological features that are essential to the conservation of the species, including aquatic habitat for breeding and non-breeding activities (PCEs 1, 2, and 3) and upland habitat for foraging and dispersal activities (PCE 4). The physical and biological features essential to the conservation of the species in this subunit may require special management considerations or protection to address threats from cumulative impacts from human activities, including direct mortality from vehicle collisions and vehicular crossings of streambeds, grazing, and nonnative predators (Bloom 1996, pp. 4-5; Bloom 1998,
in litt.,
pp. 1, 3). Please see the “Special Management Considerations or Protection” section of this proposed rule for a discussion of the threats to arroyo toad habitat and potential management considerations. We are considering the exclusion of approximately 963 ac (390 ha) of permittee-owned or controlled lands in Subunit 11a within the Southern Orange County NCCP/Master Streambed Alteration Agreement/HCP from the final revised critical habitat designation under section 4(b)(2) of the Act (see “Application of Section 4(b)(2) of the Act” section of this proposed revised rule for a detailed discussion).
Subunit 11b
Subunit 11b encompasses approximately 1 mi (2 km) of San Mateo Creek beyond the boundaries of MCB Camp Pendleton within the Cleveland National Forest near Devil Canyon. The subunit consists of 34 ac (14 ha) of Forest Service land. Subunit 11b contains the physical and biological features that are essential to the conservation of the species, including aquatic habitat for breeding and non-breeding activities (PCEs 1, 2, and 3) and upland habitat for foraging and dispersal activities (PCE 4). The physical and biological features essential to the conservation of the species in this subunit may require special management considerations or protection to address threats from nonnative predators (ECORP 2004, p. 16). Please see the “Special Management Considerations or Protection” section of this proposed rule for a discussion of the threats to arroyo toad habitat and potential management considerations.
Unit 12: Lower Santa Margarita River Basin (1,009 ac (408 ha))
This unit is located in northwestern San Diego County and consists of two subunits totaling 5 ac (2 ha) of State land and 1,004 ac (406 ha) of private land. This unit supports large arroyo toad populations in proximity to other large populations to the north (Unit 11), and provides potential connectivity to populations in the upper Santa Margarita River Basin (Unit 13). We are exempting from designation approximately 7,239 ac (2,929 ha) of military land (7,016 ac (2,839 ha) on MCB Camp Pendleton and 223 ac (90 ha) on Fallbrook Naval Weapons Station) that fall within the boundaries of this critical habitat unit from the proposed revised designation of critical habitat under section 4(a)(3)(B) of the Act because the lands are subject to the 2007 INRMP for MCB Camp Pendleton and the 2006 INRMP for the Fallbrook Naval Weapons Station, and each INRMP provides a benefit to the arroyo toad (see the “Application of Section 4(a)(3) of the Act” section of this proposed revised rule for a detailed discussion).
Subunit 12a
Subunit 12a encompasses approximately 2.1 mi (3 km) of De Luz Creek from the town of De Luz downstream to the MCB Camp Pendleton boundary. The subunit consists of 394 ac (159 ha) of private land. Subunit 12a contains the physical and biological features that are essential to the conservation of the species, including aquatic habitat for breeding and non-breeding activities (PCEs 1, 2, and 3) and upland habitat for foraging and dispersal activities (PCE 4). The physical and biological features essential to the conservation of the species in this subunit may require special management considerations or protection to address threats from cumulative impacts to the species' habitat from recreation, nonnative predators, and nonnative plants (CNDDB 2008 EO 26). Please see the “Special Management Considerations or Protection” section of this proposed rule for a discussion of the threats to arroyo toad habitat and potential management considerations.
