Moving Forward with Flood Risk Reduction in Kentfield and Ross

by Sandy Guldman

The Corte Madera Creek Flood Risk Management Project is making big strides forward, albeit with some modifications. The project currently consists of components to reduce flood risk and improve fish passage. Flood risk reduction in the Granton Park neighborhood will be accomplished by installing flood walls along the left bank (looking downstream) and constructing a pump station to remove local drainage that accumulates on streets during heavy storms. To aid maintenance of the concrete channel, a ramp allowing vehicles to drive into the channel is proposed near Granton Park. Some low walls will probably be needed along the left bank near College Avenue to reduce the flooding of homes and businesses in that neighborhood. Fish passage will be improved by removing the fish ladder at the upstream end of the concrete channel, creating a smooth transition from the concrete channel to the natural channel, and enlarging the small fish-resting pools in the upstream half of the concrete channel.

Although removing the fish ladder will provide some reduction in flood risk for Ross residents, the Town of Ross opted to preserve the concrete channel and chain link fence in Frederick Allen Park, rather than restore the riparian corridor and further reduce the flood risk in Ross, especially for homes between the park and Sir Francis Drake Boulevard. This is ironic because residents of Ross have prided themselves on stopping construction of the concrete channel since the 1970s; now they are champions of its preservation?

The riparian corridor at Allen Park in Ross would have provided major environmental benefits—another requirement, in addition to flood risk reduction and fish passage, of both the fee passed after the 2006 flood event and a grant from the Department of Water Resources. Although some habitat enhancement will take place upstream of the concrete channel, the significant habitat benefits of the overall project will come from restoring 1.5 acres of creek, riparian, and upland habitat with the Lower College of Marin (Lower COM) Project. This project will lower much of the concrete wall downstream of Stadium Way, in Kentfield, and restore tidal wetland and nearby transition zone and upland habitats. It is designed to be resilient to climate change and adapt to rising sea level, a living shoreline so to speak. It will also create an outdoor classroom where students and faculty can study hydrology, geomorphology, biology, and more.

The future scientists, technology developers, engineers, and mathematicians of Ross School could have had a new, outdoor classroom and laboratory in Town, across the street from their campus, as well. Fortunately, they will still be able to use the one at the downstream end of the concrete channel, at College of Marin, when it is restored. Maybe in the coming years, the next generation of Ross students and residents will be able to revisit creek restoration at Allen Park and pride themselves once again as leaders in creek preservation and restoration.

Funding for construction of the flood risk reduction and fish passage projects is being provided by the Ross Valley Stormwater Fee and the Department of Water Resources. Friends of Corte Madera Creek and the Flood Control District are seeking funding for the Lower COM Project.

Projected calendar:

In process         Prepare complete designs for the entire project

Feb or March    Release request for bids and let contract

April                 Begin construction of pump station and access ramp

June                  Begin construction of in-channel work in Ross and Kentfield

September         Begin construction of Lower COM Project (if funding available)

October            Complete all instream work

Winter 2022-23 Finish planting of native vegetation