The 92-year-old San Clemente Dam on California's Carmel River is slated for removal July 2013 as part of a river restoration project (AP Photo/Monterey County Herald, Vern Fisher)

The 92-year-old San Clemente Dam on California’s Carmel River is slated for removal July 2013 as part of a river restoration project (AP Photo/Monterey County Herald, Vern Fisher)

From the LA Times:

By Bettina Boxall, Los Angeles Times
June 23, 2013, 6:35 p.m.

More than 90 years ago the San Clemente Dam rose on what John Steinbeck called in a novel “a lovely little river” that “has everything a river should have.”

These days, that’s not so true of the Carmel River, which empties into the Pacific Ocean just south of Carmel. The river is overpumped. Flood plain has been lost to development, and the silted-up San Clemente is vulnerable to collapse in an earthquake, threatening 1,500 downstream structures.

But next month, in what officials say is the state’s largest-ever dam removal, work will begin on a three-year project to dismantle the 106-foot-tall concrete dam and reroute half a mile of the river.

The demolition will open up 25 miles of spawning and rearing habitat for a threatened population of steelhead trout, help replenish sand on Carmel Beach and eliminate a huge headache for the utility that owns the dam.

“I can’t tell you I know anyone who wants San Clemente to stay,” said Robert MacLean, president of California American Water, an investor-owned utility that provides water to about 100,000 people on the Monterey Peninsula.

Built in 1921 about 18 miles from the river’s mouth, the dam hasn’t been used as a water source for years. Deemed seismically unfit by the state in the early 1990s, it also has suffered the ultimate fate of dams.

It filled up with sediment. Most of what San Clemente now holds back is dirt and gravel, not water.

There is enough sediment piled behind the dam’s arch to fill 250,000 dump trucks. Figuring out what to do with it was a major challenge. Letting the dirt wash downstream would increase the flood risk. Trucking it out would be expensive and disruptive. Filling up a canyon was an environmental no-no.

So project managers decided to leave it where it is. Instead of moving the dirt, they are going to move the river channel, diverting half a mile of the Carmel into the bed of a nearby creek that flows into the river just above the dam.

“It really is innovative,” said Joyce Ambrosius, Central Coast supervisor of the federal National Marine Fisheries Service, which has worked with the utility and the California State Coastal Conservancy on the dam removal.

An official groundbreaking ceremony was held Friday for the project, which will cost about $84 million. American Water is putting up $49 million. The state is contributing $25 million from previously authorized bonds, and the federal government is providing $2.4 million.

The rest will have to be raised from foundations and private sources, including the Nature Conservancy, which has committed $1 million to the effort.

“We saw this as part of a bigger-picture effort to restore the Carmel River and bring it back to life,” said Trish Chapman of the coastal conservancy.

American Water is also under state order to stop pumping from downstream wells that are drawing from the lower reaches of the 36-mile river. That is forcing the utility to develop new supplies, which, along with the dam removal, will add about $30 to the average monthly residential water bill.

Although the dam has a fish ladder for migrating steelhead, it’s not a very good one. Fishery managers hope that free passage will increase spawning and boost the dwindling number of south Central Coast steelhead.

Biologists estimate that there are only about 500 steelhead on the river, which provides some of the region’s best habitat for the fish. Like salmon, steelhead are born in fresh water, spend several years in the ocean and then return to their native rivers and streams to spawn.

Getting rid of the dam will also help another threatened species, the California red-legged frog, by eliminating the reservoir — a breeding ground for bullfrogs that eat the red-leggeds.

The dam property includes 928 acres of chaparral and oak woodlands that American Water will donate to the U.S. Bureau of Land Management — the federal government’s largest landowner — when the demolition is complete. Neither the state nor the U.S. Forest Service, which manages the nearby Los Padres National Forest, wanted the land.

The river will not be dam free when the San Clemente structure is gone. The Los Padres Dam lies about five miles upstream. It too is filling up with sediment. But it is still used for water supply, and MacLean said his company is just beginning to evaluate its options for the Carmel’s last dam.