California Red-Legged Frog Site Assessment
for Main Ditch Project, El Dorado County
Prepared for:
El Dorado Irrigation District
June 2013
California Red-Legged Frog Site Assessment
for Main Ditch Project, El Dorado County
Prepared for:
El Dorado Irrigation District
2890 Mosquito Road
Placerville, CA 95667
Contact:
Brian Deason
Hydroelectric Compliance Analyst
530/642-4064
Prepared by:
AECOM
2020 L Street, Suite 400
Sacramento, CA 95811
Contact:
Andy Hatch
USFWS Recovery Permit #TE200340-0
916/414-5800
60301332
06.25.13
June 2013
TABLE OF CONTENTS
1
INTRODUCTION............................................................................................................................................. 3
1.1
Project Description ........................................................................................................................... 3
2
DESCRIPTION OF THE PROJECT AREA ........................................................................................................ 3
2.1
Existing Main Ditch Description ...................................................................................................... 3
2.2
Habitat Types ................................................................................................................................... 5
3
CALIFORNIA RED-LEGGED FROG ............................................................................................................... 6
3.1
Natural History ................................................................................................................................. 6
3.2
Critical Habitat ................................................................................................................................. 7
4
METHODS...................................................................................................................................................... 9
4.1
Literature Review ............................................................................................................................. 9
4.2
Field Surveys .................................................................................................................................... 9
5
RESULTS AND DISCUSSION .......................................................................................................................... 9
5.1
Known Occurrences in the Study Area ............................................................................................ 9
5.2
Habitats in the Project Area.............................................................................................................. 9
5.3
Habitats within 1 Mile of the Project Site ...................................................................................... 10
5.4
Habitats within 5 Miles of the Project Site..................................................................................... 10
5.5
Wildlife Movement Corridors and Habitat Fragmentation ............................................................ 10
6
CONCLUSIONS ............................................................................................................................................ 12
7
REFERENCES .............................................................................................................................................. 13
Appendices
A
Representative Photographs
Exhibits
Exhibit 1
Exhibit 2
Exhibit 3
Project Location...................................................................................................................................... 4
California Red-Legged Frog Occurrences and Critical Habitat ............................................................. 8
Potential Nonbreeding Aquatic Habitat Adjacent to the Project Site ................................................... 11
Tables
Table 1
California Red-Legged Frog Occurences within 5 Miles of the Project Site ......................................... 9
California Red-Legged Frog Site Assessment for Main Ditch Project
El Dorado Irrigation District
AECOM
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ACRONYMS AND OTHER ABBREVIATIONS
CNDDB
EID
U.S. 50
USFWS
AECOM
ii
California Natural Diversity Database
El Dorado Irrigation District
U.S. Highway 50
U.S. Fish and Wildlife Service
California Red-Legged Frog Site Assessment for Main Ditch Project
El Dorado Irrigation District
1
INTRODUCTION
A site assessment is typically requested by the U.S. Fish and Wildlife Service (USFWS) as discretionary
information to accurately assess the potential for California red-legged frog (Rana aurora draytonii) presence in a
project vicinity. This report assesses the suitability of on- and off-site aquatic and upland habitats to support
various California red-legged frog life history stages, describes the habitats within 1 mile of the project site, and
identifies known California red-legged frog occurrences within 5 miles of the project site. The project site
encompasses the Main Ditch from the El Dorado Forebay to the Reservoir 1 water treatment facility. Suitable
California red-legged frog habitats, as defined by USFWS, are instream and out-of-stream breeding, dispersal,
upland refugia (including aestivation), and year-round aquatic habitat (USFWS 1996, 1997, 2002, 2005, 2010).
This assessment conforms to the guidelines outlined in the Revised Guidance on Site Assessments and Field
Surveys for the California Red-Legged Frog (USFWS 2005) and is considered valid by USFWS for 2 years.
