Ventura River Watershed
Fewer than 200 Southern steelhead remain in the entire Ventura River basin. Their survival is threatened by Matilija Dam, an aging structure that has outlived every purpose it was built for.
Understanding the history
The Ventura River begins in the Transverse Ranges above the city of Ventura, dropping through chaparral and oak woodland before reaching the Pacific Ocean.
For most of its length, it runs through land that has changed enormously over the last century. Historically, the Ventura River supported robust runs of Southern Steelhead, fish that could navigate from the ocean to the headwaters and back, sustaining both the watershed and the communities that depended on it. That migration route to the pristine upper watershed tributaries has been blocked for more than 50 years by Matilija Dam.
Built in 1948 on Matilija Creek, a key tributary of the Ventura River, the dam was declared unfit for water storage before the end of the 20th century. It traps sediment that would otherwise nourish the coast. It blocks steelhead from accessing miles of cold, clear spawning habitat. And it generates no power and provides no reliable water supply. By all measures, Matilija Dam has outlived its usefulness — and its costs, to the river and to the taxpayers who maintain it, are ongoing.
190 feet tall
Removing a dam the size of Matilija — holding back an estimated 6 million cubic yards of trapped sediment — takes more than an act of will.
Matilija Dam. 190 feet tall, holding back an estimated 6 million cubic yards of sediment.
Part 1 | Matilija dam removal
Decades in the Making: Removing Matilija Dam
Removing Matilija Dam has been a goal of the conservation community for decades. CalTrout has been part of the Matilija Coalition — a partnership that includes the Ventura River Watershed Council, NOAA Restoration Center, National Marine Fisheries Service, U.S. Fish and Wildlife Service, California Department of Fish and Wildlife, the Coastal Conservancy, Ventura County Watershed Protection District, Surfrider Foundation, and others — working to bring that vision to life. Through sustained advocacy, the coalition has secured major funding milestones for removal planning and lower watershed upgrades, including a $13 million grant from CDFW to replace the Santa Ana Bridge – completed in 2022. Final engineering design for removal of the dam is underway. When Matilija Dam comes out, it will be one of the largest dam removals in Southern California history and one of the most consequential for steelhead recovery anywhere in the state.
The ecological benefits extend far beyond fish. Removing the dam will allow the natural movement of sand and gravel downstream, rebuilding the beaches and coastal habitat that have been starved of sediment for generations. Communities along the Ventura River will see reduced flood risk. And the river itself will take a major step toward functioning the way it evolved to function.
Southern Steelhead • Endangered
Every mile of restored access matters.
With fewer than 200 Southern steelhead estimated to remain in the entire Ventura River basin, every mile of restored access matters. CalTrout and our partners — including NOAA Fisheries, the Bureau of Reclamation, and the California Department of Fish and Wildlife — also fought for and won a landmark 2013 legal ruling establishing that mandatory fish passage flows do not constitute an unlawful “taking” of water, a precedent that continues to protect steelhead access throughout the watershed today.
<200
Southern steelhead estimated to remain in the entire Ventura River basin
Part 2 | Robles Fish Passage Facility
The Robles Fish Passage Facility: A Ladder Toward Recovery
While Matilija Dam remains the last major barrier on the Ventura River, an earlier success story shows what reconnection can achieve. In 2005, the Casitas Municipal Water District built the Robles Fish Passage Facility, a state-of-the-art fish ladder around the Robles Diversion Dam farther downstream. For more than fifty years, that diversion had cut steelhead off from historic spawning grounds upstream. The ladder allows fish to migrate both upstream to spawn and downstream back to the ocean but is now in need of structural upgrades to restore a piece of the life cycle that had been disrupted for generations.
Part 3 | LOWER VENTURA RIVER WATERSHED
Preparing the Lower Watershed for a Free-Flowing River
It takes careful engineering to make sure the river’s lower reaches, and the communities and infrastructure along them, are ready for a return to natural sediment flow. CalTrout and the Matilija Coalition’s Technical Advisory Committee have spent years advancing that groundwork, from sediment transport studies to the design and funding of critical infrastructure upgrades like the Santa Ana Bridge replacement.
This diligent, behind-the-scenes work is what makes large-scale dam removal possible. Every bridge redesigned, every mitigation plan refined, and every funding milestone secured brings the Ventura River one step closer to running free from the mountains to the sea. Three downstream projects need to be completed before Matilija sees the last of its negative impact on fish, water and people.
Matilija Dam. 190 feet tall, holding back an estimated 6 million cubic yards of sediment.
Matilija Dam removal is one part of a much larger vision for Southern California steelhead recovery. As part of CalTrout’s Southern Steelhead Coalition, work on the Ventura River is connected to parallel restoration efforts across the Santa Clara River, the Santa Ynez River, and other high-priority watersheds in Southern California. Reconnecting the Ventura River won’t just bring steelhead home to Matilija Creek — it will help demonstrate, for the entire region, what’s possible when communities commit to giving a river back its natural course.
VENTURA RIVER, VENTURA COUNTY
One dam away from Southern California’s biggest steelhead recovery.
Decades of coalition-building, engineering, and advocacy behind the last barrier on the Ventura River.
50+ yrs
Steelhead have been blocked from the upper watershed by Matilija Dam
$13M
CDFW grant that funded the Santa Ana Bridge replacement, completed 2022
2005
The Robles Fish Passage Facility opened, restoring access below Matilija
2013
Landmark legal ruling protecting mandatory fish passage flows
CALTROUT IN ACTION
Stories from the Ventura River.
-
Bridge Replacement Project Creates Pathway for Matilija Dam Removal
Read more →: Bridge Replacement Project Creates Pathway for Matilija Dam Removal -
Santa Ana Bridge Replacement Gets Us One Step Closer to Removing Matilija Dam
Read more →: Santa Ana Bridge Replacement Gets Us One Step Closer to Removing Matilija Dam -
Two SoCal dams on their way out
Read more →: Two SoCal dams on their way out
Support caltrout
Help Free the Ventura River
Matilija Dam is the last major barrier on the Ventura River — and one of the most consequential dam removals left in Southern California. Your support helps CalTrout finish the engineering, secure the funding, and finally give steelhead back their river, from the mountains to the sea.