By CBSLA Staff

SAN BERNARDINO (CBSLA) — A group of mountain yellow-legged frogs have been reintroduced to the San Bernardino National Forest, nearly 20 years after its population was nearly wiped out in Southern California.

The group of 253 endangered mountain yellow-legged frogs were carried into a remote site on July 8 by scientists from the San Diego Zoo Wildlife Alliance, UCLA, the U.S. Forest Service, and state and federal Fish & Wildlife. The frogs are a year old and were bred by the San Diego Wildlife Alliance in the hopes they will survive in the wild and be able to establish a self-sustaining population in this part of the San Jacinto Mountains.

READ MORE: Kat Von D Closing West Hollywood Tattoo Shop, Moving To Indiana

(credit: San Bernardino National Forest)

“Although the frogs still face many threats, this release is a tremendous example of the progress we are making towards recovery for the frog,” Scott Sobiech, field supervisor of U.S. Fish and Wildlife’s Carlsbad Office, said in a statement.

The species was once common across the San Gabriel, San Bernardino, San Jacinto, and Palomar mountain regions, but were nearly killed off by non-native predators, recreation impacts, and disease. The mountain yellow-legged frog was listed as endangered species in 2002, at which time it was estimated there were fewer than 100 adult frogs left in the wild.

READ MORE: Los Angeles Receives $224 Million Loan From EPA For Water Recycling Project

Scientists had worked for more than 20 years to help the Southern California population of mountain yellow-legged frogs recover. Besides breeding the frogs, recovery efforts included land management to minimize human impacts to the habitat. Last week’s release was no small feat either – it involved carrying the frogs in special cooler backpacks to keep the high-altitude species alive and a more than five-mile hike to the remote location.

And even though much of the state is mired in drought and at risk of wildfire, scientists determined that conditions at the San Jacinto Mountains release site could still support the frogs.

“Climate change and chytrid fungus are creating challenges to mountain yellow-legged frog survival that the species has never faced before,” Debra Shier, Ph.D. and Brown-endowed associate director of recovery ecology and Southwest hub coo-leader of the San Diego Zoo Wildlife Alliance, said in a statement.

MORE NEWS: LADWP Extends Moratorium on Utility Shutoffs

An additional release of more frogs is planned at the site for later this month, bringing the total number of juvenile frogs released this year close to 400.