Unclogging the South Fork

Resource conservationists, lending nature a helping hand, have cleared debris from the South Fork of the Kern River that had trapped sediment and created a flood hazard for fertile ranch land and a nature preserve that protects one of the state's largest remaining cottonwood and willow forests and several endangered species.

Working with borrowed labor and a shoe-string budget, the Kern Valley Resource Conservation District and the Natural Resources Conservation Service accomplished the river cleanup last October, when the water was at its lowest ebb after a long dry summer.

Kern County donated the services of a "hot shot" fire crew on firefighting standby who donned boots, grabbed chain saws, and in just 10 days cut and removed tree stumps, logs, and other obstructions from 10 miles of the river channel.

"Clearing the channel permits the river to use its own natural velocity to flush out years of accumulated sediment and move it on downstream," said Jack Connell, director of the Kern Valley RCD and a leader of the project.

The South Fork of the Kern River was designated in 1993 as a Sierra Bioregion Project initiated by the state Resources Agency and the California Association of Resource Conservation Districts (CARCD). Such a project initially was proposed by the multi-agency Sierra Summit, which was convened by the Agency in 1991.

The project is designed to restore the river's natural flushing system. So great was the sediment buildup that in dry seasons an adult standing in the channel could touch the bottom of a small bridge beneath which, 30 years ago, ranch hands on horseback drove cattle.

The South Fork of the Kern River originates in the southern Sierra Nevada at the base of Mount Whitney and flows south, then west into the San Joaquin Valley. Just before it reaches Lake Isabella, it passes through the 1,130-acre Kern River Preserve owned by The Nature
Southwestern willow flycatcher
Conservancy. The preserve, 60 miles northeast of Bakersfield near the community of Weldon, features a riparian forest that hosts 240 bird species, including the endangered yellow-billed cuckoo, willow flycatcher, and candidates for listing, such as the alkali mariposa lily and the western pond turtle.

"Most of the river forests and wetlands of the Central Valley have been converted to agricultural and urban use," preserve manager Reid Tollefson said. "Our preserve is one of California's best areas for protecting a natural example of riparian forest."

Historically, the free-flowing South Fork distributed sediment that enriched the soil for agricultural use. But damming of the river in the 1950s to form Lake Isabella created a delta effect and the sediment began to back up.

The long-term solution is to fix the sediment problem at its sources, but unclogging the lower channel met an immediate need -- allowing vigorous winter and spring currents to move some of the heaviest buildup through the river system to Lake Isabella.