1.1
PROJECT DESCRIPTION
The El Dorado Irrigation District (EID) is proposing to pipe a section of the Main Ditch to reduce leakage and
losses in the ditch and thereby conserve and extend EID water supplies. The project is an important strategy
recognized in the El Dorado County Water Agency Water Resources Development and Management Plan.
Reducing conveyance losses in the ditch would also allow EID more flexibility in meeting water supply needs in
drought years.
The section of the Main Ditch that would be piped is approximately 3 miles long and conveys a 15,080 acre-feet
of raw water annually at a maximum rate of 40 cubic feet per second from El Dorado Forebay to Reservoir 1
(Exhibit 1). The 3-mile stretch of the Main Ditch traverses properties where houses abut portions of the ditch.
Because the Main Ditch is an unlined, earthen canal, a portion of the flow is lost to seepage and evaporation.
Previous studies of the ditch have shown that water losses could be as high as 1,300 acre-feet per year, depending
on flow rates and weather conditions. In addition, raw water quality is degraded as it travels through the ditch,
which can affect EID’s ability to meet drinking water regulations and increase operational costs to treat the water.
2
2.1
DESCRIPTION OF THE PROJECT AREA
EXISTING MAIN DITCH DESCRIPTION
The section of the Main Ditch in the project area that would be piped is approximately 3 miles long and descends
from the El Dorado Forebay to Reservoir 1 through mixed conifer forest, rural residential areas, and undeveloped
parcels. A 4- to 5-foot-wide trail that runs atop the outer ditch berm is popular with dog-walkers and other
recreational users. The ditch itself is approximately 15 feet at bankfull width, is up to 5 feet deep, and is primarily
an unlined earthen canal with some sections that have gunite or vegetated banks.
California Red-Legged Frog Site Assessment for Main Ditch Project
El Dorado Irrigation District
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Locator
Area of
Detail
D
Ef Dorado
Forebay
\
Appl
I 1 .. nt on
o 11Re ort
2
0
NORTH
MILES
Somers et
Basemap: ESRI Online
X60301332
004
6/13
Source: Data compiled by AECOM in 2013
Exhibit 1
AECOM
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Project Location
California Red-Legged Frog Site Assessment for Main Ditch Project
El Dorado Irrigation District
2.2
HABITAT TYPES
Habitat types in the project area include different common vegetation types found in the Sierra Nevada foothills,
including mixed conifer forest, montane riparian along portions of the Main Ditch and in drainages, lacustrine
habitat at the El Dorado Forebay, and rural residential development. North of the Main Ditch, rural residential
development gradual eases into more natural habitats. South of the Main Ditch, residential development and
commercial development are clustered along Pony Express Trail, the main east west connector road, and U.S.
Highway 50 (U.S. 50), a four-lane divided highway. Vegetation found in the project area is described below.
2.2.1
SIERRAN MIXED CONIFER
Sierran mixed conifer is the predominant habitat type occupying most of the project area, and many of the
residences along the Main Ditch have a conifer tree canopy. The dominant tree species are ponderosa pine, white
fir (Abies concolor), Douglas-fir (Pseudotsuga menziesii), sugar pine (Pinus lambertiana), incense cedar
(Calocedrus decurrens), and California black oak (Quercus kelloggii).
2.2.2
LACUSTRINE
Lacustrine habitat (lake habitat) consists of open water habitat in El Dorado Forebay. The shoreline below the
high-water line supports plant cover, including native and nonnative grasses and occasional willows.
2.2.3
MONTANE RIPARIAN
Although most of the Main Ditch has unvegetated managed banks, montane riparian is found in places along the
Main Ditch below the adjacent dirt path, on private property, or in unmanaged areas. Dominant species in these
areas include dogwood (Cornus sp.), Himalayan blackberry (Rubus armeniacus), thimbleberry (Rubus
parviflorus), and bracken fern (Pteridium aquilinum). Additional montane riparian vegetation is found in the
small ephemeral drainages running north of the ditch, and along the potentially perennial channels fed by dam
seepage that run north of the El Dorado Forebay. In general, these montane riparian locations are narrow,
transitioning quickly into Sierran mixed conifer.
