Flood Control for Marin City

Aerial view of the small pond in Marin City  |  photo from Google Earth  |  post by Larry Clinton

If you’ve ever been caught in a flood on the Marin City off–ramp from Highway 101 south, or been forced to detour around it, you’ll be encouraged to learn that the Marin County Flood Control and Water Conservation District (the “District”) Flood Zone 3 plans to make improvements to the Marin City pond’s drainage system to alleviate that problem.

The flooding occurs during storm events and high tides, exacerbated by sea level rise, which can overwhelm the pond’s drainage system. Overflow from this stormwater pond alongside the Gateway shopping center, together with an insufficient drainage connection to the bay, has led to chronic flooding that impacts travelers and nearby neighborhoods.

The first phase of work would address the drainage problems by designing and permitting a new culvert under Highway 101, a permanent floodwall along a portion of the pond, and a new tide–gate control structure. The existing culvert drains into the bay under Gate 6 ½ Dock, and the outflow has carved a winding tidal creek in the mud of the bay, which has undermined some floating homes.

It is estimated that this design phase will be completed by March 2022, with milestones along the way presented at Shore Up Marin City meetings and Flood Control Zone 3 Advisory Board meetings, as well as updates and reports posted on the Marin Watershed website.

Upon confirmation of compliance with the California Environmental Quality Act and once permits are secured from federal and state agencies, FEMA will release additional funds for construction. If estimated project costs for the construction phase are significantly greater than grant revenue, then the project will be held until alternative funding sources can be found.

The County of Marin and the District will continue to work with the community and stakeholders within in a larger process to address necessary flood reduction projects in Marin City beyond this first project with the pond. Future projects will need support from various infrastructure agencies and property owners in the area.

Shore Up Marin City is a multi-racial environmental justice organization advocating for equitable inclusion of low-income communities in planning and community preparedness with a focus on Emergency Preparedness; Flooding and Hazard Mitigation; Sea Level Rise and Climate Adaptation; Habitat Restoration; and Social Equity.

The Marin County Flood Control and Water Conservation District works to reduce the risk of flooding through effective, transparent, and responsive planning, design, construction, operation, and maintenance of County-owned facilities such as stormwater pump stations, detention basins, bypass drains, creeks, ditches, and levees. The District’s next meeting will be in May. Check back for more info on date, place and time.