Friday March 3, 2023
Bay Nature —
When Heidi Petty began cleaning up Rodeo Creek nearly two decades ago, she pulled seventeen shopping carts out of the waterway, which runs from western Contra Costa County into San Pablo Bay. Since then, she has extracted mattresses, chairs, fake Christmas trees, a golf club, and a wig. But despite her efforts to clean up this creek-turned-dumping-ground, one particularly noxious type of trash keeps coming: tires. Parts of this urban watershed contain a mess of whole tires, mired in the mud like a monstrous serpent.
“There seems to be a pretty solid theme of using creeks as a disposal for highly toxic things,” says Petty, the watershed program manager at the Contra Costa Resource Conservation District. “And tires are hard to get rid of.”
Trouble is, they’re not just eyesores but likely fish-killers. As tires break down, they release a cocktail of chemicals that leach into the water in creeks all over the Bay Area—which in turn empty into the broader San Francisco Bay. Most pollutants have more subtle impacts on wildlife. But now we have a new—or rather, newly identified—pollutant to worry about: 6PPD-quinone (aka 6PPD-q). This chemical is formed when 6PPD, a chemical long added to tires to prevent degradation, reacts with ozone in the atmosphere. In the past few years, researchers have learned it is lethal to steelhead trout, coho salmon, and chinook salmon; it kills cohos even at very low concentrations. Now, regulators and environmentalists are working to manage 6PPD-q pollution, to protect already imperiled local steelhead trout populations.