Hwy 37 Flood Woes: Study To Identify Potential Solutions

MARIN COUNTY, CA – A study of Highway 37, with its long track record of being inundated by flooding from high tides, sea level rise and runoff from significant storms, will begin this spring to help recommend improvements to increase resiliency along the corridor, according to officials.

The Marin County Board of Supervisors will decide at its upcoming March 12 session whether to move forward with the study, estimated to cost $148,000.

The corridor recently was closed for several days due to storm-related flooding and closed for about a month in early 2017 due to heavy rains and high tides. While Marin County Flood Control and Water Conservation District-maintained infrastructure was not directly related to those incidents, all stakeholder assets in the corridor could potentially be vulnerable and need to be addressed for resiliency, authorities said.

The cost of the study was awarded a Senate Bill 1 Adaptation Planning grant from Caltrans for $130,170. The remaining $17,830 will be covered by the County of Marin, the Flood Control District and the Transportation Authority of Marin, officials said.

The project will assess recent studies of Highway 37, as well as sea-level rise studies, conducted by various local and state agencies, to gather additional data and develop recommendations for improvements along the corridor from Highway 101 to Petaluma River, according to authorities, who added that the project is an assessment and not intended to implement physical improvements along the highway corridor.

Study results, expected to be completed by winter 2020, will help determine a cost-effective, recommended approach that may include such potential solutions as raising Highway 37, enhancing nearby existing levees or a combination of solutions.

“The detailed study will provide an approach that can be used to pursue funding on the scale that is likely to be necessary,” said Dan Dawson, Marin County Department of Public Works’ principal transportation planner. “Given the scope of any potential solution and the related environmental considerations, it’s too early in the process to speculate on a potential timeline to complete appropriate and durable solutions.”

The complex issue also requires coordination between a variety of such stakeholder agencies as Caltrans, Pacific Gas & Electric, Sonoma Marin Area Rail Transit, Marin County Flood Control and Water Conservation District, Novato Sanitary District, private landowners, California Coastal Conservancy and the California State Water Resources Board.

The County of Marin has prioritized climate change adaptation the past few years and is assessing current and future effects of sea-level rise. The Flood Control District is addressing the need by making improvements to district-owned flood infrastructure whenever possible and planning specific projects that target the issue. More information on the county’s sea-level rise efforts can be found online.

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