The Outboard Marine Corporation (OMC) Superfund site is located on Lake Michigan on and around the northern Waukegan Harbor area in Waukegan, Lake County, Illinois. Waukegan Harbor is a federally-authorized and federally-maintained harbor that was constructed in the late 1800s to serve the Lake County area. The harbor is a designated port of refuge for boats caught in severe storms. Land use in the immediate area is marine-recreational and industrial. Several industries still use the harbor to deliver raw material (gypsum, cement) from Michigan to make wallboard and concrete in manufacturing facilities located directly on the harbor.

From about 1948 to December 2000, OMC manufactured outboard motors in its OMC Plant 2 facility located to the north of Waukegan Harbor. In the 1960s and 1970s, OMC had purchased an estimated 8 million gallons of hydraulic fluid containing polychlorinated bipenyls (PCBs) for use in its various types of machinery making engine parts. The fluids containing PCBs were sometimes discharged through floor drains leading into sewers that discharged onto the OMC Plant 2 grounds and into Waukegan Harbor. As a result, an estimated 700,000 pounds of PCBs were estimated to be present in the soil on the OMC Plant 2 site and another 300,000 pounds of PCBs were estimated to be in the sediment in Waukegan Harbor. Under EPA oversight, OMC cleaned up PCB-contaminated northern harbor sediment and some PCB-contaminated OMC Plant 2 site soils in 1990-1993.

OMC operated several vapor degreasers at the OMC Plant 2 facility to clean newly made boat engine parts with trichloroethylene (TCE). Leaking degreasers and/or TCE storage tanks created a widespread TCE groundwater contaminant plume and an isolated dense, non-aqueous phase liquid (DNAPL) pool of pure TCE beneath the OMC Plant 2 site. After declaring bankruptcy in December 2000, OMC legally abandoned the Plant 2 facility in December 2002.

In the early 1900s, a wood-treating plant operated on the WCP site, followed by a manufactured gas plant in the 1920s and a coke oven gas plant in the 1940s. The WCP site was purchased and the coke plant was disassembled by OMC in approximately 1972. Contamination at the WCP site was discovered during OMC's harbor cleanup in the early 1990s. It has arsenic and polyaromatic hydrocarbon (PAH) soil contamination and the groundwater is contaminated with high levels of ammonia, arsenic, benzene, and phenol.