The Portland sewage system handled storm waters and sanitary waste. In 1985, the Willamette/Slough system contained 56 pipes and concrete bunkers discharging raw sewage, industrial wastes, and toxic pollutants from city streets, into the urban waterways. Despite complaints from citizens, in 1990 the Combined Sewer Overflows (CSOs) still poured billions of gallons of rainwater runoff and sewage annually into the Willamette River and the Columbia Slough.

   Excessive bacteria endangered wildlife and humans, prompting environmentalists to place warning signs on the slough. In 1991 Northwest Environmental Advocates (NWEA) sued the city of Portland to end the discharge of raw sewage in the Willamette River and the Columbia Slough. The NWEA lawsuit resulted in an agreement between the city and the Department of Environmental Quality to clean up CSOs, and more importantly, set a precedent for citizen action in enforcing standards set by the Clean Water Act.