These same impacts affect Los Angeles's larger regional City parks, too, including Griffith Park, Hansen Dam, O'Melveny Park, Sepulveda Basin, etc. There are lessons to be learned and strategies to be developed by all agencies that protect these vital resources if they are to survive and thrive.
From the Sierra Club.
------------
Above the City of Angels
Retreat, reverie, and a skull or two in L.A.'s mountains
By Brendan Buhler

The suburban culs-de-sac share space with the catch basin, a structure best thought of as an empty, perforated dam, built to capture the mud, rocks, and trees that people expect to come sliding down the mountainside. It was overwhelmed when a 10-ton boulder tumbled and blocked a key drain, which soon caused a 35-mile-per-hour tide of mud and bowling ball-size rocks to sweep into the streets, tossing and crumpling cars like tinfoil toys. The mud filled houses like they were cake molds. If you had been standing in the kitchen of one of those houses, you would have been chest-deep in what geologists call debris flow—a fast-moving mix of water, rocks, dirt, and detritus—except, of course, you would not have been standing. You would most likely have been killed. Fortunately, no one was.
The La Canada Flintridge slide was nature's payback for the largest wildfire in the modern history of Los Angeles County. The Station Fire rampaged through the San Gabriels from the end of summer until mid-fall 2009, burning 160,000 acres. Investigators believe the fire was intentionally set alongside Angeles Crest Highway. (A vast majority of California wildfires are started by humans, either by accident or as acts of arson. Of the 20 largest fires in the recorded history of the state, only 7 had natural causes.)
Nonlocals hear about the San Gabriels only when they're ablaze or falling on people. But when they're doing neither, they are much more interesting: an untamed wilderness coexisting with one of the world's largest metropolises, a safety valve for the psyches of 18 million jangled humans. The 1,000-plus-square-mile Angeles National Forest, which encompasses the mountain range, is where hikers and campers find solitude within 30 miles of the country's second-most-populated region. It's where children learn about nature, snowboarders carve, those without air conditioning seek relief, hunters and fishermen bag prey, off-roaders crack axles, motorcyclists experiment with asphalt skin grafts, gun lovers practice the rhythms of pop-pop-pop, and the religious test their faith by being baptized in the waters of a canyon sometimes called "Diaper Alley." And that's just what's legal; it doesn't include the potential of finding (or becoming) a bullet-punctured human skull.
The forest is heavily trafficked, underfunded in its upkeep, and remote in its steepness, a landscape that John Muir—who knew of such things—called "ruggedly, thornily savage." Muir continued: "Not even in the Sierra have I ever made the acquaintance of mountains more rigidly inaccessible," yet "down in the dells, you may find gardens filled with the fairest flowers, that any child would love, and unapproachable linns lined with lilies and ferns, where the ousel builds its mossy hut and sings in chorus with the white falling water."
Read the rest at the Sierra Club newsletter site.