Portland Harbor has a long history of shipping, industrial, and commercial activity because of its key location on the Willamette River. This area of the river also has historical, natural and cultural resource significance. In the 1990s, the Oregon Department of Environmental Quality (DEQ) had ongoing cleanup work at upland sites along the banks of the harbor.

The DEQ began to consider the long term impacts of past releases to the harbor and conducted sediment studies. That work led to a joint 1997 EPA-DEQ study of sediments in Portland Harbor. The results showed that the river sediments are contaminated with DDT and other pesticides, heavy metals, polychlorinated biphenyls (PCBs), and petroleum.

On December 1, 2000, the U.S. Environmental Protection Agency (EPA) added the Portland Harbor Site to the National Priorities List (NPL) for the site cleanup to be addressed under the Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA), also known as “Superfund.”