Toxic pollutants have been identified in surface water, groundwater, sediments, and fish in the Willamette River. These include legacy and emerging pollutants. Legacy pollutants typically refer to a group of chemicals now banned from use (at least in the U.S.), but due to their chemical persistence, remain in the environment and tend to accumulate in aquatic organisms. This broad group includes such familiar pollutants as chlorinated pesticides like DDT, polychlorinated biphenyls (PCBs), and dioxins and furans.

This indicator measures how often toxics are detected at unsafe levels.

The lower 11 miles of the Willamette River were designated a federal Superfund cleanup site in 2000 due to toxic industrial contamination in river sediment.