Woodacre/San Geronimo Flats Wastewater Recycling Project

Community Development Agency

The semi-rural communities of Woodacre and San Geronimo are located in the Lagunitas Creek watershed, which drains to Tomales Bay. Homes in these communities are currently served by individual on-site septic systems, many of which are sub-standard and a source of public health and water quality concern.

Tomales Bay and the Lagunitas Creek Watershed are designated impaired water bodies for pathogens (bacteria) under Section 303(d) of the Federal Clean Water Act (see Pathogens in Tomales Bay Watershed TMDL).  Faulty on-site wastewater systems, especially for properties in close proximity to streams, have been identified as one of the sources contributing to the impaired water quality.

In 2010, Marin County and a group of concerned property owners, now called the Woodacre & San Geronimo Flats Wastewater Group, conducted a study of alternatives for managing wastewater in the Woodacre Flats area. The 2011 feasibility report, prepared by Questa Engineering Corp., indicated that one of the preferred alternatives would be to replace existing on-site septic tanks with a community wastewater system that would produce tertiary recycled water suitable for irrigating the nearby San Geronimo Golf Course.

In response to increased public interest and with funding from the State Water Resources Control Board, the County expanded the study area to include portions of the adjacent San Geronimo Flats. The 2019 final feasibility report of the community wastewater recycling option for up to 360 homes in the flat area of Woodacre and San Geronimo is available.

With funding from Marin County, Marin Municipal Water District, and the community, the County will soon prepare the environmental impact report (EIR) for the community wastewater recycling project. The environmental review is being prepared by Leonard Charles and Associates. For updates on the EIR process, go to the project’s Environmental Review.

If you have questions or would like further information, please contact the EHS office at (415) 473-6907 Monday through Friday from 8:00 AM to 4:00 PM, or the Woodacre & San Geronimo Flats Wastewater Group.