Under the federal Clean Water Act (aka Federal Water Pollution Control Act), each state must evaluate which of its water bodies are impaired by pollution. In California, the state and regional water boards assess the state’s waterways every two years to see if they meet water quality standards for beneficial uses, such as the protection of wildlife, human recreation, or drinking water. If the state or the Environmental Protection Agency (EPA) finds the level of pollution in a water body is higher than recommended levels, the state must include that water body on their 303(d) list of impaired waters, and work to identify and limit the pollution sources.

Sea lions at Elkhorn Slough, an impaired water body.

Over 1,000 of California’s water bodies are listed as impaired. Santa Cruz, Monterey, and San Luis Obispo Counties alone contain almost 100 impaired rivers, creeks, sloughs, and lakes. Pollution types include pathogens, excess nutrients, sediment, and toxic chemicals such as pesticides. The pollution comes from diverse sources, such as agriculture, industrial facilities, municipal sewage discharges, urban runoff, and construction projects.

EcoRights, through its research and sampling programs, identifies impaired water bodies and petitions to have them added to California’s 303(d) list.

For example, in 2006 EcoRights and its Humboldt Baykeeper program successfully petitioned the California State Water Resources Control Board and the EPA to add Humboldt Bay to the 303(d) list for dioxin contamination, thereby forcing state agencies to take steps to reduce dioxin pollution.

The State Water Resources Control Board considered several sets of water quality data submitted by EcoRights. The data sources included shellfish tissues samples collected by EcoRights near the Sierra Pacific Industries Arcata Mill, and oyster tissue samples collected by an independent consulting firm hired by Sierra Pacific Industries as part of a settlement agreement in our Clean Water Act lawsuit. Dioxin levels found in some Humboldt Bay oysters were four times higher than the EPA’s “do not consume” level, and most samples exceeded the human health screening level set by California’s Office of Environmental Health Hazard Assessment (OEHHA).