2.2.4
RURAL RESIDENTIAL
Rural residential development is the predominant land use in the project area. The level of development on these
residential properties varies greatly; some locations had little landscaping and are essentially a house in the
conifer forest, other locations have fully landscaped yards with ornamental vegetation, and others have horses on
the property. These properties are accessed by a network of paved and dirt or gravel roads, some of which cross
the Main Ditch. Many residential properties on the south side of the Main Ditch have built bridges across the
ditch, and the trail along the ditch is clearly a popular recreational trail.
2.2.5
DEVELOPED
Developed areas include the El Dorado Forebay dam, the Reservoir 1 water treatment plant and operations
facilities, and commercial development along Pony Express Trail and U.S. 50.
California Red-Legged Frog Site Assessment for Main Ditch Project
El Dorado Irrigation District
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3
3.1
CALIFORNIA RED-LEGGED FROG
NATURAL HISTORY
California red-legged frog (Rana aurora draytonii) is federally listed as threatened and is a California Species of
Special Concern. Optimal habitat includes ponds, stream courses, permanent pools (Storer 1925) and intermittent
streams fed by drainage areas no larger than 115 square miles (Hayes and Jennings 1988; USFWS 2006). This
species occurs between sea level and 5,000 feet in elevation (USFWS 2006). Typical habitat characteristics
include water depth of at least 2.5 feet, largely intact emergent or shoreline vegetation (e.g., cattails [Typha spp],
tules [Scirpus spp], or willows [Salix spp.]) and absence of competitors/predators, such as bullfrogs (Lithobates
[Rana] catesbeiana) and largemouth bass (Micropterus salmoides) (Hayes and Jennings 1988). California redlegged frog uses a wide variety of habitats in the absence of optimal conditions, including temporary pools and
streams, permanent watercourses, ponds, concrete-lined pools, isolated wells, stock ponds absent of shoreline
vegetation, and refuse piles near ponds. However, permanent aquatic habitat is essential to the survival of local
California red-legged frog populations.
Adults are highly aquatic and are most active at night (Storer 1925). California red-legged frogs also make use of
terrestrial habitat, especially after precipitation events, for nonmigratory forays into adjacent upland habitats and
for migratory overland movements to breeding sites. In a study conducted by Bulger et al. (2003) at a coastal site
in northern Santa Cruz County, California, red-legged frogs typically remained within 16 feet of aquatic habitat
during dry periods but moved into upland habitat as far as 426 feet during summer rains. Overland routes were
often highly oriented toward the nearest pond and were typically traversed in direct, point-to-point movements
with little to no preference or avoidance toward any particular topography or habitat type. California red-legged
frogs were documented to migrate between aquatic sites at distances up to approximately 2 miles.
Breeding typically begins between November and mid-December and lasts through April in most years but is
dictated by winter rainfall (Jennings and Hayes 1994; Stebbins 2003; Bulger et al. 2003). Breeding typically
occurs in permanent ponds and may occur in slower water of streams (i.e., pools or backwaters) (Hayes and
Jennings 1988). At breeding sites, males call in groups, or leks, of three to seven individuals to attract females
(Jennings and Hayes 1994). During amplexus (breeding posture), eggs are fertilized by the male while the female
deposits the egg mass on emergent vegetation (Storer 1925; Jennings and Hayes 1994). However, breeding has
also been documented to occur in ponds that lack emergent vegetation (Bobzien et al. 2000). Larvae typically
hatch in 6–22 days, and metamorphosis is usually completed in 4–5 months (Jennings and Hayes 1994; Bobzien
et al. 2000). There have been several documented cases of tadpoles overwintering to then metamorphose during
the following spring (Storer 1925; Bobzien et al. 2000; Fellers et al. 2001). Males and females usually attain
sexual maturity at 2 and 3 years, respectively (Jennings and Hayes 1994).
The most significant threats to California red-legged frogs are habitat loss and alteration; introduced predators;
water management; mismanagement of grazing livestock; chemical contamination from urban, agricultural, and
industrial runoff; and extended drought conditions.
