Wastewater Treatment

The Water Quality Division operates Molalla's Wastewater Treatment Plant (WWTP) and manages the resulting treatment byproducts, which are biosolids and treated effluent. Our mission is to maintain and improve the city's wastewater treatment system in a sustainable, affordable, and professional manner. 

Wastewater byproducts are managed in accordance with the National Pollutant Discharge Elimination System (NPDES) Waste Discharge Permit, issued by the Oregon Department of Environmental Quality (DEQ). Solids removed during the sewage treatment process are treated into biosolids. These are land applied to pre-approved surface sites to improve soil content for non-food source farming or sent to a landfill certified to receive biosolids. From May 1 through October 31 each year, recycled reuse water (effluent) is produced as agricultural irrigation water at pre-approved locations.  From November 1 through April 30, effluent may be discharged to the Molalla River in accordance with permit requirements.

To report sanitary sewer overflows or other wastewater related emergencies, please contact the following:

Daytime Hours 8:00am - 4:30pm (M-F) Call:  (503) 829-6855
After Hours, Weekends & Holidays Call: (503) 829-4160

To report other non-emergency wastewater treatment plant related issues:

Call: (503) 829-5407     Email: wwtp@cityofmolalla.com