CSO Advisory

November 17, 2015

Heavy rain this afternoon caused an overflow from Portland’s combined sewer system to the Willamette River in downtown Portland. The overflow began shortly before 6:00 p.m. from an outfall pipe on the east bank of the river near the Morrison Bridge.

Because of increased bacteria in the water, the public should avoid contact with the river downstream from the Morrison Bridge through Thursday evening. It is especially important to avoid recreational activities, such as jet skiing or swimming, during which water could be swallowed.

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 of sewer improvements that reduced Willamette River CSO events from an average of 50 per year to no more than four per winter and one every third summer.

For more information contact Linc Mann, 503-823-5328.

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.

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