San Anselmo Flood Risk Reduction Project


The San Anselmo Flood Risk Reduction Project is part of the District's 10-Year work plan to mitigate the 25-year flood event in the Ross Valley.

The project consists of three distinct components:

  1. Sunnyside Nursery Flood Diversion and Storage Basin (FDS) at 3000 Sir Francis Drake Boulevard
  2. Removal of buildings at 634-636 San Anselmo Ave and creek bank stabilization in San Anselmo (BB2), a structure that partially obstructs the flow of San Anselmo Creek and related creek restoration
  3. Flood mitigation measures for downstream private properties that may see a rise in water surface due to the removal of BB2 in San Anselmo

Project map


Status of San Anselmo Bridge ("BB2"):   The County of Marin, the Flood Control District, the Town of Ross and the Town of San Anselmo are currently considering next steps for the San Anselmo Bridge. An announcement to the community will be made in the near future. Thank you for your patience.

  • Planning and environmental: 2016-2023
  • Design: 2019-2023
  • Construction: 2020-2025
  • Completion: TBD

Status: Construction


The updated cost estimate is $26.1 million including real estate, design, CEQA, permitting, construction, residential flood mitigation measures, and tenant relocation.

The engineer's estimate for construction will be refined as the design is completed. Final construction costs for this project will be determined through the bidding process.

The project is partially funded through an $8,720,500 grant from the California Department of Water Resources. The remaining costs will be funded through the Flood Control Zone 9 stormwater fee.


Flood Control Zone 9: Ross Valley

Agencies and partners

  • Marin County Flood Control & Water Conservation District
  • Town of San Anselmo
  • Town of Ross
  • Town of Fairfax


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