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.