New Link to interactive fecal coliform testing map of Tomales Bay Watershed
In cooperation with the Regional Water Quality Control Board, National Park Service and Inverness Public Utility District, the Tomales Bay Foundation monitors water quality at 14 fresh and salt water sites in the Tomales Bay Watershed. This program was started in 2007 by the Tomales Bay Watershed Council and continues today as managed by the Foundation. State certified labs provide analysis of fecal coliform colony counts per 100/ml at the sites shown on the map below. In addition we analyze turbidity, pH, temperature, salinity and other variables. This project has continued (mostly) monthly since 2004 with testing at weekly intervals during some summer and winter months. Here are the East Side Tomales Bay and Inverness test results for Fecal Coliform colonies per 100/ml. The state limit is 200.
NEW!!! Here is an interactive map. You can zoom in to see Water Quality (mostly) 5-week Geomean sample results for 2023 and 2024. The geomean is the Nth root of the N (umber of) multiplied Fecal Coliform certified test results. Most of our Geomean samples included 5 tests in summer and winter. However, due to logistics and high water, occasionally a sample is missed. The linked map also shows updated sample site locations. Use this link to access the interactive GIS map.

A map of sampling locations is provided above.