Marin County, California

Bringing
beavers
back home.

Beavers were native to Marin County's streams and wetlands for thousands of years, until trappers eradicated them in the 1800s. This project aims to restore them, and with them, the water, wildlife, and wildfire resilience that Marin needs.

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A beaver sitting on a log dam across Lagunitas Creek in Marin County, gnawing a peeled stick, with green hills and a willow in the background.

Our Mission

"Marin is the only county north of San Francisco Bay without beavers."

This project aims to bring beavers back to their native homeland in Marin County. Beavers were present throughout Marin's waterways for thousands of years before European arrival, building dams, creating wetlands, and sustaining entire ecosystems. Hunters and trappers eradicated them in the late 1800s.


Today, with California facing prolonged drought, catastrophic wildfire, and declining salmon populations, the ecological services that beavers provide have never been more urgently needed. This is a story about restoration: of a species, a watershed, and a way of living alongside nature.

02 / Why It Matters

Beavers are ecosystem engineers

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Water Storage

Beaver dams raise groundwater levels, filling aquifers and keeping streams flowing through summer droughts. In a state where water scarcity shapes every aspect of life, beavers are nature's best water managers.

↑ Groundwater recharge by 3–10×

🔥

Wildfire Resilience

The wetland meadows created by beaver activity create natural firebreaks. Higher groundwater means greener vegetation, which burns slower and stops fire spread in its tracks.

Wet zones slow wildfire spread significantly

🐟

Salmon Habitat

Deep, cool, slow-moving pools created by beaver dams are ideal rearing habitat for Coho and Chinook salmon, both of which are critically threatened in Marin's streams today.

Beaver ponds double juvenile salmon survival

🌿

Biodiversity

A single beaver pond supports dozens of species, including otters, herons, frogs, dragonflies, and migratory birds. Beavers are a keystone species, and their return cascades through the whole food web.

10× more species in beaver wetlands

🌊

Flood Mitigation

A series of beaver dams acts as natural speed bumps for floodwater, slowing runoff and reducing downstream flooding. This protects farmland and communities from storm damage.

Beaver dams reduce flooding by up to 60%

🌱

Carbon Sequestration

Beaver-created wetlands trap and store organic carbon in their sediments. As California pursues its 30×30 climate goals, beavers represent one of the most cost-effective conservation investments possible.

Wetlands store 5× more carbon per acre than forests

A county without its native engineers

For thousands of years, North American beavers (Castor canadensis) shaped the waterways of what is now Marin County. Lagunitas Creek, Olema Creek, Papermill Creek, Novato Creek: these streams and their surrounding wetlands were built, in part, by beavers.

The fur trade of the 1800s brought trappers into every California watershed, and by the late 19th century, beavers had been hunted to near-extinction across the state. In Marin, they were completely eradicated.

Today, Marin County is one of the very few Northern California counties with no beaver population, and the difference is visible. Streams that once ran deep and cool through summer now run thin. Wetland meadows have dried. Salmon counts have plummeted.

A coalition of conservationists, ranchers, water managers, and community members is working to change that. A 2021 to 2022 feasibility study commissioned by the Occidental Arts and Ecology Center found that Marin has suitable habitat for beaver reintroduction. California's AB 2196, signed by the Governor, has opened the legal door. The moment is now.

Timeline: The road to restoration

1800s Fur trappers eradicate beavers from Marin County waterways
2019 Grant funding secured for initial stream habitat assessment across Marin County
2021-22 OAEC feasibility study confirms suitable beaver habitat across Marin County
2024 Assemblymember Damon Connolly introduces AB 2196, the California "Beaver Bill"
2025 Governor signs AB 2196. CDFW begins planning reintroduction at headwater sites across the state
Now Community outreach, landowner partnerships, and advocacy for Marin reintroduction underway

Follow the project as it unfolds

Adam Rivers writes dispatches from the field, with updates on the science, the politics, the landowners, and the beavers themselves. Subscribe to the Marin Beavers newsletter on Substack to stay close to the story.

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Or subscribe directly at marinbeavers.substack.com

04 / Get Involved

Take action for beavers

01

Read the Newsletter

Subscribe to Marin Beavers on Substack for in-depth writing on the project, the science, and the ongoing effort.

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02

Follow on Instagram

See photos from the field, beaver sightings, habitat updates, and event announcements on the Marin Beavers Instagram.

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03

Support EAC Marin

The Environmental Action Committee of Marin is leading the coalition for beaver reintroduction. Support their work.

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04

Learn from Marin RCD

The Marin Resource Conservation District has resources on beaver ecology, dam analogs, and ongoing research in Marin.

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About the Project

Adam Rivers

Writer, advocate, and Marin County resident documenting the effort to restore beavers to Marin's watersheds.

Substack Newsletter Instagram

Marin Beavers is a project by Adam Rivers dedicated to documenting and advancing the effort to reintroduce North American beavers (Castor canadensis) to their native habitat in Marin County, California.

The project spans journalism, advocacy, and community organizing. It follows the science, meets the people, and tells the story of what it takes to restore a keystone species to a landscape that has been without them for over 150 years.

Marin County is ideally situated for beaver reintroduction. Its streams, including Lagunitas Creek, Olema Creek, Novato Creek, and their tributaries, flow through working ranches, public open space, and protected lands in Point Reyes National Seashore and the Golden Gate National Recreation Area. These watersheds support threatened Coho salmon, steelhead trout, and a rich array of wildlife that would benefit enormously from the wetland habitats beavers create.

This work is part of a broader movement across California and the American West to recognize beavers not as pests, but as partners: cost-effective, self-sustaining allies in the fight against drought, wildfire, and ecological collapse.