In what could be the largest dam removal project ever completed in California, government officials and a Monterey water company on Monday agreed to tear down the 106-foot-tall San Clemente Dam. The move is a victory for endangered steelhead trout which for decades have been blocked from their spawning grounds by the obsolete concrete structure on the Carmel River.

Monday's signed agreement ended more than 10 years of study and debate and sets in motion an $84 million project. The dam closure — a formidable engineering and biological enterprise — is expected to be watched by scientists and water managers around the United States.

"What we're doing here is truly of national significance," said U.S.

Rep. Sam Farr, D-Salinas, who fished in the Carmel River as a boy. "We are going to have some tough days ahead. But it is the right thing to do and we are going to get it done."

Built in 1921, San Clemente Dam once stored drinking water for thousands of people around the Monterey Peninsula. It irrigated golf courses and helped run clanking sardine canneries.

But today its reservoir is 90 percent silted up, choked with sand and mud. And the dam doesn't provide electricity or flood protection.

"In 1921, this dam was a marvel of engineering. It has fulfilled its purpose and its usefulness is behind us," said Rob MacLean, president of the California American Water Co., which owns the dam.

State dam inspectors declared it

unsafe in 1991, at risk of collapse in a major earthquake. That left Cal Am with two choices: shore it up, estimated now to cost $50 million, or tear it down for $84 million.

After leaning toward repairing it for several years because the cost was cheaper, the water company in 2008 announced it would tear the structure down. But last spring, it changed course, saying that the poor state budget and liability questions made removal unfeasible.

A long-running battle, potentially involving costly lawsuits, loomed. The National Marine Fisheries Service said it was not likely to issue permits for the repair work because the dam blocked upstream migration for steelhead trout, a silvery fish protected by the federal Endangered Species Act.

"We have been telling Cal Am that a project to buttress the dam would likely result in the fish becoming extinct," said Fisheries Service central coast supervisor Joyce Ambrosius, referring to the steelhead population on the Carmel River.

The impasse was broken after Cal Am named a new president, and Farr, whose district includes Monterey, Santa Cruz and San Benito counties, renewed his push for removal.

Under Monday's agreement, Cal Am will provide $50 million by raising rates on its 110,000 water customers in Monterey County. Federal and state agencies, led by the California Coastal Conservancy in Oakland, will work to secure the remaining $34 million.

Sam Schuchat, executive officer of the Coastal Conservancy, said he expects to tap existing state bond money, federal grants and private foundations for the money.

Biologists consider the Carmel River one of the top steelhead runs between Los Angeles and San Francisco, with 400 to 800 steelhead returning each year to spawn, although that number has been declining. Removing the dam would open up 25 miles of the river.

Under Monday's plan, the Carmel River would be rerouted for half a mile around the dam, the dam would be torn down, and the sediment would be left in place, held by large rocks. That way, the debris, which would fill 250,000 dump trucks, won't have to be hauled away. Construction on the channel to reroute the river would start in 2013, with completion of the project three years after that.

The largest dam ever removed in California was the 55-foot Sweasey Dam near Eureka in 1970 after it silted up. About 50 smaller dams in California, mostly 10 feet or so high, have been removed in the past 20 years. A $150 million project to tear down the 165-foot Matilija Dam in Ventura County, which is also silted up, was approved in 2004 by county officials, but has not been implemented yet because of funding shortfalls.

The question is which one will get the permits and the funding to go first.

"It's kind of a no-brainer when you have dams that provide no benefits," said Steve Evans, conservation director with Friends of the River, a Sacramento environmental group. "But these projects are a little more complicated than taking down some concrete."

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