Cascades Frog 

Conservation Assessment

Karen Pope, Catherine Brown, Marc Hayes, 

Gregory Green, and Diane Macfarlane

Pacific Southwest 

Research Station

General Technical Report

PSW-GTR-244

March 2014

DEPAR TMENT OF AGRICULT URE

United States Department of Agriculture

Forest Service
Technical Coordinators

Karen Pope is a research wildlife biologist, U.S. Department of Agriculture, Forest Service, 

Pacific Southwest Research Station, 1700 Bayview Drive, Arcata, CA 95521; Catherine 

Brown is a wildlife biologist, U.S. Department of Agriculture, Forest Service, Stanislaus 

National Forest, currently located at the Pacific Southwest Research Station, 800 Buchanan 

Street, Albany, CA 94710; Mark Hayes is a senior research scientist, Washington Department 

of Fish and Wildlife, 600 Capitol Way North, Olympia, WA 98501; Gregory Green is a 

wildlife ecologist, Tetra Tech EC, 19803 North Creek Parkway, Bothell, WA 98011, currently 

located at Owl Ridge Natural Resource Consultants, Inc., 22116 45th Ave SE, Bothell, WA 

98021; Diane Macfarlane is a wildlife biologist, U.S. Department of Agriculture, Forest 

Service, Pacific Southwest Region, 1323 Club Drive, Vallejo, CA 94592. 

Cover photograph by Karen Pope.

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Abstract

Pope, Karen; Brown, Catherine; Hayes, Marc; Green, Gregory; Macfarlane, 

Diane, tech. coords. 2014. Cascades frog conservation assessment. Gen. Tech. 

Rep. PSW-GTR-244. Albany, CA: U.S. Department of Agriculture, Forest 

Service, Pacific Southwest Research Station. 116 p.

The Cascades frog (Rana cascadae) is a montane, lentic-breeding amphibian 

that has become rare in the southern Cascade Range and remains relatively 

widespread in the Klamath Mountains of northern California. In the southern 

Cascades, remaining populations occur primarily in meadow habitats where 

the fungal disease, chytridiomycosis, and habitat desiccation pose threats to 

persistance. Major risk factors in the Klamath Mountains include introduced 

fish and chytridiomycosis. Conservation actions are needed for the Cascades 

frog in California and especially in the southern Cascades. Conservation options 

include restoration of breeding pools in the southern Cascades, fish removals in 

the Klamath Mountains, and adaptive methods to help alleviate the effects of 

chytridiomycosis rangewide. 

Keywords: Rana cascadae, southern Cascades, Klamath Mountains, risk 

factors, chytridiomycosis.
Summary

The Cascades frog (Rana cascadae) was once abundant in the aquatic habitats 

of the southern Cascade Range and Klamath Mountains of California. Currently, 

the species remains fairly widespread in the Klamath Mountains but has become 

extremely rare in the southern Cascades. Declines and extirpations were first recognized during the early 1980s and have continued to the present. The realization 

that these patterns might place the species at risk of further declines led to a USDA 

Forest Service-initiated multiagency effort to develop a conservation assessment 

focused on attenuating the risk factors responsible. This conservation assessment 

consists of three parts: (1) a synopsis of Cascades frog ecology, (2) a review of 

Cascades frog distribution and abundance over its historical geographic range in 

California, and (3) an evaluation of risk factors to identify those that may affect the 

Cascades frog and its habitat currently and in the future.

Cascades frogs in California, Oregon, and Washington are currently recognized 

as one taxonomic unit, but genetic evidence suggests that the California populations 

may be genetically distinct. In California, Cascades frogs occupy a range of aquatic 

habitats including lakes, wet meadows, ponds, and adjacent streams. They breed in 

still or very slow-flowing water, and their larvae metamorphose in the same season 

they develop from eggs. 

Most of the historical range in California is on federal land, including three 

national forests (Lassen, Klamath, and Shasta-Trinity), and Lassen Volcanic 

National Park (LVNP); the remainder of the range is on private and state-owned 

lands. In the southern Cascades, only 11 known populations remain and the species appears to be extirpated in LVNP. The species remains more common in the 

Klamath Mountains from the east side of the Trinity Alps Wilderness to Castle 

Crags Wilderness.

Researchers are making major strides in understanding the primary reasons for 

declines of the Cascades frog in California. In the Klamath Mountains, introduced 

fishes are common and have been shown to have negative impacts on Cascades frog 

populations. In addition, recent studies have found the fungal pathogen Batrachochytrium dendrobatidis (Bd), which causes the amphibian disease chytridiomycosis, 

to be widespread across the range in California. Some Cascades frog populations 

seem relatively unaffected by the disease, while others seem to be experiencing 

decreased survival, especially juvenile frogs. In the southern Cascades, remaining 

populations of Cascades frogs seem to have extremely low recruitment of juvenile 

frogs into the adult population. Researchers recently concluded that the primary 

reasons for low recruitment were insufficient duration of standing water in breeding 

pools, and low survival of juvenile frogs owing to chytridiomycosis. Now that 
populations are so few and abundances so small, any disturbance that reduces 

survival may pose a high risk to population persistence. Other risk factors that 

may affect population persistence include airborne contaminants, climate change, 

vegetation and fuels management activities, recreational activities, and livestock 

grazing. 

Conservation actions are needed for the Cascades frog in the southern 

Cascades. In 2009 and 2010, the Lassen National Forest initiated habitat restoration 

measures in three meadows to improve breeding habitat conditions. They expanded 

and deepened breeding pools and dug several additional pools. If determined 

successful, restoration measures could be expanded to other remaining populations. 

In addition, research into ways to help alleviate the effects of Bd on the remaining 

populations is needed. Other conservation options include additional protection 

of remaining populations on private lands, more site-by-site assessments of 

appropriate restoration options, investigation of captive breeding and translocation 

options, and ongoing monitoring of the remaining populations. For the Klamath 

Mountains, conservation options include increasing the amount of fishless habitat, 

research into ways to help alleviate the effects of Bd, and monitoring of rangewide 

population status. 
Contents 

1 Introduction

1 Purpose

2 Geographic Scope

2 Document Organization

4 Ecology

4 Systematics and Taxonomy

5 Habitat Requirements

8 Life History

10 Population Dynamics

11 Movement

11 Feeding

12 Mortality

13 Status

13 Southern Cascades

15 Klamath Mountains

16 Conclusions About Status

16 Risk Factors Affecting the Status of the Species

18 Airborne Contaminants

24 Climate Change

25 Disease

27 Fire Suppression

29 Introduced (Nonnative) Fish and Other Predators

31 Livestock Grazing

33 Recreational Activities

35 Relative Importance of Risk Factors

35 Southern Cascades

35 Klamath Mountains

36 Rangewide

36 Existing Management and Research

36 Conservation Options

37 Within California in General

37 Southern Cascades
38 Acknowledgments

38 English Equivalents

39 References

64 Appendix 1: Agency Direction

64 USDA Forest Service

65 National Park Service

67 California Department of Fish and Wildlife

68 U.S. Fish and Wildlife Service

69 References

71 Appendix 2: Museum Standard Symbolic Codes

72 Appendix 3: Status—Administrative Units

72 Lassen National Forest

77 Lassen Volcanic National Park

79 Shasta-Trinity National Forest

81 Klamath National Forest

83 References

87 Appendix 4: Surveys in the Southern Cascade Range Since 1980

89 References

91 Appendix 5: Other Risk Factors

91 Habitat Loss

91 Locally Applied Pesticides

94 Mining

95 Research Activity

97 Restoration Activities

98 Roads

100 UV-B Radiation

103 Vegetation and Fuels Management

104 Water Development and Diversion

105 References

113 Appendix 6: Cascades Frog Working Group

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Cascades Frog Conservation Assessment

Introduction

Purpose 

Since about 1970, Cascades frog numbers and populations have undergone precipitous declines in California (Fellers and Drost 1993, Fellers et al. 2008, Jennings 

1996, Jennings and Hayes 1994 ). Estimates indicate disappearance from over 95 

percent of historical localities in the Lassen region centered around Lassen Peak 

(Fellers and Drost 1993, Jennings and Hayes 1994), and continued surveys suggest 

that Cascades frogs are still declining in this region (Fellers et al. 2008, Pope et al. 

2011). Many factors, individually and likely in combination, have contributed to 

the species’ decline. Nonnative fishes and pathogens (especially Batrachochytrium 

dendrobatidis [Bd]) have been found to have widespread impacts, and several other 

factors including pesticides, livestock grazing, recreational activities, increased 

occurrences of drought, and ultraviolet radiation have been identified as potential 

contributing factors affecting this species and its habitats.

The Sierra Nevada Forest Plan Amendment (SNFPA) Record of Decision 

(ROD) commits the USDA Forest Service to complete a conservation assessment 

for the Cascades frog in cooperation with other federal agencies, state agencies, 

universities, and research scientists (USDA Forest Service 2001b). The conservation assessment is envisioned to be the first of a three-phase process that also 

includes a conservation strategy and a conservation agreement. The conservation 

assessment synthesizes available conservation- or management-pertinent information on life history, habitat associations, distribution and abundance, and risk 

factors providing the informational foundation for the conservation strategy. The 

conservation strategy delineates specific conservation actions, and leads to an 

agreement among various agencies and partners to implement the conservation 

strategy. Following approval of the SNFPA ROD, a working group of biologists 

from the Pacific Southwest Region of the USDA Forest Service, National Park 

Service (NPS), U.S. Fish and Wildlife Service (USFWS), California Department 

of Fish and Wildlife (CDFW), and academic and independent research scientists 

was established to develop this assessment. Each agency has specific directives 

and guidelines that direct its actions in relation to management and protection of 

native at-risk species. These directives and guides for each participating agency are 

explained in appendix 1.
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GENERAL TECHNICAL REPORT PSW-GTR-244

Geographic Scope 

Populations of Cascades frogs occur in the southern Cascade Range and Klamath 

Mountains in northern California (fig. 1), and in Oregon and Washington. The 

initial direction for this effort was to address the range of the species within the 

planning area described by the Sierra Nevada Forest Plan Amendment (USDA 

FS 2001a), which, for this species, was limited to California’s southern Cascades 

region. Because populations are believed to be near extirpation in this area, the geographic scope of the assessment was expanded to the species’ entire range within 

California (see fig. 1). Thus, the assessment was extended to include the Klamath 

Mountains in addition to the southern Cascades. Two national forests (Klamath and 

Shasta-Trinity), including four wilderness areas (Trinity Alps, Marble Mountains, 

Russian, and Castle Crags) encompass this added segment of the Cascades frog 

range in California. California populations face similar risks and occur primarily 

on federal lands with similar management directives. However, populations at the 

southern extent of the species’ range in the southern Cascades have become so 

reduced relative to the Klamath Mountains that geographically targeted conservation measures are appropriate. Cascades frog populations in the latter region may 

provide important information about habitat requirements, population structure, and 

conservation options that may be critical for maintaining populations throughout 

the historical range.

Document Organization

The three main sections of this document address the ecology and status of the 

Cascades frog and an assessment of the factors that might present a risk to the 

Cascades frog’s continued survival in California. The ecology section details 

the species’ ecological requirements, an understanding of which is necessary to 

develop a successful strategy to recover this species. The status section provides 

information on distribution and abundance within the species’ California range, 

plus discussion on how these populations have changed pre- and post-1980. 

Appendix 3 provides more geographical detail on the changes pre- and post-1980 

by subdividing the discussion for each of the national forests and Lassen Volcanic 

National Park (LVNP). The risk factor section identifies, describes, and evaluates 

the relative importance of key risk factors for the species. Risk factors include 

management activities (e.g., fish introduction, pesticide use, fire suppression) and 

large-scale factors (e.g., disease, climate change) that may have played a role in 

current Cascades frog trends in California, and are important considerations in 

future population recovery. These sections provide the conceptual and scientific 

foundation for the subsequent conservation strategy.
3

Cascades Frog Conservation Assessment

Figure 1—Recent and historical distribution of the Cascades frog (Rana cascadae) in California. This map contains 

known localities up to 2011. The sites in Trinity and Siskiyou Counties are in the Klamath Mountains and the sites in 

Shasta, Tehama, Butte, and Plumas Counties are in the southern Cascade Range. The southernmost grouping of points 

around Lassen Volcanic National Park is considered the Lassen region. 
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GENERAL TECHNICAL REPORT PSW-GTR-244

Ecology

Systematics and Taxonomy

The Cascades frog is a member of the true frog family, Ranidae, and is a morphologically (Dunlap 1955, Slater 1939) and genetically (Case 1976, 1978; Green 1986a, 

1986b) distinct species. Published data on genetic variation within R. cascadae

(Case 1976, 1978; Monsen and Blouin 2003, 2004) indicate some potentially 

significant within-species variation. Recent genetic analysis of the Cascades frog 

using both mitochondrial and nuclear DNA suggests that California populations differ significantly from populations in Oregon and Washington (Monsen and Blouin 

2003). The California populations differ from the Oregon/Washington populations 

by 3.2 percent at the mtDNA loci studied by Monsen and Blouin (2003), which they 

concluded represents two distinct population segments. As currently recognized, 

however, the Cascades frog is distributed along the length of the Cascades Mountain axis from northern California to northern Washington with a disjunct population on the Olympic Peninsula in Washington (Blaustein et al. 1995, Jennings and 

Hayes 1994, Pearl and Adams 2005, Stebbins 2003). In California, the frog occurs 

in mountainous areas from the Klamath-Trinity region (fig. 2) and the Cascades 

Mountain axis in the vicinity of Mount Shasta southward to the headwater tributaries of the Feather River (fig. 3), and has a known altitudinal range from 230 to 

approximately 2500 m (Jennings and Hayes 1994). 

Figure 2—Diamond Lake in the Trinity Alps Wilderness, Klamath Mountains.

Karen Pope
5

Cascades Frog Conservation Assessment

Habitat Requirements

Cascades frogs can be found in a range of aquatic habitats, including large lakes, 

ponds, wet meadows, and flowing streams, but occurrence in these habitats varies by life stage and season (fig. 4). Reproduction occurs in shallow still-water 

habitats that are the first to become exposed by snowmelt early in the spring and 

retain water long enough for egg and tadpole development (about 3 to 4 months 

depending on water temperature). These habitats include shallow alcoves of lakes, 

ponds, potholes, flooded areas in meadows, and occasionally slow-moving streams 

or stream backwaters. In the Klamath Mountains, Cascades frogs breed primarily 

in lakes, ponds, and wet meadows that hold water throughout the summer, are free 

of fish, and contain a high percentage of silt in the near-shore habitat (Welsh et al. 

2006). In the southern Cascades, eight of the known remaining breeding sites are 

located in stream-associated wet meadow habitats and the other two are in ponds 

with adjacent stream habitats (Pope et al. 2011). Historical reports show that Cascades frogs used to breed in lake, pond, and meadow habitats in LVNP (Grinnell et 

al. 1930, Stebbins 1951a). Many of the historical records from the Lassen National 

Forest coincide with fens, which are wetlands characterized by neutral to alkaline 

water chemistry and high mineral but low nutrient content.

Figure 3—Juniper Lake in Lassen Volcanic National Park.

Karen Pope
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GENERAL TECHNICAL REPORT PSW-GTR-244

Figure 4—Habitat types used by Cascades frogs: (A) recently metamorphosed Cascades frogs in 

a shallow pond in the Trinity Alps Wilderness, (B) adult male Cascades frog and an egg mass in 

a meadow pool on the Lassen National Forest, and (C) adult Cascades frog along a stream on the 

Shasta-Trinity National Forest.

Carla Mingione Jon Stead
7

Cascades Frog Conservation Assessment

Nonbreeding active-season habitat is more variable than breeding habitat 

(Garwood 2009, Pope et al. 2011). Adults and subadults use a wide array of aquatic 

habitats during the nonbreeding season; these include ponds, meadows, lakes, and 

streams (Brown 1997, Bury and Major 1997, 2000, Garwood 2009, Pope et al. 2011). 

Adults often use sites with open, sunny areas, often along the shorelines, which 

may be favorable because they provide basking and foraging opportunities (Fellers 

and Drost 1993). They also use floating logs or emerged rocks that provide basking 

and foraging opportunities while also providing an aquatic escape from predators. 

Juveniles are often found in similar habitats as adults (Pope et al. 2011). Stream 

use increases dramatically during summer months; in Deep Creek Basin in the 

Trinity Alps Wilderness, Garwood (2009) found adult females in streams about 40 

percent of the time and males about 20 percent of the time. Pope et al. (2011) found 

similar habitat use in the southern Cascades with larger frogs moving to flowing 

water habitats in the summer. Larger frogs can negotiate stream currents better than 

smaller frogs and likely gain abundant food resources and refuge sites.

Based on the frog’s movement patterns and distribution in early spring and late 

fall, overwintering habitat is almost as restrictive as breeding habitat (Garwood 

2009). In late fall, Garwood (2009) found frogs congregated at spring-fed ponds 

and lakes, and perennially flowing streams (although the frogs may have been using 

Figure 4—Continued. 

Monty Larson
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GENERAL TECHNICAL REPORT PSW-GTR-244

the streams as movement corridors to lentic overwintering habitats). The frogs are 

suspected of overwintering in aquatic sites that do not freeze solid (e.g., springs 

and deep lakes), similar to the mountain yellow-legged frog (Rana muscosa and R. 

sierrae) in the Sierra Nevada (Bradford 1983). Briggs (1987) found Cascades frogs 

overwintering in deep, loose silt at the bottom of a pond and in surrounding springwater saturated ground at Bear Spring Pond in Oregon.

Life History

Cascades frogs breed shortly after spring snowmelt (Briggs 1987, Garwood and 

Welsh 2007, Nussbaum et al. 1983, Olson 1988). Males appear first and form 

chorusing groups when melting ice and snow creates open water along the edges 

of water bodies (Briggs 1987, Garwood and Welsh 2007). Males do not defend 

territories, but male-male interactions may produce a regular spacing pattern in the 

breeding habitat (Olson 1988). Females are highly cryptic during breeding, swimming primarily underwater to breeding sites and leaving the site as soon as breeding is complete (Olson 1992).

Oviposition occurs between April and July, depending on seasonal conditions 

and elevation. Egg masses are often laid communally in pond and lake habitats 

(Garwood 2009, Garwood et al. 2007, Pope and Larson 2010). In the southern 

Cascades, more than 90 percent of the egg masses found in pond habitats were 

clumped, whereas more than 80 percent of the egg masses found in meadow pools 

were singletons (Pope and Larson 2010). A small percentage of egg masses in the 

southern portion of the southern Cascades have been found in small, low-gradient 

channels with slow flow (Pope 2008b). Egg masses are usually found at the surface 

in shallow water with emergent vegetation, but have been found in deep water (2 m) 

and free-floating in lakes (Garwood et al. 2007, Pope and Larson 2010). They can 

also be attached to emergent vegetation, wood, boulders, or the shoreline (Pope and 

Larson 2010). 

Length of embryonic development appears highly temperature-dependent as 

shown by both laboratory and field studies (Blouin and Brown 2000, Olson 1988, 

Sype 1975), but generally takes about 3 weeks in both the Klamath Mountains and 

southern Cascades (Garwood and Larson, n.d.). Consistently cold water conditions 

(2 to 10 °C), such as found in some springs, may delay hatching by a few days 

but eggs generally are laid in shallow open-water locations where the sun quickly 

warms the water surrounding the egg mass to temperatures above 13 °C that are 

more optimal for development. In the high-elevation habitats in California, larvae 

usually hatch in early to mid-July and metamorphose into frogs in September. However, some larvae do not successfully complete metamorphosis prior to the onset 
9

Cascades Frog Conservation Assessment

of winter (Garwood and Welsh 2007). No larvae have been observed to survive the 

winter (Garwood 2009). In the southern Cascades, larvae usually hatch in June and 

metamorphose in late August (Pope and Larson 2010). 

Tadpoles can tolerate a wide range of water temperatures. They tend to aggregate in the warmest areas of ponds and lakes during the day (Brattstrom 1963; 

Pope, n.d.; Wollmuth et al. 1987); this generally consists of wind-protected, gently 

sloping, shallow near-shore areas (O’Hara 1981, Olson 1992, Welsh et al. 2006) 

where temperatures can warm to more than 20 °C on a sunny afternoon but drop to 

near freezing at night. In shallow meadow breeding pools in the southern Cascades, 

daytime water temperatures have been measured at 38 °C. This seems to be above 

their temperature tolerance as the tadpoles appeared highly stressed; they moved 

between cooler temperatures in the silt substrate and the surface where they gulped 

air (Pope and Larson, n.d.). 

Tadpoles and metamorphs are known to discriminate between kin and nonkin 

(kin recognition) and preferentially associate with kin in laboratory and field experiments (Blaustein and O’Hara 1982a, 1982b, 1987; Blaustein et al. 1984; O’Hara and 

Blaustein 1981, 1985). Kin association can influence growth, predator avoidance, 

and other factors (Hokit and Blaustein 1994, 1995, 1997). Tadpoles are sensitive to 

visual and physical disturbances of the water and have an explosive escape response 

when startled (Hews and Blaustein 1985). Tadpoles occasionally become stranded 

at sites with short hydroperiods and desiccate as the water evaporates (Garwood 

2009, O’Hara 1981, Pope et al. 2011, Sype 1975). Newly metamorphosed frogs tend 

to stay near their natal ponds (Garwood 2009).

Cascades frogs are relatively long-lived and late maturing. A skeletochronology 

study conducted in the Klamath Mountains found that frogs can live more than 10 

years (Garwood, n.d.). Ages at maturity are between 3 and 4 years for males and 4 

to 5 years for females based on mark-recapture studies in the Klamath Mountains 

and southern Cascades (Garwood and Larson, n.d.). Adult Cascades frogs display 

a high degree of site fidelity (Blaustein and Olson 1992, Briggs and Storm 1970, 

Garwood 2009, Olson 1992). At Deep Creek Basin in the Trinity Alps Wilderness, 

Garwood (2009) found that adults commonly move among unique breeding, feeding, and overwintering habitats following a consistent annual pattern (see “Movement” section). At other sites where breeding, feeding, and overwintering habitat 

occur at the same site, frogs may remain at the same water body throughout the 

year (Pope 2008a).
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GENERAL TECHNICAL REPORT PSW-GTR-244

Population Dynamics

Populations of Cascades frogs can reach high densities because the species is not 

territorial and there seems to be ample algal and detrital food for larvae and terrestrially and aquatically derived insects for adults (Briggs and Storm 1970, Joseph 

et al. 2011, Larson 2012). As is true for many long-lived species, annual survival 

rates of adult Cascades frogs is fairly high. In a 16-lake population dynamics study 

conducted in the Trinity Alps Wilderness, annual survival of adult frogs ranged 

from 68 to 93 percent with significantly higher survival rates when introduced fish 

were removed from the system (Pope 2008a). Annual survival estimates calculated 

for four sites in the southern Cascades varied strongly by life stage and site. Adult 

survival ranged from >70 percent at Carter Meadow and Nelson Creek to only 44 

percent at Old Cow Creek (Pope et al. 2011). Survival of metamorphs and young-ofprevious-year (YOPY) was low at all sites (<1 and <20 percent, respectively). These 

survival values are likely being affected by the amphibian disease, chytridiomycosis, which has been found to be widespread in both the Klamath Mountains (PioviaScott et al. 2011) and southern Cascades (Pope et al. 2011). New evidence suggests 

that the effects of the disease can differ by site and year depending on its prevalence 

and density at a site (Pope et al. 2011) and its virulence (Piovia-Scott et al. 2013). 

