County of Marin - News Releases - Flood Board Reviews Detention Basin Sites

For Immediate Release
June 19, 2015

Ross Valley Flood Board Reviews Detention Basin Sites

San Rafael, CA – While the Golden State Warriors won their first NBA title since 1975 on Tuesday, the Ross Valley Flood Zone 9 Advisory Board was presented with the findings of a draft flood control study to a crowd of more than 60 at Drake High School. The June 16 meeting was the latest in a series of public advisory board meetings aimed at evaluating the existing flood control program, exploring alternatives and seeking the community’s input in finding solutions to mitigate the effects of a 100-year flood in Ross Valley.

The panel and speakers at the recent Ross Valley flood control meeting

With the state well into its fourth consecutive year of drought, the devastating flood of December 2005 which caused nearly $100 million in damages in the Ross Valley is a distant memory for some, but for others provides the baseline and catalyst for flood prevention efforts in the Valley.

The Flood Zone 9 Advisory Board which oversees major flood control capital improvement projects in the Ross Valley, is working hard to implement solutions identified in the Ross Valley Watershed Program to ensure that homes and properties in the Valley are protected from an inevitable future flood event. On Tuesday night the Advisory Board identified a total of ten detention basin sites consisting of five original program sites and five additional alternatives.

The Board directed staff to move forward with further review and analysis of the ten detention basin sites pending confirmation by property owners involved as part of the upcoming Programmatic Environmental Impact Report (PEIR). The PEIR is the next step in implementing the broader flood control program, and includes a high-level review of possible impacts for a range of flood reduction strategies, including bridge replacements, detention basin sites, and creek alterations.

The PEIR will also establish a framework for project-level environmental documents that are consistent with the overall flood control program and serve as an important resource for local jurisdictions to use in preparing documentation for flood control projects in their cities and towns.

The PEIR process is expected to take 18-months and includes many opportunities for public input as more detailed designs and alternatives for specific projects are developed.  Meanwhile, the district staff has extended the public comment on the draft flow reduction study (presented at the June 16 meeting) to Tuesday, June 23. E-mail input on the study can be sent to Senior Civil Engineer Russ Eberwein at

Ross Valley Flood Protection and Watershed Program is a collaboration between the County and the municipalities of Fairfax, San Anselmo, Ross, and Larkspur. The program goals are to reduce the risk of flooding using a watershed-wide approach; integrate environmental restoration features with the flood mitigation projects; and leverage funds obtained through the Ross Valley storm drainage fee to secure state and federal grant funding to study and construct flood protection projects.

The next Flood Zone 9 Advisory Board meeting is scheduled for August, 2015. The latest documents on Flood Control in Ross Valley can always be found at


Neal Conatser
Capital Planning & Project Manager
Ross Valley Flood Protection & Watershed Program, Department of Public Works

3501 Civic Center Drive
Suite 304
San Rafael, CA 94903
(415) 473-2941
Email: Neal Conatser
Public Works website