Removing Matilija Dam:
About the Matilija Coalition:
Sediment Management:The fundamental challenge with dam removal is sediment management. In the case of Matilija Dam, this consist of 6 million cubic yards of silt, sand, gravel, and cobble. See Impacts: Sediment for a summary of the problem.
The Feasibility Study determined that “Full Dam Removal with Short-Term Sediment Stabilization” was determined to be the best overall concept, given the watershed hydrology and constraints. The primary design constraint is floodplain development downstream of the dam. Residences, roads and bridges, and water supply facilities all need to be protected under any project alternative. Approximately 2 million cubic yards of fine sediments currently trapped in the reservoir area will be slurried downstream (see Slurry Disposal) The remaining 4 million cubic yards will be stored upstream of the dam site as illustrated below.
The Matilija Dam Ecosystem Restoration project plan will allow for full dam removal with controlled sediment release. Environmental benefits are maximized, including renewed public access to Matilija Canyon, while the potential downstream impacts are minimized.
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Page last updated: May 2002