Two sets of water quality tests point to human waste

Water quality tests commissioned by the San Geronimo Valley Planning Group have largely confirmed the county’s continued findings that human waste makes its way into San Geronimo and Woodacre Creeks.
Yet the planning group, which has long questioned the need for a large-scale solution to the contamination problem, continues to call for more testing before the county moves ahead with a proposed community wastewater system.
Meanwhile, the county’s agreement to purchase the former San Geronimo Golf Course has thrown a wrench into its plans for the wastewater system, whose treatment plant was proposed to be located on the course.
“Maybe we don’t need a whole new system.” The problem of leaky septic systems in the valley was first identified in 2005 in response to anecdotal accounts from residents, who banded together to form the Woodacre and San Geronimo Flats Wastewater Group.
“To justify the proposed treatment plant, supporters of the project frequently claimed that the Woodacre Flats was heavily contributing to contaminants in the Lagunitas Creek Watershed,” the planning group’s analysis of the new study out of Berkeley Labs states.
“It therefore became critical that the [planning group] definitively determine the sources of any creek contaminants.” As the county began working to secure funding from the regional water quality control board for microbial testing—taking over a proposal that originated with the Tomales Bay Watershed Council—the planning group took matters into its own hands.
During last week’s planning group meeting, Dr. Anderson and Lorene Jackson, project manager with the county, disputed which scientific method was more “sensitive.” “While PhyloChip is an exciting technology with many uses, one of its best uses is trying to understand unknown sources of contamination,” Ms. Jackson explained in an email last week.
The county’s study found markers for human waste at each of the testing sites, with the marker appearing at the Woodacre Creek site each of the four testing times, at Meadow Way three out of the four testing times and at San Geronimo above Woodacre Creek two out of the four testing times.
In December 2016, the first month in their study, all three of the sites tested were positive for human waste.
Mr. Naffziger said the results proved that contamination was occurring in areas outside of the San Geronimo and Woodacre flats, the area that the proposed wastewater system would address.

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