The Environmental Protection Agency has at last proposed to update its 1992 water-quality standards for the San Francisco Bay-Delta to address threats from a dangerous heavy metal called selenium.
Selenium is a naturally occurring element and actually needed in tiny amounts by people -- but it becomes toxic in high concentrations when allowed to build up in the environment. In the 1980s concentrated selenium from agricultural runoff poisoned thousands of birds at the Kesterson National Wildlife Refuge in California's Central Valley.
It's also deadly for endangered fish such as chinook salmon and other wildlife like ducks that feed on clams (clams absorb high amounts of selenium when they filter water as they feed).
Selenium is released into rivers and streams via oil refinery wastewater and agricultural runoff. But a new source could make matters worse: A proposal to build twin tunnels under the Bay-Delta could increase selenium concentrations by recycling selenium-laden water to Central Valley farms.
Tell EPA to keep the Bay-Delta wild and livable by creating strong water-quality standards.