Water Quality in the

Tomales Bay Watershed


The first goal identified in the TBWC Watershed Stewardship Plan adopted in 2004 was to "Ensure water quality in Tomales Bay and tributary streams is sufficient to support natural resources and sustain beneficial uses." This goal is central to the past and current activities and interests of the TBWC and its members.


In order to best identify future restoration needs, trends in water quality, and sources of nonpoint water pollution, TBWC has been assessing surface water quality throughout the watershed since 2007. TBWC also provides a clearinghouse for regional water quality data, collected by member and outside agencies and groups leading to compilation and analysis of all available data to provide the "big picture" that is necessary to inform our resource management decisions and priorities.


The Council is currently involved in water quality monitoring through the following elements:


Long-Term Trends – The Council established eleven tributary sites and four Bay sites in the fall of 2007 and regularly monitors these sites to document the long-term water quality trends in tributaries and in the Bay. Learn more on our Trends Monitoring page.


Beach Water Quality -  The Marin County Environmental Health Services monitors bacteria levels at water recreation sites throughout the county on a weekly basis from April 1-October 31, including many sites in West Marin.  The TBWC helps

disseminate the advisory conditions though our website, and through social media.  Learn more on the Beach Water Quality page.


Source Area Monitoring -   From 2007 through 2011, the TBWC conducted storm monitoring at multiple sites in selected subwatersheds to document conditions and relative pollutant contributions from different parts of the watershed.  Results of this monitoring are detailed in the 2013 Final Technical Water Quality Report available in our electronic library.


Giacomini Wetland Restoration -   The TBWC partnered with the Point Reyes National Seashore Association to implement some grant-funded elements of the restoration of over 550 acres of marsh at the head of Tomales Bay.  The funding also supported water quality monitoring of the marsh before, during and after the restoration to evaluate the effect on water quality.  Details of this monitoring are available in Appendix A of the 2013 Final Technical Water Quality Report available in our electronic library.


Growing out of concern for water quality, the Council’s Water Quality Monitoring Program was initiated in 2003 with support from the Marin Community Foundation and County of Marin.  Initial monitoring activities included sampling at three local swimming locations – Ink Wells, Samuel P. Taylor and Green Bridge – and source area monitoring in Inverness – at Third Valley Creek and at Chicken Ranch Beach – to gather information about sources of watershed pollution from septic systems and other human-related activities. Subsequent Proposition 50 funds from the State Waters Resources Control Board

San Geronimo Creek during January 4, 2008, storm. Photo by Rob Carson.

helped fund the Municipal Stormwater Assessment and Recommendation Report. For which the TBWC monitored the stormwater systems in the communities of Woodacre, Point Reyes Station and Tomales during the 2006-2007 winter season. The information and analysis gained from this monitoring is available in Appendix M of the ICWMP in our electronic library.


In 2007, the TBWCF was awarded another Proposition 50 grant from the State Water Resources Board to implement the Tomales Bay Wetlands Restoration and Monitoring Program to integrate the Giacomini Wetland Restoration Project (GWRP) and water quality monitoring to reduce and

 eliminate existing threats and to identify emerging threats that face this critically important watershed. This funding supported three main elements through the 2012 water year: 1) restoration and monitoring of the GWRP, 2) source area monitoring, and 3) trends monitoring - by establishing long-term water quality monitoring at fixed-sites at bottom of eleven tributary watersheds, and at four bay sites, enabling the analysis of long-term water quality trends in the watershed. More details, and recent results are available on the Trends Monitoring page.


TBWC Water Quality Publications & Reports are available in our electronic library.


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