Montane amphibians probably exhibit metapopulation structure (Bradford 1991, 

Brown 1997, Olson 1992). Individual local populations may go extinct because of 

a variety of chance events (e.g., severe winters, prolonged drought), but they are 

eventually recolonized by animals from other nearby populations (Hanski and Gilpin 1991, Levins 1970). In the Klamath region, Welsh et al. (2006) found a positive 

association between site occupancy and the proximity of additional suitable habitats. Isolated sites were less likely to support populations of frogs. In a study examining recolonization patterns after the eruption of Mount St. Helens in Washington, 

frogs quickly recolonized a barren posteruption lake 2.5 km from the nearest extant 

population (C. Crisafulli, pers. comm., in Brown 1997). In contrast, one extirpated 

R. cascadae site in Oregon was reported to have taken 12 years to be recolonized 

despite the presence of a R. cascadae population within 2 km (Blaustein et al. 

1994). In a detailed movement study, Garwood (2009) found 19 of his study animals 

(1 percent) dispersed outside of the study basin, travelling distances over 1 km 

and across ridgelines. These results suggest that gene flow is sufficient to maintain 

genetic diversity among subsets of larger metapopulations (Garwood 2009, Mills 

and Allendorf 1996). Although metapopulation structure may be maintained among 

neighboring basins, genetic data suggest that local populations of Cascades frog 

have high degrees of isolation at relatively small geographic scales (Monsen and 

Blouin 2004). Specifically, the authors determined that the genetic “neighborhood,” 
11

Cascades Frog Conservation Assessment

the distance over which the exchange of individuals between “populations” drops 

sharply, is roughly 10 km. These data generally agree with movement information 

for the Cascades frog and other ranid frogs, which suggest maximum movement 

scales of a few kilometers (Garwood 2009, Smith and Green 2005, see “Movement” 

below). In many regions of California (southern Cascades, Russian Wilderness, and 

Castle Crags), populations of Cascades frogs seem to be small isolated remnants 

(see “Status” section), so are more vulnerable to chance events that could result in 

extirpation, with low likelihood of later recolonization. 

Movement

Movement ecology was studied in detail and at multiple scales from 2003 to 2008 

in a large, complex basin in the Trinity Alps Wilderness of California (Garwood 

2009). Garwood found that movement patterns varied strongly by life stage. Newly 

metamorphosed animals stayed close to natal rearing habitats while juvenile frogs 

moved frequently among habitat patches without evidence of site fidelity (Garwood 

2009). In contrast, adult frogs often migrate seasonally among habitat patches for 

breeding, feeding, and overwintering, and express annual site fidelity to specific 

patches (Garwood and Welsh 2007). Pope and Larson (2010) found similar results 

in the southern Cascades with many adult frogs returning to the breeding, feeding, 

and overwintering habitats year after year, whereas seasonal distribution patterns of 

juveniles were much less predictable. 

Distances traveled between habitat patches can range from very short to over 

1 km from wintering sites to breeding ponds. Garwood and Welsh (2007) found 

that 71 of 1,669 frogs moved over 1 km. Intrabasin dispersal movements were 

documented 19 times with minimum distances traveled averaging 1.2 km 

(Garwood 2009). These dispersals were primarily made by juvenile frogs prior 

to their first breeding season (Garwood 2009). Potential gene flow from these 

dispersers via “leapfrogging” spanned an air distance of 4 km, which included 

four neighboring basins. The maximum vertical gain from a dispersal event was 

308 m (Garwood 2009). 

Feeding

Postmetamorphic Cascades frogs are generalist predators, primarily of aquatically 

and terrestrially derived insects and spiders (Joseph et al. 2011, Larson 2012). At 

Deep Creek Basin in the Trinity Alps Wilderness, Larson (2012) identified insects 

from 102 different families in the stomach contents of frogs. Only rarely were 

larval aquatic insects found in stomach contents, suggesting that most foraging is 

terrestrial or on the surface of the water (Larson 2012). Joseph et al. (2011) found 
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GENERAL TECHNICAL REPORT PSW-GTR-244

that the diet of Cascades frogs varied in lakes with fish versus those without; in 

lakes with fish, the frogs ate more terrestrial insects such as grasshoppers, and 

in lakes without fish they ate more adult aquatic insects such as caddisflies. The 

authors concluded that introduced trout may influence native amphibians indirectly 

through competition for food resources. Although their diet primarily consists 

of invertebrates, Cascades frogs occasionally prey upon larvae and recently 

metamorphosed Pacific chorus frogs and conspecifics.

Mortality

Cascades frogs are susceptible to a variety of stochastic environmental events. 

Breeding occurs soon after thaw, so eggs are vulnerable to late freezes (Pope and 

Larson 2010). In some ephemeral habitats that dry out during the summer, larvae 

may desiccate before metamorphosis (Pope et al. 2011). Survival of all life stages 

may also be affected by unusually long winters with heavy snowfall if the frogs 

do not have enough energy stored to last until the thaw. In a study conducted in 

the central Oregon Cascades, Briggs and Storm (1970) estimated a relatively high 

mortality rate for adults ( about 45 percent) and suggested that most adult mortality 

occurred during overwintering. 

During the summer active season, Cascades frogs face a wide range of predators including nonnative fish (Simons 1998, Welsh et al. 2006), garter snakes 

(Garwood and Welsh 2007, Pope et al. 2008); birds such as American dippers 

(Garwood and Welsh 2007), American robins (Briggs and Storm 1970) and Clark’s 

nutcrackers (Garwood 2006); mammals such as river otters (ARRIS 2013); other 

amphibians including rough-skinned newts (Peterson and Blaustein 1991); aquatic 

insects including diving beetles, giant water bugs, and dragonfly naiads (Garwood 

and Wheeler 2007, Nauman and Dettlaff 1999, Peterson and Blaustein 1991); and 

predatory leeches (Stead and Pope 2010). 

In the southern Cascades, predatory leeches have been proposed as a potential 

predator of eggs and larvae of Cascades frogs (Stead and Pope 2010). The authors 

observed the predatory leech Haemopis marmorata probing or tearing at eggs on 

several occasions in two meadows, and found that leeches were observed 10 times 

more frequently in plots centered on egg masses than in similar plots without egg 

masses. Six species of leeches were identified from the region, five of which may be 

predators of amphibian eggs and hatchlings (Stead and Pope 2010).

Frogs are also susceptible to diseases. Batrachochytrium dendrobatidis (Bd) 

is now widely distributed throughout the range of Cascades frogs in California 

(Piovia-Scott et al. 2011, Pope et al. 2011) (see “Disease Risk Factor” section). 

Batrachochytrium dendrobatidis is a fungal pathogen that has been implicated in 

die-offs and extinctions of amphibians worldwide (Skerratt et al. 2007). From more 
13

Cascades Frog Conservation Assessment

than 100 sites sampled throughout the Klamath Mountains, Bd was detected at 64 

percent of them and was commonly found associated with Cascades frogs (PioviaScott et al. 2011). 

Mass mortality of developing Cascades frog eggs in Oregon has been documented and linked to the pathogenic water mold, Saprolegnia ferax (Blaustein et al. 

1994). The communal pattern of oviposition makes Cascades frogs more susceptible 

to mortality from this fungus (Kiesecker and Blaustein 1997). In California, no 

major mortality events have been observed resulting from Saprolegnia ferax despite 

numerous egg mass surveys (Pope n.d.).

Status

Comparisons between recent (1980 to 2011) and historical (prior to 1980) distributions and abundances of Cascades frogs are provided in the following sections. 

Documentation from museum collections is listed according to the standard 

symbolic codes for each institution (app. 2) and the pertinent specimen number(s). 

Appendix 3 provides distribution and abundance information for individual national 

forests and national parks.

In California, Cascades frogs were historically distributed from the ShastaTrinity region to the Modoc Plateau and extended southward through the Lassen 

National Forest (NF) to the upper Feather River (Jennings and Hayes 1994) (fig. 1). 

Traditionally, the geographic range in California has been considered two disjunct 

regions, the southern Cascades and the Klamath Mountains, although the degree 

of separation is unclear. Regardless, because the regions differ physiographically 

(Norris and Webb 1990) and have different levels of decline of Cascades frogs, the 

species’ distribution and abundance are discussed separately for each region. The 

southern Cascades represent roughly 40 percent of the species’ California range and 

the Klamath Mountains represent about 60 percent of that range. 

Southern Cascades

Pre-1980—

No systematic surveys were conducted prior to 1980, but Cascades frogs appear 

to have been fairly widespread. They were present in and around LVNP and in 

the northwestern and southern portions of Lassen NF; an area that encompasses 

portions of the Pit River and most of the headwater tributaries of Hat, Deer, Mill, 

Battle, and Butte creeks, and upper North Fork and West Branch Feather River (see 

app. 3 for more details).

Prior to 1980, more than 250 animals from at least 39 localities were collected 

in Lassen NF or its vicinity and more than 130 Cascades frogs were collected from 

at least 16 different localities in LVNP (app. 3). Records extend back to the 1920s in 
14

GENERAL TECHNICAL REPORT PSW-GTR-244

this region, when survey parties associated with the Museum of Vertebrate Zoology 

began collecting data across an elevational transect at the latitude of the recently 

established LVNP (Grinnell et al. 1930). Although data are limited, no evidence of 

declines was observed until the 1970s.

Few data exist on the historical abundance of Cascades frogs in the southern 

Cascades, but scattered data from LVNP and Lassen NF suggest that the species 

was historically abundant, at least in some areas (Fellers and Drost 1993; see app. 

3). In their 1925 visit to Emerald Lake, Grinnell et al. (1930) implied that the species 

was abundant, recording “one frog for nearly every meter around the lake.” Borrel 

(1924) also described Cascades frogs as abundant at Lake Helen. 

Post-1980— 

Declines in the southern Cascades were first observed in the 1990s when surveys 

of historical sites in LVNP found few or no frogs (Fellers and Drost 1993, Jennings 

and Hayes 1994). Based on data accumulated over the interval 1988–1992, Jennings 

and Hayes (1994) estimated that the species had disappeared from about 99 percent of its historical range in the Lassen region (LVNP and south) of the southern 

Cascades (see also Jennings 1996). Davidson et al. (2002) reevaluated these data, 

and found that only 1 of 32 historical Cascades frog sites (defined as pre-1990) was 

still occupied in the early 1990s.

Since that time, extensive surveys have been conducted for Cascades frogs (app. 

4) and, as declines became increasingly apparent, an increased effort was made to 

detect individuals across the historical range (Fellers et al. 2008). Cascades frogs 

have been recorded from 12 sites since 1993, all with low counts of frogs. A 4-year 

(2008–2011) repeated capture-mark-recapture study conducted on five populations 

found that estimated population sizes ranged from five frogs at Colby Creek (the 

southern-most known extant population) to 150 frogs at Carter Meadow, Lassen 

NF (Pope et al. 2011). Although population sizes at some sites were larger than 

previously thought (Fellers et al. 2008), they were found to be slowly declining 

over the course of the study. The most current data on the status of the remaining 

populations indicate that about half are near extirpation and the rest are at risk of 

continued declines. No remaining populations have been found in LVNP since 

2008 despite multiple resurveys of the most recent known locations and additional 

extensive surveys of appropriate meadow habitat (Pope and Larson, n.d.). However, 

three populations have been discovered since 2010 on private lands south of the 

park adjacent to Lassen NF lands (Pope and Larson, n.d.). In addition, three populations have been found north of the park since 2006 (Pope and Larson, n.d.).
15

Cascades Frog Conservation Assessment

Klamath Mountains

Pre-1980—

Records for the Klamath Mountains extend back to the 1890s, when Rutter and 

Chamberlain collected two Cascades frogs from the Shasta-Trinity NF. By the close 

of the 1970s, the species had been recorded from at least 25 different localities from 

the vicinity of this forest (see app. 2). On the Klamath NF, only four verifiable historical records exist. Available data provide no evidence for or against the decline 

of Cascades frogs on the Shasta-Trinity NF through the 1970s. Data on population 

abundances are unavailable prior to 1980.

Post-1980—

Up to the mid-1990s, Cascades frogs seemed common in appropriate habitat in the 

Klamath Mountains (Jennings and Hayes 1994). Davidson et al. (2002) estimated 

that 20 (77 percent) of 26 historical Cascades frog sites (defined as pre-1990) 

associated with the Shasta-Trinity NF were still occupied in the early 1990s. From 

1999 to 2002, systematic surveys in wilderness areas in the Klamath Mountains 

were conducted. Abundance data as well as occupancy data were collected for all 

mapped lakes, ponds, and wet meadows in the Trinity Alps Wilderness, Russian 

Wilderness, Marble Mountains Wilderness, Siskiyou Wilderness, Red Buttes Wilderness, Castle Crags Wilderness, and parts of the Shasta-Trinity and Klamath NFs 

outside of wilderness areas (Welsh and Pope 2004, Welsh et al. 2006). Of 380 water 

bodies surveyed in the Trinity Alps Wilderness, 58.7 percent (n = 223) were found 

to support at least one individual of any life stage of Cascades frogs (Welsh and 

Pope 2004). Evidence of reproduction (egg masses or larvae) was recorded at 30.5 

percent (n = 116) of the sites. Approximately 250 water bodies were searched in the 

Marble Mountains and 54 water bodies were searched in the Russian Wilderness. 

Cascades frogs were recorded from 32 percent of the water bodies in the Marble 

Mountains (n = 80) and at 31 percent of water bodies in the Russian Wilderness 

(n = 17). However, evidence of reproduction (egg masses or tadpoles) was found 

at even fewer sites: only 11 percent of sites in the Marble Mountains (n = 28) and 

at only 5.5 percent of sites in the Russian Wilderness (n = 3). Cascades frogs were 

also detected at three of 16 water bodies in Castle Crags Wilderness, three sites on 

the Klamath NF outside of a wilderness area and 15 sites on the Shasta-Trinity NF 

outside of a wilderness area (Welsh and Pope 2004). No Cascades frogs were found 

in the Siskiyou or Red Buttes wilderness areas (Welsh and Pope 2004). 

In 2008, 112 sites where Cascades frogs were found to be present in the 

1999–2002 surveys were resurveyed and 79 percent were found to still support 

frog populations (Piovia-Scott et al. 2011). No major declines in frog numbers were 

observed. However, at the majority of sites surveyed since 1999, abundances of 
16

GENERAL TECHNICAL REPORT PSW-GTR-244

Cascades frogs appeared low (Welsh et al. 2006). Of 695 water bodies searched 

from 1999 to 2001 in the Trinity Alps, Marble Mountains, and Russian Wildernesses, the maximum number of adults seen at a water body was 32 and the mean 

number of adults encountered at sites with Cascades frogs was four (Welsh and 

Pope 2004). Since then, eight populations in the Trinity Alps Wilderness have been 

studied for 9 years using mark-recapture techniques (Garwood, n.d.; Pope 2008a). 

While adult numbers were less than 25 in five of these populations, three populations appeared fairly robust. Two headwater lakes were estimated to support more 

than 500 adult frogs in 2010 (Pope and Piovia-Scott, 2010). Only one other site in 

the Trinity Alps is thought to have comparable numbers. 

Conclusions About Status

The Cascades frog has declined in the southern Cascades. Based on recent survey 

data, there are 11 remaining populations in this region. Population viability at these 

sites is of concern because numbers of individuals are low and population growth 

trajectories appear to be stable or declining (Pope et al. 2011). Without active 

management, some of the remaining populations may disappear within 10 years and 

the rest will be at risk of extirpation.

Cascades frogs are still widespread and fairly abundant in the Klamath Mountains. However, a prevalence of small populations and some recent extirpations 

suggest the need for caution and continued monitoring. Populations in the eastern 

portion of the region in the Castle Crags Wilderness and the Klamath NF may be 

particularly at risk owing to low population numbers and more sites where frogs 

have recently disappeared (Pope and Piovia-Scott 2010). 

Risk Factors Affecting the Status of the Species

Risk factors include environmental conditions and human activities that may negatively affect individuals, populations, or their habitat. The following are the risk 

factors (listed in alphabetical order) identified and evaluated for the Cascades frog.

• Airborne contaminants (including pesticides)

• Climate change

• Disease

• Fire suppression

• Habitat removal 

• Introduced fish and other predators

• Livestock grazing

• Locally applied pesticides

• Mining
17

Cascades Frog Conservation Assessment

• Recreational activities (including packstock)

• Research activities 

• Restoration activities

• Roads

• UV-B radiation

• Vegetation and fuels management

• Water development and diversion

Weighing the relative importance of each risk factor provides the rationale for 

the conservation actions to be developed in the conservation strategy. The following 

evaluation criteria were used to assess the importance of each risk factor relative to 

other risk factors:

• Spatial extent—Does the risk have the potential to affect a large proportion 

of the frog’s range? 

• Duration and persistence—Is the risk ongoing and expected to continue in 

the short or long term? 

• Intensity—What proportion of frogs or their habitats are affected and how 

severely?

• Ecological permanence—Does the effect on the species persist or can the 

frog recover from or adapt to the risk?

• Potential for management to reduce or reverse impacts—Can the risk be 

reduced or eliminated by management?

• Weight of the evidence—Is the risk well researched with minimal uncertainty?

Based on an assessment of the risk factors, 7 of the 16 were deemed to be of 

highest current or future concern for the persistence of the species in one or both of 

the geographic regions in California and are discussed here in alphabetical order. 

The other nine risk factors are discussed in appendix 5. The seven major risk factors for the Cascades frog are: 

• Airborne contaminants 

• Climate change

• Disease

• Fire suppression

• Introduced fish and other predators

• Livestock grazing

• Recreational activities 
18

GENERAL TECHNICAL REPORT PSW-GTR-244

The following section describes each risk factor in alphabetical order and includes 

its potential impacts (summarized in table 1) and relative importance. 

Airborne Contaminants 

The transport and deposition of pesticides from the Central Valley to the Sierra 

Nevada is well documented (Aston and Seiber 1997, Bradford et al. 2010, Datta et 

al. 1998, Hageman et al. 2006, Lenoir et al. 1999, McConnell et al. 1998) and residues of some of the pesticides have been found in the bodies of frogs in the Sierra 

Nevada (Cory et al. 1970, Fellers et al. 2004). Pesticides used in the Central Valley 

can be carried on wind currents or as part of eastbound storm systems into the 

Sierra Nevada (Aston and Seiber 1997, Cahill et al. 1996, Seiber et al. 1998, Zabik 

and Seiber 1993) and southern Cascades (Davidson 2004, Davidson et al. 2002). In 

the Central Valley, between 48 to 69 million kg (106 to 152 million lbs.) of pesticides were recorded as having been used annually from 1990 to 2002; use generally 

increased through 1998, declining somewhat thereafter (CDPR 1989–2003). 

Davidson et al. (2002) proposed that airborne pesticides could be responsible 

for the greater declines of Cascades frogs in the Lassen region of the southern Cascades compared to the Klamath Mountains. They found about four times as much 

agricultural land use upwind of sites where Cascades frogs had almost disappeared, 

compared to sites where the species was still present. However, in a followup study 

comparing pesticide residuals in water, sediment, and anuran tissue in the Klamath Mountains and southern Cascades, no significant pattern between pesticide 

concentrations and Cascades frog distribution patterns were found (Davidson et 

al. 2012). None of the 73 chemicals assessed showed a pattern of greater concentrations in the southern Cascades compared to the Klamath Mountains, and residual 

concentrations of pesticides in frog tissue and sediment were no different at sites 

where Cascades frogs have declined or remain relatively abundant (Davidson et al. 

2012). In another recent study in the Sierra Nevada that compared concentrations of 

historically and currently used pesticides with the population statuses of southern 

mountain yellow-legged frogs and Sierra Nevada yellow-legged frogs (Rana muscosa and R. sierra, respectively) over a wide area of the southern Sierra Nevada, 

the authors also found no association between either species’ population status and 

measured pesticide concentrations (Bradford et al. 2011). In addition, pesticide 

concentrations in water and amphibian tissue were consistently below concentrations found to be toxic to amphibians (Bradford et al. 2011). The authors conclude 

that chytridiomycosis is more likely responsible for the decimation of these yellowlegged frog populations in a generally west-to-east pattern across the Sierra Nevada 

(Bradford et al. 2011). 
19

Cascades Frog Conservation Assessment

Airborne 

contaminants 

Regional; variable 

owing to composition and regional loading. 

Persistence 

depends on chemical use patterns and chemical type. DDT is still found in sediment and amphibian tissue, despite being banned for use in the United States in 1972.

Likely low 

owing to low concentrations found in amphibian and soil samples; may be interactive effects.

Depending on 

chemical, nonpermanent. But airborne contamination from the Central Valley is not likely to cease.

Requires broad 

coordination among multiple regulatory agencies; may be able to reduce use of particularly harmful chemicals, if identified.

One published 

study measured residual contaminant levels in amphibians and habitats in the Klamath Mountains and Lassen region of the southern Cascades. Another study in the Sierra Nevada found similar results.

None, although 

agencies can guide the development of management and science.

Climate change Global with 

regional effects documented. 

Long term and 

persistent; changes regional hydrology.

Unknown; 

may reduce the quality of breeding sites and increase chances of severe weather events.

Essentially 

permanent given time scales addressed by management. 

Requires broad 

coordination among multiple regulatory agencies. Local and regional mitigations to improve habitat resilience can be implemented; effectiveness unknown. 

Climate change is 

well documented, but impacts are unknown. Only correlative studies link climate change to Cascades frog declines. 

Some, over the 

development and management of habitat resiliency projects.

