Country United States Opening date 1947 Type of dam Concrete arch dam | Status 90% silted Construction cost about $4M | |
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Location Ventura County, California Owner Ventura County Watershed Protection District Similar Rindge Dam, Matilija Falls, Casitas Dam, Foster Park, San Clemente Dam | ||
Matilija Dam is a concrete arch dam completed in 1947. Designed for water storage and flood control, it impounds Matilija Creek to create the Matilija Reservoir in the Los Padres National Forest, south of the Matilija Wilderness and north of Ojai, California.
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Map of Matilija Dam, Ojai, CA 93023, USA
The drainage area above the damsite is 55 square miles, and the reservoir had an original capacity of 7,018 acre·ft (0.008657 km3). Matilija Creek flows on to become the main tributary of the Ventura River.
Matilija was one of the Chumash rancherias under the jurisdiction of Mission San Buenaventura. The meaning of the Chumash name is unknown.
Silting and notching
Modern officials describe the dam design as "flawed from the outset". Many experts including the U.S. Army Corps of Engineers and the California Department of Fish and Game aligned themselves against the project, and before construction an architect advised that the proposed materials would react together badly. An engineering survey twenty years later proved him right, finding "internal swelling, external cracking, disintegration of the wall and movement of the abutments". Absolutely no provision was made for fish passage, causing spawning habitat loss for steelhead trout. The year after the dam opened, there was a major upstream fish kill caused by heated and/or stagnant water.
The dam also began silting up, which had the side effect of depriving ocean beaches 17 miles downstream of replenishing sand. The dam was notched (level of the dam face reduced in height) after being condemned in 1965 and notched again in 1977. Taking into account the reservoir's reduced capacity and losses to sedimentation, the reservoir is projected to be completely silted up by the year 2020.
Proposed removal
Ventura County official set the course for removal of the dam as early as 1998. In October 2000 United States Secretary of the Interior Bruce Babbitt visited the site, operated a crane to remove a ceremonial concrete slab from the dam face, and brought national attention to the then-novel concept of dam removal.
The dam has been a candidate for removal ever since, along with the 1924 Rindge Dam near Malibu, completely silted up since 1950, and also built blocking steelhead trout spawning grounds.
A bill allowing funding for the Matilija Dam Ecosystem Restoration Project reached Congress and survived President Bush's veto in November 2007, but the actual funding stalled. As of 2013 stakeholders including government agencies, non-profits and individuals seemed to concur that complete removal is the best option.
The watershed is also challenged by invasive, non-native species, such as Giant Cane (Arundo donax).