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The City of Portland, Oregon

Environmental Services

working for clean rivers

Phone: 503-823-7740

Fax: 503-823-6995

MAILING ADDRESS: 1120 SW 5th Ave, Room 1000, Portland, OR 97204

More Contact Info

Lagoon Reconstruction

lagoon constructionThe city constructed the Triangle Lake Lagoon just north of the Columbia Boulevard Wastewater Treatment Plant in 1970 to store and treat solids produced during the wastewater treatment process. Environmental Services is working on a long-term lagoon reconstruction project. Phases three and four of the project have begun and will continue until the end of 2020

The work includes dewatering parts of the lagoon, removing solids (watch the video below to see how they do it), and reconstructing and lining the lagoon system. To maintain daily plant operations, Environmental Services is completing the project in phases over several years.

Environmental Services began depositing dried solids in the south section in summer 2013 and will continue depositing dried solids in that section for several years while work continues on the lagoon’s north section.

Columbia Slough Trail Closures

Construction occasionally requires the project contractor to close the Columbia Slough trail to safely move equipment and vehicles in and out of the construction area. The city posts signs and maintains a recorded hotline (503-823-1993) to advise trail users of periodic closures during the lagoon reconstruction project.

map of Lagoon reconstruction project

Odor Advisory and Reporting

During construction, the contractor dewaters portions of the lagoon to allow solids at the bottom to dry before removal. There may be a slight increase in odor during drying and solids removal. The contractor uses special equipment and techniques to minimize odors during construction. Neighbors can subscribe to the Plant’s Odor Notification System to receive notice when maintenance and construction projects will result in odors beyond treatment plant boundaries. Go to to sign up for odor notifications, or to report an odor online.

For More Information

Contact Debbie Caselton at 503-823-2831.