Table 1—Summary of the evaluations of risk factors for the Cascades frog

Risk factor

Spatial extent of the risk

Duration and persistence

Intensity of the threat

Ecological permanence

Potential for managementa

Weight of evidence

Jurisdiction of participating agencies
20

GENERAL TECHNICAL REPORT PSW-GTR-244 Table 1—Summary of the evaluations of risk factors for the Cascades frog (continued) Disease Large scale. 

Amphibian chytrid has been found throughout the frog’s range.

Unknown, but 

likely persistent. 

For chytrid, 

high. New research shows low survival of infected juvenile frogs in both the Klamath Mountains and southern Cascades.

Unknown; some 

frog populations seem to persist with the disease while others are declining.

Promising. 

Studies are ongoing on the effectiveness of tools to improve chances of survival of frogs with Batrachochytrium dendrobatidis(Bd).

Chytrid detected 

throughout range. Cascades frogs are known to be susceptible to the disease. Studies are ongoing.

Some, toward 

the prevention of spread and implementation of new techniques to reduce the virulence of Bd.

Fire suppression Widespread in 

Lassen NF and areas outside LVNP and wilderness areas.

Variable. Short 

term for water removal; potentially long term for habitat alteration. 

Variable, 

potentially severe; may reduce risk of severe fires.

Impacts 

reversible, but recovery is likely to vary with local conditions.

Yes; effectiveness 

depends on implementation approach.

Unstudied relative 

to this species but studies exist on fire management and its effects on riparian and aquatic habitats. 

Yes, within the 

jurisdiction of participating agencies.

Risk factor

Spatial extent of the risk

Duration and persistence

Intensity of the threat

Ecological permanence

Potential for managementa

Weight of evidence

Jurisdiction of participating agencies
21

Cascades Frog Conservation Assessment

Table 1—Summary of the evaluations of risk factors for the Cascades frog (continued)

Introduced 

fish and other predators

Widespread 

in lake and stream habitats throughout the range.

Long term and 

persistent in many habitats; persistence depends on continued stocking in some habitats.

For fish, high 

with direct and indirect effects; less intense threats from other introduced predators (leeches, bullfrogs) but may increase in the future.

In some lakes, fish 

populations are self-sustaining unless actively removed. 

Yes, fish removals 

are effective in lentic habitats.

Strong correlative 

and direct experimental evidence showing negative effects of introduced fish. Recovery of frog populations following fish removals also has been demonstrated. 

Yes. Some fish 

stocking has been stopped in habitats containing Cascades frogs and fish removals are planned.

Livestock grazing Widespread 

except in LVNP, remote wilderness basins and, more recently, known breeding sites on the Lassen NF. Heavy grazing occurred historically throughout the range.

Potential for longterm persistence 

depends on management decisions. 

Variable 

dependent on grazing management practices, intensity and implementation of best management practices; can be severe under heavy grazing.

Level of habitat 

damage affects recovery timeline. Severe alterations to hydrology due to historical grazing practices are long term.

Can reduce 

impacts by removing cattle, creating pools for breeding, repairing incised channels and raising water tables to reduce long-term impacts. 

Grazing effects 

on habitats are relatively well studied. Lowered water tables can result in reduced egg and larval survival, especially in the meadow habitats of the southern Cascades.

Yes.

Risk factor

Spatial extent of the risk

Duration and persistence

Intensity of the threat

Ecological permanence

Potential for managementa

Weight of evidence

Jurisdiction of participating agencies
22

GENERAL TECHNICAL REPORT PSW-GTR-244 Table 1—Summary of the evaluations of risk factors for the Cascades frog (continued)

Recreational 

activities 

Widespread but 

usually dispersed regionally.

Occurs most 

in summer months when frogs are active. Recreational activities expected to continue at current or increased levels for the long term.

Low to variable 

where only lowimpact activities are permitted. May be locally high in areas where high recreation use occurs.

Impacts are 

reversible, but recovery time depends on habitat type and severity of impact.

Yes; management 

effectiveness potentially high but social considerations exist. 

Direct 

documentation anecdotal; effects primarily inferred indirectly from impacts to habitat (meadows and riparian areas).

Yes; within 

jurisdiction of participating agencies. 

a Potential for management to reverse or reduce impacts.

LVNP = Lassen Volcanic National Park;. NF = national forest; chytrid = chytridiomycosis. 

Risk factor

Spatial extent of the risk

Duration and persistence

Intensity of the threat

Ecological permanence

Potential for managementa

Weight of evidence

Jurisdiction of participating agencies
23

Cascades Frog Conservation Assessment

Regardless, Davidson et al. (2012) did find residues of currently used pesticides 

(Chlorpyrifos, Dacthal, and Endosulfan), banned organochlorines, and polycyclic 

aromatic hydrocarbons (PCBs) in several of the frog tissues collected from the 

range of the Cascades frog. However, estimated exposure concentrations were 

extremely low. For example, endosulfan and trans-nonachlor were more than four 

orders of magnitude below short-term water-exposure concentrations known to be 

acutely lethal to amphibians (Davidson et al. 2012). The authors caution that there 

is no information on what concentrations of chemicals may cause sublethal effects 

and warn about falsely rejecting the entire pesticide hypothesis based on limited 

evidence (Davidson et al. 2012). 

Pesticides can act synergistically with other stressors, which could render 

Cascades frogs more susceptible to other threats including aquatic pathogens 

such as Aeromonas bacteria or Bd (Blaustein et al. 2011, Davidson et al. 2007). 

A recent laboratory study, however, did not find any synergistic effects of Bd and 

endosulfan pesticide exposure on juvenile Cascades frogs (Reagan and Davidson 

2012). In contrast, adult Woodhouse toads (Bufo woodhousei) experimentally 

infected with Aeromonas hydrophila bacteria and exposed to sublethal levels of the 

organophosphate pesticide malathion sustained higher mortality than infected toads 

that were not similarly pesticide dosed; susceptibility to disease appeared linked to 

suppressed immune responses (Taylor et al. 1999). Another study exposed foothill 

yellow-legged frogs (Rana boylii) to the pesticide carboryl and found that exposed 

frogs experienced reduced production of skin peptides that inhibit Bd growth in 

culture, suggesting that pesticide exposure may contribute to the frog’s susceptibility to the disease (Davidson et al. 2007). Contaminants can also affect amphibians 

indirectly through food web changes (Blaustein et al. 2011). For example, low 

concentrations of malathion are not directly lethal to tadpoles but are highly lethal 

to zooplankton (Relyea and Diecks 2008).

Extent of risks related to airborne contaminants—

Currently, evidence suggests that airborne contaminants pose a low direct risk to 

Cascades frogs. However, complex interactions may exist between contaminants and 

other stressors that we are just beginning to examine. Such indirect effects would 

likely be strongest in low- to mid-elevation habitats downwind of agricultural areas. 

Conservation options related to airborne contaminants—

We first must better understand the complex interactions of airborne contaminants 

with other primary stressors to Cascades frogs. With better information, it may be 

possible to influence the use of specific harmful contaminants to reduce impacts to 

at-risk populations. 
24

GENERAL TECHNICAL REPORT PSW-GTR-244

Climate Change

Climate models estimate that temperatures in California will increase from 1.5 to 

4.5 °C by the end of the 21st century (Cayan et al. 2008). Warmer temperatures are 

predicted to result in lower annual snowpack in the mountains (Cayan et al. 2008, 

Young et al. 2009), which in turn will affect the hydroperiod of small lakes and 

ponds. Reduced hydroperiods could directly reduce the amount of available habitat 

for all life stages of Cascades frogs and could increase the instances of stranding 

mortality of eggs and tadpoles, especially in meadow habitats in the southern 

Cascades where early pool drying is already causing egg and tadpole mortality 

(Pope et al. 2011). Because introduced fish occur in the majority of lakes in the 

Klamath Mountains, there may be an interactive effect of fish and climate change, 

with fish preventing breeding by Cascades frogs in some lakes and climate change 

increasing the likelihood of drying of shallow lakes and ponds that do not support 

fish (e.g., Lacan et al. 2008). Warmer temperatures could also affect the distribution 

of pathogens and their vectors, possibly exposing frogs to new pathogens (Blaustein 

et al. 2001).

Some climate change models predict more frequent anomalous weather events 

including storms, droughts, and severe winters (Groisman et al. 2004, Parmesan et al. 2000). Severe winters may force extended overwintering, which may 

increase the chance of overwinter mortality, or may weaken frogs so that they have 

increased susceptibility to other stressors during the summer active period. In 

addition, more frequent early-season storms would increase the likelihood of egg 

masses disconnecting from attachment substrates and drifting freely, resulting in 

more failed hatchings of eggs (Garwood et al. 2007).

Extent of risks related to climate change—

The risk to Cascades frogs from climate change is potentially high, particularly 

for populations that breed in ephemeral waters. More frequent weather extremes 

could increase in the probability of extirpations. This risk is greatest in the southern 

Cascades where the species is already rare and, therefore, highly susceptible to 

environmental stochasticity.

Conservation options related to climate change—

Agencies have the opportunity to develop and implement local measures to help 

mitigate the predicted effects of climate change on habitats. For example, the 

Lassen NF has altered breeding pools to increase their annual hydroperiods and 

decrease maximum summer water temperatures (Pope et al. 2011). Efforts are 

underway to expand mitigations to additional habitats on both public and private 

lands. More research is needed to provide a better understanding of climate effects 
25

Cascades Frog Conservation Assessment

on this species including how climate-change linked habitat alteration may affect 

Cascades frog population dynamics, and how climate changes may interact with 

other risk factors such as emerging pathogens.

Disease

Although amphibians are susceptible to a wide array of diseases, one disease has 

emerged as the greatest conservation concern for amphibians worldwide (Skerratt 

et al. 2007). Chytridiomycosis, an amphibian-specific fungal disease caused by

Bd (Berger et al. 1998, Longcore et al. 1999), has been implicated in declines and 

extinctions of amphibian populations worldwide (e.g., Bosch et al. 2001, Lips et al. 

2004), and in the Sierra Nevada of California (Briggs et al. 2010, Rachowicz et al. 

2006, Vredenburg et al. 2010). It has been found in populations of Cascades frogs 

throughout the range in California (Piovia-Scott et al. 2011, Pope et al. 2011). Survival of juvenile frogs may be greatly reduced when they are infected by Bd (Garcia 

et al. 2006), but survival of adults appears minimally affected by the disease 

(Piovia-Scott et al. 2011, Pope et al. 2011). Recent lab and field research provides 

compelling evidence that an especially virulent strain of Bd was responsible for a 

significant die-off of juvenile frogs from a large population in the Klamath Mountains (Piovia-Scott et al. 2013). 

Research is ongoing to explain among-population variation in resistance to Bd 

(Knapp et al. 2011, Piovia-Scott et al. 2013). One important finding is that large 

populations have a higher likelihood of persisting with the disease (Knapp et al. 

2011), so continued efforts to increase local population sizes (e.g., by removing 

introduced trout from lakes) may also be important for improving chances of 

survival with the disease. A recently conducted 6-year study of five of the remaining populations of Cascades frogs in the Lassen area is providing a better understanding of the local temporal and spatial aspects of the disease-host dynamics and 

how they may relate to population persistence of Cascades frogs (Pope et al. 2011). 

Researchers are comparing apparent survival of frogs in relation to Bd zoospore 

loads and modeling individual variation in susceptibility. 

We currently have a poor understanding about potential interactive effects of 

different amphibian diseases. In nature, multiple infectious organisms frequently 

infect hosts, but research examining the combined effects of multiple diseases 

is lacking (Blaustein et al. 2011). In addition, interactions between Bd and other 

nondisease factors are likely but not well understood. One study assessing the 

interaction between the pesticide carbaryl and susceptibility to Bd found that 

carbaryl reduced production of amphibian skin peptides that inhibit the growth of

Bd (Davidson et al. 2007).
26

GENERAL TECHNICAL REPORT PSW-GTR-244

Other diseases may contribute to local anuran declines including Saprolegnia

fungal infections (Blaustein et al. 1994b), iridovirus and bacterial infections (Carey 

et al. 1999), and trematode infections (Johnson et al. 1999). Research conducted in 

Oregon found Saprolegnia ferax and trematodes to be potentially important sources 

of mortality of Cascades frogs. Saprolegnia ferax, a species of water mold that 

commonly infects fish, has caused die-offs of eggs in Cascades frogs and western 

toads (Bufo boreas) in Oregon (Blaustein et al. 1994b, Kiesecker and Blaustein 

1997). Kiesecker and Blaustein (1997) found that the communal egg-laying behavior 

of these species increased their risk of infection. Further, a synergistic effect may 

exist between UV-B radiation and S. ferax infection whereby together they reduce 

egg survival more than either stressor alone (Kiesecker and Blaustein 1995). Neither 

S. ferax nor massive die-offs of eggs, similar to those in Oregon, have been documented among the Cascades frog in California despite numerous egg mass surveys. 

The family Iridoviridae contains five genera, some of which infect amphibians 

(Chinchar 2002, Green et al. 2002). All iridovirus-caused mortality in the United 

States has involved larval or metamorphosing salamanders, frogs, and toads (Green 

et al. 2002). In the Western United States, iridovirus-caused mortality may be much 

more common in salamanders than in frogs and toads (Green et al. 2002). Iridoviruses may move between fish and amphibians under natural conditions (Mao et al. 

1999), raising the possibility that stocked fishes may act as vectors for iridoviruses 

(see “Introduced Fishes and Other Predators”). 

Extent of risks related to disease— 

Chytridiomycosis is present in Cascades frog populations across the range in 

California (Piovia-Scott et al. 2011, Pope et al. 2011). Based on the impact that Bd is 

having on amphibian populations worldwide, the risk of the disease to populations 

is high. However, extant populations appear to be coexisting with the pathogen 

at least in the short term. It appears that Bd is significantly reducing juvenile frog 

survival in many populations. Reduced recruitment resulting from the disease 

increases extinction risk. 

Conservation options related to disease—

Research on the extent, impact, and epidemiology of Bd for the Cascades frog is a 

high priority. Considerable recent research has been undertaken to devise methods 

to combat the impacts of Bd on amphibians in the wild. Among the most promising is application of anti-Bd bacteria such as Janthinobacterium lividum to the 

skin of frogs to help protect them from the disease (Harris et al. 2009). Testing of 

the effectiveness of augmenting the skin of Cascades frogs with disease-fighting 

bacteria is ongoing and may be able to be used as a conservation tool in the southern Cascades in the near future. Additionally antifungal drugs such as itraconazaole 
27

Cascades Frog Conservation Assessment

and terbinafine hydrochloride have been used to treat diseased frogs with some success (Berger et al. 2010, Bowerman et al. 2010). Other mitigation efforts to increase 

population sizes of Cascades frogs may also help reduce their susceptibility to Bd 

because evidence suggests that large populations have a better chance of persisting 

with the disease compared to small populations (Knapp et al. 2011).

Fire Suppression

Issues related to fire management are diverse (see “Vegetation and Fuels Management,” app. 5), but this section focuses specifically on fire-suppression activities 

that may affect Cascades frogs. The effects of fire suppression activities on native 

flora and fauna, and in particular amphibians, have not been studied well, so most 

evidence is anecdotal (Pilliod et al. 2003). Regardless, impacts have the potential to 

be strong only in the southern Cascades because in the Klamath Mountains the frog 

primarily occurs within subalpine aquatic habitats with long fire return intervals 

and in wilderness areas where fire suppression activities are less than they are 

closer to the wildland-urban interface. Fire suppression activities do occur regularly 

in the frog’s lower elevation forested habitats outside of wilderness areas, and 

potential direct impacts include water drafting from ponds and streams, application 

of fire retardant, and construction of fuel breaks. These activities could also produce changes in aquatic and riparian habitats via sedimentation changes, alteration 

in down woody debris, and reduction (producing both positive and negative effects) 

in amounts of vegetation associated with the habitat. Only anecdotal evidence 

is available specific to Cascades frogs for any of these activities. In June 2008, 

northern California was struck by a severe dry lightning storm that started more 

than 2,700 fires. With dry conditions and heavy fuel loads, several strikes turned 

into major fires, including those in the Marble Mountains Wilderness, Trinity Alps 

Wilderness, and Lassen NF. In the Marble Mountains and Trinity Alps, no known 

Cascades frog populations were harmed because fire suppression activities occurred 

in lower elevations and wilderness edges, and the fires only patchily burned inside 

the areas where the majority of the frog populations are found. On the Lassen NF, 

fires got close to two southern populations of Cascades frogs and a fire line was 

placed on the ridge above one meadow population. In the following 3 years, no 

noticeable damage occurred to the population or its habitat from the fire suppression activities that occurred in the area. 

Fire crews and other fire personnel attempt to minimize impacts to aquatic and 

semiaquatic species and their habitats, but inadvertent impacts can occur. During 

the severe 1987–1991 drought in California, fire suppression personnel in the Sierra 

Nevada were forced to take water from locations where aquatic amphibians and 

reptiles had often concentrated. 
28

GENERAL TECHNICAL REPORT PSW-GTR-244

The construction of fire lines or firebreaks by firefighters using hand tools or 

machinery such as bulldozers may be extensive and result in habitat changes similar 

to those associated with road and road construction (see “Roads” section). Fire line 

or firebreak restoration features, such as water bars and revegetation, may mitigate 

erosion rates and roadlike effects (Pilliod et al. 2003). Sedimentation may be the 

most detrimental roadlike effect of firelining on amphibians, as unpaved roads 

are responsible for greater increases in sediment mobility and erosion than either 

logging or fire per se (Rieman and Clayton 1997). Mechanized equipment is not a 

permitted activity in wilderness areas for fire suppression.

Application of retardant has become an important wildlife issue (Pilliod et 

al. 2003). In large wildfires, large amounts of ammonia-based fire retardants and 

surfactant-based fire-suppressant foams are dropped from air tankers and sprayed 

from fire engines to slow or stop the spread of fire. Some fire-suppressant cocktails 

are toxic or hazardous to aquatic organisms (Buhl and Hamilton 2000, Gaikowski 

et al. 1996, MacDonald et al. 1996). Concerns regarding the effects of aerial application of fire retardant on aquatic systems and threatened, endangered, or candidate 

species were addressed in the Forest Service Chief’s Record of Decision (USDA 

FS 2011). This directs tanker pilots to avoid aerial application of retardant or foam 

within 91 m of waterways. A “waterway” is considered to be any body of water 

including lakes, rivers, streams, and ponds irrespective of whether they contain 

aquatic life. This is considered binding direction, subject to qualifications and 

exceptions only as noted in the Decision Notice. However, accidental contamination 

of aquatic habitats can and has occurred, especially from aerial applications (Minshall and Brock 1991). For example, during fire-suppression activities, a direct “hit” 

of fire-retardant was dropped adjacent to the Buck’s Lake Wilderness in a small 

mountain yellow-legged frog breeding pond. No studies occurred to determine the 

effects, but there was a noticeable decline in the tadpoles within this pond (Hopkins 

2007). 

Successful forest fire suppression over the past century has resulted in dense 

forests with very high fuel loads. The Forest Service initiated a program of active 

management to reduce fuel loading in an effort to reduce the intensity and extent of 

wildfires. Catastrophic fire can produce some of the most intensive and extensive 

changes in watershed condition of any disturbance (Kattelmann 1996). In addition, 

dense forests reduce snowpack on forested slopes and take up water for transpiration, resulting in reduced water yields downslope (Kattelmann 1996). These 

indirect large-scale effects of fire suppression can affect Cascades frog habitats by 

decreasing water input, altering peak flows, and increasing sediment yield. 
29

Cascades Frog Conservation Assessment

Extent of risks related to fire suppression—

The impact of fire suppression activities on Cascades frogs is unlikely to be high 

across the majority of its range because much of the habitat occurs in wilderness and 

high-elevation areas with sparse vegetation, where fire-suppression activities are 

rarely conducted and mechanized equipment is not used (e.g., mechanized equipment generally is not allowed in wilderness areas). The risk is potentially high for 

Lassen NF populations primarily because so few populations and animals remain. 

Conservation options related to fire suppression—

Management can influence fire suppression techniques and their mode of application to minimize impacts to the Cascades frog and its habitat. Caution will be most 

important in the Lassen area and outside wilderness areas in the Klamath Mountains. Minimum-impact fire suppression techniques that avoid aquatic habitats represent the best alternative to protecting Cascades frogs and their habitat. Controlled 

burns and forest thining of over-dense managed forests near populations of frogs in 

the southern Cascades and Klamath Mountains may reduce risk of high-intensity 

fire impacts and increase water yields to frog habitats.

Introduced (Nonnative) Fish and Other Predators

Most of the range of the Cascades frog in California was historically fish-free, both 

in the southern Cascades and Klamath Mountains, although a few watersheds such 

as the Pit and Feather River drainages historically contained native salmonids that 

overlapped with the distribution of the Cascades frog. Fish stocking has been widespread throughout the mountains of California starting in the early 1900s, though 

it was discontinued in the national parks in the 1980s (Knapp 1996). Recently in 

California, stocking has ceased in any waters known to support Cascades frogs or 

mountain yellow-legged frogs (ICF Jones & Stokes 2010). Although new stocking 

has ended, many populations of stocked fish are likely self-sustaining (Armstrong 

and Knapp 2004, Pope 2008a). Currently, the majority of large (> 2 ha), deep (> 

3 m) lakes in the Klamath Mountains and southern Cascades support introduced 

populations of brook trout (Salvelinus fontinalis) or rainbow trout (Oncorhynchus 

mykiss) (Welsh et al. 2006). In addition, most perennial streams also support trout. 

The lake habitats are important for breeding and overwintering of Cascades frogs 

(Pope 2008a, Welsh et al. 2006). Surveys have shown that, where introduced trout 

are present, amphibians are often absent (Bradford 1989, Knapp 2005, Knapp and 

Matthews 2000, Welsh et al. 2006). Trout are effective predators of native ranid 

frogs (Vredenburg 2004), prevent dispersal (Bradford et al. 1993), and compete for 

food resources (Finlay and Vredenburg 2007, Joseph et al. 2011). Welsh et al. (2006) 

found that Cascades frogs were less likely to be found in water bodies with trout, 

and when they were found, numbers were depressed. When fish were removed from 
30

GENERAL TECHNICAL REPORT PSW-GTR-244

selected lakes in the Klamath Mountains, survival, recruitment, and population 

densities of Cascades frogs rapidly increased compared to fish-occupied control 

lakes (Pope 2008a). 