Subunit 12b
Subunit 12b encompasses approximately 5.5 mi (9 km) of the Santa Margarita River upstream from the MCB Camp Pendleton boundary. The subunit consists of 5 ac (2 ha) of State land and 610 ac (247 ha) of private land. Subunit 12b contains the physical and biological features that are essential to the conservation of the species, including aquatic habitat for breeding and non-breeding activities (PCEs 1, 2, and 3) and upland habitat for foraging and dispersal activities (PCE 4). The physical and biological features essential to the conservation of the species in this subunit may require special management considerations or protection to address threats from cumulative impacts to the species' habitat from nonnative predators, nonnative plants, and vehicular traffic (Varanus Biological Services, Inc. 1999, pp. 34-35). Please see the “Special Management Considerations or Protection” section of this proposed rule for a discussion of the threats to arroyo toad habitat and potential management considerations.
Unit 13: Upper Santa Margarita River Basin (8,137 ac (3,293 ha))
This unit is located in southern Riverside County and northern San Diego County and consists of three subunits totaling 23 ac (9 ha) of Bureau of Land Management land, 434 ac (176 ha) of Forest Service land, and 7,682 ac (3,109 ha) of private land. This unit provides potential links to arroyo toad populations in the lower Santa Margarita River Basin and other nearby drainages containing suitable habitat.
Subunit 13a
Subunit 13a encompasses approximately 7.3 mi (12 km) of Arroyo Seco Creek from just south of the San Diego-Riverside County boundary downstream to Vail Lake. The subunit consists of 343 ac (139 ha) of Forest Service land and 813 ac (329 ha) of private land. Subunit 13a contains the physical and biological features that are essential to the conservation of the species, including aquatic habitat for breeding and non-breeding activities (PCEs 1, 2, and 3) and upland habitat for foraging and dispersal activities (PCE 4). The physical and biological features essential to the conservation of the species in this subunit may require special management considerations or protection to address threats from nonnative predators and campground activities (USGS 2000, p. 3). Please see the “Special Management Considerations or Protection” section of this proposed rule for a discussion of the threats to arroyo toad habitat and potential management considerations. We are considering the exclusion of approximately 690 ac (279 ha) of private land in Subunit 13a within the Western Riverside County MSHCP from the final revised critical habitat designation under section 4(b)(2) of the Act (see “Application of Section 4(b)(2) of the Act” section of this proposed revised rule for a detailed discussion).
Subunit 13b
Subunit 13b encompasses approximately 16.3 mi (26 km) of Temecula Creek from Dodge Valley downstream to Vail Lake. The subunit consists of 91 ac (37 ha) of Forest Service land, 23 ac (9 ha) of Bureau of Land Management land, and 4,643 ac (1,879 ha) of private land. Subunit 13b contains the physical and biological features that are essential to the conservation of the species, including aquatic habitat for breeding and non-breeding activities (PCEs 1, 2, and 3) and upland habitat for foraging and dispersal activities (PCE 4). The physical and biological features essential to the conservation of the species in this subunit may require special management considerations or protection to address threats from road maintenance and sand-mining operations (HELIX 2004, p. 1). Please see the “Special Management Considerations or Protection” section of this proposed rule for a discussion of the threats to arroyo toad habitat and potential management considerations. We are considering the exclusion of approximately 2,318 ac (938 ha) of private land in Subunit 13b within the Western Riverside County MSHCP from the final revised critical habitat designation under section 4(b)(2) of the Act (see “Application of Section 4(b)(2) of the Act” section of this proposed revised rule for a detailed discussion).
Subunit 13c
Subunit 13c encompasses approximately 6.5 mi (10 km) of Wilson Creek from the confluence with Cahuilla Creek downstream to Vail Lake. The subunit consists of 2,226 ac (901 ha) of private land. Subunit 13c contains the physical and biological features that are essential to the conservation of the species, including aquatic habitat for breeding and non-breeding activities (PCEs 1, 2, and 3) and upland habitat for foraging and dispersal activities (PCE 4). The physical and biological features essential to the conservation of the species in this subunit may require special management considerations or protection to address threats from direct mortality and habitat degradation from off-highway vehicular traffic, and upstream sedimentation caused by urbanization, agriculture, or wildfire (R. Haase, MCAS Camp Pendleton,
in litt.