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California Red-Legged Frog Site Assessment for Main Ditch Project
El Dorado Irrigation District
3.2
CRITICAL HABITAT
In designating critical habitat for the California red-legged frog, USFWS evaluated the specific habitat elements
required by the species for all of its biological needs. These habitat elements, called Primary Constituent
Elements, are necessary for the conservation of the species and were used to evaluate whether habitat present in
proposed critical habitat units would indeed have the entire habitat element suite required for the continued
survival of the species. These habitat elements can also be used to evaluate potential habitat locations as part of a
habitat assessment. If a suspected habitat location does not have one or more of these Primary Constituent
Elements, it is unlikely to support California red-legged frog populations.
As defined in the USFWS critical habitat designation (USFWS 2010), the Primary Constituent Elements for
California red-legged frog are:
►
►
►
►
aquatic breeding habitat,
nonbreeding aquatic habitat,
upland habitat, and
dispersal habitat.
Aquatic breeding habitat includes low-gradient freshwater habitats, such as pools and backwaters of streams,
natural or artificial ponds, marshes, and lagoons. Aquatic breeding habitat should hold water for a minimum of 20
weeks in most years and have salinity less than 7.0 parts per thousand.
Nonbreeding aquatic habitat includes habitat that could be defined as aquatic breeding habitat and also includes
intermittent creeks, seeps, springs, or other areas that could provide refuge or foraging habitat during drought
periods but that may not provide suitable water duration for breeding.
Upland habitat is defined as the terrestrial habitat within 200 feet of aquatic habitat and could include riparian,
grassland, or woodland habitats. Upland habitat considered suitable includes features that provide refuge for the
species, such as dense riparian vegetation, active mammal burrows, or any other element that could provide shade,
shelter, moisture, or cooler temperatures.
Dispersal habitat can be a variety of upland habitat types, provided that it is free of barriers. USFWS considers 1
mile a dispersal distance that in most cases will provide for connectivity between breeding habitats and
nonbreeding aquatic and upland habitats. However, dispersal movements should be considered highly site specific
(USFWS 2010). Regardless of the specific critical habitat designation of dispersal habitat, site-specific factors
need to be considered when evaluating potential dispersal habitat. Dispersal barriers could include moderate- to
high-density urban development, highways, and large reservoirs.
The project site does not encompass federally designated California red-legged frog critical habitat. The closest
critical habitat unit to the study area is ELD-1, Spivey Pond Unit, in El Dorado County, which is located 0.3 mile
from the project site (Exhibit 2) within an adjacent watershed, Weber Creek.
California Red-Legged Frog Site Assessment for Main Ditch Project
El Dorado Irrigation District
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Sources: CNDDB 2013, USFWS 2010, data compiled by AECOM in 2013
Exhibit 2
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California Red-Legged Frog Occurrences and Critical Habitat
California Red-Legged Frog Site Assessment for Main Ditch Project
El Dorado Irrigation District
4
4.1
METHODS
LITERATURE REVIEW
Before field investigations, the California Department of Fish and Wildlife’s California Natural Diversity
Database (CNDDB) (CNDDB 2013) was reviewed for reported occurrences of California red-legged frog within
5 miles of the project site.
4.2
FIELD SURVEYS
Field surveys were conducted by AECOM wildlife biologist Andy Hatch on June 13, 2013. Habitat was evaluated
for all aquatic and upland features in the project site and vicinity. Any potentially suitable breeding locations were
visited in the field, and notes were taken on site quality, including presence of perennial water, pool habitat, and
predators. Habitat within 1 mile of the project site was examined using a combination of field visit and aerial
photograph interpretation where access was limited. Appendix A provides photographs of the project site
and vicinity.