Although no studies have specifically addressed the impact of introduced fish in 

the southern Cascades, the contribution of fish to population declines of Cascades 

frogs in lake habitats was likely similar to that in the Klamath Mountains. In LVNP, 

fish were stocked from 1928 or before through 1965 in 41 lakes. This represents 

most of the lakes in LVNP that could support fish. In 1966, fish stocking ceased in 

14 lakes considered marginal habitat for fish, but continued in the 27 remaining previously stocked lakes through 1967. In 1968, a phase-out policy was implemented, 

resulting in the cessation of all stocking by 1980. Since cessation of stocking, fish 

have naturally extirpated from approximately 34 lakes in LVNP, but Cascades 

frog populations continued to decline (Stead et al. 2005) suggesting there are other 

stressors affecting population persistence and recovery (Fellers et al. 2008). 

Introduced fish may interact with other risk factors to cumulatively affect 

Cascades frogs. For example, fish occur in the majority of deep lakes and reduce 

the likelihood of successful breeding in these waters, and climate change increases 

the likelihood of drying of shallow lakes and ponds that do not support fish (Lacan 

et al. 2008). Therefore, fish and climate change cumulatively reduce the amount 

of suitable breeding habitats. Introduced fish may also affect the balance of native 

predators and Cascades frogs. For example, high densities of aquatic garter snakes 

can affect Cascades frog populations where fish have already reduced population 

sizes (Pope et al. 2008). 

Other predators may also affect Cascades frog populations. Stead and Pope 

(2010) propose that a proliferation of freshwater leeches (subclass Hirudinida) in 

the southern Cascades may negatively affect R. cascadae populations by preying 

on eggs and hatchlings and by contributing to the spread of pathogens and secondary parasites. 

Extent of risks related to introduced fish and other predators— 

The risks of introduced fish to Cascades frogs are high and widespread. Introduced 

fish are found over most of the California range of the species and are known to 

affect presence and densities of Cascades frogs. How important the role of stocking has been to the frog’s decline in the southern Cascades is unclear. However, 

fish introductions across most of its California range coupled with evidence of a 

fish effect in the Klamath Mountains strongly implicates fish as a contributor to 

declines. Risks associated with the interactive effects of fish and other stressors 

(e.g., climate change, disease) may also be high. 
31

Cascades Frog Conservation Assessment

Conservation options related to fish and other predators—

The stocking of fish in aquatic water bodies represents a management action over 

which participating agencies have the ability to exert both direct and indirect controls. Because stocking has occurred throughout the range of the frog, actions taken 

toward this factor have the potential to be far-reaching. Further, the rapid recovery 

of Cascades frog populations following fish removal in lentic systems indicates that 

fish removals have the potential to be effective restoration tools. Removal of fish 

from streams without the use of toxicants (e.g., rotenone) is extremely difficult, so 

lakes with natural fish barriers near their inlets and outlets are better targets than 

streams (Knapp et al. 2007).

Recent policy changes have been implemented in California regarding fish 

stocking in water bodies where species of special concern occur or may occur. 

Prompted by a 2006 lawsuit, the California Superior Court ruled in 2008 that 

the CDFW must consider the effects of hatchery operations and fish stocking on 

aquatic species of special concern when making stocking decisions (Pacific Rivers 

Council Center for Biological Diversity v. CDFG [now CDFW]. 2007. Case number 

06 CS 01451, California Superior Court of Sacramento County). A joint CDFW/

USFWS Hatchery and Stocking EIR/EIS was completed in January 2010 (ICF 

Jones and Stokes 2010). Included are measures to mitigate impacts of introduced 

fish, including not stocking any waters found to currently support Cascades frogs, 

and to develop basin-scale management plans within the range of Cascades frogs 

that include detailed objectives for both sport fisheries and protection and recovery 

of frog populations. Thus far, CDFW has stopped fish stocking in most water bodies known to support Cascades frogs, but has not begun any fish removal projects in 

the Klamath Mountains or southern Cascades. 

Livestock Grazing

Livestock grazing has been considered the most widespread influence on native 

ecosystems of western North America (Fleischner 1994, Kattlemann 1996). Seasonal grazing of sheep and cattle across the mountains of California has occurred 

since the early 1800s and continues today, except in national parks (Fleischner 

1994, Menke et al. 1996). Because of the long timeframe, we lack a clear ecological 

benchmark for determining the effects of grazing. Regardless, researchers have 

found widespread impacts, including loss of native species, changes in species composition, alteration of hydrology including lowered water tables, soil deterioration, 

degradation of fish and aquatic insect habitat, and changes in ecosystem structure 

and function (Belsky et al. 1999, Flenniken et al. 2001, Fleischner 1994, Kauffman 

and Krueger 1984). Where historical grazing has resulted in channel incision and 

lowered water tables, Cascades frogs may be affected by less available breeding 
32

GENERAL TECHNICAL REPORT PSW-GTR-244

habitat and shorter hydroperiods (Pope et al. 2011), but these long-term effects are 

difficult to quantify. Short-term direct impacts such as trampling and local water 

quality degradation are also a concern, especially in the southern Cascades where 

populations are small.

Currently, livestock grazing occurs throughout much of the range of the Cascades frog, but, at least on public lands, livestock distribution and numbers have 

been reduced dramatically compared to historical numbers. One recently discovered 

occupied Cascades frog site in Childs Meadow includes a portion of the Lassen NF 

that is currently grazed, but exclusion fencing is planned for around the breeding 

pool (Foote 2012). Occupied meadow sites on private lands both north and south of 

LVNP in the southern Cascades are still grazed. Much of the species’ range in the 

Klamath Mountains is still grazed, although portions of the wilderness areas are 

inaccessible by cattle or are not permitted for grazing. 

Minimal data exists on the impacts of livestock grazing on Cascades frogs; 

however, a research team in the Sierra Nevada recently assessed the short-term 

impacts of grazing on Yosemite toads (Anaxyrus canorus) through a 5-year exclosure experiment over nine meadows (Allen-Diaz et al. 2010, Lind et al. 2011, Roche 

et al. 2012). Within meadows, Yosemite toads breed in aquatic habitats similar 

to those of Cascades frogs, but they differ from the frogs in that after breeding 

and metamorphosis, toads leave the aquatic habitats and move into nearby upland 

habitats (Liang 2010). The researchers did not detect differences between grazed 

and ungrazed meadows in survival or abundance of Yosemite toads and saw no 

improvement in breeding habitat quality after cattle were removed from meadows 

(Lind et al. 2011, Roche et al. 2012). Two other studies assessing livestock grazing impacts on the Columbia spotted frog (Rana luteiventris) in pond habitats in 

northeastern Oregon also found no significant amphibian responses to grazing 

(Adams et al. 2009, Bull and Hayes 2000). A recent unpublished study assessing 

landscape-scale patterns of Cascades frog occurrence in relation to cattle grazing in 

wet meadow habitats of the Trinity Alps Wilderness found no relationship between 

grazing and frog occupancy (Cole and North 2010). 

Extent of risks related to livestock grazing—

Livestock grazing is still fairly widespread throughout the California range of the 

Cascades frog. However, current risks related to ongoing livestock grazing for these 

frogs in California are likely low because livestock use has not been permitted for 

more than 10 years in most breeding habitats on public lands in the Lassen region 

where sensitive frog populations occur. Livestock numbers have been reduced on 

other public lands across the range, and recent studies have not found significant 

evidence of direct effects on meadow-associated amphibian population numbers 
33

Cascades Frog Conservation Assessment

(e.g., Roche et al. 2012). However, even minimal effects such as trampling of a 

couple of adult frogs could be harmful to population persistence of some small 

populations in the southern Cascades. In addition, legacy effects to riparian and 

wet meadow habitats are likely extensive, especially in the southern Cascades and 

eastern Klamath Mountains. Although it is difficult to measure legacy effects or 

to separate them from legacy effects owing to other stressors such as logging or 

fire suppression, some montane meadows in northern California have become too 

degraded and desiccated to support appropriate habitats for Cascades frogs. However, there do remain many high-quality wet meadows on the Lassen NF and LVNP 

that support appropriate habitat for Cascades frogs but on which frogs are absent.

Conservation options related to livestock grazing—

The current altered condition of individual breeding pools within meadow habitats 

resulting from decades of livestock grazing is of concern for the conservation of the 

Cascades frog in the southern Cascades. Measures to restore hydrologic function 

to degraded meadows could benefit Cascades frogs by increasing available surface 

water habitat. Specific measures within meadows to increase the hydroperiod and 

decrease the temperature of important breeding pools could also help alleviate some 

of the legacy effects of livestock grazing. In addition, continued management of 

grazing activities will likely help minimize or eliminate potential ongoing impacts 

to this species and its habitat. Studies on the extent and scope of livestock grazing 

impacts to Cascades frog are needed. 

Recreational Activities 

The geographic range of the Cascades frog in California occurs primarily on public 

lands with about 5 percent on national park land and 62 percent on national forest 

lands (USDA FS 2001a). About half of the range on national forest lands occurs 

within designated wilderness areas where recreational use is limited to non-motorized and dispersed activities such as hiking, backpacking, fishing, and camping. 

Outside the wilderness areas and national parks, recreational activities can include 

motorized activities such as off-highway vehicle use that have the potential for 

greater impact. About 33 percent of the historical range of the Cascades frog in 

California lies on private lands with restricted public recreation (owned by timber 

companies), but some private lands with camps and lodges support heavy recreational use. 

To date, no studies have specifically examined the impacts of recreational 

activities on Cascades frogs. However, some information exists on the effects of 

selected recreational activities on the aquatic habitats also used by Cascades frogs. 

The mid to high mountain lakes, streams, ponds, and wet meadows inhabited by 

Cascades frogs receive a disproportionate amount of recreational use through trail 
34

GENERAL TECHNICAL REPORT PSW-GTR-244

networks, campsites, angling opportunities, and swimming. Establishment of trails 

and camps has been shown to disturb vegetation and soil structure, resulting in 

changes in habitat structure and microclimate (Boyle and Samson 1985, Garton 

et al. 1977, Knight and Cole 1991). Anglers often create shoreline trails for access 

to fishing spots even at remote wilderness lakes. These activities that occur near 

high-elevation meadows, ponds, lakes and streams can result in increases in pool 

sediments, modification of pool mudflats, erosion, bank trampling, and vegetation 

disturbance (Bronmark and Hansson 2002). Generally, studies have found that 

recreation impacts can happen rapidly even with light use, whereas recovery occurs 

only after lengthy periods of no use (Cole and Marion 1988). 

Studies examining the effects of recreational packstock (usually horses and 

mules used to assist travel into the backcountry) grazing on alpine meadow habitat 

have found significant changes in meadow structure resulting from horse and mule 

grazing (Cole et al. 2004; Moore et al. 2000; Olson-Rutz et al. 1996a, 1996b ). 

These changes in meadow condition may affect breeding habitat of Cascades frogs. 

Cascades frogs typically breed in small potholes in meadows or fens, and shallow 

areas of ponds and lakes (see “Habitat Requirements in Ecology” section). These 

shallows are especially prone to damage by trampling of hikers, packstock, or 

off-highway vehicles. Recreational activities may also result in direct mortality to 

Cascades frogs through trampling (see Bartelt 1998). 

Recreational activities that reduce habitat quality or frequently disturb normal 

basking and feeding behaviors of Cascades frogs can increase the glucocorticoid 

stress hormones in the frogs. Long-term physiological effects of glucocorticoid 

exposure include the suppression of growth, reproduction, and immune system 

components (Moore and Jessop 2003). Stress hormones in amphibians are also 

elevated by exposure to Bd and cause increases in metabolic rates which are energetically costly (Peterson 2012, Wack et al. 2012). The interactive effects of Bd and 

environmental stress on amphibians are currently being studied and initial results 

suggest that stressed Australian green treefrogs (Litoria caerulea) experience lower 

energy stores and lower survival when exposed to Bd compared to unstressed frogs 

(Peterson 2012).

Extent of risks related to recreational activities—

Recreational use through most of the range of the Cascades frog is light and 

dispersed, so risk associated with recreational activities is assumed to be low to 

moderate, depending on the geographic region and habitat type. In high-use areas, 

such as lakes outside of wilderness areas with road access, recreational activities 

likely have measurable impacts to frogs and habitats. Recreational impacts also act 

synergistically with other stressors to increase stress, which reduces the health and 

resilience of the frogs.
35

Cascades Frog Conservation Assessment

Conservation options related to recreational activities—

Encouraging diffuse recreation such as limiting the number of campers using lakes 

inhabited by Cascades frogs could further minimize potential impacts of recreational activities on the Cascades frogs. Recreational activities are within the direct 

purview of agencies participating in this assessment. A better understanding of how 

recreation-related impacts interact with other stressors is needed. 

Relative Importance of Risk Factors

Southern Cascades 

Because Cascades frogs have become so rare in the southern Cascades, any of 

the risk factors that affect frog survival or breeding habitat quality are important. 

Based on existing information, the current primary cause of low survival of frogs in 

the southern Cascades is Bd (Pope et al. 2011; Pope, n.d.). The degree to which Bd 

was responsible for the extirpations of Cascades frogs in LVNP is unknown, but the 

disease was likely a contributor. In addition, legacy effects from past disturbances 

such as grazing, logging, and road construction have likely contributed to shorter 

hydroperiods in breeding pools that result in poor annual survival of eggs and 

tadpoles. Other ongoing factors that contribute to habitat drying or physiological 

stress such as climate change, vegetation and fuels management, and recreation 

may have additional impacts on population persistence. Even without additional 

stressors, the species is at a risk of extirpation, therefore, active management may 

be needed to preserve and restore the distribution and genetic structure of the frogs 

in the southern Cascades. 

Klamath Mountains

In the Klamath Mountains, introduced fish and Bd may be the most important 

threats to address for conservation of the Cascades frog. Data directly address the 

effects of fish on Cascades frogs in this region, fish stocking is widespread, and 

populations of Cascades frogs recover when fish are removed from lake habitats 

(Pope 2008a). Bd occurs in Cascades frog populations throughout the Klamath 

Mountains (Piovia-Scott et al. 2011). The apparent persistence of populations 

between 1999–2002 and 2008–2009 at the majority of sites surveyed suggests that 

widespread die-offs associated with the disease did not occur during this period 

(Piovia-Scott et al. 2011). However, the majority of population sizes are relatively 

small and recent data suggest that the disease may be affecting the survival of 

juvenile frogs, which may have eventual effects on population persistence. Recreation is in the second tier of importance because effects are widespread, frequent, 

persistent, and likely to interact with other stressors. However, the level of impact or 

risk to the Cascades frog as a result of recreational activities is not known. 
36

GENERAL TECHNICAL REPORT PSW-GTR-244

Rangewide

The extent of risk for the Cascades frog from Bd is high. Bd has been detected 

across the range of the species in California, but the role it has played in population 

declines is just beginning to be understood. Based on data obtained thus far for this 

and other related species in the Sierra Nevada, Bd is a primary risk factor rangewide. Understanding how other risk factors and environmental factors interact with

Bd will be important to predict regions of greatest conservation concern.

Climate change also poses a potentially high risk given the susceptibility of 

montane amphibians to climatic extremes such as drought. Successful metamorphosis is often dependent on snowmelt into the late summer to maintain water levels 

and temperatures for egg and tadpole growth. With introduced fish in many of the 

deeper lakes in the Klamath Mountains, increased desiccation of shallower pond 

and pool habitats could affect population persistence. Desiccation of breeding pool 

habitat in the southern Cascades is already a problem that could be exacerbated by 

hydrological changes resulting from climate change.

Understanding how these risk factors affect the Cascades frog will facilitate the 

development of a conservation strategy that can effectively address all of the risk 

factors together. Synergistic effects may exist between risk factors. Not recognizing 

these may result in the failure of management actions focused on only those factors 

that management can address. For example, breeding pool enhancements at Carter 

Meadow may increase survival to metamorphosis, but if Bd kills the newly metamorphosed frogs, then the increased survival does not result in increased abundances. Additional measures to reduce mortality from Bd would also be needed for 

a positive effect on population dynamics. 

Existing Management and Research 

Current research topics being conducted by the USDA Forest Service Pacific Southwest Research Station (PSW), University of California-Davis, and San Francisco 

State University, include (1) assessing the population dynamics (survival, immigration, emigration, population size, and population growth rates) of the remaining 

Cascades frog populations in the southern Cascades; (2) assessing the populationlevel effects of Bd on Cascades frogs throughout their range; (3) assessing the 

synergistic effects of pesticides and Bd on the survival of Cascades frogs; and (4) 

assessing the effects of cattle grazing on Cascades frog breeding success.

Conservation Options

Because Cascades frog populations are near depletion in the southern Cascades, 

more extensive measures may be appropriate there. Other measures provide more 

general guidelines to be applied throughout the California range of the species.
37

Cascades Frog Conservation Assessment

Within California in General

Provide for the ecological requirements and population viability of 

Cascades frogs—

• Increase the amount of fishless aquatic habitat by continuing CDFW’s plan 

to not stock waters supporting Cascades frogs and by restoring selected 

aquatic habitats to a fishless condition.

• Determine population-level effects of Bd across the range and devise 

research techniques to reduce those effects.

• Institute a long-term, rangewide monitoring program in California. 

• Determine effects of existing levels of management for vegetation and fuels 

management and livestock grazing. 

Develop strategies for addressing high-priority information gaps—

• Determine the effectiveness of different active management approaches—

such as modifying breeding pools, removing livestock from breeding habitats, thinning riparian vegetation in occupied streams to improve basking 

habitat, or thinning lodgepole pines (Pinus contorta Douglas ex Louden) 

adjacent to breeding pools in meadow habitats in the southern Cascades—

by testing these methods and monitoring populations pre- and post-treatment. 

• Investigate the genetic structure of Cascades frogs within California 

and compare to populations in Oregon and Washington to determine if 

the Cascades frog in California or in the southern Cascades is a Distinct 

Population Segment.

Southern Cascades

• On a site-by-site basis, implement targeted restoration actions (e.g., deepen 

and extend meadow breeding pool habitat, thin riparian vegetation) and 

monitor their effects on populations.

• Employ research techniques, such as bioaugmentation of anti-Bd skin 

microbes or the use of antifungal drugs, to reduce mortality of juvenile 

frogs caused by Bd. 

• Inform landowners and other stakeholders about the status of Cascades 

frogs, with the goal of collaborating to protect and restore populations on 

private as well as public lands.

• Investigate the feasibility and options for translocation to historically occupied habitats in LVNP.

• Monitor remaining populations.
38

GENERAL TECHNICAL REPORT PSW-GTR-244

Other conservation options may become important during conservation strategy development; these should be considered for incorporation into the conservation strategy at that time.

Acknowledgments

We give our sincere thanks to all members of the Cascades Frog Working Group 

listed in appendix 6. It has been a long process and very much a tag-team effort. 

Particular thanks go to Melanie McFarland, who willingly and promptly responded 

to multiple requests for information, text, reviews, and perspectives. Because this 

document was written in conjunction with assessments for four other frog species, 

members of the other conservation teams also contributed to this document. Robert 

Bingham, Nichole Patrick, and Matt Wacker contributed to several of the risk factor 

sections. Linda Long formatted the final draft and Jan Werren produced the map. 

Bret Harvey, Mike Adams, Grant Hokit, and Dede Olson provided reviews and 

comments on an earlier draft of this document.

English Equivalents

When you know: Multiply by: To get:

Centimeters (cm) 0.394 Inches

Kilometers(km) .621 Miles 

Meters (m) 3.28 Feet

Hectares (ha) 2.47 Acres
39

Cascades Frog Conservation Assessment

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Forest supervisors. Herbicides and ground/surface water monitoring. On file 

with: Pacific Southwest Region, 1323 Club Drive, Vallejo, CA 94592.

U.S. Department of Agriculture, Forest Service [USDA FS]. 2001c. Unpublished 

geographic information system (GIS) data. On file with: Pacific Southwest 

Region, 1323 Club Drive, Vallejo, CA 94592.

U.S. Department of Agriculture, Forest Service [USDA FS]. 2002. Unpublished 

data. On file with: Lassen National Forest, 2550 Riverside Drive, Susanville, CA 

96130.

U.S. Department of Agriculture, Forest Service [USDA FS]. 2011. Nationwide 

aerial application of fire retardant on National Forest System land. Record of 

Decision. Washington, DC: U.S. Department of Agriculture, Forest Service. 74 p.

U.S. Department of the Interior, National Park Service [USDI NPS]. 2005. 

Repave and rehabilitate a portion of the Lassen Volcanic National Park highway 

(mileposts 6.7 to 28.4) Environmental assessment. Unpublished report. Mineral, 

CA: U.S. Department of Interior, National Park Service. 
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Vindum, J.; Koo, M. 2003. Amphibians and reptiles of the Lassen National Forest: 

results of 02-CS-11050650-029. The 2002 California Academy of Sciences 

Survey. Unpublished report. On file with: U.S. Department of Agriculture, Forest 

Service, Lassen National Forest, 2550 Riverside Drive, Susanville, CA 96130.

Vos, C.C.; Chardon, J. P. 1998. Effects of habitat fragmentation and road density 

on the distribution pattern of the moor frog Rana arvalis. Journal of Applied 

Ecology. 35: 44–56. 

Vredenburg, V. 2004. Reversing introduced species effects: experimental removal 

of introduced fish leads to rapid recovery of a declining frog. Proceedings of the 

National Academy of Sciences of the United States of America. 101: 7646–7650.

Vredenburg, V.T.; Knapp, R.A.; Tunstall, T.S.; Briggs, C.J. 2010. Dynamics 

of an emerging disease drive large-scale amphibian population extinctions. 

Proceedings of the National Academy of Sciences, USA. 107: 9689–9694.

Wack, C.L.; DuRant, S.E.; Hopkins, W.A.; Lovern, M.B.; Feldhoff, R.C.; 

Woodley, S.K. 2012. Elevated plasma corticosterone increases metabolic rate 

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Wake, D.B. 1991. Declining amphibian populations. Science. 253: 860.

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Contamination and Toxicology. 43: 378–385.

Welsh, H.H., Jr.; Ollivier, L.M. 1998. Stream amphibians as indicators of 

ecosystem stress: a case study from California’s redwoods. Ecological 

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Welsh, H.H., Jr.; Pope, K.L. 2004. Impacts of introduced fishes on the native 

amphibians of northern California wilderness areas. Final report to the 

California Department of Fish and Game. 22 p. Unpublished report. On file with: 

U.S. Department of Agriculture, Forest Service, Pacific Southwest Research 

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Welsh, H.H., Jr.; Pope, K.L.; Boiano, D. 2006. Subalpine amphibian distributions 

related to species palatability to non-native salmonids in the Klamath Mountains 

of northern California. Diversity and Distributions. 12: 298–309.
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Wojtaszek, B.F.; Staznik, B.; Chartrand, D.T.; Stephenson, G.R.; Thompson, 

D.G. 2004. Effects of Vision® herbicide on mortality, avoidance response, and 

growth of amphibian larvae in two forest wetlands. Environmental Toxicology 

and Chemistry. 23: 832–842.

