Dec 24, 2020

Portland’s Willamette River Experiences Sewer Overflow

Portland’s Willamette River almost had a sewage-free year, until a recent sewer overflow.

willamette river

Heavy rains in northwest Oregon have caused a sewer overflow into the Willamette River, according to the Portland Bureau of Environmental Services.

Portland’s investment in the Big Pipe Project, a $1.4 billion 20-year-long public infrastructure project, dramatically reduced such incidents, according to the city of Portland. 

“Overflows that used to be common - occurring about 50 times a rainy season, sometimes for days on end - now are rare. Environmental Services projects about four overflows per rainy season, a 94% reduction,” said the city.

“The Big Pipe Project continues to make a big difference,” said Environmental Services Director Michael Jordan. “We enjoy the benefits every day of a river clean enough to swim, paddle, and play. The result of our investment is that river recreation has soared, and river water quality has vastly improved for people and wildlife.”

The sewer overflow is about 80% storm water and 20% sewage, reported the city.

The overflow began around 11 a.m. on Dec. 10 and was occurring from eight outfalls between the Ross Island Bridge and Swan Island, officials said.

During an overflow, and 48 hours after, people were advised to avoid contact with the river because of an increase in bacteria in the water, reported the Portland Bureau of Environmental Services

“Overflows will continue to be rare well after 2020 is over,” said Environmental Services engineer Arnel Mandilag in the press release. “Portlanders have invested in the health of the Willamette River. That investment is making overflows the exception rather than the rule, creating a healthier river for wildlife and people.”

Portland embarked on a project in 2011 which has helped make overflows less common in the city. The Environmental Services' goal is to eliminate 94% of these incidents. 

Before the sewer flow incident, the department was on track to exceed that goal in 2020.

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