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King County’s Wastewater Treatment Division and its predecessor Metro have worked for more than 40 years to restore the Lower Duwamish Waterway.

The Lower Duwamish Waterway (LDW) represents the last five miles of the Duwamish River. Historic activities such as wartime manufacturing, shipping activities and the disposal of raw sewage left the waterway polluted by contaminants including PCBs and phthalates. Now, stringent environmental laws no longer permit industries to discharge process water directly into the river. The biggest source of pollution in our waterways today comes from stormwater runoff from streets, parking lots, homes and commercial/industrial businesses.

In 2001, the U.S. Environmental Protection Agency (EPA) used the federal Superfund law (also known as CERCLA) to begin its own cleanup efforts and liability assignments in the Lower Duwamish. The Washington State Department of Ecology is also involved, using its authority under the Model Toxics Control Act.

Duwamish Waterway, looking southeast with Mount Rainier in the distance