Tryon Creek Wastewater Treatment Plant

Photo shows aerial image of an industrial wastewater treatment plant by a river
The Tryon Creek Wastewater Treatment Plant, located at the confluence of Tryon Creek and the Willamette River was built in 1965, expanded in 1976, and modified in 2003. The plant treats sewage from parts of southwest Portland, areas of Multnomah and Clackamas counties, and the city of Lake Oswego.

The City of Portland Bureau of Environmental Services owns and operates the Tryon Creek Wastewater Treatment Plant although the plant treats wastewater from sewer customers of both Portland and Lake Oswego under an inter-city contract.

In 2014, Environmental Services completed a facilities planning process for the plant. The plan identified current and future capital improvements required to ensure the plant continues to meet levels of service and regulatory requirements for the next 30 years. The plant is aging and must be upgraded to meet stricter treatment standards, accommodate higher flows, improve plant reliability and resiliency, and to capture and treat odorous air. 

Environmental Services had begun the process of designing and constructing these improvements but will pause this work while Lake Oswego assesses the feasibility of a new treatment plant that takes up less space than the current facility and meets the goals of the upgrade projects. Find more information and get project updates about the Lake Oswego Wastewater Treatment Facility project.

Tryon Creek is an activated sludge, secondary treatment plant. It’s about one-tenth the size of Portland’s Columbia Boulevard Wastewater Treatment Plant.