by Sandy Guldman
Providing protection from an event with a one percent chance of occurring in any year (aka the 100-year event) was an original goal of the Ross Valley Watershed Program. Opposition to proposals to achieve this goal from residents of San Anselmo and Fairfax means that it is no longer a realistic goal in the near term. Most of the floodplain is occupied by homes, businesses, and public facilities and many portions of the channel overflow and flood in a 6-year event., turning our communities into detention basins by default.
The current program has a goal of providing protection from 10- to 25-year events by 2027 when the current storm drainage fee ends. It includes projects with plausible funding that are being designed and un-der environmental review, discussed below. Other program components (e.g., creek cleanups; webcams, stream gauges, and warning systems; and some limited assistance for land-owners) are described on the Ross Valley Watershed Program website.
Corte Madera Creek Flood Risk Management Project: This is the old US Army Corps of Engineers (USACE) project, revived with the goal of finally completing it. The Environmental Impact Statement/Environmental Impact Report (EIS/EIR) is in preparation and the draft should be available by spring 2018. Funds for the construction of the USACE project depend on congressional authorization, which may not be forthcoming. To speed implementation of some actions, the project has been divided into phases.
Phase 1 includes the Frederick Allen Park Riparian Corridor, removal of the fish ladder in Ross, and construction of a floodwall along Granton Park in Kentfield. Phase 1 reduces flood risk in parts of Ross and Kentfield and will not increase flood risk at downstream locations. Because the Phoenix Lake Integrated Regional Water Management project
is infeasible under the funding and schedule constraints of the funder, the intent is to request reallocation of Phoenix Lake funds to pay for Phase 1. If stakeholders involved in Phase 1 work collaboratively and promptly agree to submit the project to the funder for approval as a substitute for the Phoenix Lake project, design and permitting for Phase 1 can continue. If the schedule slips, then it is unlikely that other grant funding could be obtained and Phase 1 would have to be delayed until Congress provided funding for construction of the entire USACE project.
Friends of Corte Madera Creek Watershed funded the preparation of conceptual plans, described in the last issue of Creek Chronicles, for partial removal of the concrete channel on the College of Marin (COM) campus. That design is being evaluated in the EIS/EIR and, with completed environmental review in hand, we plan to work with the Flood Control District and COM to seek funding for it from sources other than the USACE so that it can be implemented concurrently with replacement of the Student Center and Student Learning Center at COM. If this schedule can be met, it would be-come Phase 2 of the overall project.
San Anselmo Flood Risk Reduction Project: This project would use funding originally intended for the Memorial Park Detention Basin to provide equivalent flood risk reduction and environmental benefits, but in different locations. The pro-posed detention basin would be located west of Fairfax on the former site of the Sunnyside Nursery growing grounds, which is now owned by the County of Marin. It would reduce the flood risk in Fairfax and, to a lesser extent, San Anselmo. This project also includes removal of the building at 634-636 San Anselmo Avenue, where floodwater first leaves the channel in downtown San Anselmo. The Draft EIR will be re-leased in early 2018.
Bridges: Bridges at Azalea Avenue in Fairfax, Madrone and Nokomis avenues in San Anselmo, and Winship Avenue in Ross are considered structurally or functionally deficient by Caltrans and will be redesigned and replaced by the end of 2020, with most of the funding sup-plied by federal highway funds administered by Caltrans. The funds are already committed. All of these bridges currently contribute to flooding. Some measures, such as low walls, may be needed to protect downstream property from the increased flow under the bridges.
The complex intersection at Bridge and Sycamore avenues is being evaluated. A range of alternative designs is expected, with a Draft EIR, in late 2019. The design for this project, but not its construction, is funded by federal highway funds. If federal funding for bridges remains available, construction could occur in 2021.