For 13 years, one of Southern California’s premier and most popular climbing destinations, Williamson Rock, located 20 miles northeast of Pasadena in the Angeles National Forest, has been off-limits to climbers. The reason? An endangered amphibian, the diminutive mountain yellow-legged frog.

In recent decades, the frog’s population had dwindled to roughly 100 individuals. As climbers began their ascent at Little Rock Creek below Williamson Rock, they unwittingly disturbed the frog’s habitat, ruining egg clutches and presumably stepping on tadpoles and adult frogs. The frogs were placed under the protection of the Endangered Species Act and Williamson Rock was closed to all climbing to help bolster the little frog’s numbers.

But now the Forest Service is reviewing options to re-open Williamson Rock to climbing. A small section of the Pacific Crest Trail that crosses Little Rock Creek, and which had been rerouted, may also be reopened, according to the Forest Service, if a bridge is built across the creek.


Since the closure, biologists have succeeded in breeding the frogs in captivity and have released nearly 4,000 tadpoles and young adults into waterways throughout the San Gabriel Mountains. It’s also thought that the native population rebounded to as many as 200 individuals just doing what frogs do naturally, after Williamson was declared off-limits to human activity.

There are actually several plans in place to reopen Williamson Rock, taking into account the sensitivity of the frog’s habitat, as well as peregrine falcons, which nest in Williamson’s granite crags.

The Forest Service favors an option that would allow climbers to access Williamson after securing a paid permit (between $10 and 12 per climber), and even then, only through the dates of August 1 through November 15. This brief window is timed with the goal of interfering as little as possible with the falcon chicks.

This option would also keep the number of climbers limited to 90 per day, employ monitors to ensure nobody gets too close to the falcon nests, and would require the aforementioned bridge over Little Rock Creek, allowing PCT hikers to pass over the creek without disturbing the sensitive frogs.

The Forest Service last week held two meetings in Southern California to invite public comments on the proposal to reopen Williamson. Climbers turned out in significant numbers, enthused at the reopening potential of one of California’s best climbing options. Williamson Rock is crisscrossed with some 300 sport routes rated from 5.6 to 5.13, offering options for all skill levels.

“It would certainly open up a tremendous resource for climbers,” said Terry Lee, a climbing shop owner in Orange County. “Especially in the summer time when it is so hot — it is one of the few places to go climbing, given its proximity to L.A.”

A further environmental impact report for the plan will be prepared, a lengthy public comment period will be held, and, finally, by next summer, a resolution is expected. Forest Service supervisor Jeff Vail is expected to make the decision and, during recent public meetings, supported opening Williamson to climbing once again while also preserving the mountain yellow-legged frog’s habitat.

Good news for southern California climbers. And mountain yellow-legged frogs.

Photo top: USDA; bottom: Kuyper/USFWS

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