Matilija Dam Ecosystem Restoration Project

Cover Photo: Matiljia Dam, August 2019 (© Paul Jenkin, Matiljia Coalition)

CDFW has sponsored large portions of the Matilija Dam Ecosystem Restoration Project (MDERP), located in the Ventura River watershed. Overall, the MDERP will enhance 33.6 miles and 2,268 acres of instream and riparian habitat along the Ventura River and its tributaries. The main component of the MDERP is the removal of the defunct Matilija Dam, which is expected to have wide-ranging benefits to local biodiversity, especially the endangered southern California steelhead trout. Dam removal will also release trapped sediment allowing it to move downstream to replenish sediment-starved river sections and coastal beaches. 

The Ventura River once supported one of the largest runs of the now endangered southern California steelhead. In the past, southern California steelhead used almost every part of the watershed, reproducing in the high tributaries of Matilija Creek and maturing in the Ventura River and the lower estuary before migrating to the ocean. Since its construction in 1947, the Matilija Dam has completely blocked passage of the southern California steelhead, as well as other migratory fish, to important headwater habitat. The Dam stops fish from reaching at least 50% of the spawning and rearing habitat of the Ventura River system.

In addition to the endangered southern California steelhead, the Ventura River watershed supports 119 plant and animal species that are protected at the local, state, or federal level. The southern California steelhead is an ‘indicator species’, meaning if steelhead are doing poorly in the watershed then other native species are also suffering. Likewise, efforts aimed at recovering the southern California steelhead will benefit other native species with critical habitat in the watershed.

In addition to impacts on fish, the Matilija Dam blocks sand and gravel from naturally moving downstream to the ocean. If not stopped by the Dam, sand and gravel would flow downstream and create important habitat on the streambed, estuary, or ocean beaches.  Instead, the Matilija Dam has trapped so much sand and gravel that its water storage function has been largely eliminated. 

 A broad coalition of environmental groups and resource agencies have been working together for almost 20 years to bring health back to Matilija Creek and the Ventura River. During this time, agencies have presented alternative plans for dam removal and the project has gained the national spotlight. In 2012, the National Marine Fisheries Services’ Southern California Steelhead Recovery Plan cited passage of southern California steelhead at the Matilija Dam as a top priority recovery action. 

In 2017, dam removal took a huge leap forward when CDFW funded the 65% design phase for the selected project alternative.  Other financial support has since boosted the dam removal project, including a $13 million dollar grant to replace one of the undersized downstream bridges across the Ventura River. In addition, the recent successful removal of other large dams has demonstrated that removal of the Matilija Dam is feasible and will put the Matilija Creek and Ventura River watersheds on the path to recovery. 

• Project Proponent: Ventura County Watershed Protection District
• Focus Habitat/Species: Southern California steelhead (federally listed as endangered)
• CDFW Grant Support: $3,300,504
• Location: Matilija Creek, Ventura County
• Scale: The MDERP will restore steelhead access to 17.3 miles of perennial headwaters habitat; enhance 33.6 miles and 2,268 acres of instream and riparian habitat throughout the watershed.
• Timing: 6/2017 – 9/2021
• Funding Source: Proposition 1 and Proposition 68
• Priority: Protect and Restore Anadromous Fish Habitat

In 2017, CDFW funded Matilija Dam Removal 65% Design Planning Project. This project will develop designs to protect and restore fish habitat and coastal wetland ecosystems in the Ventura River watershed. The dam and sediment removal plans aim to restore fish passage within one year after the Matilija Dam is removed. Designs will include natural restoration around the former Matilija Reservoir once it is drained of sediments. In addition, the plans will include replacement of two undersized bridges over the Ventura River, flood protection for flood-prone properties, structural or management modifications to the Robles Diversion and Fish Passage Facilities, and recreational facilities to accommodate public access to and along the Ventura River and Matilija Creek. 

CDFW provided funding for the 65% Design Planning support field investigations, a dam removal feasibility study (10% design), an independent technical review, 30% and 65% project design, CEQA/NEPA compliance, and stakeholder engagement. The design objectives were developed by federal, state, and local agencies, along with non-governmental organizations that have worked together in a Design Oversight Group, a Technical Advisory Committee, Management Team, and a Funding Committee.

For more information about the dam removal, see:  http://matilijadam.org/ 

• Project Proponent: Ventura County Watershed Protection District
• Focus Habitat/Species: Southern California steelhead (federally listed endangered)
• CDFW Grant Support: $13,426,938
• Location: Ventura River, Ventura County
• Scale: The MDERP will restore steelhead access to 17.3 miles of perennial headwaters habitat; enhance 33.6 miles and 2,268 acres of instream and riparian habitat throughout the watershed.
• Timing: Estimated 7/1/2019 – 4/30/2022
• Funding Source: Proposition 68
• Priority: Benefit Southern California Steelhead

In 2019, CDFW funded the Santa Ana Bridge Replacement Project, the first major step toward the Matilija Dam Ecosystem Restoration Project. The design of the current Santa Ana Bridge creates a bottleneck in the Ventura River by narrowing the river channel.  The bridge constricts the floodplain and causes sand and gravel to be deposited upstream of the bridge. As a result, the site requires frequent mechanical sediment removal, which causes environmental impacts and high maintenance costs.  

The new Santa Ana Bridge is designed to be 50% longer than the current bridge. This longer design will partially restore the Ventura River’s natural channel capacity.  The new bridge will improve fish passage and habitat for the endangered southern California steelhead and other species.  Widening the river channel at the Santa Ana Bridge will also improve water and sediment flows in the Ventura River watershed. The improved water flows will boost migration of the endangered Southern steelhead. The improved flows will also allow sand and gravel to move into the lower watershed and restore wetland and coastal beaches. 

For more information on the bridge replacement, see:  https://www.venturariver.org/2019/05/santa-ana-bridge-replacement-awarded.html 

To see other Project Highlight StoryMaps like this one, see:  https://www.wildlife.ca.gov/Conservation/Watersheds/Project-Highlights 

For Information on Proposition 1/68 Projects, please see:  https://www.wildlife.ca.gov/Conservation/Watersheds/Restoration-Grants/Projects 

For further information, please contact:  WatershedGrants@wildlife.ca.gov