5
5.1
RESULTS AND DISCUSSION
KNOWN OCCURRENCES IN THE STUDY AREA
One California red-legged frog occurrence is located within 5 miles of the project site. This occurrence is the
Spivey Pond California red-legged frog population, one of six known populations of California red-legged frog in
the Sierra Nevada (CNDDB 2013). The details of this occurrence are given below in Table 1, and the location is
shown in Exhibit 2. No known occurrences exist in the project site.
Table 1
California Red-Legged Frog Occurences within 5 Miles of the Project Site
CNDDB
Occurrence
Number
586
5.2
Date of Occurrence
April 17, 2008
Details
Spivey Pond: located within BLM property along
Weber Creek. Six adults and one tadpole observed in
1997, six adults and two unknown observed in 2002,
three adults and five juveniles observed in 2007, and
five adults and two juveniles observed in 2008
Distance from Project Area
(miles)
0.85 mile
HABITATS IN THE PROJECT AREA
No suitable aquatic breeding habitat is located in the project area. The El Dorado Forebay could provide potential
breeding habitat; however, the forebay is an artificial reservoir that is stocked with rainbow trout, is subject to
heavy shoreline disturbance by recreational users, is managed for water storage, and experiences regular daily
changes in water levels associated with hydropower generation needs; therefore, it is unlikely to support
California red-legged frog. The Main Ditch is also unlikely to support California red-legged frog because of high
California Red-Legged Frog Site Assessment for Main Ditch Project
El Dorado Irrigation District
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water velocities in the ditch and lack of suitable pool habitat for breeding. Long Canyon Creek below the forebay
could provide suitable dispersal, upland, and nonbreeding aquatic habitat, but no suitable breeding pools were
located in the section of the creek below the forebay that was examined during the field survey. Between the
intake of the Main Ditch into the Reservoir 1 water treatment facility and the operations building, a continuation
of the ditch has residual flow and could provide suitable nonbreeding aquatic habitat. This location would not
support California red-legged frog breeding because of the lack of pool habitat and shallow water (2–5 inches in
most places). Potential nonbreeding aquatic habitats in and adjacent to the project area are shown in Exhibit 3.
Photographs are presented in Appendix A.
5.3
HABITATS WITHIN 1 MILE OF THE PROJECT SITE
The Spivey Pond California red-legged frog population is found within 1 mile of the project site, and along with
the Weber Creek drainage. Spivey Pond provides suitable aquatic, upland, and dispersal habitats for California
red-legged frog. The pond and other habitats located along Weber Creek are located within another watershed
south of the project site and south of U.S. 50 and the commercial development along the highway, which likely
isolates the occupied locations from the project site. Because of these barriers, it is unlikely that dispersing frogs
could travel from the occupied habitat into the project site. No suitable breeding habitat was located within 1 mile
of the project site during the field survey or during aerial photograph interpretation, but it remains possible that in
areas north of the highway that are accessible from the project site, there is potentially suitable habitat in
agricultural or stock ponds on private property and in drainages, including Long Canyon.
5.4
HABITATS WITHIN 5 MILES OF THE PROJECT SITE
As described above, the occupied suitable aquatic, upland, and dispersal habitats for California red-legged frog in
and around Spivey Pond are mostly or totally isolated from the project site by development and U.S. 50. In
locations accessible from the project site, there are likely suitable aquatic and upland habitats both in rural areas
with artificial stock ponds and along creek and river drainages. Because of the extremely limited distribution of
California red-legged frog in the Sierra Nevada and the presence of barriers such as U.S. 50, and at times the
South Fork American River to the north of the project site due to flow conditions, it is unlikely that any of these
potentially suitable habitats are occupied by the species.
5.5
WILDLIFE MOVEMENT CORRIDORS AND HABITAT FRAGMENTATION
Wildlife movement includes migration (e.g., usually one direction per season), interpopulation movement (e.g.,
long-term genetic exchange), and small travel pathways (e.g., daily movement corridors) in an animal’s territory.