2009b, p. 1). Please see the “Special Management Considerations or Protection” section of this proposed rule for a discussion of the threats to arroyo toad habitat and potential management considerations. We are considering the exclusion of approximately 2,225 ac (900 ha) of private land in Subunit 13c within the Western Riverside County MSHCP from the final revised critical habitat designation under section 4(b)(2) of the Act (see “Application of Section 4(b)(2) of the Act” section of this proposed revised rule for a detailed discussion).
Unit 14: Lower and Middle San Luis Rey River Basin (12,906 ac (5,223 ha))
This unit is located in northern San Diego County and encompasses approximately 30 mi (48 km) of the San Luis Rey River from the western edge of the La Jolla Indian Reservation downstream to the confluence with Guajome Creek near the City of Oceanside. It also includes approximately 3.4 mi (5.5 km) of Pala Creek and 1.7 mi (2.7 km) of Keys Creek upstream from their confluence with the San Luis Rey River. The unit consists of approximately 5 ac (2 ha) of Bureau of Land Management land, 10 ac (4 ha) of State land, 3,540 ac (1,432 ha) of tribal land, and 9,351 ac (3,785 ha) of private land, and supports one of the largest
contiguous river reaches that is occupied by the species. Unit 14 contains the physical and biological features that are essential to the conservation of the species, including aquatic habitat for breeding and non-breeding activities (PCEs 1, 2, and 3) and upland habitat for foraging and dispersal activities (PCE 4). The physical and biological features essential to the conservation of the species in this unit may require special management considerations or protection to address threats from dams and water diversions, intensive urbanization, agriculture, and nonnative predators and plants. Please see the “Special Management Considerations or Protection” section of this proposed rule for a discussion of the threats to arroyo toad habitat and potential management considerations.
As discussed in the “Application of Section 4(b)(2) of the Act” section of this proposed revised rule, we recognize the importance of government-to-government relationships with Tribes; therefore, we are considering the exclusion of approximately 1,155 ac (467 ha) of Rincon Band of Luiseño Mission Indians Tribal Lands and approximately 2,385 ac (963 ha) of Pala Band of Luiseño Mission Indians Tribal Lands in Unit 14 from the final revised critical habitat designation under section 4(b)(2) of the Act. We are seeking public comment on the appropriateness of the inclusion or exclusion of these lands from final designation of revised critical habitat and whether the conservation needs of the arroyo toad can be achieved by limiting the designation to non-tribal lands (see Public Comments section).
Unit 15: Upper San Luis Rey River Basin (12,026 ac (4,867 ha))
This unit is located in northern San Diego County and encompasses: (1) Approximately 8.6 mi (14 km) of the West Fork of the San Luis Rey River from Barker Valley downstream to the upper end of Lake Henshaw, (2) approximately 11.4 mi (18 km) of the upper San Luis Rey River from the Indian Flats area downstream to the upper end of Lake Henshaw, and (3) approximately 6.9 mi (11 km) of Agua Caliente Creek from the western edge of section 13 (T10S, R3E) to the confluence with the San Luis Rey River. The unit consists of 1,428 ac (578 ha) of Forest Service land and 10,598 ac (4,289 ha) of private land. This unit supports a unique assemblage of several small, disjunct, high-elevation arroyo toad populations and one significant population on Agua Caliente Creek (Gergus 1992,
in litt.
; Ervin 2000,
in litt.
; CNDDB 2008, Element Occurrences (EOs) 27, 32) in an area where in-stream and overland dispersal between populations is likely still possible. Unit 15 contains the physical and biological features that are essential to the conservation of the species, including aquatic habitat for breeding and non-breeding activities (PCEs 1, 2, and 3) and upland habitat for foraging and dispersal activities (PCE 4). The physical and biological features essential to the conservation of the species in this unit may require special management considerations or protection to address threats from groundwater pumping on private lands, nonnative predators, and grazing. Please see the “Special Management Considerations or Protection” section of this proposed rule for a discussion of the threats to arroyo toad habitat and potential management considerations.
