Board unanimously approves Russian River floodplain restoration project to fill former pits and restore habitat
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Summary
The Board approved a 360-acre Russian River floodplain restoration project that fills historic mining pits, reconnects floodplain to the river, adds regulated public access and aims to improve salmonid habitat and reduce methylmercury risk; the project was found statutorily CEQA-exempt as a restoration project with CDFW concurrence.
The Sonoma County Board of Supervisors on April 22 unanimously approved a 360-acre Russian River Floodplain Restoration Project that would transform former terrace-mining pits west of Windsor into restored floodplain and riparian habitat, add regulated public access, and include a monitoring and adaptive-management program.
Permit Sonoma staff described the history: the site was mined from the 1950s through the early 2000s, resulting in multiple open-water pits and an incised river channel disconnected from its natural floodplain. County and project partners said the open pits create ecological and geomorphic problems including fish entrapment, habitat for invasive predatory fish, elevated methylmercury production under anoxic bottom-water conditions and risks of channel instability or pit capture in high flows.
The restoration plan, developed through multi-agency collaboration and published as a feasibility study, proposes to regrade and reconnect portions of the floodplain without importing or exporting fill (cut/fill balance on site). The project includes phased construction (sub-phases to allow seasonal construction windows), a monitoring and adaptive-management phase for vegetation establishment, and later development of public-access improvements such as perimeter multi-use trails, day-use parking and a walk-in/boat-in campground. County staff said public access will be designed to be secondary to restoration goals and that revised public-access plans must be shared with neighboring landowners and can be adaptively managed if problems occur.
Project documents include a CDFW concurrence that the proposal qualifies for the CEQA statutory exemption for restoration projects; no further CEQA environmental review was required for this statutory exemption. Staff also noted groundwater and water-quality analyses to test for mercury impacts. Staff said filling the pits removes the anoxic bottom-water conditions that produce methylmercury and that monitoring is built into the plan; consultants told the board that the water in the pits does not have elevated mercury concentrations but that pit-bottom conditions are a methylmercury risk and that filling removes that mechanism.
Public comment included multiple supporters ' conservation organizations, the Coastal Conservancy and Riverkeeper ' and neighbors such as the Mariani family and Ledbetter Farms who worked with staff to address access, trespass, and agricultural impacts. County conditions require revised public-access plans and neighbor notification; the conditions also preserve existing water rights and require ongoing engagement. The board approved the general-plan amendments, rezones and the use permit by voice vote. Supervisors thanked staff and project partners for years of collaboration.
Why it matters: The project aims to restore river-floodplain dynamics, improve habitat for listed salmonid species, reduce methylmercury bioavailability from anoxic pit waters, and provide managed public access while protecting neighboring agricultural operations.
What happens next: Project implementation will proceed in phased construction seasons with monitoring and adaptive management; staff and project partners will continue neighbor engagement and post-construction monitoring as required by the conditions of approval.
