Conservation News
Dam Removal Effort Aims at Helping Steelhead
By Paul Rogers, San Jose Mercury News 2/17/04
Submitted by Bruce Dau
Dam Removal Effort Aims at Helping Steelhead
By Paul Rogers, San Jose Mercury News 2/17/04
Submitted by Bruce Dau
In the deep oak forests above Carmel Valley, 18 miles upstream from postcard ocean views of the Monterey Peninsula, dozens of muscular, silvery fish are struggling relentlessly upstream to spawn. As they have every February for thousands of years, steelhead trout are returning to the Carmel River from the Pacific Ocean. Soon, however, their journey could change considerably.
In a project almost unprecedented in California's 150-year history of using dams to make an arid state habitable, scientists, environmental groups and water officials are trying to determine whether they can tear down the fishes' main obstacle. For the past 83 years, the 107-foot-tall San Clemente Dam has blocked steelhead from returning smoothly to the upper Carmel River. The challenge: how to help the fish they are seeking to rescue from the Endangered Species List, without accidentally killing them in the process.
Built in 1921, San Clemente Dam is a graceful curve of smooth concrete. Once it stored drinking water for thousands of people around Monterey. But today its reservoir is almost entirely choked with sediment. It holds less than 10 percent of its original water capacity. Nor does the dam provide electricity or flood protection. State inspectors declared it unsafe in 1986, at risk of collapse in a major earthquake, and ordered it fixed. If the dam were torn down, it would be the largest dam ever removed in California.
"Dams like this are public nuisances," said Jim Edmondson, a spokesman for Cal Trout, an environmental group that supports removing obsolete dams to restore depleted salmon and trout populations. "They serve no purpose for storing water or generating power," he said. "They create man-made impediments that keep salmon and steelhead from getting upriver."
Complicating matters is a mountain of sediment - fine sands and gravel - piled up behind the San Clemente. The mass is so huge, estimated at roughly 2.5 million cubic yards, that it would take 250,000 dump trucks to haul it all away. If the dam were suddenly torn out, the avalanche of mud and silt could smother the river below for miles, wiping out fish and other wildlife. The release also would raise the height of the streambed, putting hundreds of expensive homes downstream and several Carmel Valley golf courses at greater risk of flooding.
Some experts say the project can be done, providing a national model of river restoration, if the engineering is careful. Others say it would be best to leave the dam in the river for another 100 years. Officials at Cal-Am Water, the private company that owns the dam and provides water to 110,000 people from Seaside to Monterey and Carmel, say that the best solution is to shore up the dam and leave it in place. For $30 million, crews could roughly double its thickness, and construct a new fish ladder to help fish get over the structure. Tearing the dam down would cost more than twice that, an estimated $70 million, said Steve Leonard, manager of Cal-Am's central coast operations. "Our customers need us to watch their pocketbooks," Leonard said. "The buttressing project moves us forward. We have a delicate balance of human safety, fish and the rates of water customers."
Cal-Am continues to study various options for dam removal, however. For a while, it considered cutting the dam down in 15-foot sections over 20 years, or barging the silt to San Francisco International Airport for bay fill to build new runways. The latest idea is to dredge the silt, and move it three miles downstream by conveyer belt, storing it on hundreds of acres of vacant Cal-Am property in the woods and then removing the dam. Cal-Am says if it can find someone to share the costs - private foundations, state water bond money, Congress or other sources - it will consider removal.
Some local anglers say they aren't sure they want the risk. They note that in recent years 400 to 800 steelhead have made it up the 27 steep steps of the dam's antiquated fish ladder - among the highest in the state - to the other side. "From the fisherman's view, it would be better not to have a dam or a fish ladder," said Clive Sanders of Pacific Grove, who has spent 40 years fly fishing on the Carmel. "That's the majority view from fishermen and from environmental groups. There are few of us who are more concerned about the impact on the river from letting loose large amounts of sediment. It's a hell of a dilemma for everybody."
Historically, biologists estimate the Carmel River once supported 12,000 to 20,000 steelhead. But development, dams, logging, gravel mining and water diversions have lowered numbers across the West. The fish were listed as threatened in 1997 by the federal government. Today, even with its limited population, the Carmel is considered the best steelhead river between San Francisco and Mexico, rivaled only perhaps by the San Lorenzo, biologists say.
The decision comes down to short-term risk vs. long-term gain. Tearing out the dam would open up five miles of river - upstream as far as the Los Padres Dam, the only other dam on the river. It would allow gravels to naturally flow downstream, creating better spawning beds all the way to the ocean. "If you remove the dam, the river will stabilize and in the long run it would be better," said Kevan Urquhart, a state fish and game biologist in Monterey. "It could be that there would be severe impacts from the sediment for the next 10 to 30 years. Which is better: stabilizing the dam, or going into the gamble? There's no scientific answer to that. It's a judgment call."
Dam removal has gained momentum in the past decade. More than 50 dams a year have been removed nationwide in the past few years, nearly all of them small, but most notably the Edwards Dam on the Kennebec River in Maine, which former Interior Secretary Bruce Babbitt battered symbolically with a sledgehammer in 1999.