CARMEL VALLEY (AP) — The largest dam removal project in California history hit an important milestone last week with the successful diversion of the Carmel River into a man-made river bed, an engineering feat that experts said was the first of its kind.
The 93-year-old San Clemente Dam has to come down because it was built on an earthquake fault and because the reservoir behind it is 95 percent packed with mud, the San Francisco Chronicle reported.
State regulators worried that if the privately owned dam collapsed, homes and businesses downstream would be inundated. But just taking down the dam without removing the built-up muck posed a threat to both property and the 36-mile-long river’s ecosystem, the newspaper said.
With approval from the state and conservation groups, California American Water, the dam’s owner, instead decided to build a half-mile-long channel upstream from the dam so the river could be rerouted around the reservoir and into a creek, a task completed last week.
The built-up sludge is going to be left in place, planted with native trees and grasses, and surrounded with a rock berm, which should allow the reservoir to revert to nature once the dam is removed next year.
“We are playing Mother Nature a little bit,” Bill McGowan, who is managing the $83 million project, told the Chronicle. “We’re moving the river around and essentially building a new river. It’s uncharted waters.”
The land where the 106-foot-tall dam now stands and 928 acres of forest around it is going to be donated to the U.S. Bureau of Land Management, said California American Water spokeswoman Catherine Stedman.
The Chronicle said the project may become a model for other dam removals in California, which has 1,400 dams that are either no longer needed or in poor condition.
The Carmel River was featured in John Steinbeck’s 1945 novel “Cannery Row,” in which Steinbeck wrote that “the Carmel is a lovely little river. It isn’t very long but in its course it has everything a river should have.”