Matilija Dam was constructed by the Ventura County Flood Control District (now Ventura County Public Works Agency – Watershed Protection) in 1947 to provide water supply and flood control to the Ventura River watershed. The dam no longer serves its original purpose and has been considered non-functional for decades due to structural concerns and sediment build-up. Matilija Lake has essentially disappeared with a capacity of less than 2 percent of the original lake volume for short periods during the winter rainy season; during the majority of the year the lakebed is dry.

The aging dam presents safety concerns for downstream communities and has a negative impact on watershed health. A 2022 report by the California Division of Safety of Dams classified the Matilija Dam to be in poor condition with an extremely high downstream hazard classification. For additional information, see the DSOD’s Dams Within Jurisdiction of the State of California by Dam Name in Reports.

Matilija Dam negatively impacts habitats and wildlife along the river. It blocks aquatic species movement in Matilija Creek, including preventing the federally-endangered Southern California Steelhead from reaching prime spawning habitat in the Matilija Creek headwaters. The dam has captured nearly 9 million cubic yards of silt, sand, gravel, and cobble, preventing it from reaching the Ventura River, estuary, and coastline to support these habitats.

The Matilija Dam Ecosystem Restoration Project (MDERP) is a public-private partnership to remove the obsolete Matilija Dam from the Ventura River Watershed. Ventura County Public Works Agency – Watershed Protection (VCPWA – Watershed Protection) and its project partners are preparing for sediment release by 2030, with complete dam removal to follow.

To prepare for removal, MDERP includes a series of projects to restore habitat and upgrade downstream flood protection and water supply infrastructure.

See completed and planned improvements below: