The Shell oil refinery in Martinez discharges too much toxic selenium into San Francisco Bay, harming wildlife, Baykeeper recently told regulators. We urged the Regional Water Quality Control Board to tighten limits on the amount of selenium in treated wastewater Shell is permitted to release into the Bay.
At trace levels, selenium is an essential micronutrient. But selenium is also a byproduct of oil refining. At moderate levels in water, it’s a potent toxic pollutant. Selenium inhibits growth and causes gross deformities in wildlife, and can kill bottom-feeding ducks and fish.