Environmental investigations focused on two basic concerns. The first was whether contaminants escaped from locations where the Port of Portland disposed of dredged materials within the Ross Island Lagoon. Between 1992 and 1998, the Port of Portland received state and federal authorization to bury contaminated dredged materials from the Portland shipyard and Port terminals in underwater disposal areas, called confined aquatic disposal cells. The Port investigated whether the original disposals were properly handled and whether any contaminants escaped into the environment.
The second concern was potential environmental impacts of upland and in-water disposals at the island complex from sources other than the Port of Portland. Ross Island Sand & Gravel, owner of the islands and lagoon, conducted an assessment to determine what, if any, effects such disposals had. The company also investigated the nature and extent of contaminant releases caused by the breaching of a Port disposal cell during gravel mining operations. The Oregon Department of Environmental Quality provided oversight and coordinated both efforts to assure that the work met objectives.