THE DAM
Matilija Dam, located in the Ventura River watershed on Matilija Creek north of Ojai, is a concrete arch dam built in 1947. Infamous for the scissors painted on the dam by graffiti artists in 2011 that have become an iconic symbol for dam removal, it was originally designed for water storage and flood control.
Owner:
Ventura County Watershed Protection District
Matilija Dam Location:
Ventura River
Completion Date:
1947
Size:
Height: 168 ft, Length: 620 ft, Total designed capacity: 7,018 acre ft., Current capacity: less than 500 acre ft.
Stakeholders:
Ventura County Watershed Protection District, California Department of Fish and Wildlife, Matilija Coalition, Patagonia, State Coastal Conservancy, Surfrider Foundation, National Marine Fisheries Service, and Wildlife Conservation Board.
Land Acknowledgment
Matilija Dam is located on the ancestral land of Barbareño/Ventureño Band of Mission Indians.The Problem
The reservoir behind Matilija Dam is nearly completely clogged with sediment, significantly reducing storage capacity to the point that the dams is rendered non-functional. With no fish ladder or bypass structure present, it is a complete barrier to the migration of endangered Southern California steelhead. The dam also causes degraded water quality, an altered flow system, and a disorder to the sediment flows going to the lower watershed, the estuary, and beaches, which they need to replenish themselves. Matilija Dam has impounded approximately 8 million cubic yards of sediment; the physical condition of the dam continues to deteriorate. Historically inhabiting the Ventura River watershed, Southern California steelhead are an incredibly important species because they evolved in seasonally disconnected river systems and are an adaptable species, able to survive in warmer waters than other steelhead populations. With only an estimated 500 individual species remaining, this unique life history trait makes them a particularly valuable population to protect in the face of climate change and shifting weather patterns. Removal of Matilija Dam will reconnect access for steelhead to their important prime habitat, 17 miles in fact of spawning, rearing, and foraging locations above the dam. This is all critical to the hefty task of recovering steelhead throughout Southern California.
Current Situation
Spanning 20 years of effort, a broad coalition of community groups and resource agencies have advocated for Matilija Dam removal, working together to develop a comprehensive strategy to restore the Ventura River. The specific project we are currently implementing, the Matilija Dam Ecosystem Restoration Project, will cost millions of dollars. Unfortunately, we’ve experienced a lack of dedicated funding, which has been a major impediment to action. Other factors, such as determining an appropriate release strategy for all the sediment build-up, needing to modify downstream roads, levees, and bridges, and impacts from the Thomas fire on the surrounding landscape, have all added to the challenges of the dam removal undertaking. In 2021, however, we saw immense progress. With funds from California Department of Fish and Wildlife (CDFW), construction began to replace Santa Ana Bridge, a downstream structure that must be modernized before the river can be set free since the current bridge’s span is undersized. The new bridge will improve our ability to transport the sediment, while also expanding fish migration opportunities for Southern steelhead at a critical location and providing greater flood flows passage. This pre dam removal work is moving forward and on-schedule for completion in 2022. Ventura County also is in the process of finalize funding awards with the State Coastal Conservancy and the Wildlife Conservation Board to fully fund final designs to update Camino Cielo. This part of the project will replace an undersized box culvert with a full span bridge, achieving similar ecologic and community benefits as the Santa Ana Bridge replacement.
Potential for Removal
With no uncertainty, Matilija Dam is set to come down; with each of the construction projects downstream, we are creating the pathway to achieve total dam removal. Removing Matilija Dam will restore a free-flowing river from the headwaters to the ocean, re-establish access for steelhead trout to required habitat, revitalize a healthy, native ecosystem, and expand opportunities for outdoor recreation. Ventura County officially made the decision in 1998 to officially remove the dam. In March 2016, the group overseeing design alternatives voted in favor of a removal plan. The approved alternative will use two bore holes at the base of the dam to remove and transport the impounded sediment. This concept represents a “natural transport” alternative that concentrates the downstream movement of the built-up sediment during the first storm events that follow. This alternative will minimize ecological impact downstream and lower the overall project cost by reducing the need to truck material in and out of the reservoir. Current projections estimate that once the bore holes are opened, complete dam removal and a free-flowing river will be achieved in 2 to 5 years. In 2020, Ventura County was awarded $5 million from the Wildlife Conservation Board to fully fund securing Final Designs and engineering approval. The county is currently working to finalize the 65% design plan and technical analysis for dam removal.
Voice of Matilija Dam
