San Rafael, CA – Residents and businesses near Corte Madera Creek in Ross Valley have been inundated by flooding for years. To improve public safety and protect property, the Marin County Flood Control and Water Conservation District has partnered with the Town of San Anselmo to develop the San Anselmo Flood Risk Reduction Project. An environmental impact report (EIR) for the proposed project is nearing completion and the draft is expected for public review in April, rather than February, 2018, as originally scheduled.
Local residents attended a previous meeting about flood-reduction efforts at the former Sunnyside Nursery location. The project is a component of 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. An EIR for the entire program is underway in parallel with the San Anselmo Project EIR.
EIRs require public agencies to document and consider the environmental implications of their actions. The San Anselmo Project EIR contemplates a proposed project comprised of two complementary parts. A basin to temporarily divert and store floodwater would be constructed at the former Sunnyside Nursery site at 3000 Sir Francis Drake Boulevard, about a mile north of downtown Fairfax. The basin would be coupled with the acquisition and removal of a building at 634 San Anselmo Avenue that obstructs the creek’s natural flow.
In March 2017, the Marin County Flood Control District Board of Supervisors, which is comprised of the same five members of Marin County Board of Supervisors, approved a services agreement for Environmental Science Associates to prepare the project EIR. The report is expected to cost $400,968, which is covered under the program’s $8.7 million state grant and the $8.7 million local match funds.
District staff sought input from the community, the Zone 9 Flood Advisory Board and the San Anselmo Town Council for project recommendations to include in the environmental review. A public scoping meeting was held in April 2017 to help facilitate community involvement.
During the course of the environmental analysis, design features at the Nursery Basin were refined and it became necessary to move the completion date for the draft from February to April 2018. The revised features included updated topographic surveys, soils and groundwater data, as well as community feedback. With that information, new hydraulic model runs were performed to quantify the impacts and benefits of the proposed design features.
Some of the design refinements to the Nursery basin include flatter basin side slopes, newer topographic surveys that reflect the most up-to-date conditions of the creek bed and banks, and a 15-foot perimeter road for maintenance access. Those features, along with the proposed 50-foot setbacks from adjoining properties, reduce the flood storage capacity of the basin to about 30 acre feet from the original concept plan of 50 acre feet.
The next opportunity for the public to provide feedback will be in April when the draft EIR is released. The Flood District Board of Supervisors will hold a public meeting in April during the 45-day review period. Additional information on how and when to participate in the environmental review will be provided in March.
Businesses at 634-636 San Anselmo Avenue continue to operate during the preparation of the project EIR. The district is preparing a relocation plan for the tenants and their businesses should the project EIR be certified by the Flood District Board of Supervisors for the proposed plan. The final San Anselmo Project EIR is expected to be brought to the Flood District Board of Supervisors for consideration and approval in June.
Learn more about the San Anselmo Flood Risk Reduction Project on the Ross Valley Watershed program website.