Although small travel pathways usually facilitate movement for daily home range activities, such as foraging or
escaping from predators, they also provide connection between outlying populations, permitting gene flow
between populations, thereby buffering against the adverse genetic effects of small population sizes. These
linkages between habitat types can extend for miles between primary habitat areas and occur on a large scale
throughout California. Habitat linkages facilitate movement between populations located in discrete areas and
populations located in larger habitat areas. The mosaic of habitats found in large-scale landscapes result in
wildlife populations that consist of discrete subpopulations composed of a large single population, often referred
to as a metapopulation. Even where patches of pristine habitat are fragmented, such as occurs with coastal scrub,
the movement between wildlife populations is facilitated through habitat linkages (i.e., migration and movement
corridors). Depending on the condition of the corridor, gene flow between populations may be frequent, thus
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California Red-Legged Frog Site Assessment for Main Ditch Project
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0
700
1,400
FEET
NORTH
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Source: Data compiled by AECOM in 2013
Exhibit 3
Potential Nonbreeding Aquatic Habitat Adjacent to the Project Site
California Red-Legged Frog Site Assessment for Main Ditch Project
El Dorado Irrigation District
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allowing for high genetic diversity in the population. Potentially low-frequency gene flow may lead to complete
isolation and, if pressures are strong, potential local extinction (McCullough 1996; Whittaker 1998).
Habitat fragmentation, by definition, creates a greater number of habitat patches that are smaller than the original
contiguous tract(s) of habitat. Fragmentation of primary habitat types can hinder local and/or regional wildlife
movements. The resulting reduced interaction between individuals changes the long-term dynamics of
populations distributed among fragments and an inability to genetically adapt or respond to environmental
pressures. This increases the probability of extinction for these populations compared to those associated with
nonfragmented landscapes (Zuidema et al. 1996; Kupfer et al. 1997). Effects of fragmentation on the movement
or dispersal of organisms is crucial to composition and diversity (Opdam 1990; Tiebout III and Anderson 1997).
Considering the impacts resulting in potential fragmentation of primary habitat types and loss of valuable
dispersal corridors is imperative when assessing the biological impacts of a project.
In general, the foothills of the Sierra Nevada are moderately to highly fragmented near major highways, such as
U.S. 50, and less so farther from major roads. Rural residential and agricultural land uses are common in the
greater vicinity of the project area; however, these land use types are less fragmenting than major commercial
centers or linear features, such as U.S. 50.
6
CONCLUSIONS
California red-legged frog has a low potential to occur on the project site. Potential nonbreeding aquatic habitat is
located in and adjacent to the project area; however, because of the lack of suitable breeding habitat and the
presence of dispersal barriers and isolation from known occurrences of the species, the project area is unlikely to
support a permanent population of California red-legged frog.
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REFERENCES
Bobzien, S., J. E. DiDonato, P. J. Alexander. 2000. Status of the California Red-Legged Frog in the East Bay
Regional Park District, California. Oakland, CA.
Bulger, J. B., N. J. Scott, Jr. and R. Seymour. 2003. Terrestrial Activity and Conservation of Adult California
Red-Legged Frogs Rana aurora draytonii in Coastal Forests and Grasslands. Biological Conservation
110:85–95.
California Natural Diversity Database. 2013. Database query. California Department of Fish and Wildlife.
Fellers, G. M., A. E. Launer, G. Rathbun, S. Bobzien, J. Alvarez, D. Sterner, R. B. Seymour, and M. Westphal.
2001. Overwintering Tadpoles in the California Red-Legged Frog (Rana aurora draytonii).
Herpetological Review 32.
Hayes, M. P., and M. R. Jennings. 1988. Habitat Correlates of Distribution of the California Red-Legged Frog
(Rana aurora draytonii) and the Foothill Yellow-Legged Frog (Rana boylii): Implications for
Management. Pages 144-158 in R. C. Szaro, K. E. Severson, and D. R. Patton (tech. coords.),
Proceedings of the Symposium on the Management of Amphibians, Reptiles, and Small Mammals in
North America, July 19–21, 1988. U.S. Forest Service, General Technical Report 166.
Jennings, M. R., and M. P. Hayes. 1994. Amphibian and Reptile Species of Special Concern in California. Final
Report to the California Department of Fish and Game.
