Will Carruthers, NORTH BAY BOHEMIAN
On May 10, the Environmental Protection Agency (EPA) quietly signed off on a plan meant to reduce pollution in the 146-square-mile Petaluma River Watershed.
That’s right. Although the problem is rarely discussed, the Petaluma River has been listed as “impaired” by excessive levels of bacteria since 1975.
The bureaucratic document approved by the EPA is known as a Total Maximum Daily Load (TMDL). It sets levels of acceptable waste discharge from various sources in an attempt to lower the levels of fecal bacteria found in the watershed until the water is deemed clean.
While preparing the TMDL, scientists from the San Francisco Bay Regional Water Quality Control Board tested water from throughout the watershed for Fecal Indicator Bacteria to determine the amount of waste from warm-blooded mammals that has seeped into the water. Although indicator bacteria themselves are not dangerous, scientists use the strains to detect potentially dangerous levels of contamination in the water.
In a report accompanying the TMDL, water board staff identified 12 sources of pollution, which they then lumped into three general categories: human waste, animal waste and municipal stormwater runoff. In tests conducted between 2015 and 2016, water board scientists found bacteria tied to humans, horses, cows and dogs throughout the Petaluma River and its tributaries.
When asked in late 2019 about the levels of E. coli discovered in the Petaluma River, Farhad Ghodrati, an environmental scientist with the San Francisco Bay board, said the test results showed “some of the highest concentrations we have seen in the region.”
At the same time, Dr. Celeste Philips, who then served as Sonoma County’s Health Officer, warned Petaluma River users against drinking the river water or using the water for cooking due to the levels of E. coli. “Adults and children should wash hands/shower and towel dry after swimming; rinse off pets after they come into contact with the water,” Philips added.