Unit 16: Santa Ysabel Creek Basin (13,567 ac (5,490 ha))
This unit is located in north-central San Diego County and consists of two subunits totaling 6 ac (2 ha) of Bureau of Land Management land, 138 ac (56 ha) of Forest Service land, 182 ac (74 ha) of State land, 143 ac (58 ha) of local government land, 23 ac (9 ha) of tribal land, and 13,074 ac (5,291 ha) of private land. This unit supports large amounts of suitable habitat connecting large populations with several additional populations.
Subunit 16a
Subunit 16a encompasses: (1) Approximately 12 mi (19 km) of Santa Ysabel Creek from the confluence with Temescal Creek downstream to the confluence with Santa Maria Creek, (2) approximately 10 mi (16.1 km) of Guejito Creek from the 2,000 ft (610 m) elevation contour downstream to the confluence with Santa Ysabel Creek, (3) approximately 2.5 mi (4.0 km) of Boden Canyon upstream from the Santa Ysabel Creek confluence, (4) approximately 4.3 mi (7 km) of Temescal Creek from the northern edge of Pamo Valley to the confluence with Santa Ysabel Creek, and (5) approximately 9.1 mi (15 km) of Santa Maria Creek from the west side of Ramona to the confluence with Santa Ysabel Creek. The subunit consists of 138 ac (56 ha) of Forest Service land, 6 ac (2 ha) of Bureau of Land Management land, 182 ac (74 ha) of State land, 143 ac (58 ha) of local government land, and 11,667 ac (4,721 ha) of private land. Subunit 16a contains the physical and biological features that are essential to the conservation of the species, including aquatic habitat for breeding and non-breeding activities (PCEs 1, 2, and 3) and upland habitat for foraging and dispersal activities (PCE 4). The physical and biological features essential to the conservation of the species in this subunit may require special management considerations or protection to address threats from grazing, nonnative predators, and urbanization (Tierra Environmental Services 2001,
in litt.
; CNDDB 2008, EOs 59, 61). Please see the “Special Management Considerations or Protection” section of this proposed rule for a discussion of the threats to arroyo toad habitat and potential management considerations. We are considering the exclusion of approximately 3,915 ac (1,585 ha) of private lands in Subunit 16a within the San Diego MSCP-City and County of San Diego Subarea Plans from the final revised critical habitat designation under section 4(b)(2) of the Act (see “Application of Section 4(b)(2) of the Act” section of this proposed revised rule for a detailed discussion).
Subunit 16d
Subunit 16d encompasses approximately 5.2 mi (8.3 km) of Santa Ysabel Creek about 0.5 mi (0.8 km) east of Highway 79 downstream to approximately 0.25 mi (0.4 km) downstream of the confluence with Witch Creek. The subunit consists of 23 ac (9 ha) of Mesa Grande Reservation tribal land and 1,408 ac (570 ha) of private land. Subunit 16d contains the physical and biological features that are essential to the conservation of the species, including aquatic habitat for breeding and non-breeding activities (PCEs 1, 2, and 3) and upland habitat for foraging and dispersal activities (PCE 4). The physical and biological features essential to the conservation of the species in this subunit may require special management considerations or protection to address threats from grazing (CNDDB 2008, EO 62). Please see the “Special Management Considerations or Protection” section of this proposed rule for a discussion of the threats to arroyo toad habitat and potential management considerations.
As discussed in the “Application of Section 4(b)(2) of the Act” section of this proposed revised rule, we recognize the importance of government-to-government relationships with Tribes; therefore, we are considering the exclusion of approximately 23 ac (9 ha) of Mesa Grande Band of Diegueno Mission Indians Tribal Lands in Subunit 16d from the final revised critical habitat designation under section 4(b)(2) of the Act. We are seeking public comment on the appropriateness of the inclusion or exclusion of these lands from final designation of revised critical
habitat and whether the conservation needs of the arroyo toad can be achieved by limiting the designation to non-tribal lands (see Public Comments section).