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selection during development in a montane anuran species, Rana cascadae. 

Physiological Zoology. 60: 472–480.

Young, C.A.; Escobar-Arias, M.I.; Fernandes, M. [et al.]. 2009. Modeling the 

hydrology of the climate change in California’s Sierra Nevada for subwatershed 

scale adaptation. Journal of the American Water Resources Association. 45: 

1409–1423.

Zabik, J.M.; Seiber, J.N. 1993. Atmospheric transport of organophosphate 

pesticides from California’s Central Valley to the Sierra Nevada mountains. 

Journal of Environmental Quality. 22: 80–90.

Zustak, J.; Mangels, F. 2002. Personal communication. Fisheries biologist, USDA 

Forest Service, Shasta-Trinity National Forest, P.O. Box 1185, Weaverville CA 

96093; Wildlife biologist, U.S. Department of Agriculture, Forest Service, 

Shasta-Trinity National Forest, 204 West Alma, Mount Shasta, CA 96067.
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Appendix 1: Agency Direction 

USDA Forest Service

The National Forest Management Act requires the Secretary of Agriculture to 

specify guidelines for land and management plans developed to achieve goals which 

“provide for diversity of plant and animal communities” [16 USC 1604 (g)(3)(B)] as 

part of its multiple-use mandate. 

Within the range of the Cascades frog in California, management of National 

Forest System (NFS) lands fall under the direction of different land and resource 

management plans (LRMPs) and include those developed for the Lassen National 

Forest (NF), Shasta-Trinity NF, and Klamath NF. These plans were developed 

using the direction provided in the 1982 Planning Rule. This rule has since been 

superseded by the new Planning Rule released on April 9, 2012 (36 CFR Part 219). 

The transition provisions of the 2012 Rule are listed at 36 CFR 219.17. At 219.17(c), 

and state that “This part supersedes any prior planning regulation. No obligations remain from any prior planning regulation, except those that are specifically 

included in a unit’s existing plan. Existing plans will remain in effect until revised.”

Although management direction for aquatic areas differs slightly among the 

forests, all three forest plans include direction specific for management and protection of aquatic and riparian-dependent species, including habitat for the Cascades 

frog. In areas of NFS lands that are available for multiple-use management (e.g., 

most nonwilderness areas), riparian and aquatic ecosystems receive special consideration through the designation of riparian management zones. Riparian management zones are land area allocations designated around all water bodies and fluvial 

systems to ensure riparian-dependent resources receive primary emphasis and serve 

to help maintain the integrity of aquatic ecosystems. In general, only activities that 

contribute to the maintenance or restoration of riparian-driven objectives and goals 

are permitted. 

In addition to management direction contained in forest plans for the protection 

and restoration of aquatic and riparian habitats, the USDA Forest Service Pacific 

Southwest Region (Region 5) includes the Cascades frog on its Sensitive Species 

List (USDA FS 1998). The Sensitive Species List is derived from the Forest Service 

Manual (FSM 2670.5) for those plant and animal species identified by a regional 

forester for which population viability is a concern, as evidenced by:

1. Significant current or predicted downward trends in population numbers 

or density.

2. Significant current or predicted downward trends in habitat capability that 

would reduce a species’ existing distribution.
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Cascades Frog Conservation Assessment

Forest Service Manual 2672.1 states that sensitive species of native plants and 

animals must receive special management emphasis to ensure their viability and 

to preclude trends toward endangerment that would result in the need for federal 

listing. Sensitive species cannot be affected without an analysis of significance of 

adverse effects on the populations, their habitat, and on the viability of the species 

in the area covered by the forest LRMP. For all Forest Service planned, funded, 

executed, or permitted programs and activities, a review for possible effects on 

endangered, threatened, proposed, or sensitive species is conducted through a Biological Assessment (FSM 2670) and Evaluation (FSM 2672.4). Biological Assessment and Evaluation objectives are to:

1. Ensure that Forest Service actions do not contribute to loss of viability 

of any native or desired nonnative plant or animal species or contribute 

towards trends for federal listing of any species;

2. Comply with the requirements of the Endangered Species Act that actions 

of federal agencies not jeopardize federally listed species or adversely 

modify their critical habitat; and

3. Provide a process and standard by which threatened, endangered, proposed, 

and sensitive species receive full consideration in the decisionmaking process.

It should be noted that the 2670 portion of the FSM is in the process of revision 

to reflect the 2012 Planning Rule. Meanwhile, however, the affected national forests 

are guided by their individual forest LRMPs.

National Park Service

The guiding principles for managing biological resources on National Park Service 

(NPS) lands include maintenance of animal populations native to park ecosystems, 

or more specifically:

“...preserving and restoring the natural abundances, diversities, dynamics, 

distributions, habitats, and behaviors of native plant and animal populations 

and the communities and ecosystems in which they occur; restoring native 

plant and animal populations in parks when they have been extirpated 

by past human-caused actions; and minimizing human impacts on native 

plants, animals, populations, communities, and ecosystems, and the processes that sustain them” (NPS 2006).

These guiding principles also commit NPS to “work with other land managers to encourage the conservation of the populations and habitats of these species 

outside parks whenever possible,” including a commitment to “participate in local 

and regional scientific and planning efforts, identify ranges of populations of native 
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GENERAL TECHNICAL REPORT PSW-GTR-244

plants and animals, and develop cooperative strategies for maintaining or restoring 

these populations in the parks.” 

The Resource Management Plan for Lassen Volcanic National Park (LVNP) 

(NPS 1999) recognizes that Cascades frog populations have declined in the park 

and provides management language relevant to Cascades frog conservation:

1. Maintain, rehabilitate, and perpetuate water and aquatic systems to preserve their inherent natural integrity. 

2. Populations of endangered, threatened, and other species of concern are 

protected from population decline and are monitored sufficiently to detect 

significant changes in population trends. 

3. The health of Lassen region ecosystems, of which park lands are only a 

part, will be preserved as a result of cooperative work among federal, state, 

and private entities. 

4. Exotic animal species that have the potential to substantially disrupt native 

animal populations or plant communities are eliminated or controlled.

5. Extirpated animal species are, to the extent feasible, restored in accordance 

with NPS policy. 

Broad-based resurveys of historical survey localities initiated in the 1990s have 

provided insights into the status of the amphibian assemblages found in LVNP 

(Fellers and Drost 1993, Fellers et al. 2008, NPS 1999; see also “Status” section for 

LVNP). During comprehensive surveys of lentic waters in the park conducted in 

2004 (Stead et al. 2005), a few Cascades frogs were found in the vicinity of Juniper 

Lake at the south edge of the park. Resurveys in 2005 and 2006 revealed only one 

adult female frog remaining. All resurveys of this area since 2007 have been unsuccessful at finding frogs and currently no known Cascades frogs remain in LVNP 

(Pope et al. 2011). 

Fish stocking in LVNP had begun prior to the establishment of the park in 

1916 and continued until 1980. A gradual phase-out was initiated in 1968. By 

1975, stocking was restricted to four lakes (Butte, Crystal, Manzanita, and Summit Lakes) and two streams (Kings Creek and Hot Springs Creek). Fish stocking 

was discontinued at all sites within the park in 1992 (Stead et al. 2005). Because of 

the long history of stocking, it is unclear which lakes and streams were naturally 

barren, which contained fish, and what species of fish are native to each system. 

As of 2004, 16 percent (9 of 57) of the park’s lakes still supported introduced fish, 

including brook trout (Salvelinus fontinalis), rainbow trout (Oncorhynchus mykiss), 

brown trout (Salmo trutta), and Lahontan redside (Richardsonius egregious) (Stead 

et al. 2005).
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Cascades Frog Conservation Assessment

California Department of Fish and Wildlife (CDFW)

The state of California considers the Cascades frog to be a “Species of Special 

Concern” (SSC). This is an administrative designation and carries no formal legal 

status. The intent of designating SSCs is to:

• Focus attention on animals at conservation risk by the department, other 

state, local and federal governmental entities, regulators, land managers, 

planners, consulting biologists, and others; 

• Stimulate research on poorly known species; 

• Achieve conservation and recovery of these animals before they meet 

California Endangered Species Act criteria for listing as threatened or 

endangered. 

An SSC is a species, subspecies, or distinct population of an animal native 

to California that currently satisfies one or more of the following (not necessarily 

mutually exclusive) criteria: 

• Is extirpated from the state or, in the case of birds, in its primary seasonal 

or breeding role; 

• Is listed as federally, but not state, threatened or endangered; 

• Meets the state definition of threatened or endangered but has not formally 

been listed; 

• Is experiencing, or formerly experienced, serious (noncyclical) population 

declines or range retractions (not reversed) that, if continued or resumed, 

could qualify it for state threatened or endangered status; 

• Has naturally small populations exhibiting high susceptibility to risk from 

any factor(s) that, if realized, could lead to declines that would qualify it for 

state threatened or endangered status. 

More information about SSCs is available at http://www.dfg.ca.gov/wildlife/

nongame/ssc/index.html.

The California Environmental Quality Act (CEQA; California Public Resources 

Code §§ 21000-21177, 1970) requires state agencies, local governments, and special 

districts to evaluate and disclose impacts from “projects” in the state. Section 

15380 of the CEQA Guidelines clearly indicates that SSCs should be included in an 

analysis of project impacts if they can be shown to meet the criteria of sensitivity 

outlined therein. 

Sections 15063 and 15065 of the CEQA Guidelines, which address how an 

impact is identified as significant, are particularly relevant to SSCs. In assigning 

“impact significance” to populations of nonlisted species (including SSCs), analysts 

usually consider factors such as population-level effects, proportion of the taxon’s 
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GENERAL TECHNICAL REPORT PSW-GTR-244

range affected by a project, regional effects, and impacts to habitat features. More 

information about CEQA and CEQA guidelines is available at http://ceres.ca.gov/

ceqa/stat.

Sport take of Cascades frogs with a fishing license is prohibited (Title 14, Section 5.05), and scientific take is regulated by permit (Title 14, Section 650).

CDFW/USFWS Hatchery and Stocking Environmental Impact Report/

Environmental Impact Statement (EIR/EIS)—

For over a century, CDFW has been operating a statewide system of fish hatchery 

facilities that rear and subsequently release millions of fish into state waters. After 

the passage of CEQA in 1970, CDFW continued to operate its hatchery facilities 

and stocking of fish without undertaking a CEQA impact evaluation. Stocking 

activities were considered exempt from CEQA review on several grounds, including Section 15301 (j) of the state CEQA Guidelines, which specifically provides an 

exemption from CEQA review to fish stocking conducted by California Department 

of Fish and Game. Prompted by a 2006 lawsuit, the California Superior Court 

ruled in 2008 that the CDFW must consider the effects of hatchery operations and 

fish stocking on sensitive aquatic species when making stocking decisions (Pacific 

Rivers Council Center for Biological Diversity v. California Department of Fish and 

Game. 2007. Case number 06 CS 01451, California Superior Court of Sacramento 

County). A joint CDFW/U.S. Fish and Wildlife Service (USFWS) Hatchery and 

Stocking EIR/EIS was completed in January 2010 (ICF Jones & Stokes 2010). In 

this document, predation and competition impacts of introduced fish on Cascades 

frogs are acknowledged. Measures to mitigate the impact include not stocking any 

waters found to currently support Cascades frogs and to develop basin-scale management plans within the range of Cascades frogs that include detailed objectives 

for both sport fisheries and protection and recovery of populations of the frog. 

U.S. Fish and Wildlife Service

The overarching mission of the USFWS “is, working with others, to conserve, 

protect and enhance fish, wildlife, and plants and their habitats for the continuing 

benefit of the American people.” The long-term goals of the USFWS relevant to this 

assessment include:

• Recovery of threatened and endangered species

• Protection and conservation of trust species

• Habitat conservation

The recovery of threatened and endangered species, and the ecosystems on 

which they depend, fall under USFWS responsibilities under the Endangered Species Act. 
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Cascades Frog Conservation Assessment

References

Fellers, G.M.; Drost, C.A. 1993. Disappearance of the Cascades frog Rana 

cascadae at the southern end of its range, California, USA. Biological 

Conservation. 65: 177–182.

Fellers, G.M.; Pope, K.L.; Stead, J.E.; Koo, M.S.; Welsh, H.H., Jr. 2008.

Turning population trend monitoring into active conservation: Can we save 

the Cascades frog (Rana cascadae) in the Lassen region of California? 

Herpetological Conservation and Biology. 3: 28–39.

Forest Service Manual 2670. Threatened, endangered, and sensitive plants and 

animals. Washington, DC: U.S. Department of Agriculture, Forest Service.

Forest Service Manual 2670.5. Definitions. Chapter 2670—Threatened, 

endangered, and sensitive plants and animals. Washington, DC: U.S. Department 

of Agriculture, Forest Service.

Forest Service Manual 2672.4. Biological evaluations. Chapter 2672—Planning 

for management and recovery. Washington, DC: U.S. Department of Agriculture, 

Forest Service.

ICF Jones & Stokes. 2010. Hatchery and stocking program environmental impact 

report/environmental impact statement. Final. January. (ICF J&S 00264.08) 

(SCH #2008082025). Prepared for the California Department of Fish and Game 

and U.S. Fish and Wildlife Service, Sacramento, CA. 

Pope, K.L.; Larson, M.D.; Piovia-Scott, J. 2011. Status of remnant populations 

of Cascades Frogs (Rana cascadae) in the Lassen area of California. Final report 

for years 2008–2010 to the US Forest Service, Lassen National Forest, ISA 

#05-06-03. 38 p. Unpublished report. On file with: Lassen National Forest, 2550 

Riverside Drive, Susanville CA 96130.

Stead, J.E.; Welsh, H.H., Jr.; Pope, K.L. 2005. Census of amphibians and fishes 

in lentic habitats of Lassen Volcanic National Park: a report to the National Park 

Service. LVNP Study Number LAVO-00717. Unpublished report. On file with: 

USDA Forest Service, Pacific Southwest Research Station, 1700 Bayview Drive, 

Arcata, CA 95521. 77 p. 

U.S. Department of Agriculture, Forest Service [USDA FS]. 1998. Region 5 

sensitive species list. San Francisco, CA: Pacific Southwest Region.
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GENERAL TECHNICAL REPORT PSW-GTR-244

U.S. Department of the Interior, National Park Service [NPS]. 1999. Assessment 

of amphibians found in national parks in the Sierra Nevada of California. Report 

of the U.S. Department of the Interior, National Park Service, Point Reyes 

National Seashore, Point Reyes, California.

U.S. Department of the Interior, National Park Service [NPS]. 2006.

Management policies 2006. Washington, DC. 168 p. 

http://www.nps.gov/policy/mp2006.pdf.
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Appendix 2: Museum Standard Symbolic Codes

Documentation of records from museum collections in the text are listed according to 

the standard symbolic code for each institution based on Leviton et al. (1985), and its 

update (Leviton and Gibbs 1988).

Institution Symbolic code

American Museum of Natural History (New York) AMNH

California Academy of Sciences (San Francisco) CAS

California Academy of Sciences—Stanford University Collection CAS-SU

California State University Chicoa CSUC

Los Angeles County Natural History Museum LACM

Museum of Vertebrate Zoology (University of California at Berkeley) MVZ

Oregon State University Museum of Natural History OS

Texas Cooperative Wildlife Collection (Texas A&M University) TCWC

University of Michigan Museum of Zoology UMMZ

United States National Museum (Smithsonian Institution) USNM

a Institution lacks a standard symbolic code, for which one was added.
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GENERAL TECHNICAL REPORT PSW-GTR-244

Appendix 3: Status—Administrative Units

This appendix provides information on distribution and abundance for individual 

administrative units that encompass at least a portion of the recent historical range 

of the Cascades frog in California as currently understood (see “Systematics and 

Taxonomy in Ecology” section). This includes all national forest and national park 

units. Shasta-Trinity National Forest (NF) lands administered by the Lassen NF 

(e.g., the Pit River area) are discussed below, and are considered to be within the 

southern Cascades in the conservation assessment. The Shasta-Trinity NF includes 

lands in both the Klamath Mountains and southern Cascades.

Lassen National Forest

Pre-1980—

The Lassen NF is the federal unit with the most historical data on Cascades frogs 

in California, including more than 250 specimens from at least 39 localities on the 

forest or its vicinity. Cascades frogs were historically present in the western and 

much of the southern portions of the Lassen NF and vicinity that encompass the 

tributaries of Deer and Butte Creeks, the tributaries of the North Fork and West 

Branch Feather River, and Mill and Battle Creeks. Records extend back to the 

1920s, when survey parties associated with the Museum of Vertebrate Zoology 

began collecting data across an elevational transect at the latitude of the recently 

established Lassen Volcanic National Park (LVNP) (Grinnell et al. 1930). In 1923, 

Cascades frogs were collected from three localities on the forest, Butte Meadows 

(MVZ 9108) and Jonesville (MVZ 10357) in Butte County; and Chester (MVZ 

10358) in Plumas County. In 1924, four additional localities were collected; Battle 

Creek Meadows near Mineral (MVZ 9982, 10002–10003, 10010–10011, 10027) and 

Summit Creek, 3.2 km east of Mineral (MVZ 10001, 10008–10009, 10012, 10023) 

in Tehama County; and Warner Creek near Chester (CAS-SU 2083) and Willow 

Lake, northwest of Chester (MVZ 10021–10022) in Plumas County. In 1926, the 

Mineral/Battle Creek Meadows locality was recollected (CAS 218397, 218407). 

In 1928, Joseph Grinnell collected nine Cascades frogs from Martin Creek near 

Mineral (MVZ 10875–10883). At the close of the 1920s, Cascades frogs had been 

recorded from nine different localities on the Lassen NF and vicinity.

Only two localities were recorded during the 1930s. In 1934, the Warner Creek 

locality was recollected (UMMZ 77904); and an unverified Cascades frog was collected along the North Fork of the Feather River above Chester (UMMZ 77903).

Four records exist for the 1940s, all from previously unrecorded localities. 

In 1945, Thomas Rodgers collected a Cascades frog along Deer Creek 17.6 km 
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Cascades Frog Conservation Assessment

west-southwest of Lake Almanor (Plumas County). In 1946, five Cascades frogs 

were collected from Little Grizzly Valley at points 8 km (MVZ 56841–56844) and 

9.8 km (MVZ 56840) west of Longville also in Plumas County. In 1948, D. Issac 

collected one frog from the Deer Creek Guard Station (CSUC 1420). In 1949, two 

Cascades frogs were collected from Elam Creek near Deer Creek Meadows (CASSU 11061–11062). At the close of the 1940s, Cascades frogs had been recorded from 

14 different localities on the Lassen NF and vicinity.

Four records also exist for the 1950s, all from previously unrecorded localities. In 1950, a Cascades frog was collected from Kimshew Creek, 6.4 km east of 

Sterling City (MVZ 56839). In 1952, Thomas Rodgers collected 15 Cascades frogs 

in August from Coon Hollow, a tributary of the West Branch of the Feather River 

(MVZ 57338–57532); and Richard Zweifel recollected this locality, taking three 

frogs in October (MVZ 58165–58166, 59656). In 1954, Bayard Brattstrom collected 

22 Cascades frogs from the vicinity of Lee’s Camp, 8 km southeast of Drakesbad 

(LACM 13408–13427, 74422–74423). In 1959, Alan Ziegler collected 22 Cascades 

frogs from Butt Creek 12.8 km south of Chester (MVZ 69499, 69501–69521). At the 

close of the 1950s, Cascades frogs had been recorded from 19 different localities on 

the Lassen NF and vicinity.

The number of records peaked during the 1960s, when 80 Cascades frogs were 

collected from 17 different localities, 14 of which had not been previously recorded. 

In 1960, 18 Cascades frogs were recorded from southwest Deer Creek Meadows 

(CSUC 1070–1087), four frogs were collected at Jonesville (CSUC 1033–1036), 

one frog was collected 0.8 km east-northeast of the Butte Meadows store (CSUC 

1032), 11 frogs were collected from Coon Hollow (CSUC 1021–1031), three frogs 

were collected along Mill Creek, 3.2 km downstream from Highway 36 (CSUC 

1037–1039), and six frogs were collected from upper Butt Creek, 0.3 km southwest 

of [Lake] Almanor (CSUC 1040–1045). One last frog collected in 1960 was taken 

from Anderson Fork (CSUC 1020), which at 230 m (750 ft) represents the extreme 

low-elevation outlier for the species in California. In 1961, one frog was collected 

along Mill Creek just north of Highway 36 (CSUC 1058); one frog was collected 

along Mill Creek southeast of Camp Tehama (CSUC 1088); six frogs were collected along Little Grizzly Creek in Grizzly Meadows (CSUC 1091–1097); seven 

more frogs were collected from Coon Hollow (CSUC 1051–1057); one frog was 

collected along Butte Creek from each of 12.8 km (CSUC 1059), 14.5 km (CSUC 

1060), and 16.0 km (CSUC 1061) east of Jonesville; four frogs were collected from 

Yellow Creek, 1.2 km upstream from Humbug Valley (CSUC 1062–1065), and two 
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GENERAL TECHNICAL REPORT PSW-GTR-244

frogs were collected from Warner Creek (5059’) 11.3 km NW of Chester (CSUC 

#1049–1050). In 1966, four Cascades frogs were collected from Fanani Meadows 

along Butt Creek (CSUC 1066–1069); and one frog was collected 1.6 km east of the 

Coon Hollow-Skyway junction (CSUC 1545). In 1967, the Fanani Meadows locality 

was recollected and one frog was taken (UMMZ 223093). At the close of the 1960s, 

Cascades frogs had been recorded from 32 different localities on the Lassen NF and 

vicinity.

During the 1970s, 45 Cascades frogs were collected from seven different localities on the Lassen NF and vicinity; all seven of these localities had not been previously recorded. In 1971, one frog was collected from Hot Springs Creek, Plumas 

County (AMNH A86584); two frogs were collected from Warner Valley Camp 

(AMNH A86585–A86586); and three frogs were collected along Warner Creek, 

6.4 km north and 11.2 km west of Chester (AMNH A86587–A86589). In 1972, 16 

Cascades frogs were collected along Domingo Creek, a tributary of the North Fork 

of the Feather River (LACM 76638–76653); and 19 frogs were collected from Willow Lake and adjacent Willow Creek northwest of Chester (LACM 76617–76635). 

