Santa Clara River

History and Overview

The Nature Conservancy has made major strides in protecting one of the most important and intact river systems in Southern California. The Santa Clara River is a vital source of drinking water for the local community, as well as a key resource for many prosperous farms. It also offers some of the last riverside and freshwater habitat for wildlife in the bustling Los Angeles-Ventura region. Despite its local and regional ecological importance, the lower Santa Clara River is threatened by invasive non-native vegetation, intense levee building, poor water quality, conversion from agriculture to urban land uses and increasing development in the floodplain. In 2005, American Rivers designated the Santa Clara River as one of the most threatened rivers in the nation.

THE STAKES ARE HIGH

Starting high up in the Angeles National Forest in Los Angeles County, flowing down into Ventura County and into the estuary at McGrath State Beach, the Santa Clara River and its tributaries are surrounded by more than 12 million people. As the population soars, urban sprawl bears down on the river and its watershed, threatening:

• The supply and quality of the region’s freshwater, including precious groundwater reservoirs that are fed by the river;
• The farmers whose fields and groves line the river and surrounding lands, making a healthy contribution to the local economy and regional identity; and
• The plants and animals within the watershed that rely on the extensive habitat of the river system, including a staggering 16 species within one mile of the mainstem of the river that are federally and/or state listed as threatened or endangered.

Adding to the pressure, 95 percent of Southern California’s river and wetland habitat has already been lost. In fact, this is one of the last rivers in Southern California that remains relatively natural. Other major rivers in the region, including the Santa Ana, San Gabriel and Los Angeles, have been reduced from lush, flowing rivers to largely concrete channels with very little wildlife habitat.

THE IMPORTANCE OF FARMERS

When TNC launched the Santa Clara River project in 1999, Southern California was at the peak of one of its largest real-estate booms, with building plans being approved as fast as they were proposed. It became clear that protecting the 84-mile-long river and its numerous tributaries would require a buffer zone between the river and the developed areas. Threatened farmland could provide that buffer.

We began partnering with the farmers, open-space advocates and county agencies of the region to develop innovative land-use and flood-control policies that protected the farmers’ livelihoods. Together, we explored ecologically compatible farming techniques that safeguarded the habitat and water supply and would prevent the river from suffering the channelized, concrete-lined fate of its sister rivers.

To date, TNC has protected a total of 4,156 acres—or approximately 21 miles of riverside habitat—on the Santa Clara River. We have purchased easements that cover 551 acres of farmland and floodplain habitat adjacent to the river, encouraging farmers to continue farming, and permanently preventing suburban development.

This land protection provides wildlife habitat and improves the health of the river and its floodplain. The farms on the floodplain allow the river’s natural hydrologic process to continue by absorbing flows during periods of flooding, which provides natural downstream flood protection to cities and towns that would otherwise have to rely on levees to keep the river at bay. The avoided cost of flood damage is estimated to be over $1 billion and there’s no need to build or maintain a levee when nature does the job for us more effectively and affordably.

Supporting the Native Species

Since 2014, TNC has worked to restore approximately 769 acres of riparian and upland habitat along the Santa Clara River. The many benefits of restoring the Santa Clara River floodplain include:

• repairing the hydrology of the river
• connecting habitats for species migration
• supporting recovery of endangered species
• recharging the groundwater
• sequestering carbon
• reducing wildfire and flooding risk
• helping nearby communities adapt to climate change

TNC is working with partners, such as the Friends of the Santa Clara River, Santa Clara River Conservancy, and University of California Santa Barbara, to combat the tremendous problems brought on by invasive weeds, like Arundo donax. Arundo is a head-high grass that chokes out the native plants which hundreds of animals depend on for food and shelter. We are removing extensive stands of Arundo to allow the native vegetation to return which provides habitat for nesting species including two federally endangered songbirds, the least Bell’s vireo and the southwestern willow flycatcher. Arundo is a high user of water, highly flammable, and contributes to bulk flows in the Santa Clara River. It causes blockages around infrastructure such as bridges and culverts which can lead to flooding. Removing Arundo can help reduce the risk of flooding and fires and may contribute to greater groundwater infiltration.

Community Engagement

TNC is actively engaging with the public at the Santa Clara River, by providing public outreach and education opportunities through guided naturalist tours, volunteer workdays, and formal research partnerships. We host two monthly guided hikes led by an experienced naturalist to help members of the community learn about and appreciate the natural treasures of this landscape. Our vision is to open some of this conserved and restored habitat to the public to improve people’s quality of life and sense of connection to nature. Get more information about TNC events at the Santa Clara River.

Public Access

TNC is now working on opening the HANSON NATURE PRESERVE to the public. This is our first publicly accessible preserve on the Santa Clara River.

The Hanson nature preserve is nearly 1,000 acres of river and upland habitat, spanning almost two miles of the Santa Clara River. The preserve is in unincorporated Ventura County at the end of Mission Rock Road, off the Briggs road exit on CA State Route 126. Since purchasing this property in 2004, TNC has worked with various partners, such as the California State Coastal Conservancy, the Wildlife Conservation Board, and Caltrans, to restore nearly 250 acres of this former gravel mine site. This work has included extensive removal of the non-native Arundo plant, wetland creation, and planting with native plants. Restored native riparian forest in the project area supports several state and federally listed species of birds, fish, and reptiles.

There are few locations on the Santa Clara River that are accessible to the public. It is the hope of TNC that this preserve will provide a beautiful place for outdoor education, as well as a place for communities to gather, view wildlife, hike, and connect with the dynamic Santa Clara River.

Get Involved

Join the Santa Clara River email list to stay updated on the progress of this project and receive invitations for community meetings and events.

If you would like to help the Nature Conservancy and our many community partners in Ventura County better understand your needs and desires for access to the outdoors, please take this 5-10 minute Hanson Nature Preserve survey

For queries, email santaclarariver@tnc.org.

Groundwater Sustainability

Groundwater is found deep in underground reservoirs. These vital reserves of water account for one-third of the state's water supply, and double that in drought years. While we’ve been treating it like an endless resource, the state has recently passed a new law that will cap groundwater use. The Sustainable Groundwater Management Act (SGMA) calls for state-level actions to make groundwater use more sustainable, including projects like floodplain restoration that would help reduce flood risk, create habitat for migratory birds, and replenish groundwater.

In the Santa Clara River watershed, TNC worked with the Fox Canyon Groundwater Management Agency to draft a plan for sustainable groundwater use, a key part of SGMA implementation. TNC provided science and data to ensure that nature’s water needs were reflected in the plan and balanced with needs of local farmers. TNC was also integral in the development of water market technology, the first of its kind in California. Once completed, TNC will use this as a model to influence dozens of other SGMA plans in the state.

Wildlife Linkages

While the river and its floodplain provide shelter and food for many species, several animals such coyotes, bobcats, mountain lions and black bears rely on the floodplain to move great distances to find resources and mates. Roads and large urban developments can be major barriers to wildlife and can fragment their habitat. This leads to local extinctions and interruptions of key ecological processes. In one of the nation’s most ambitious carnivore studies, our partner, the National Park Service, is studying how large predators like bobcats and mountain lions cope with urban development. Research and advocacy by the National Park Service, Santa Monica Mountains Conservancy, SC wildlands, and many others, have helped us identify ways to protect viable habitats in the face of increasing development pressures. In 2019, TNC and our partners advocated for a piece of landmark legislation passed by the Ventura County Board of Supervisors called the Habitat Connectivity and Wildlife Corridor project. The project includes an overlay zone for the purpose of regulating development near wildlife crossings.