The Superfund Process

Need for cleanup

King County believes cleaning up contaminated sediments in the Lower Duwamish Waterway is the right thing to do and has been working to restore the Lower Duwamish for decades. Balancing the waterway's recreational, ecological and maritime uses will make the river healthier for people and wildlife.

Where does the contamination come from?

The Lower Duwamish Waterway is Seattle's primary industrial waterway. Its 32 square-mile drainage area is home to more than 80,000 jobs and a variety of contaminants linked to common, widespread human activities. Decades of unchecked industrial use deposited tons of harmful contaminants including PCBs, arsenic, dioxin and mercury in the waterway's sediments. Today, contaminants continue to enter the waterway from the air, upriver, cars and trucks passing overhead, surface water runoff and sewer outfalls.

What is the risk?

Contamination from nearly 100 years of industrial and commercial activities in the drainage basin has settled into the sediments at the bottom of the waterway.  The contaminated sediments pose health risks to:

• People who eat seafood living in the waterway (but not salmon)
• People who come into contact with sediments along the waterway’s banks and beaches
• Benthic organisms living in the sediments that are important to the waterway’s food chain
• Some wildlife living in the waterway, including river otters

The Lower Duwamish Waterway Superfund cleanup is intended to reduce the risks to these four groups posed by the waterway’s sediments.