In 1974, two frogs were collected from Beauty Lake in the Caribou Wilderness by 

T. Rodgers (Jennings 1997). In 1975, two frogs were collected from along Little 

Grizzly Creek, 1.9 km west of upper Yellow Creek Road (CAS 178503–178504) and 

one frog was collected at Chester (CAS 178493). At the close of the 1970s, Cascades 

frogs had been recorded from 39 different localities on the Lassen NF and vicinity. 

No data are available for the late 1970s, but based on information through the early 

1970s, none of the limited information available suggested that Cascades frogs had 

declined on the Lassen NF.

Post-1980—

More than 200 hours of systematic surveys addressing ranid frogs conducted at the 

Butte Meadows and Jonesville historical localities in 1981 and 1983 failed to detect 

any Cascades frogs (Hayes, n.d.). No additional forestwide and vicinity survey data 

are known to be available for the 1980s.

In their summary on amphibian declines, Davidson et al. (2002) included 32 

historical Cascades frog sites (defined therein as pre-1990) associated with the 

Lassen NF based on the data from Jennings and Hayes (1994). Their summary 

indicated that 3 percent (n = 1) of these historical sites were still occupied in the 

early 1990s.

Since 1993, both informal amphibian surveys (e.g., USDA FS 1993; EA EST 

1995, 1996) and formal amphibian surveys using visual encounter survey methods 
75

Cascades Frog Conservation Assessment

(Fellers 1995, 1998; Koo et al. 2004; Vindum and Koo 2003; Welsh and Pope 

2004) have been conducted on the Lassen NF to assess the relative distribution 

and abundance of amphibian species, including the Cascades frog. Although most 

surveys were geographically widespread and included sites that had been occupied 

historically, only three sites were found to contain the Cascades frog in the Lassen 

region (excluding the LVNP portion).

Informal surveys in 1993 detected the first two LNF populations of the 

Cascades frog (USDA LNF 1993), as confirmed by Dr. Gary Fellers. Subsequent 

surveys by Fellers in 1993, 1994, 1996, and 1997 covered approximately 152 total 

sites forestwide (Fellers 1995, 1998). The only additional populations of Cascades 

frogs detected during these efforts were found on Shasta-Trinity NF lands administered by the Lassen NF (see section for Shasta-Trinity NF below); no additional 

populations were found in the bulk of the survey area in the Lassen region. In 1995, 

approximately 120 sites, representing a total of 14 miles of tributary streams to 

Deer and Mill Creeks, were surveyed, but no Cascades frogs could be confirmed 

(EA EST 1996). Surveys during 2001, covering 22 sites on the Almanor Ranger 

District, revealed no Cascades frogs (USDA LNF 2002). Surveys conducted again 

in 2002 on the Almanor Ranger District covered more than 130 acres of wet 

meadow/riparian habitat and 29 miles of stream habitat, yet no additional sites 

containing the Cascades frog were found (Vindum and Koo 2003). In 2002, formal 

visual encounter surveys of 76 lentic water bodies in the Thousand Lakes Wilderness were conducted and no Cascades frogs were found (Welsh and Pope 2004). In 

2002, 386 water bodies in the Caribou Wilderness were searched and no Cascades 

frogs were found (Welsh and Pope 2004). This area encompasses Beauty Lake, 

from which two Cascades frogs were collected during the 1970s (see “Pre-1980” 

section). In 2003, forestwide surveys covered approximately an additional 690 

acres of wet meadow/riparian habitat and 56 miles of stream habitat (Koo et. al. 

2004) and only three “sites” were found to have the Cascades frog (all were previously known populations in tributaries to the Pit River, on Shasta-Trinity NF lands 

administered by the Lassen NF, see below). 

In the Butte Creek drainage, frogs are known to have persisted from 1993 to 

2005 in Colby Creek, a small headwater tributary (USDA LNF 1993; Fellers 1995, 

1998, 2005). Frogs were not found in the drainage during follow up surveys in 2006 

(Fellers 2006) but were found again in 2007 through 2012 (Pope and Larson 2012). 

The frogs have been monitored since 2008 and the adult population is estimated to 

be between two and seven frogs (Pope and Larson 2012).
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GENERAL TECHNICAL REPORT PSW-GTR-244

In the Deer Creek drainage, frogs are known to be persisting in a small headwater tributary (Fellers 1995, 1998; Pope and Larson 2012, Pope et al. 2011; Vindum and Koo 2003). Additionally, in 2002 one adult was observed by a Lassen NF 

fisheries biologist (Roby 2002) in another upper Deer Creek tributary, Alder Creek, 

roughly 3 air miles from the extant population. A population of Cascades frogs was 

discovered in Childs Meadow on Gurnsey Creek by biologists from The Nature 

Conservancy and Lassen NF in 2010 and another population was found in Round 

Valley by a Sierra Pacific Industries biologist in 2009. A second small population 

was found in 2012 by a Collins Pine Company biologist, L. Thomasma, about 1 km 

from Round Valley and within the same drainage system (Pope and Larson 2012).

Frogs were incidentally seen at two localities within the North Fork Feather 

River drainage. In 1996, one adult was observed in Butt Creek (Brown 2000) and in 

1998, one adult was observed in Warner Creek (Smith 1998). Frogs (one adult and 

two subadults) were observed in Warner Creek during surveys in 2002 (Vindum 

and Koo 2003). A frog and tadpoles were found in Warner Meadow in 2010 (Pope 

et al. 2011).

In the Pit River drainage (Shasta-Trinity NF land administered by the Lassen 

NF), frogs have been observed in Rock Creek and neighboring Screwdriver Creek 

since 1994 (EAEST 1995). In 2002, one adult and one subadult were observed 

by Lassen NF Fisheries biologist M. McFarland in a portion of a small unnamed 

tributary of Rock Creek (McFarland 2002). This same drainage was surveyed more 

extensively in 2003 and two adults and one juvenile were observed (Koo et al. 

2004). Frogs were again found in the Rock Creek drainage, including the tributary, 

in 2009 (Pope and Larson 2010). Breeding Cascades frogs have not been found on 

Rock Creek but have been found in a pond at the headwaters of Screwdriver Creek, 

which is an adjacent tributary to the Pit River, since 1996 (Fellers 1998, Koo et. al. 

2004, Pope et al. 2011). After breeding, most frogs move into the perennial waters 

of Screwdriver Creek, up to 2 km downstream of the pond (Pope et al. 2011). They 

also are known to move into the Rock Creek drainage, so the Rock Creek and 

Screwdriver Creek frogs are likely one population. Likely, more than 40 adult frogs 

remain in this population (Pope et al. 2011).

In 2006, two meadows, Old Cow Creek and Cutter Meadow, on lands managed 

by W.M. Beaty & Associates, Inc. but near Shasta-Trinity NF land administered by 

the Lassen NF were discovered to support Cascades frogs. These populations have 

been monitored between 2008 and 2011 and likely support close to 100 frogs each 

(Pope et al. 2011).
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Cascades Frog Conservation Assessment

Lassen Volcanic National Park

Pre-1980—

Similar to Lassen NF, LVNP is relatively data rich historically with more than 130 

specimens from at least 16 different localities. LVNP was established in 1917, but 

historical records of Cascades frogs from LVNP date from the 1920s, and scattered data indicate that the species was common. In 1923, Leo Wilson collected 

20 Cascades frogs from upper Warner Creek (MVZ 9087–9106). In 1924, four 

Cascades frogs were collected from “The Falls Creek,” 3.2 km west of Black Butte 

on Mount Lassen Road (MVZ 10005, 10013–10015); one frog was collected from 

“Boomer Lake”, 4 km southwest of Black Butte (MVZ 10004), and Adrey Borrel 

and Joseph Grinnell collected seven frogs from Lake Helen at the southern base of 

Lassen Peak (MVZ 10006–10007, 10016–10020). Borrel (1924) described Cascades 

frogs as abundant at Lake Helen. In 1925, three additional frogs were collected 

from Lake Helen (MVZ 10063, 10065–10066) and two frogs were collected from 

Emerald Lake (MVZ 10062–10064). Grinnell et al. (1930) recorded “one frog for 

nearly every meter around the lake” from the 1925 visit to Emerald Lake. In 1926, 

four Cascades frogs had been collected from Manzanita Lake (MVZ 10140–10143) 

and one frog was taken from a small lake, probably Conard Lake, 6.4 km due south 

of Lassen Peak (CAS 218398). By the close of the 1920s, Cascades frogs had been 

recorded from eight different localities within LVNP, which represented at all eight 

localities surveyed within the park.

Only two localities were collected during the 1930s. Two Cascades frogs were 

taken from the creek at Manzanita Lake (CAS 218449-218450) and two frogs were 

collected from a small lake (probably Shadow Lake) 4.8 km southwest of Summit 

Lake (CAS 218391, 218448).

In the 1940s, only one locality was collected; the creek at the outflow of Manzanita Lake was recollected, four frogs were taken (MVZ 41237-41240).

During the 1950s, five localities were recorded, two of which were new. In 

1951, one frog was collected at Manzanita Creek (OS 6189); Stebbins (1951b) found 

13 or more frogs at small pools (Stebbins 1951b, in Fellers and Drost 1993). In 1952, 

four frogs were collected at Snow Pond (MVZ 57087–57088, 57707–57708), one 

frog was collected at Emerald Lake (MVZ 57083), and five frogs were collected at 

Dersch Meadows (MVZ 5708957091, 57709–57710). In 1954, one frog was collected 1.6 km east of Drakesbad (UMMZ 119019).

No records exist for the 1960s.
78

GENERAL TECHNICAL REPORT PSW-GTR-244

During the 1970s, Cascades frogs were collected from five localities within 

LVNP, three of which had not been previously recorded. In 1972, two frogs were 

taken from the north arm of Rice Creek (LACM 76636–76637). In 1973, seven 

frogs were collected from Kings Creek Meadow (MVZ 136131–136137). In 1974, 

Dersch Meadows was revisited, at which time Richard Sage collected 48 Cascades 

frogs (MVZ 148944–148988, 175949–175954). Also in 1974, two frogs were collected from Emerald Lake (MVZ 136125–136126). In 1975, one frog was collected 

along a stream 0.4 km north of Crumbaugh Lake (MVZ 136127), and 6 additional 

frogs were collected from Dersch Meadows (MVZ 136138–136143). Dersch Meadows is the most heavily collected historical locality within LVNP; 59 frogs were 

collected over the interval 1952–1975. No collections exist during the 1970s after 

1975. By the close of the 1970s, Cascades frogs had been recorded from 16 localities within LVNP, of which collections existed for 15 (Fellers and Drost 1993). At 

least through the mid-1970s, available data provide no indication that Cascades 

frogs were declining.

Post-1980—

We are not aware of any survey data from the 1980s for LVNP. 

Surveys completed in the early 1990s indicate that the Cascades frog was 

already rare in LVNP (Fellers and Drost 1993, Jennings and Hayes 1994). Surveys 

in 1990 failed to reveal Cascades frogs at 10 historical sites in LVNP (Jennings 

2006). Davidson et al. (2002) included these same six unoccupied historical 

Cascades frogs sites (defined therein as pre-1990) in their summary of amphibian 

declines. In 1991, Fellers and Drost (1993) found Cascades frogs at only 1 of 50 sites 

that included the 16 pre-1980 localities. At the only site where frogs were found, 

Crumbaugh Lake, only two frogs were detected and no evidence of breeding was 

recorded. Resurvey of this site in 1992 failed to detect frogs.

More recent surveys (1999–2002) have detected frogs at only 4 of 400 sites surveyed that included both sites within LVNP and the immediate vicinity (G. Fellers, 

pers. comm., in Pearl and Adams 2005). Moreover, population sizes appeared small 

at all four sites. As of 2002, frogs were no longer found at two of these four sites (G. 

Fellers, pers. comm., in Pearl and Adams 2005).

Extensive surveys of lentic habitats in LVNP in 2004 (Stead et al. 2005) found 

only three frogs at or near Juniper Lake. Resurveys in this area in 2006 and 2007 

found only one adult female at this site. In 2008, 2009, and 2011 no frogs were 

found (Pope et al. 2011, Pope and Larson 2012). There are no known locations with 

Cascades frogs remaining in LVNP.
79

Cascades Frog Conservation Assessment

Shasta-Trinity National Forest

Pre-1980—

Some historical data for Cascades frogs exist for the Shasta-Trinity NF. Records 

from this national forest and vicinity extend back to the 1890s, when Cloudsley 

Rutter and Frederick Chamberlain collected two Cascades frogs from lower Cliff 

Lake (USNM 38832–38833), and William Osgood collected one frog at each of 

Warmcastle Soda Springs in Squaw Creek Valley (USNM 45877) and Deer Flat 

(USNM 45878).

One additional record was obtained in the 1900s: three Cascades frogs were 

taken from Gumboot Lake (CAS 13303–13305).

Two locality records were obtained during the 1910s, when Tracy Storer collected two frogs 0.8 km west of Sisson (now Mount Shasta City; MVZ 5567–5568) 

and an additional frog 2.4 km west of Sisson (MVZ 5566).

No locality records exist for the 1920s.

Cascades frogs were recorded from five localities on the Shasta-Trinity NF 

during the 1930s. In 1932, five frogs were collected from the Dale Meadows on 

Mount Eddy (MVZ 17937–17939). In 1934, two frogs were collected at Dale Creek 

on Mount Eddy (MVZ 17942–17943); one frog was collected 0.8 km southwest of 

Weed (MVZ 17941); two frogs were collected from Crater Lake on Mount Eddy 

(MVZ 17948–17949); and two frogs were collected from Wagon Valley Creek also 

on Mount Eddy (MVZ 17946–17947). In 1939, four Cascades frogs were collected 

on Bear Creek, 8 km southeast of Bartle (CAS 218393–218396).

Three locality records exist for the 1940s. In 1941, one Cascades frog was collected at each of Castle Lake (MVZ 37088) and Baird Land, about 0.4 km northwest 

of the State Fish Hatchery in Mount Shasta City (MVZ 37128). In 1946, Thomas 

Rodgers collected two Cascades frogs along Pole Creek, 32 km northwest of Fall 

River Mills (MVZ 56845–56846).

During the 1950s, Cascades frogs were identified from four different localities, 

only one of which had been previously recorded. In 1953, at least two different collections comprising a total of seven frogs were made in the vicinity of Bartle (MVZ 

60494–60498; UMMZ 110131, 110133); two frogs were collected 3.2 km south of 

the Mount Shasta State Fish Hatchery along the South Fork of the Sacramento River 

(MVZ 60499, UMMZ 110132); and one frog was taken 6.4 km east of Bartle (MVZ 

110134). In 1959, the Dale Creek Meadows locality on Mount Eddy was recollected, 

at which time nine Cascades frogs were taken (MVZ 71062–71070). By the close of 

the 1950s, Cascades frogs had been recorded from at least 17 different localities on 

the Shasta-Trinity NF and vicinity.
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GENERAL TECHNICAL REPORT PSW-GTR-244

Cascades frogs were recorded from three localities during the 1960s. In 1960, 

four frogs were collected from Moosehead Creek (MVZ 70511–70514) and one frog 

was collected from Upper Nash Mine (CAS 91517). The latter was one of the localities summarized in the synoptic brief of Bury (1973) on Cascades frogs in the North 

Coast Range of California. In 1962, 10 Cascades frogs were collected from Colby 

Creek Meadow (MVZ 74315–74324).

During the 1970s, Cascades frogs were identified from six localities, only 

one of which had been previously recorded. In 1970, two frogs were taken 0.2 km 

northwest of Upper Canyon Creek Lake (MVZ 94817–94818). In 1971, four frogs 

were collected from Black Basin in the Deer Creek drainage (MVZ 97943-97946), 

and four additional frogs were collected from Ward Lake in the Swift Creek drainage (MVZ 97948–97951). In 1975, three Cascades frogs were taken from Colby 

Meadow (MVZ 136128–136130), and six frogs were collected along the Union 

Creek trail in the Trinity Alps Wilderness Area (MVZ 136144–136149). A sighting 

of unknown origin also exists in the Shasta-Trinity NF database for 1975 for one 

adult frog in Big Bear Lake in the Bear Creek drainage. By the close of the 1970s, 

Cascades frogs had been recorded from no fewer than 25 different localities on the 

Shasta-Trinity NF and vicinity. Available data provide no evidence for or against 

the decline of Cascades frogs on the Shasta-Trinity NF through the 1970s.

Post-1980—

From 1982 to 2001, Mangels (2002) compiled field maps of Cascades frog sightings 

from the Shasta-Trinity NF. These records lack precise dates and were predominantly collected through methods other than formal amphibian surveys including 

fish distribution/population surveys, aquatic habitat surveys, during fieldwork 

related to livestock grazing management, and recreation or other nonbusiness 

activities; many sites were visited multiple times (Zustak and Mangels 2002). 

Localities included the following drainage basins:

1. Klamath River drainage (Klamath River, Elk Creek, Ukonom Creek, other 

small tributaries), Trinity River (Stuart Fork Trinity River, North Fork 

Trinity River, Little North Fork Trinity River, East Fork Trinity River, 

Stuart Fork Trinity River, Swift Creek, Coffee Creek, Canyon Creek, and 

other small tributaries), Scott River and South Fork Scott River, Salmon 

River (South Fork Salmon River, North Fork Salmon River, Little North 

Fork Salmon River, Wooley Creek, other small tributaries);
81

Cascades Frog Conservation Assessment

2. Sacramento River drainage (Sacramento River, South Fork Sacramento 

River, North Fork Sacramento River, Middle Fork Sacramento River, Castle 

Creek, other small tributaries), and McCloud River. Only three of the sites 

had observations of more than 10 adult frogs including the following: 12 

adults were seen in Toad Lake, Middle Fork Sacramento River drainage; 

and 10 to 20 adults were observed in Landers Creek Meadow, Trinity River 

drainage. All the latter records were for 1995.

In 1990, Marc Hayes and Mark Jennings collected Cascades frogs at the 

McCloud River below Colby Meadow (CAS 176557–176560; n = 4), Mumbo Lake 

(CAS 176530; n = 1), Gumboot Creek at Road 26 (CAS 176531–176551, 180306–

180307; n = 21); and a small unnamed pond 1.6 km north of Picayune Lake (CAS 

176552–176555; n = 4). These collections and associated observations of additional 

Cascades frogs were part of the basis of comments that the species could still be 

commonly observed north and west of the McCloud River in California (Jennings 

and Hayes 1994).

In their summary on amphibian declines, Davidson et al. (2002) included 26 

historical Cascades frogs sites (defined therein as pre-1990) associated with the 

Shasta-Trinity NF based on the data from Jennings and Hayes (1994). Their summary indicated that 77 percent (n = 20) of these historical sites were still occupied 

in the early 1990s.

Between July 1999 and August 2002, formal amphibian surveys of all lentic 

habitats were conducted in the Trinity Alps Wilderness west of Highway 3 (Welsh 

et al. 2006). Of 380 water bodies surveyed, 58.7 percent (n = 223) were found to 

support at least one individual of any life stage of Cascades frogs (Welsh et al. 

2006). Evidence of reproduction (egg masses or larvae) was recorded at 30.5 percent 

(n = 116) of the sites. The maximum number of adult Cascades frogs found at any 

site was 32 and the maximum number of larvae was 4,000. All localities were from 

the central and eastern portions of the wilderness.

Klamath National Forest

Pre-1980—

Only four verifiable historical records of Cascades frogs exist for the Klamath NF 

and vicinity. The earliest records date from 1914, when Halstead G. White collected 

five Cascades frogs from the T.H. Benton estate along Butte Creek (Siskiyou County; 

MVZ 7497–7501); this location is about 24 km south of the Oregon state line.

One record exists from the 1920s. Halstead recollected the Benton estate along 

Butte Creek in August 1920, where he took 16 Cascades frogs (MVZ 7502–7517).
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GENERAL TECHNICAL REPORT PSW-GTR-244

One record exists from the 1930s. David H. Johnson collected three frogs from 

Antelope Creek in September 1933 (MVZ 17940, 17944–17945).

No records exist for the 1940s and 1950s. An unconfirmed record exists for 

Duck Lake near the town of Callahan on Highway 3, but the basis of this record 

is unclear.

One record exists from the 1970s. In 1973, Kurt Rademacher collected one 

Cascades frog from the Sky High Lakes in the Marble Mountain Wilderness (MVZ 

107354).

Post-1980—

No records or survey data exist for the Klamath NF during the 1980s but some data 

are available for the 1990s. In their summary on amphibian declines, Davidson et 

al. (2002) included two historical Cascades frogs sites (defined therein as pre-1990) 

associated with the Klamath NF based on the data from Jennings and Hayes (1994). 

Their summary indicated that 100 percent of these historical sites were still occupied in the early 1990s.

Positive sighting maps for the Klamath NF show that Cascades frogs were 

observed in Antelope Creek (pre-1980 historical locality), the vicinity of Tamarack 

Spring, and Trail Creek; however, no additional data exist for the Cascades frog 

records from these localities.

Systematic surveys of segments of the Klamath NF were not initiated until 

2001. Complete visual encounter surveys of all lentic habitats were conducted 

in the Marble Mountains and Russian Wildernesses between July 2001 and July 

2002 (Welsh et al. 2006). Approximately 250 water bodies were searched in the 

Marble Mountains, and 54 water bodies were searched in the Russian Wilderness. 

