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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

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Combined sewer overflow to the Willamette River

Heavy rain on the afternoon of Friday, March 28, 2014 caused Portland’s combined sewer system to overflow to the Willamette River. The public should avoid contact with the river from the Milwaukie Boat Ramp (just south of the Sellwood Bridge) downstream to the Willamette’s confluence with the Columbia River near Kelley Point Park.

The combined sewer overflow (CSO) event began at about 5:20 p.m. on March 28. As a precaution, the public should avoid contact with river water until Sunday afternoon, March 30.

It is especially important to avoid recreational activities, such as jet skiing or swimming, during which water could be swallowed. CSOs are contaminated with bacteria from untreated sewage. Environmental Services recommends these precautions to protect public health.

People who fish for 48 hours after a CSO event should wash their hands following contact with river water. Those who choose to eat fish caught in the Willamette River for 48 hours after a CSO event should cook the fish thoroughly to kill bacteria.

Portland’s combined sewer system carries sewage and stormwater runoff in the same pipes. During very heavy rainstorms, the increased stormwater runoff can cause combined sewers to overflow into the Willamette River.

In December 2011, Portland completed a 20-year program to improve the sewer system and reduce Willamette River CSO events from an average of 50 per year to no more than four per winter and one every third summer.

The Bureau of Environmental Services provides city residents with programs to protect water quality and public health, including wastewater collection and treatment, sewer construction and maintenance, stormwater management, and stream and watershed restoration.