The Tri-City Water Pollution Control Plant uses physical, biological and chemical treatment to clean approximately 8.4 million gallons of wastewater per day, created by the cities of Gladstone, Oregon City and West Linn. Following the treatment process, clean water is released into the Willamette River.

In 2010, a 14,200 sf greenroof was constructed atop the Tri-City Waste Water Treatment plant using the American Hydrotech greenroof system.