County of Marin - News Releases - San Anselmo Flood Prevention

For Immediate Release
August 31, 2018

San Anselmo Flood Project Final Report Released

Board of Supervisors to address environmental review for risk reduction

San Rafael, CA – On September 18, the Marin County Flood Control and Water Conservation District Board of Supervisors will consider and potentially certify the final environmental impact report (EIR) for the San Anselmo Flood Risk Reduction Project. The key report, which was released in draft format earlier this year, presents an analysis of the environmental impacts of potential flood mitigation projects. The final EIR has been released and is available online.

A view of the former Sunnyside Nursery property, which would be used as a flood basinThe former site of the Sunnyside Nursery is proposed as a location for a temporary floodwater storage basin in the case of a severe threat of flood.

The project components under consideration are designed to improve public safety and protect residential and business properties along Fairfax and San Anselmo creeks in the Ross Valley, a region that has suffered significant damages from flood events for decades. In addition to reducing frequency and severity of flood events, multiple environmental and recreational enhancements are assessed under the EIR.

Responses to the comments received during the draft report public comment period, including input from the May 22 public hearing, will be published as part of the final EIR. The completed report, including appendices and response to comments, will be presented September 18 for certification and a potential project recommendation by the Marin County Flood Control and Water Conservation District’s Board of Supervisors. The session will be held at the Marin County Civic Center, Suite 330, 3501 Civic Center Drive, in San Rafael, and the public is encouraged to attend. Comments on the final EIR can be provided to Liz Lewis, DPW Planning Manager, via email.

The flood district has been working with the towns in the Ross Valley since 2016 to develop and analyze the San Anselmo Project. District staff sought input during 40 meetings with various community stakeholders, neighbors, public EIR scoping sessions, the Flood Control Zone 9 Advisory Board and the San Anselmo Town Council. Feedback from these public engagement activities has been considered and incorporated in the completed EIR.

EIRs require public agencies to address the potential environmental implications of their actions. The San Anselmo Project EIR, which adheres to the California Environmental Quality Act as well as federal guidelines, presents a proposed project comprised of two complementary parts. A basin to temporarily divert and store floodwater is proposed at the former Sunnyside Nursery site at 3000 Sir Francis Drake Boulevard, about a mile north of downtown Fairfax. The 33-acre basin would be coupled with the anticipated acquisition and removal of a building at 634-636 San Anselmo Avenue that obstructs the creek’s natural flow.

Businesses at 634-636 San Anselmo Avenue have continued to operate during the preparation of the EIR and will do so until a project decision is made by the District Board of Supervisors. If the recommended project requires the building’s removal, the district will assist the tenants with relocating their businesses. 

The flood risk reduction project is proposed to be funded by a $8.7 million state grant and $8.7 million in local match funds coming from Flood Zone 9 funds. If a project is recommended at the September 18 meeting, project design and permitting would begin in fall 2018 and that process would potentially be completed in summer 2019. Construction of the nursery site would be started first and, in summer 2020, construction work could progress to downtown San Anselmo.

The San Anselmo project would result in a net reduction in flooding for about 530 parcels during chronic flood events that have a 10 percent chance of occurring any given year. An estimated 18 to 19 parcels may be impacted downstream of the project area, north of the Sir Francis Drake Bridge in Ross and east of Sir Francis Drake Boulevard, and upstream of the nursery site. The EIR describes mitigation measures to offset that impact, including installation of flood barriers in Ross and San Anselmo. The replacement of the Winship Bridge in Ross, while not a component of the San Anselmo Project, would help reduce the impacts to parcels upstream of the bridge. A discussion of those impacts can be found in the draft EIR, chapter 4.9, as well as the final EIR.

An EIR for the Ross Valley Watershed Flood Risk Reduction Program, which looks at broader flood mitigation measures for Corte Madera Creek and its tributaries within the 28 square-mile watershed, is currently underway. Learn more by visiting the Ross Valley Watershed program website.


Liz Lewis
Water Resources Manager
Public Works

3501 Civic Center Drive
Suite 304
San Rafael, CA 94903
(415) 473-7226
Email: Liz Lewis
DPW Website