California’s largest-ever dam removal is set to begin in July. Officials are calling this the state’s largest dam removal project ever. Dismantling the 106-foot-tall concrete dam and reroute half a mile of the river is schedules to take three years.
From Wikipedia:
The San Clemente Dam, built in 1921, is located 18 miles upstream from the ocean, and once provided drinking water throughout the Monterey Peninsula. It had an original capacity of 1,450 acre·ft (1,790,000 m3), but as of 2002, the capacity had fallen to less than 150 acre feet (190,000 m3). It is no longer used to store water and is now 90 percent silted up. State regulators declared in 1991 that it was in danger of collapsing in an earthquake and spilling the 40 million US gallons (150,000 m3) of water trapped behind its crumbling walls. In January, 2010 an agreement was reached with the California American Water Company to dig a new half-mile channel to bypass and strand the sediment behind the dam at a cost of $84 million, beginning in 2013. This will open up a 7 miles stretch of historic steelhead rainbow trout habitat on the river.
From the L.A. Times:
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.
You can read the L.A. Times article HERE.
You can read the complete Wikipedia article on the Carmel River HERE.