Parks Conservancy begins Bothin Marsh Restoration Project


A pole in the Bothin Marsh Open Space Preserve showing projected sea level rise by designated years. (Johanna Meezan)

By Claire Conger

The Marin County Parks and the Golden Gate National Parks Conservancy began the Bothin Marsh Restoration project this year to defend against rising sea levels in Richardson Bay. Extending 106 acres, the Bothin Marsh Open Space Preserve in Mill Valley is expected to see 10 inches of sea level rise in the next 10 years, a measurement that would result in a regular flooding of 90 percent of Bothin’s wetlands, according to the Evolving Shorelines vision, an overview created by One Tam, a collective conservancy of local parks services and conservancies. The restoration project plans to strengthen the natural tidal marsh processes to accommodate up to three feet of sea level rise, and is planned to be implemented in five years.

In the beginning stages of the project, in-depth scientific research on the Richardson Bay’s tidal marshes was conducted to anticipate the effects of sea level rise and potential renovations on Bothin Marsh, according to project manager Rob LaPorte. The project was funded by the Marin County quarter cent sales tax Measure A, which supports parks, open space, and agricultural lands across Marin.

“Existing sea levels are threatening the preserve’s shoreline habitats and their ability to support abundant native wildlife, including special-status species, migratory birds, and rare plant species,”  LaPorte said. “In addition, existing public active transportation and recreational access to and through the Preserve is severely threatened by sea level rise. The Mill Valley-Sausalito Pathway is a critical link in the San Francisco Bay Trail and regularly floods at the Preserve over 30 times each year.”

Bothin Marsh Restoration is currently in the design phase and will begin conceptual design this fall. Marin County Parks and the Parks Conservancy are working with wetland ecologists, landscape architects, and coastal engineers to design and develop a plan for enhancing the marsh in order to mitigate sea level rise–induced flooding. The project was recently awarded a grant from the State Coastal Conservancy and the Marin Community Foundation to complete this phase.

Once all of the potential solutions and challenges for the marsh and multi-use path are understood, the community will be presented with these ideas. On October 17, One Tam held an informational community event to present the Bothin Marsh Restoration project

“I sincerely believe that the next generation is crucial to the Project’s success and for coming up with creative solutions to the challenges of climate change and sea level rise,” LaPorte said. “It is key to continue spreading the word to [others] about the importance of climate change mitigation.”