Lower Duwamish Waterway is a superfund site located at Rk 2.5 To Rk 10.8, Seattle, WA 98168. The Environmental Protection Agency (EPA) identifies sites such as Lower Duwamish Waterway because they pose or had once posed a potential risk to human health and/or the environment due to contamination by one or more hazardous wastes. Lower Duwamish Waterway is currently registered as an Active NPL superfund site by the EPA. Because it is on the NPL (National Priorities List), Lower Duwamish Waterway is considered one of the worst hazardous waste sites identified by the EPA.