Unit 17: San Diego River Basin/San Vicente Creek (4,263 ac (1,725 ha))
This unit is located in central San Diego County and consists of three subunits totaling 35 ac (14 ha) of Bureau of Land Management land, 390 ac (158 ha) of Forest Service land, 93 ac (38 ha) of Capitan Grande Band of Diegueno Mission Indians tribal land, and 3,746 ac (1,516 ha) of private land. This unit supports suitable habitat for population expansion, thus increasing the probability of the long-term persistence of these populations.
Subunit 17a
Subunit 17a encompasses: (1) Approximately 8.7 mi (14 km) of the San Diego River from Temescal Creek downstream through 0.5 mi (0.9 km) of the Capitan Grande Reservation to the upper edge of El Capitan Reservoir, and (2) approximately 1 mi (2 km) of lower Cedar Creek. The subunit consists of 354 ac (143 ha) of Forest Service land, 92 ac (37 ha) of Capitan Grande Band of Diegueno Mission Indians tribal land, and 795 ac (322 ha) of private land. Subunit 17a contains the physical and biological features that are essential to the conservation of the species, including aquatic habitat for breeding and non-breeding activities (PCEs 1, 2, and 3) and upland habitat for foraging and dispersal activities (PCE 4). The physical and biological features essential to the conservation of the species in this subunit may require special management considerations or protection to address threats from urbanization and nonnative predators. Please see the “Special Management Considerations or Protection” section of this proposed rule for a discussion of the threats to arroyo toad habitat and potential management considerations.
As discussed in the “Application of Section 4(b)(2) of the Act” section of this proposed revised rule, we recognize the importance of government-to-government relationships with Tribes; therefore, we are considering the exclusion of approximately 92 ac (37 ha) of Capitan Grande Band of Diegueno Mission Indians Tribal Lands in Subunit 17a from the final revised critical habitat designation under section 4(b)(2) of the Act. We are seeking public comment on the appropriateness of the inclusion or exclusion of these lands from final designation of revised critical habitat and whether the conservation needs of the arroyo toad can be achieved by limiting the designation to non-tribal lands (see Public Comments section).
Subunit 17b
Subunit 17b encompasses approximately 7.2 mi (12 km) of the San Diego River downstream from San Vicente Reservoir. The subunit consists of 12 ac (5 ha) of Bureau of Land Management land, 36 ac (15 ha) of Forest Service land, and 1,817 ac (735 ha) of private land. Subunit 17b contains the physical and biological features that are essential to the conservation of the species, including aquatic habitat for breeding and non-breeding activities (PCEs 1, 2, and 3) and upland habitat for foraging and dispersal activities (PCE 4). The physical and biological features essential to the conservation of the species in this subunit may require special management considerations or protection to address threats from urbanization, agriculture, nonnative predators, and adverse water releases (based on timing or amount) from the Sutherland/San Vicente Aqueduct. Please see the “Special Management Considerations or Protection” section of this proposed rule for a discussion of the threats to arroyo toad habitat and potential management considerations. We are considering the exclusion of approximately 1,730 ac (700 ha) of private lands in Subunit 17b within the San Diego MSCP-City and County of San Diego Subarea Plans from the final revised critical habitat designation under section 4(b)(2) of the Act (see “Application of Section 4(b)(2) of the Act” section of this proposed revised rule for a detailed discussion).
Subunit 17d
Subunit 17d encompasses approximately 7.6 mi (12 km) of San Vicente Creek upstream from San Vicente Reservoir. The subunit consists of 23 ac (9 ha) of Bureau of Land Management land and 1,134 ac (459 ha) of private land. Subunit 17d contains the physical and biological features that are essential to the conservation of the species, including aquatic habitat for breeding and non-breeding activities (PCEs 1, 2, and 3) and upland habitat for foraging and dispersal activities (PCE 4). The physical and biological features essential to the conservation of the species in this subunit may require special management considerations or protection to address threats from urbaniz
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