Cascades frogs were recorded from 32 percent of the water bodies in the Marble 

Mountains (n = 80) and at 31 percent of water bodies in the Russian Wilderness (n 

= 17). However, evidence of reproduction (egg masses or tadpoles) were found at 

only 11 percent of sites in the Marble Mountains (n = 28) and at only 5.5 percent of 

sites in the Russian Wilderness (n = 3). Further, adult and larval numbers observed 

seemed low. The maximum number of adults found at any site was 26 in the Marble 

Mountains and 19 in the Russian Wilderness; the maximum number of tadpoles 

was 5,950 in the Marble Mountains and 130 in the Russian Wilderness (Welsh et 

al. 2006). Besides these wilderness surveys, one adult Cascades frog was recorded 

from a permanent pond in the Sugar Creek Watershed and 62 tadpoles were found 

in a wet meadow in the Meeks Meadow Creek Watershed north of the Russian 

Wilderness boundary (Welsh et al. 2006).
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Cascades Frog Conservation Assessment

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GENERAL TECHNICAL REPORT PSW-GTR-244

Fellers, G.M.; Drost, C.A. 1993. Disappearance of the Cascades [sic] frog 

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GENERAL TECHNICAL REPORT PSW-GTR-244

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Cascades Frog Conservation Assessment

Appendix 4Surveys in the Southern Cascade Range since 1980 Years Location and extenta Effort Cascades frog detections Description Reference

1981, 1983 Butte Meadows 200 hours None Systematic surveys Hayes 2005

 and Jonesville

1990 Lassen Volcanic 10 historical None Jennings 2006

 National Park sites

1991 Lassen Volcanic 50 sites One site Formal visual Fellers and 

 National Park encounter surveys Drost 1993

1993 Forestwide 106 sites Two locations Informal visual USDA FS 1993

 and include first encounter surveys observations of conducted by Lassen extant populations National Forest on Lassen National seasonal personnel  Forest under supervision of 

 Lassen National  Forest permanent  biologists

1993–1994 Deer and Mill Creek 40 sites Two locations (same Formal visual Fellers 1995

 watersheds (including as 1993 Lassen encounter surveys some sites in the Butte National Forest survey) Creek watershed)

1994 Rock Creek, tributary 4.25 noncontiguous Two locations that may Informal visual

 to the Pit River stream miles represent one population encounter surveys EA EST 1995

1995 Lassen National Forest 60 sites Two sites (same as 1993 Formal visual Fellers 1995

 Lassen National Forest encounter surveys  survey)
88

GENERAL TECHNICAL REPORT PSW-GTR-244 Years Location and extenta Effort Cascades frog detections Description Reference 1995 Deer and Mill Creek 120 sites (totaling Possible but could not be Informal visual EA EST 1996 tributaries 14 stream miles) confirmed encounter surveys 1996–1997 Lassen National Forest, 112 sites Three (two sites are same Formal visual Fellers 1998 Caribou and Thousand as 1993 Lassen National encounter surveys

 Lakes Wilderness Forest survey)

2001 Almanor Ranger District, 22 sites None Informal visual USDA FS 2002

 geographically widespread encounter surveys

2002 Almanor Ranger District, Approximately 56.0 Two sites (one site is same Formal visual Vindum and

 geographically widespread ha of meadow, 46.7 as 1993 Lassen National encounter surveys Koo 2003

 km of stream Forest survey)

2003 Lassen National Forest Approximately 280 Five sites including four Formal visual Koo et al. 2004

 ha of meadow, 91.8 found in prior surveys encounter surveys km of stream

2002 Thousand Lakes Wilderness All lentic water bodies None Formal visual Welsh and

 encounter surveys Pope 2004

2002 Caribou Wilderness Over 300 water bodies None Formal visual Welsh and 

 encounter surveys Pope 2004

2004 Lassen Volcanic National Park All lentic water bodies One site Formal visual Stead et al. 2005

 encounter surveys

2007–2011 Lassen National Forest, 50 historical or 11 sites including six Formal visual Pope and 

 adjacent private lands, Lassen unsurveyed sites found in prior surveys encounter surveys Larson 2011,  Volcanic National Park Pope et al. 2011

a Surveys include those on Shasta-Trinity National Forest lands administered by the Lassen National Forest. Surveys in the Southern Cascade Range since 1980 (continued)
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Cascades Frog Conservation Assessment

References

EA Engineering, Science, and Technology [EA EST]. 1995. Rock Creek and 

Screwdriver Creek aquatic resource inventories. Final report prepared for 

the Lassen National Forest, Hat Creek Ranger District. 11 p. + appendixes. 

Unpublished report. On file with: Lassen National Forest, 2550 Riverside Drive, 

Susanville, CA 96130.

EA Engineering, Science, and Technology [EA EST]. 1996. Aquatic resources 

survey of Deer and Mill Creek tributaries, volume 1 of 4. Report prepared for the 

Lassen National Forest. Report + Appendixes A–C. Unpublished report. On file 

with: Lassen National Forest, 2550 Riverside Drive, Susanville, CA 96130.

Fellers, G. 1995. Aquatic amphibian surveys. Unpublished report. On file with: 

U.S. Department of Agriculture, Forest Service, Lassen National Forest, 2550 

Riverside Drive, Susanville, CA 96130.

Fellers, G. 1998. 1996–1997 Aquatic amphibian surveys. Unpublished report. 

On file with: U.S. Department of Agriculture, Forest Service, Lassen National 

Forest, 2550 Riverside Drive, Susanville, CA 96130.

Fellers G.M.; Drost, C.A. 1993. Disappearance of the Cascades frog Rana 

cascadae at the southern end of its range, California, USA. Biological 

Conservation. 65: 177–182.

Hayes, M. 2005. Personal communication. Senior research scientist, Washington 

Department of Fish and Wildlife, 600 Capitol Way North, Olympia, WA 98501.

Jennings, M. 2006. Personal communication. Senior associate ecologist and 

herpetologist, Live Oak Associates, Inc., P.O. Box 2697, Oakhurst, CA 93644.

Koo, M.S.; Vindum, J.V. ; McFarland, M. 2004. Results of 02-CS-11050650-

029, the 2003 California Academy of Sciences survey: amphibians and reptiles 

of the Lassen National Forest. San Francisco, CA: California Academy of 

Sciences, Department of Herpetology. 172 p. Unpublished report. On file with: 

U.S. Department of Agriculture, Forest Service, Lassen National Forest, 2550 

Riverside Drive, Susanville, CA 96130.

Pope, K.; Larson, M. 2011. Unpublished data. On file with: U.S. Department of 

Agriculture, Forest Service, Pacific Southwest Research Station, 1700 Bayview 

Drive, Arcata, CA 95521.
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GENERAL TECHNICAL REPORT PSW-GTR-244

Pope, K.; Larson, M.; Piovia-Scott, J. 2011. Status of remnant populations of 

Cascades frogs (Rana cascadae) in the Lassen Area of California. Report to the 

Lassen National Forest. On file with: U.S. Department of Agriculture, Forest 

Service, Lassen National Forest, 2550 Riverside Drive, Susanville, CA 96130.

Stead, J.; Welsh, H.H., Jr.; Pope, K. 2005. Census of amphibians and fishes in 

lentic habitats of Lassen Volcanic National Park: a report to the National Park 

Service LVNP Study Number: LAVO-00717. Unpublished report. On file with: 

U.S. Department of Agriculture, Forest Service, Lassen Volcanic National Park, 

PO Box 100, Mineral, CA 96063.

U.S. Department of Agriculture, Forest Service, [USDA FS]. 1993. FY 1993 

Amphibian Surveys. Unpublished report. On file with: Lassen National Forest, 

2550 Riverside Drive, Susanville, CA 96130.

U.S. Department of Agriculture, Forest Service [USDA FS]. 2002. Unpublished 

data. On file with: Lassen National Forest, 2550 Riverside Drive, Susanville, 

CA 96130.

Vindum, J.; Koo, M. 2003. Amphibians and reptiles of the Lassen National Forest: 

results of 02-CS-11050650-029. The 2002 California Academy of Sciences 

Survey. Unpublished report. On file with: U.S. Department of Agriculture, Forest 

Service, Lassen National Forest, 2550 Riverside Drive, Susanville, CA 96130.

Welsh, H.H., Jr.; Pope, K.L. 2004. Impacts of introduced fishes on the native 

amphibians of northern California wilderness areas. Final report to the 

California Department of Fish and Game, 30 March. 22 p. Unpublished report. 

On file with: U.S. Department of Agriculture, Forest Service, Pacific Southwest 

Research Station, 1700 Bayview Drive, Arcata, CA 95521.
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Cascades Frog Conservation Assessment

Appendix 5: Other Risk Factors

The following risk factors were identified because of their potential to negatively 

affect individuals or populations of Cascades frogs or their habitat. In an initial 

evaluation, they were deemed not to be of current or expected future major risk 

to the conservation of the species; however, they may be of concern at a local or 

regional level and may interact with other risk factors. 

Habitat Loss 

Direct habitat loss is one of the most visible causes of amphibian population 

declines (Lehtinen et al. 1999, Stuart et al. 2004). Habitat loss for many amphibians 

can be attributed to the conversion of wetlands to urban or agricultural use (Corn 

1994). Much of the Cascades frog range is on public lands including wilderness 

areas or national parks at higher elevations. Thus, except in limited areas, opportunities for urbanization are lacking. However, increased population growth and 

development in northern California may put Cascades frog populations at risk from 

this kind of habitat loss in the future.

Other opportunities for habitat loss are a function of other risk factors discussed 

in their respective sections (e.g., see sections on “Introduced Fish and Other Predators” and “Recreation, Water Development, and Diversion”). 

Extent of risks— 

Direct habitat loss by urbanization and agriculture is low risk for Cascades frogs 

because much of the species’ range occurs on public lands. Habitat loss via 

urbanization and development is not currently considered to be significant, but 

may have local importance in parts of the species’ range in California. Continued 

development in California may increase the importance of this factor in the future. 

However, other risk factors (e.g., introduced fish) may result in habitat loss and have 

severe consequences. 

Conservation options—

Authorization and analysis of proposals for development and urbanization are 

directly within the jurisdiction of agencies participating in this conservation assessment through agency planning processes. Consideration of impacts to populations 

of Cascades frogs or their habitat could prevent unnecessary losses to populations 

and habitats. 

Locally Applied Pesticides

In forested areas of California, pesticides are used to control rodents, insects, fungi, 

noxious weeds, and brush. In the past, aerial spraying of herbicides was experimented with on national forest lands, but was mostly terminated when water quality 
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GENERAL TECHNICAL REPORT PSW-GTR-244

tests found that the herbicides were entering watercourses (USDA FS 2001b). In 

recent years, nearly all herbicide application on Forest Service lands is conducted 

via backpack sprayers, as this mode of ground application affords greater control 

of the spray direction and coverage. During the National Environmental Policy 

Act process for any project involving the application of a pesticide, buffers are 

designated around streams and water bodies to protect aquatic species from adverse 

effects. Buffer distances are determined depending on potential toxic effects of 

each herbicide type, the potential for them to enter the ground water or move 

offsite, and the known aquatic species that could be affected downstream. 

The most common pesticides used on national forests in descending order of 

frequency are glyphosate, triclopyr, clopyralid, hexazinone, aminopyralid, chlorsulfuron, imazapyr, and aluminum phosphide (for burrowing rodents). Common 

surfactants include R-11, methylated seed oil (Hasten), methylated seed oil/silicone 

blend (Syl-tac), and dyes, including highlight blue, bas-oil red, and colorfast purple. 

Surfactants assist the herbicide with adhering to plant surfaces, and dyes assist with 

viewing where areas have been recently sprayed. Glyphosate has been studied for 

its potential to affect amphibians. In general, the isopropylamine salt of glyphosate, 

the active ingredient in Roundup® and Rodeo®, has been found to be practically 

nontoxic to frogs (Mann and Bidwell 1999). These commercial herbicides, however, 

may contain or be combined with surfactants such as polyethoxylated tallowamine 

(POEA), which have been shown to be toxic to aquatic life, including several species of ranid frogs (Folmar et al. 1979, Howe et al. 2004, Mann and Bidwell 1999, 

Mitchell et al. 1987, Servizi et al. 1987, Wan et al. 1989). Surfactants may affect 

aquatic organisms by damaging gills, which may be why tadpoles were found to 

be more sensitive to the full Roundup formulation of glyphosate than juveniles or 

adults (Bidwell and Gorrie 1995, Mann and Bidwell 1999). A recent study showing 

high toxicity of larval and postmetamorphic northern leopard frogs (Rana pipiens) 

to Roundup1

 may also be a function of POEA (Relyea 2005a); this study did not 

separate the effects of glyphosate and surfactant. Nevertheless, several studies 

(Giesy et al. 2000, Hildebrand et al. 1982, Mitchell et al. 1987, Sullivan et al. 1981, 

Thompson et al. 2004, Wojtaszek et al. 2004) have concluded that glyphosate-based 

herbicides under normal usage do not pose a hazard to aquatic environments where 

both the glyphosate and surfactant would be diluted by large or flowing bodies of 

water or protected by a terrestrial buffer. Past water quality monitoring in Region 

5 of the USDA Forest Service has concluded that glyphosate (and triclopyr) are 

1 Use of trade or firm names in this publication are for reader information and do not imply 

endorsement of the U.S. Department of Agriculture of any product or service.
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Cascades Frog Conservation Assessment

rarely detected in surface water when these herbicides are used with stream buffers (USDA FS 2001b). Triclopyr (Garlon®) and clopyralid (Transline®) are used to 

control noxious weeds. Both pesticides are applied from backpack sprayers, and use 

near water is avoided. Triclopyr, especially in its formulation marketed as Garlon 

4, approaches the toxicity of surfactants used with various herbicides in terms of 

its effects on African clawed frog (Xenopus laevis) embryos (Perkins et al. 2000). 

Garlon 3A is the amine formulation of triclopyr (triclopyr TEA); is water-soluble, 

less volatile, and less toxic than Garlon 4 (Perkins et al. 2000) because it tends not 

to penetrate tissue or bioaccumulate. Berrill et al. (1994) measured the toxicity 

of three chemicals including triclopyr and hexazinone to embryos and tadpoles 

of three frog species. Embryos were not affected by triclopyr, whereas tadpoles 

became unresponsive to prodding (reflecting avoidance response) at exposures of 

1.2 ppm (or higher) and mortality at higher doses (2.4 and 4.8 ppm). Tadpoles whose 

behavioral responses were affected recovered within 3 days. No effects to either 

embryos or tadpoles were observed from exposure to hexazinone.

Additive, multiplicative, or synergistic effects of herbicides with other risk factors have only recently begun to be studied among amphibians, and remain unstudied in Cascades frogs. Both Chen et al. (2004) and Edginton et al. (2004) found that 

the Vision® formulation of glyphosate increased in toxicity to the embryonic and 

larval stages of green frogs (Rana clamitans) and northern leopard frogs at higher 

pH treatments (≥7.5). Recently, Relyea (2005b) also emphasized the importance 

of examining pesticide effects in a community context. In an outdoor mesocosm 

experiment using larvae of three anuran species (gray treefrog [Hyla versicolor], 

American toad [Bufo americanus], and northern leopard frog), zooplankton, and 

algae, where combinations of predators (no predators; red-spotted newts [Notophthalmus viridescens]; and larval diving beetles [Dytiscus sp.]) and pesticides (no 

pesticides, the insecticide Malathion®, and the herbicide Roundup) were manipulated, Roundup (at a level of 1.3 mg of active ingredient/L) had substantial direct 

negative effects on the tadpoles, reducing total tadpole survival and biomass by 40 

percent. However, Roundup had no indirect effects on the amphibian community 

via predator survival or algal abundance.

Extent of risks related to locally applied pesticides—

Pesticides are not often applied in or near waters across the majority of the Cascades frog range in California because the land is within designated wilderness 

areas, national parks, or in other sensitive habitat designations (meadow habitats in 

Lassen National Forest (NF). Outside of these protected areas, legal local spraying 

of pesticides may accidentally affect short-term water quality but is unlikely to 

have long-lasting or widespread effects on Cascade frog populations in California. 
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GENERAL TECHNICAL REPORT PSW-GTR-244

Unregulated use of pesticides associated with illegal use of public lands (e.g., illegal 

marijuana plantations) may affect local frog populations but very little information 

is known about amounts or types of pesticides applied. 

Management considerations related to locally applied pesticides—

Continued regulation of locally applied pesticides to prevent impacts to Cascades 

frogs and their aquatic habitats would minimize potential impacts to this species. 

This is of particular importance in the southern Cascades where the species is rarest. Agencies participating in this conservation assessment have direct jurisdiction 

over this activity.

Mining

Several types of mining have occurred in the California range of the Cascades frog. 

Among these, hydraulic mining of placer deposits, instream and terrace mining of 

aggregate material, and suction dredge gold mining are discussed below as potential 

contributors to Cascades frog declines. 

Hydraulic mining—

Hydraulic mining methods consisted of using water to erode away hillsides of 

placer (gravel, sand, or silt) deposits (CSLC 1993). Hydraulic mining drastically 

alters water quality and stream geomorphology by releasing pollutants such as acid, 

cadmium, mercury, and asbestos in waterways (CSLC 1993, Larson 1996). This 

practice has been outlawed since 1884, but its effects on water pollution may still be 

apparent in portions of the mid-elevation Pit and Feather River systems within the 

range of Cascades frogs. No studies of Cascades frogs have focused on any of these 

pollutants.

Aggregate mining—

Aggregate mining is conducted to obtain materials used in construction, such as 

roads, highways, and buildings. Industries performing such mining often prefer 

instream to terrace mining, as the aggregate requires minimal sorting and washing 

(CSLC 1993). Instream mining affects the geomorphology of rivers by changing 

sediment transport regimes, eroding beds and banks, and incising channels (CSLC 

1993). Terrace mining, which occurs outside of the wetted perimeter of the river 

but within the floodplain, may result in creating large ponds filled by ground water; 

in flood events, these ponds may become connected to the river (CSLC 1993). 

Aggregate operations are typically found in larger riverine channels, downstream, 

and outside the range of the Cascades frog. Yet, the USDA Forest Service maintains 

a few small quarries for road construction, maintenance, and road treatments that 

occur within the Cascades frog range.
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Suction-dredge gold mining—

Suction-dredgers seeking gold use a method in which water, sediment, and rocks 

are extracted from portions of streams and rivers and sorted to obtain gold (CSLC 

1993). These activities may increase suspended sediment, change the geomorphology of the stream, directly remove aquatic organisms (potentially including 

Cascades frogs), and rearrange the substrate of streams (CDFG [now CDFW] 1994). 

Suction dredging activities have the potential to trap and kill juvenile or adult frogs 

using the stream corridor during the active season (see CDFG 1994). Since 2009, all 

California instream suction dredge mining has been suspended following the Governor’s signature on state law SB 670, which prohibits the use of vacuum or suction 

dredge equipment in any California river, stream or lake, regardless of whether the 

operator has an existing permit issued by the state. The moratorium does not apply 

to suction dredging operations performed for the regular maintenance of energy or 

water supply management infrastructure, flood control, or navigational purposes. 

Extent of risks related to mining—

Mining was common in the Klamath Mountains and has permanently altered 

numerous waterways within the range of the Cascades frog. It was much less common in the southern Cascades and has had minimal long-term consequences to frog 

habitats. Currently, mining is localized and rarely occurs within the range of the 

frog. Legacy effects of mining may be significant to habitats, but there is minimal 

risk of new impacts. 

Conservation options related to mining—

Most mining activities do not currently overlap with Cascades frog’s habitat. 

Continuing the ban on suction dredging would minimize potential future impacts to 

populations and habitats. Mining is within the jurisdiction of agencies participating 

in this assessment. Additional restoration of remnant tailing ponds that serve as 

habitat for invasive species such as American bullfrogs (Lithobates catesbeiana) 

could help alleviate indirect effects of mining resulting from the spread of detrimental invasive species.

Research Activity

Researchers have the potential to negatively affect anuran populations by handling 

or marking animals, attracting predators in numbers or frequencies greater than 

typical background levels, or spreading pathogens among water bodies via clothing 

and equipment. Currently, evidence is lacking to suggest that research activities 

have negatively affected Cascades frog populations. Andrew Blaustein, Gary 

Fellers, Deanna Olson, Karen Pope, Justin Garwood, and Hart Welsh have studied 

Cascades frogs intensively at several sites over several-year periods, and have not 
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found evidence that their activities have negatively influenced frog survival (Blaustein and Wake 1990, Blaustein et al. 1995, Fellers and Drost 1993, Garwood 2009, 

Pope 2008, Pope et al. 2011,Welsh et al. 2006). Effects from these investigators are 

unlikely, but cannot be unequivocally excluded.

Historically, handling and marking of animals has been viewed as innocuous, 

but recent work addressing marking techniques (Murray and Fuller 2000) and 

pathogen epidemiology has led to a reassessment of this view. A review of studies 

involving toe-clipping to mark individual animals has revealed an incremental 

decrease in survivorship with each additional toe clipped, where previous analyses 

of the same data had revealed no effect across low numbers of clips (McCarthy 

and Parris 2004). No effects on survival or body condition have been found using 

passive integrated transponder tags, but comparison to unmarked reference animals 

have been restricted to laboratory analyses (Perret and Joly 2002), leaving open the 

question of how well such analyses translate to field conditions. Further, the poorly 

understood epidemiology of aquatic pathogens (e.g., chytrids, water molds; see 

section on “Disease”) has focused attention on their transmission between water 

bodies, and between diseased and healthy animals. Researchers now disinfect all 

sampling gear between surveys at different lakes, wash all sampling gear between 

frogs and use clean gloves or wash hands before handling a new animal (e.g., 

Johnson and Speare 2003, Piovia-Scott et al. 2011).

Extent of risks related to research activity—

Researchers typically have their study species’ best interest in mind when designing 

their studies. As long as researchers are aware of potential risks, take precautions 

to minimize those risks, and communicate with each other to reduce duplication 

in activities that may damage habitats or harass animals, then the extent of risks 

related to research activities should be minimal. 

Conservation options related to research activity—

Agencies participating in this conservation assessment have a large amount of 

control over the extent and distribution of research activities. It is important that 

managers ensure that researchers consider potential impacts of their actions prior to 

initiating research and incorporate means to assess those impacts while conducting 

research. If risks are deemed to be stronger than benefits, research activities should 

be halted. Promotion of prophylactic measures that prevent disease transmission 

serves to mitigate potential risk from researchers moving among sites and handling 

multiple individuals.
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Cascades Frog Conservation Assessment

Restoration Activities

Restoration refers to a large suite of activities that may involve remediation or restoration of degraded habitats, some of which have the potential to influence Cascades 

frogs. Historically limited, habitat restoration has become a prominent activity 

addressing degraded habitat, and is expected to become even more important in the 

future. Habitat restoration efforts may be diverse, but several categories of restoration may be important to Cascades frogs. These include:

• Fish removal from Cascades frog habitats—Fish removal may be the 

most significant restoration activity for Cascades frogs in lentic habitats. 

Population densities have increased significantly following fish removal and 

frogs have dispersed to previously unoccupied habitats. Recent experiments 

with mountain yellow-legged frogs (Vredenburg 2004, Knapp et al. 2007) 

and Cascades frogs (Pope 2008) have been successful at increasing abundances of frog populations. See sections on Introduced Fish and Other Exotic 

Predators and Existing Management and Research for more information.

• Meadow restoration activities that create ponded habitats such as “plug and 

pond” methods—Some restoration activities to raise the water table out of 

incised stream channels involve creation of ponded habitats. While a raised 

water table and ponded habitat per se may represent a benefit, ponded habitat with an inappropriate structure constructed within the dispersal range of 

bullfrog-occupied sites may negatively influence Cascades frogs. 

