Once abundant in the Sierra, their population numbers are estimated to have declined over 90% over their range, and they are now considered endangered and a vulnerable species by the IUCN.

The ecological effects of their loss have been significant as they were a keystone species and important for nutrient and energy cycling in the aquatic and terrestrial ecosystems.

[4][failed verification] However, a 2016 survey in Yosemite indicated hopeful success with reestablishing populations there by removing trout predation threats, with a sevenfold increase in their numbers reported.

Considerable variance exists in species looks and Sierra Nevada yellow legged frogs can also be grey, red, or greenish-brown with dark splotches.

[7] These frogs hibernate during the winter, staying submerged in the mud or dirt around lakes, rivers and streams.

[6][failed verification] Breeding for this species starts in spring which varies on the elevation of the area between April and July.

The frogs inhabit both the East and Western Sierras, and remain well-represented in the areas around Lake Tahoe.

[8]Breeding sites include ponds, lakes, and streams that do not dry out, are deep enough to prevent freezing, and are without fish.

Studies show that a recently discovered amphibian chytrid fungus is contributing to the decline of the Sierra yellow-legged frog.

Chytrid fungus lives on keratin which is found on the external mouthparts of tad poles and the outer skin layer of adults.

Once the site is fishless, lakes are inhabited by native species, including the Sierra Nevada yellow-legged frog.

[citation needed] In 2016, another survey indicated great success with Yosemite's conservation program, with the frogs' numbers increasing sevenfold.