Capital project
San Anselmo Flood Risk Reduction Project
Watershed Reference

About the Project

The San Anselmo Flood Risk Reduction Project will reduce the acute risk of flooding in Ross Valley by purchasing two parcels along to San Anselmo and Fairfax Creeks and implementing flood mitigation projects on each; one to remove a channel-constricting building and one to construct a flood diversion and storage basin. The basin property is located in unincorporated Fairfax on the 7.7 acre parcel that is the former location of Sunnyside Nursery growing grounds. By excavating and grading the land to construct a depression that creek water can be diverted into, it can serve to temporarily reduce downstream flooding. For more information about the Sunnyside detention basin visit this web page specific to that component of the project. The building to be removed is located over the creek in downtown San Anselmo, where its foundation envelops and constricts the creek. The project Environmental Impact Report is currently being prepared and will analyze the impacts of the proposed project, along with two other alternatives and the “no basin” alternative. This project replaces the former Memorial Park Detention Basin project and retains the grant funding authorized for Memorial Park to fund similar flood protection projects within the Ross Valley.

The project is located in downtown San Anselmo and along Sir Francis Drake upstream of Fairfax

Preliminary Schedule (Pending Funding & Project Approval)

Oct 2016

Phase 1 Memorandum of Agreement between San Anselmo and District approved to perform CEQA and Feasibility Engineering

Apr 20, 2017

Project EIR Public Scoping Meeting

Apr 2018

Draft Project EIR Public Hearing

Apr-May 2018 Public Draft EIR Release-45 day review/comment period

June 2018

Final Project EIR Public Hearing

June 2018

Final EIR certification at Board of Supervisors meeting (merits project approval meeting)

June 2018

Finalize design work for San Anselmo Project, secure permits, possible property acquisition and business relocation activities. Community outreach continues.

Jan 2019

Construction begins (planning for construction in either 2019 or 2020). Outreach continues during construction.

Dec 2020

Construction completed. Community outreach continues



Status & Next Steps

Project design has begun as part of a community-driven process with multiple opportunities for public participation and input on different design alternatives. Design alternatives are being developed to: 

  • maintain the quality of adjoining neighborhoods;
  • ensure basin  design meets community needs;
  • ensure compliance with local, state, and federal environmental laws and regulations; 
  • provide opportunities for consistent public participation & input at key decision points; and,
  • protect the public's health and safety.

The project is currently in the Environmental Review phase. In March or April 2018 the draft EIR will be released and a public meeting will be held. This initiates a 45-day review and comment period.

In June of 2018 the District Board of Supervisors meeting will hold a public hearing for certification of the final EIR.

Upcoming Public Meetings

Exact dates to be determined

Draft EIR Public Review- March or April 2018

Final EIR Public Review- June 2018

EIR Certification Hearing by Board of Supervisors

Past Public Meetings

September 6, 2017: The Town of Fairfax Council received a presentation on the San Anselmo Flood Risk Reduction Project (video).

September 26, 2017: The Town of San Anselmo Council received a presentation on the Project  (presentation & video).

October 10, 2017: The Town of Ross Council received a presentation on the Project (audio).

April 20, 2017: Approximately 30 community members viewed a presentation on Thursday evening at San Anselmo Town Hall in San Anselmo for the EIR Public Scoping meeting. Written comments on the scope of the environmental report (see the Notice of Preparation (NOP) were accepted until May 8, 2017.

January 24, 2016: Approximately 20 community members gathered on Thursday evening at San Anselmo Town Hall in San Anselmo to learn about the alternative project options for the Memorial Grant funds and to learn how the potential projects and hear help reduce flooding. Attendees asked several questions, shared ideas & concerns, and provided feedback to the council and staff. View the meeting presentation, minutes & comments, and video .

    Cost & Funding 

    The project is preliminarily estimated to cost $17.4 million. Cost estimates will be refined with modeling and through the design process.  Further project development and feasibility analysis may result in increased estimated cost. Identified funding sources include the Department of Water Resources Grant, Ross Valley Flood Control Zone 9 Storm Drainage Fee and other potential grant funding sources.

    Implementing Agency & Partners

    Marin County Flood Control & Water Conservation District in cooperation with the Town of San Anselmo and the Town of Fairfax. 


    Liz Lewis, Planning Manager ( or Russ Eberwein, P.E., Senior Civil Engineer ( project manager for the Marin County Flood Control & Water Conservation District.


    If you are a person with a disability and require this document in an alternate format (example: Braille, Large Print, Audiotape, CD-ROM), you may request an alternate format document by using the contact information below. If you require an accommodation (example: ASL Interpreter, reader, note taker) to participate in any county program, service or activity, you may request an accommodation by calling (415) 473-4381 (voice) / (415) 473-3232 (TTY) or by e-mail at not less than four work days in advance of the event.