Saturday Sewage Overflow Only 2nd This Year, Officials Say

PORTLAND, OR — A brief sewage overflow into the Willamette River occurred over the weekend near the St. Johns Bridge, according to the Portland Bureau of Environmental Services. The overflow was reportedly caused by heavy rain in the area on Saturday.

City officials are unsure how long the overflow lasted and it's unclear how much combined sewage spilled. They advised the public to avoid contact with the river through the rest of the day Saturday.

Combined sewage overflows are reportedly a mix of 80 percent stormwater and 20 percent sewage. Overflows are rare enough, though they tend to happen around periods of heavy precipitation — be it snow or rain.

Incidentally, overflows into the Willamette were reportedly reduced by 94 percent following the completion of a pipe project in 2011. The same project also saw a 99 percent reduction in overflows to the Columbia Slough, officials said.

Dubbed "The Big Pipe" project, a $1.4 billion investment saw to the construction of several water infrastructure improvements specifically focused on mitigating stormwater runoff. Prior to the project's completion, overflows occurred roughly 50 times per year, with some overflows carrying on for days at a time.

Now, overflows happen about seven times per year — four times in the winter and roughly three times in the summer. Saturday's was only the second overflow in 2018.

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For more more information on combined sewage overflows, visit PortlandOregon.gov/BES.

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