The habitat includes sunny riverbanks, meadow streams, isolated pools, and lake borders in the Sierra Nevada, and rocky stream courses in southern California. The species seems to prefer sloping banks with rocks or vegetation next to the water's edge (Stebbins 1985). Zweifel (1955) observed that individuals in southern California are typically found in steep gradient streams in the chaparral belt and may range into small meadow streams at higher elevations. In contrast, those in the Sierra are most abundant in high elevation lakes and slow-moving portions of streams. This species seldom is found away from water, but it may cross upland areas when moving between summer and winter habitats (Matthews and Pope 1999). Wintering sites include areas nearshore under ledges and in deep underwater crevices (Matthews and Pope 1999). This species breeds by larval development. In the Sierra Nevada, this species is known to hibernate underwater in lakes and streams for periods of 6–9 months prior to the spring breeding season (Bradford 1984). Although hibernation has never been directly observed in the Southern California subpopulations, it is believed that individuals in this area may hibernate for up to 6 months underwater, utilizing deep stream pools (Santana et al. 2015). This species is diurnal, individuals often bask on sunny rocks, and tadpoles are present year-round in streams, thus making this species easy to detect (Zweifel 1955, Jennings and Hayes 1994, Vredenburg et al. 2005, 2007). 

In southern California, USFWS (2006) concluded that this species requires permanent water sources at the appropriate elevations, which can include streams, rivers, perennial creeks (or permanent plunge pools within intermittent creeks), and impounded pools. These water sources should maintain a natural flow pattern, including periodic natural flooding. Breeding sites must maintain water throughout the tadpole growth phase, which can last up to two years. Preferred aquatic habitats should include bank and pools substrates that consist of varying percentages of soil, silt, sand, gravel cobble, rock and boulders, and should also have open gravel banks and rocks that project above or just below the waters surface to serve as sunning posts. Aquatic refugia, including pools with bank overhangs, downed logs and branches, and rocks are also needed to provide cover from predators. This species also requires streams or stream reaches between occupied sites that can function as movement corridors between breeding and foraging sites. Additionally, this species requires riparian habitat and upland vegetation (e.g. Ponderosa Pine, montane hardwood conifer, montane riparian woodlands, and chaparral) that extends 80 meters from each side of the centre-line for each stream and its tributaries, as this provides areas for feeding and movement. The canopy overstory should not exceed 85% to allow sunlight to reach the stream (USFWS 2006).

Historically, this species occurred from Palomar Mountain in San Diego County northward and westward through the San Jacinto, San Bernardino, and San Gabriel Mountains of Riverside, San Bernardino, and Los Angeles counties, in California, USA. These localities formed four isolated clusters of montane populations (Vredenburg et al. 2007). Additionally, an isolated cluster of subpopulations occurred on Breckenridge Mountain, south of the Kern River in Kern County, and in the Sierra Nevada (west of the crest) in Tulare, Inyo and Fresno counties, extending north to Mather Pass (Vredenburg et al. 2007). It is now extirpated throughout much of its former range, including on Palomar and Breckenridge mountains, and occurs only in a few isolated subpopulations in the Sierra Nevada and areas of Southern California. In the Sierra Nevada, it occurs at elevations ranging from 1,600–3,790 m asl, while at the localities of Palomar Mountain, San Jacinto, San Bernardino, and the San Gabriel Mountains it has been recorded from 300–2,300 m asl (Green et al. 2014). This species was thought to have been extirpated from the San Bernardino Mountains until a small subpopulation was recently discovered (Green et al. 2014). Its extent of occurrence (EOO) is 14,901 km².

Conservation Actions In-Place
All known subpopulations and the majority of habitat in southern California occur on lands managed by the U.S. Forest Service (USFWS 2002). Elsewhere, most occurrences are on lands administered by the U.S. Forest Service or U.S. National Park Service. Occurrence in protected, pristine areas does not ensure population persistence, due to threats from non-native fishes and disease. A total of 8,283 acres (33.5 square kilometres) of stream segments and riparian habitat in portions of Los Angeles, Riverside and San Bernardino counties have been designated as critical habitat for the southern California distinct population segment of mountain yellow-legged frog (USFWS 2006). Almost all of the areas proposed as critical habitat are managed by the U.S. Forest Service's Angeles National Forest (ANF) and San Bernardino National Forest (SBNF). A small amount of privately owned land (approximately 119 acres) are also included as critical habitat. The Southern Distinct Population Segment (DPS) of this species was listed as Endangered under the Endangered Species Act in 2002, and the Northern DPS was listed in 2014. It is also listed under the California Endangered Species Act. 

Removal of non-native trout has occurred at Little Rock Creek, Dark Canyon, and Fuller Mill Creek, and is being considered as a management tool at other localities. These efforts appear to be critical in assisting the rebound of these subpopulations (USFWS 2012). A captive breeding program has been established at the San Diego Zoo Institute for Conservation Research (ICR), which is part of an active reintroduction program that is working to supply individuals to re-establish populations in suitable but unoccupied habitat (Santana et al. 2015).

Conservation Needed
Continued and strengthened management of existing protected areas is essential for the conservation of this species, as are efforts aimed at the restoration of this species' habitat. The continued removal of non-native fishes in areas where this species occurs is recommended. 

Research Needed
More information is needed on this species' distribution, population status, ecology, and threats. There is a need for close monitoring of the status of this species given its small population size and the abundance of existing and potential threats, such as climate change and chytridiomycosis.