Wondering what's in your water, and whether it might make you sick? You might want to check with your next-door neighbors.
A new study by the San Francisco Estuary Institute indicates that suburban pollution like pesticides and fertilizer contribute more pollution to the San Francisco Bay than do the massive farms in the Central Valley. High levels of chemicals such as mercury and PCBs are showing up in the creeks that drain to the bay, and nearby cities seem to be the primary source.
That's a surprise to researchers, who thought that massive industrial farms were overloading tributaries with pollution. It turns out instead that waterways passing through Alameda, Contra Costa, and San Mateo Counties might be more to blame. Luckily, those counties have recently been ordered by the Water Quality Control Board to reduce the amount of trash in their storm-water. Items like trash bags, Styrofoam, and cigarettes are responsible for a large portion of the pollution.
Other culprits: fireplaces, exhaust pipes, and barbecues, which belch soot into the air, where it mixes with humidity and then falls to the ground.
San Franciscans needn't feel too guilty: due to a unique sewer system that dates back to the 1800s, almost all of the City's storm-water is treated before being released into the bay, so the likelihood of suburban human contamination is somewhat diminished.
Challenges remain of course. Some creeks, such as Lobos Creek in the Presidio, drain directly to the ocean without passing through any sort of treatment. Lobos Creek empties on Baker Beach, where recent testing showed high concentrations of potentially harmful substances.
And although we might like to think otherwise, residents of The City have been known to dump garbage on the street.
Until we can figure out how to reduce our chemical dependency -- or scrub every drop of water that falls from the sky -- we can expect more dirty water in the years ahead.