OJAI, Calif. - The Matilija Dam was designed to hold back water, but today it cradles mostly rocks and pebbles.

Decades worth of sediment are choking the reservoir it created - so much muck that a waterfall cascades over the dam's lip when just an inch of rain falls in the mountains northwest of Los Angeles.

Environmentalists and engineers agree that the dam has outlived its usefulness and should be removed. The benefits, they hope, would include the restoration of eroded beaches downstream and one less barrier to endangered southern steelhead trout struggling to reach spawning habitat inland.

The removal of the Matilija, by itself a massive undertaking, is part of a nationwide effort by environmentalists and government agencies to restore dammed rivers where wildlife suffers and coastlines are deprived of silt that replenishes land lost to erosion.

"For a long time we looked at the benefits of water development - dams, levees and such - and ignored the costs," said Daniel McCool, a University of Utah political science professor who studies environmental issues. "Now the things that were damaged by the levees and dams are the things that we value."

Among other restoration projects:

On Washington's Olympic Peninsula, planning is under way to dismantle the 108-foot-tall Elwha Dam and the 210-foot-tall Glines Canyon Dam as part of a $182 million plan to restore the Elwha River, reopening 70 miles of salmon and steelhead habitat.

Environmentalists want to restore the Louisiana coastline, harmed by dams and channels on the Mississippi. In central Florida, ecologists are removing manmade channels from the Kissimmee River that destroyed wetlands and plant and animal life.

At least 145 dams have been dismantled in the last five years because they were unsafe, outlasted their usefulness, or degraded land and wildlife, according to Blair Greimann, a hydraulic engineer with the U.S. Bureau of Reclamation.

Greimann is studying the 198-foot-tall Matilija to prepare for its removal, which won't begin until at least 2007. A proposed plan has been presented to the public for comment, and funding will need to come mostly from Congress.

The dam was built in 1947 to harness Ventura River water for small communities such as Ojai, a peaceful town known for its art galleries and spas. Now, so much has settled that only 800,000 cubic yards of water skim 6 million cubic yards of sediment - enough to bury a football field two-thirds of a mile deep.

Jeff Pratt, director of the Ventura County Watershed Protection District which is leading the removal effort, said the sediment makes the reservoir all but useless. The local water district says it could tap the supply during a severe drought.

The dam is also bad news for fish. Before it was built, an estimated 5,000 steelhead swam the Ventura River, but fewer than 100 do today.

To help what fish remain, engineers designed a series of small pools leading to a holding pond where the trout would be picked up and driven upstream by truck. But rocks carried over the dam by water broke the fish ladder.

The leading proposal for removing the dam calls for gradually pumping 2 million cubic yards of mud to the flood plain downstream. After temporarily stabilizing the rest of the sediment, crews would probably use jackhammers and small explosives to break the dam down a section at a time, said Pam Lindsey, a watershed district ecologist.

"It's not just something that you can go in there and remove in a day," said Steve Evans, conservation director of the Friends of the River, which monitors dam removals across California.

Part of the dam is already gone. Workers took out slabs built with materials that engineers said were subpar, reducing the dam's height to 165 feet in the middle, as if creating a channel at the top.

As the rest is removed, the watershed district is promising to take steps to avoid flooding along the 16 miles of the river that lead to the Pacific Ocean.

The riverbank ranges from lushly shaded to dry and craggy where the river goes underground.

Among the land that could be partially flooded is the riverside estate of Brooks Greene-Barton, a former real estate broker who now conducts spiritual seminars. Greene-Barton supports the dam's removal, even though he and his wife were in escrow to sell the 10-acre property for $3 million when the prospective buyer backed out because of flooding concerns.

Instead of filing suit, Greene-Barton hopes to help the project by leasing his land to the district. As an added benefit, he would retain the lush riverbank where his two Labrador retrievers can still play.

"If you love trees and you love the forest - they come back," he said.

ON THE NET

http://www.matilijadam.org/

http://www.casitaswater.org

http://www.friendsoftheriver.org/