Shallow groundwater response to sea-level rise: Alameda, Marin, San Francisco, and San Mateo Counties

Pathways Climate Institute LLC (Pathways) and the San Francisco Estuary Institute (SFEI) gathered and analyzed multiple data sets and collaborated with city and county partners to analyze and map the existing “highest annual” shallow groundwater table and its likely response to future sea-level rise. This effort covers four counties (Alameda, Marin, San Francisco, San Mateo) and was funded by the Bay Area Council’s California Resilience Challenge.

The response of shallow groundwater to sea-level rise is a relatively new field of study. For low-lying coastal communities, sea-level rise adaptation efforts must consider the potential for groundwater rise to avoid maladaptation. The need to better understand this slow and chronic threat was identified as a critical data gap in the San Francisco Bay Area’s (Bay Area’s) adaptation efforts during the Bay Area Groundwater and Sea-Level Rise Workshop in 2019. The study focused on the San Francisco Bay side of each county and does not include the Pacific coastline of Marin, San Francisco, nor San Mateo Counties. An advisory committee composed of city and county representatives provided essential support by gathering data and reviewing depth-to-groundwater maps. Additional academic and agency advisors participated in project team meetings and informed project direction.