LOS ANGELES — Now that the shock of a series of January storms has worn off, Los Angeles County officials face a herculean chore: Five reservoirs along south-facing San Gabriel Mountain slopes are filled with so much debris and soupy mud that they pose a flood risk to the communities below.
Another intense storm, they say, could unleash new surges of dirt, toppled trees and boulders down canyons stripped of their binding vegetation by the 2020 Bobcat fire, sending chocolate-colored floodwaters over the dams and into the cities of Arcadia, Sierra Madre, Pacoima, Sun Valley and Sunland.
An urgent concern is emptying the reservoir behind 96-year-old Santa Anita Dam of about 600,000 cubic yards of muck more than 80 feet deep. Two of the three valves that control releases of stormwater from the 20-story-tall dam are blocked with silt.