• Meadow restoration efforts designed to reduce encroachment of lodgepole pines (Pinus contorta Douglas ex Loudon) into meadow systems (see 

Sharsmith 1961). This may improve breeding habitats by reducing shading 

(solar exposure is important for embryonic development) and, potentially 

increasing water availability by raising the water table.

• Efforts designed specifically to improve breeding conditions for Cascades 

frogs—Efforts have been initiated to augment pools in a few meadows on 

the Lassen NF to increase the hydroperiod and provide cool water refuges 

for larvae. The Forest Service expanded or deepened five known breeding 

pools, supplemented water inflow at two, and dug seven additional pools 

(Pope et al. 2011). They have begun monitoring of egg mass and larval survival in these restored habitats.

Monitoring is needed to evaluate both the positive and negative effects of various types of restoration on Cascades frogs. 
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GENERAL TECHNICAL REPORT PSW-GTR-244

Extent of risks related to restoration—

Restoration activities are anticipated to increase within the range of the Cascades 

frog in California. Some activities such as fish removals and breeding habitat 

improvement projects are designed to specifically improve conditions for Cascade 

frog populations and have minimal risk involved. Risks associated with other 

projects with different goals, such as restoring meadow hydrology and vegetation, 

are less clear and may be positive or negative. The potential effects of restoration 

techniques such as “pond and plug” have just begun to be examined in relation to 

positive and negative effects to native amphibians.

Conservation options related to restoration—

Restoration efforts are promising for preserving and improving population persistence of Cascades frogs. Restoration of fishless waters would greatly contribute to 

the conservation of this species. In addition, breeding habitat enhancement could 

improve tadpole survival to metamorphosis, and localized vegetation thinning 

could increase appropriate basking habitats. Examination of potential watershedlevel efforts to increase water input and persistence to meadow habitats in the 

southern Cascades could also be valuable for improving aquatic habitat conditions 

in a changing climate. Restoration, through regional planning processes, is under 

the jurisdiction of agencies participating in this conservation assessment. Science 

and monitoring is needed to inform how different types of restoration may affect 

Cascades frogs and their habitat, from both short- and long-term perspectives.

Roads

Roads are prominent features throughout the Cascades frog range outside of wilderness areas, and include all types, from little-used logging roads to major interstate 

highways. Six major highways (Interstate 5 and Highways 32, 36, 44, 89, and 299) 

partly or completely fragment portions of the Cascades frog range in California. 

Interstate 5 runs between the populations in the Klamath Mountains to the west 

and southern Cascade Range to the east. Roughly 62 percent of the Cascades frog 

range occurs on national forest lands that contain a total of 115 km of paved roads 

(primary/secondary highways and improved paved roads), 258 km of gravel roads, 

1714 km of dirt roads (dirt and unimproved dirt roads) and 300 km of trails (USDA 

FS 2001c). 

The degree to which roads affect Cascades frogs has not been studied, and 

depends on many factors such as road density, road type, and traffic intensity. Most 

populations of Cascades frogs are not likely to be affected by roads directly (i.e., 

via mortality from collision with vehicles) because the frogs rarely move away 

from water so would have little reason to cross a road surface. However, indirect 

effects to their habitats and dispersal ability may be significant. At least eight 
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Cascades Frog Conservation Assessment

physical characteristics of the environment may be altered by roads: soil density, 

temperature, soil water content, light, dust, surface-waterflow, pattern of runoff, 

and sedimentation (Trombulak and Frissell 2000). Because Cascades frogs depend 

on aquatic habitats for survival and successful recruitment, changes in the hydrology of the high mountain lake, meadow, and stream systems they inhabit, may 

be detrimental. These areas can be affected by fluctuations in the frequency or 

magnitude of peak and debris flows of adjacent streams. Because Cascades frogs 

require breeding sites that are sufficiently deep to avoid drying or freezing of eggs 

or larvae, fluctuations that ultimately cause a reduction in available water could 

severely affect recruitment. In contrast, a drastic increase in flooding or debris 

flows could dislodge, bury, or destroy eggs deposited in pond shallows (see “Habitat 

Requirements in Ecology” section). 

Roads may also serve as barriers to frog movement. Road crossings of water 

courses may block in-channel migrations and dispersal events because culverts are 

too steep, become blocked by debris, or become disconnected from the streambed 

(i.e., hanging culverts). Research on habitat fragmentation is biased towards highly 

fragmented landscapes, but one study was done in Europe on the moor frog (Rana 

arvalis) in lessfragmented habitat (Vos and Chardon 1998). This study revealed 

that roads increase isolation, and therefore contribute to habitat fragmentation (Vos 

and Chardon 1998). The study also showed that even in a relatively large and stable 

habitat patch, the effects of habitat fragmentation on frog populations were strongly 

negative (Vos and Chardon 1998). Barriers or partial barriers as a result of fragmentation may have a strong effect on populations of Cascades frog if they operate as 

metapopulations (Bradford 1991). Barriers, such as roads, could prevent recolonization of locations where extirpations have occurred.

Maintenance and use of roads have the potential to contribute at least five 

different general classes of chemicals to the environment: heavy metals, salt, 

organic molecules, ozone, and nutrients (Trombulak and Frissell 2000). These 

chemicals plus pollution from vehicular emissions and road runoff contain various 

toxic chemicals that can have negative effects on amphibian populations, including reduced survival, deformities in tadpole oral cavities, elevated levels of stress 

hormones, and inhibited growth and metamorphosis (Lefcort et al. 1997, Mahaney 

1994, Welsh and Ollivier 1998). Similarly, roads may cause increases in sedimentation and water pollutants (Spellerberg 1998). 

Direct transfer of sediment (and other material) to streams and other water bodies at road crossings is an inevitable consequence of road construction (Richardson 

et al. 1975). The surfaces of unpaved roads can route fine sediments to streams, 

lakes, and wetlands, increasing turbidity of the water (Reid and Dunne 1984). High 
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concentrations of suspended sediment may directly kill aquatic organisms and 

impair aquatic productivity (Newcombe and Jensen 1996). The effects are further 

heightened if the sediments contain toxic materials (Maxell and Hokit 1999). 

Increased sedimentation may also reduce availability of important food resources 

for tadpoles like algae (Power 1990). Fine sediment deposits also tend to fill pools 

and smooth gravel beds, degrading habitats (Forman and Alexander 1998).

New road construction often facilitates increased human use of newly roaded 

areas. An increase in human activity may increase direct and indirect road effects 

previously discussed. Much of Cascades frog habitat lies within national forests, 

which have many roads, and some conversion of unimproved roads to more developed roads occurs over time; thus, significant opportunity exists for increased 

human use and vehicular traffic in that landscape. National parks and wilderness 

areas are unlikely to expand their road networks (NPS 2005), so an increase in 

human use in these areas, which may result from population growth, will not be 

facilitated by new road construction or conversion toward more developed roads. 

However, increased use of existing roads can be anticipated.

Extent of risks related to roads—

In Lassen Volcanic National Park (NP) and wilderness areas in the Klamath 

Mountains, the risks related to roads are low. However, outside these areas, and 

particularly on private lands and on the Lassen and Klamath NFs, risks associated 

with population isolation and habitat alteration are expected to be moderate. 

Conservation options related to roads—

Agencies manage road construction, planning, and proliferation to minimize 

impacts to aquatic habitats. Special attention in areas known to be upstream of Cascades frog breeding habitats would minimize potential short- or long-term impacts 

to these sensitive areas. These activities are within the jurisdiction of agencies 

participating in this conservation assessment. 

UV-B Radiation

Increases in mid-range ultraviolet radiation (UV-B; 290-320 nanometers) resulting 

from depletion of atmospheric ozone are hypothesized to contribute to amphibian 

declines (Blaustein and Wake 1990, Wake 1991). Yet, experimental and field studies 

addressing UV-B are controversial and have produced mixed results (Licht and 

Grant 1997), suggesting that the actual effects on amphibian growth and survivorship vary across a variety of conditions (e.g., species, life stages, and habitats) and 

that this factor is, at best, limited in its ability to explain declines (Licht 2003).

To date, much work on UV-B has involved experiments that address the vulnerability of the embryos and newly laid eggs of several amphibian species found in 
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western North America. This work has shown that the direct effects of exposure to 

elevated UV-B resulted in reduced hatching success, reduced larval growth rates, 

or sometimes increased physical abnormalities ( Anzalone et al. 1998, Belden et al. 

2000, Blaustein et al. 1994b). Differences in responses among species have been 

attributed in part to differences in the behavioral, physiological, and molecular 

defenses these amphibians possess against UV-B (Blaustein and Belden 2003); 

for example, Pacific treefrogs (Pseudacris regilla), Columbia spotted frogs (Rana 

luteiventris), northern red-legged frogs (Rana aurora), and Oregon spotted frogs 

(Rana pretiosa) possess two to five times as much of the UV-B damage repair 

enzyme photolyase as Cascades frogs, western toads, and long-toed salamanders 

from western Oregon (Blaustein et al. 1998).

Most studies of UV-B effects on amphibians have focused on the egg stage, 

but some studies have shown that the effects of exposure can extend beyond the 

egg stage (e.g., Ankley et al. 2000, 2002). In particular, some ranid frog species 

appear most susceptible to UV-B exposure between hatching and late larval stages 

of development (Ankley et al. 2002, Tietge et al. 2001). Further, the possibility that 

UV-B exposure of embryos may have more subtle effects than direct mortality 

remains poorly studied. In studies in which embryos and tadpoles of the northern 

red-legged frog were exposed to sublethal UV-B levels, exposed animals had 

depressed growth rates when compared to a control group (Belden and Blaustein 

2002). Little has been done to address UV-B effects on the postmetamorphic stages 

of anurans, although Fite et al. (1998) described retinal damage found in adult 

wild-collected Cascades frogs as similar to UV-B-induced retinal damage in adult 

northern leopard frogs as evidence that Cascades frogs are exposed to increased 

UV-B radiation; unexposed Cascades frogs were not available for controls.

Although field and laboratory experiments suggest that embryos and larvae of 

some ranid frogs can either be killed or sustain sublethal damage from UV-B exposure, information from the environments in which these life stages exist suggest 

that habitat conditions for large geographic areas in western North America limit 

UV-B exposure (Licht 1996, 2003). Notably, the realization that dissolved organic 

material (DOM) or dissolved organic carbon (DOC) can effectively absorb UV-B 

(Morris et al. 1995, Scully and Lean 1994) has refocused attention on the levels of 

these solutes in the aquatic habitats amphibians use. Levels of DOM/DOC in 85 

percent of 136 western toad breeding sites in the Cascade Mountains of Oregon and 

Washington were sufficient to reduce UV-B to levels below those that Blaustein et 

al. (1994a) had found to affect embryos (Palen et al. 2002). Further, the percentage 

of these breeding sites over which UV-B radiation did not reach the potentially 

harmful levels that Blaustein et al. (1994a) described were similar for three other 
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montane species: Cascades frog, northwestern salamander (Ambystoma gracile), 

and long-toed salamander (Palen et al. 2002). In addition, Adams et al. (2001) 

examined the distribution of three amphibians in the montane Pacific Northwest 

and found that Cascades frogs were most likely to breed in fishless shallow ponds 

with relatively low transmission of UV-B radiation. Davidson et al. (2002) examined the spatial pattern of population declines in Cascades frogs as well as six other 

anuran species to see if patterns were consistent with what might be expected with 

a UV-B effect (e.g., an increase in declines at higher elevations and more southern 

latitudes, coincident with altitudinal and latitudinal patterns of increased UV-B). 

They found no significant pattern of change in occupancy with elevation; a decrease 

in occupancy with elevation would be expected if declines were the result of UV-B. 

Most recently, Adams et al. (2005) compared amphibian presence to site-specific 

estimates of UV-B levels in 683 ponds and lakes in across a broad geographic 

range in western North America that included sites in Olympic NP in western 

Washington state and Sequoia-Kings Canyon NPs in the southern Sierra Nevada. 

Of eight amphibian species examined, only three species (long-toed salamanders, 

Pacific treefrogs, and roughskin newts [Taricha granulosa]) showed relationships 

with UV-B that were potentially attributable to negative effects. No relationship 

was found between the occupancy of lakes and ponds by Cascades frog and UV-B 

dose in Olympic NP, the only location that Adams et al. (2005) studied in which 

Cascades frogs were present.

Failure to reveal a convincing link between amphibian declines and UV-B may 

result from the fact that significant effects are more likely if UV-B interacts with 

another stressor. Kiesecker et al. (2001) hypothesized that periodic mass mortality 

of toad embryos in Oregon resulted from a synergism between UV-B radiation, the 

pathogenic watermold Saprolegnia ferax, and the climatic event El Niño. Long et 

al. (1995) found that embryos of northern leopard frogs exposed to levels of UV-B 

and low pH that were nonlethal when each was individually applied produced 

significant mortality when the same levels of each stressor were applied simultaneously. A similar synergism between UV-B and low pH was observed for embryos of 

the common frog, Rana temporaria (Pahkala et al. 2002). Kiesecker and Blaustein 

(1995) found that exposing Cascades frog embryos to UV-B increased mortality 

from S. ferax over embryos treated by the same levels of each alone. Many other 

additive or synergistic effects are possible, but remain unstudied in Cascades frogs.

Extent of risks related to UV-B radiation—

Increased UV-B radiation does not appear to be a primary factor in the rangewide 

decline of Cascades frogs. However, the synergistic relationships between UV-B, 

other stressors, and frog declines is poorly understood, so UV-B has the potential 
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to contribute to declines in ways that remain unidentified. Moreover, levels of 

ambient UV-B appear to be still on the increase (Middleton et al. 2001) so effects of 

increased UV-B on Cascades frogs may occur at some threshold level that becomes 

manifest in the future.

Conservation options related to UV-B radiation—

At this time, UV-B radiation does not warrant management consideration. Should 

the risk level for this risk factor increase, effective management would require coordination of agencies outside the jurisdiction of those involved in this assessment. 

Agencies responsible for Cascades frog management could participate in guiding 

the development of the management and science to inform this issue.

Vegetation and Fuels Management

Vegetation and fuels management encompasses all management activities that alter 

vegetation structure and composition, including timber harvest, fuels management, 

salvage logging, and prescribed fire. Changes in vegetation, shade, and woody 

debris can alter breeding, active-season, refuge, and overwintering habitat quality. 

Changes in vegetation can also influence soil stability, erosion, and sediment loading to aquatic habitats. These activities can pose a risk to Cascades frogs in areas of 

their range where such activities are permitted (e.g., national forest lands outside of 

wilderness areas). 

The effects of controlled burns for fuel reduction on fauna, including Cascades 

frogs, are poorly understood (Pilliod et al. 2003). Prescribed fire could benefit 

Cascades frogs if it reduced the risk of future high-intensity wildfire or reduced 

encroachment of woody vegetation into meadows that provide aquatic habitat for 

frogs. One hypothesis for the declines of this species in the Lassen area is the loss 

of open meadow habitat resulting from fire suppression (Fellers and Drost 1993). 

Some of the Cascades frog range is on granitic soils, so improperly implemented 

prescribed burning could be risky because erosion rates of burned areas on such 

soils can be 66 times as great as in undisturbed watersheds, and can elevate annual 

sediment yields for 10 years or more (Megahan et al. 1995). 

Extent of risks related to vegetation management—

Overall, the risk of vegetation and fuels management activities is low because most 

of the range of the Cascades frog is protected. If activities occur in areas adjacent 

to habitat for Cascades frogs on Forest Service lands, vegetation management 

activities are generally on a small scale and closely regulated. Outside of these 

areas, risk depends on a project’s scale, intensity, and proximity to Cascades frog 

populations. Fire management that preserves open aquatic habitats may benefit the 

species in the longterm. 
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GENERAL TECHNICAL REPORT PSW-GTR-244

Conservation options related to vegetation management—

Precautions taken to minimize potential impacts, such as sediment loading, to 

Cascades frog habitats would reduce risks associated with vegetation and fuels 

management. On a smaller scale, selected actions intended to reduce lodgepole pine 

encroachment in meadows or to thin overstory vegetation in riparian areas may 

benefit habitat for Cascades frogs because all life stages of Cascades frogs use open 

habitats. These activities are directly within the jurisdiction of agencies participating in this conservation assessment.

Water Development and Diversion

Water developments, such as dams and diversions, can radically change aquatic 

habitats and are a prominent component of the landscape in the Sierra Nevada 

Forest Planning Area (Harris et al. 1987, Moyle and Randall 1998), and Klamath 

Mountains. Most major water development and diversions, whether assessed based 

on number, scale, or size, have occurred at lower elevations (Moyle and Randall 

1998), and much of them below 1219 m, or below much of the elevation range over 

which Cascades frogs are known to occur (see “Status” section). However, dams 

and water diversions also exist in higher elevation areas that have more overlap 

with the Cascades frog range. Purposes of these water developments are varied but 

primarily include hydroelectric power generation and water storage. 

Dams likely to be found in Cascades frog areas may raise the levels of existing lakes or ponds or flood meadow habitat, eliminating or in some cases creating 

Cascades frog habitat. Diversions may alter the hydrology and water retention at a 

site potentially affecting breeding.

Major water projects within the southern Cascades that overlap with the species’ range are limited to the Pit River system and North Fork Feather River (e.g., 

Lake Almanor, Butt Valley Reservoir). Selected smaller water projects are located 

within the West Branch Feather River watershed (e.g., Snag Lake and Philbrook 

Lake). Elsewhere, the headwater reaches of a number of drainages (e.g., Butte 

Creek, Deer Creek, Mill Creek, Battle Creek) with current or historical Cascades 

frog populations remain hydrologically undeveloped. Major water projects within 

the Klamath Mountains include Shasta and Trinity Dams on the upper Sacramento 

River and upper Trinity River systems, respectively. In addition to these, about 15 

small lakes and meadow systems in the known historical range of the Cascades frog 

in California have some form of hydrological development. The majority of these 

consist of small dam structures to raise the water level of an existing water body 

(e.g., Gumboot Lake). However, most of the headwater area of the Klamath Mountains lacks water development.
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Extent of risks related to water development and diversions—

Existing dams and diversions are not a widespread risk for Cascades frogs 

(although, through initial development of such structures, they may have eliminated critical areas of historical habitat and increased fragmentation). Most of the 

Cascades frog range is at relatively high elevations where water development and 

diversion projects are few and are generally small. However, where dams and diversions occur, local impacts can be significant and permanent. 

Conservation options related to water development and diversions—

Preventing or mitigating future water development and diversion projects where 

they overlap with Cascades frog habitat would minimize impacts to Cascades frogs. 

Permitting for water developments and diversion are directly or indirectly within 

the jurisdiction of agencies participating in this conservation assessment. 

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113

Cascades Frog Conservation Assessment

Appendix 6: Cascades Frog Working Group

Aguilar, Bernard

Associate Fisheries Biologist

California Department of Fish and Wildlife

P.O. Box 1640

Weaverville, CA 96093

(530) 778-0218

(530) 778-3979 (fax)

baguilar@dfg.ca.gov

Arnold, Jonathan

Forester

Lassen Volcanic National Park

P.O. Box 100

Mineral, CA 96063-0100

(530) 595-4444 x5171

(530) 595-3262

jonathan_arnold@nps.gov

Bolster, Betsy

Staff Environmental Scientist, retired

(Statewide Coordinator for Conservation of Amphibians and Reptiles)

California Department of Fish and Wildlife

Wildlife Branch, Nongame Wildlife Program 

1812 9th St.

Sacramento, CA 95811

(916) 445-3684

(916) 445-4048 (fax)

bbolster@dfg.ca.gov

Brown, Catherine

Monitoring Team Leader

Sierra Nevada Monitoring Strategy

Pacific Southwest Research Station

USDA Forest Service

800 Buchanan Street

Albany, CA 94710

(510) 559-6433 – Albany

(209) 532-3571 x241 – Sonora

(510) 559-6499 (fax)

cathybrown@fs.fed.us
114

GENERAL TECHNICAL REPORT PSW-GTR-244

Garwood, Justin

Biologist

California Department of Fish and Wildlife

50 Ericson Court

Arcata, CA 95521

(707) 825-4723

Jennings, Mark R.

Herpetologist/Fishery Biologist

Rana Resources

P.O. Box 2185

Davis, CA 95617-2185

(530) 753-2727

(530) 753-2727 (fax)

Ranaresources@aol.com

Lehr, Stafford

Fisheries Branch Chief

California Department of Fish and Wildlife

830 S Street

Sacramento, CA 95811

(916) 327-8840

slehr@dfg.ca.gov

Macfarlane, Diane

Threatened, Endangered, and Sensitive Species Program Leader

Ecosystem Management Staff

Pacific Southwest Region

USDA Forest Service

1323 Club Drive

Vallejo, CA 94592

(707) 562-8931

(707) 562-9054 (fax)

dmacfarlane@fs.fed.us

McAllister, Robert

Fisheries Biologist

California Department of Fish and Wildlife

(530) 225-2866

bmcallis@dfw.ca.gov
115

Cascades Frog Conservation Assessment

McFarland, Melanie

Forest Fisheries Biologist

Ecosystems Staff

Supervisor’s Office

Lassen National Forest

USDA Forest Service

2550 Riverside Drive

Susanville, CA 96130

(530) 252-6663

(530) 252-6428 (fax)

mmcfarland02@fs.fed.us

Pearl, Christopher A.

Wildlife Biologist

U.S. Geological Survey Forest and Rangeland Ecosystem Science Center

777 NW 9th St., Suite 400

Corvallis, OR 97330

(541) 750-1011 

(541) 753-6848 (fax)

christopher_pearl@usgs.gov

Perrot, Laurie 

Environmental Coordinator

Supervisor’s Office

Tahoe National Forest

USDA Forest Service

631 Coyote Street

P.O. Box 6003

Nevada City, CA 95959

(530) 478-6244

(530) 478-6109 (fax)

lperrot@fs.fed.us

Pope, Karen

Wildlife Biologist

Redwood Sciences Laboratory

Pacific Southwest Research Station

USDA Forest Service

1700 Bayview Drive

Arcata, CA 95221

(707) 825-2957

(707) 825-2901 (fax)

kpope@fs.fed.us
116

GENERAL TECHNICAL REPORT PSW-GTR-244

Welsh, Hart H., Jr.

Research Wildlife Ecologist

Redwood Sciences Laboratory

Pacific Southwest Research Station

USDA Forest Service

1700 Bayview Drive

Arcata, CA 95221

(707) 825-2956

(707) 825-2901 (fax)

hwelsh@fs.fed.us
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