Kupfer, J. A., G. P. Malanson, and J. R. Runkle. 1997. Factors Influencing Species Composition in Canopy Gaps:
The Importance of End Proximity in Hueston Woods, Ohio. Professional Geographer 49:165–178.
McCullough, D. 1996. Metapopulations and Wildlife Conservation. Island Press.
Opdam, P. 1990. Dispersal in Fragmented Populations: The Key to Survival. Pages 3–17 in R. G. H. Bunce and
D. C. Howard (eds.), Species Dispersal in Agricultural Habitats. Bellhaven Press, London.
Stebbins, R. C. 2003. A Field Guide to Western Reptiles and Amphibians. Peterson Field Guides. Third edition.
Houghton Mifflin. Boston.
Storer, T. I. 1925. A Synopsis of the Amphibia of California. University of California Publications in Zoology 27.
University of California Press. Berkeley.
Tiebout, III, H. M., and R. A. Anderson. 1997. A Comparison of Corridors and Intrinsic Connectivity to Promote
Dispersal in Transient Successional Landscapes. Conservation Biology 11:620–627.
U.S. Fish and Wildlife Service. 1996. Federal Register: Endangered and Threatened Wildlife and Plants;
Determination of Threatened Status for the California Red-legged Frog. 50 CFR. Part 17. Vol. 61. No.
101:25813–25833. May 23, 1996. Available: http://endangered.fws.gov/frpubs/f960523.pdf.
California Red-Legged Frog Site Assessment for Main Ditch Project
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———. 1997. Guidance on Site Assessment and Field Surveys for California Red-legged Frogs (Rana aurora
draytonii). Sacramento Field Office.
———. 2002 (May 28). Recovery Plan for the California Red legged Frog (Rana aurora draytonii). Portland, OR.
———. 2005 (August). Revised Guidance on Site Assessments and Field Surveys for the California Red-Legged
Frog. Sacramento Field Office. Available:
http://www.fws.gov/pacific/sacramento/es/documents/crf_survey_guidance_aug2005.pdf.
———. 2006. Federal Register: Endangered and Threatened Wildlife and Plants; Designation of Critical Habitat
for the California Red-Legged Frog, and Special Rule Exemption Associated with Final Listing for
Existing Routine Ranching Activities; Final Rule. Part II. 50 CFR. Part 17. Vol. 71. No. 71:19243–19346.
April 13, 2006.
——— . 2010. Federal Register: Endangered and Threatened Wildlife and Plants; Critical Habitat for the
California Red-Legged Frog (Rana aurora draytonii); Final Rule. 50 CFR. Part 17. Vol. 75. No.
51:12815–12959.
USFWS. See U.S. Fish and Wildlife Service.
Whittaker, R. 1998. Island Biogeography: Ecology, Evolution and Conservation. Oxford University Press.
Zuidema, P. A., J. A. Sayer, and W. Dijkman. 1996. Forest Fragmentation and Biodiversity: The Case for
Intermediate-Sized Conservation Areas. Environmental Conservation 23:290–297.
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California Red-Legged Frog Site Assessment for Main Ditch Project
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APPENDIX A
Representative Photographs
Potential nonbreeding aquatic habitat located near the Reservoir 1 treatment plant.
Potential nonbreeding aquatic habitat located near the Reservoir 1 treatment plant.
Appendix A
California Red-Legged Frog Site Assessment for Main Ditch Project
El Dorado Irrigation District
Representative Photographs
AECOM
A-1
View of the Main Ditch with montane riparian vegetation on the banks.
Typical view of the Main Ditch, showing gunite banks.
Appendix A
AECOM
A-2
Representative Photographs
California Red-Legged Frog Site Assessment for Main Ditch Project
El Dorado Irrigation District
El Dorado Forebay reservoir.
Potential nonbreeding aquatic, upland, and dispersal habitat in the Long Canyon
drainage.
Appendix A
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Representative Photographs
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