The City of McMinnville Wastewater Treatment Plant is located at 100 Cope Street. It is a 4 million gallon per day activated sludge treatment plant with a 3.22 million gallon Envirex Oxidation Ditch. The treatment consists of three two-staged screw pumps, two mechanically cleaned bar screens and a two channel aerated grit removal system. The secondary clarifiers are two 80 ft. diameter Envirex Rim-Flo Tow-Bro Clarifiers with Sodium Hypochlorite for disinfection and Sulfur Dioxide for dechlorination. The sludge process uses two sludge holding tanks and 1-two meter belt filter press to de-water the sludge. The sludge then is processed through a lime stabilization process to produce a Class-A Biosolid which is then given away to farmers who come and get it to use as a soil amendment.
In 2020, the City of McMinnville completed a 4 Million Dollar Plant Upgrade.