Portland Says Avoid Contact With The Willamette For Next Few Days

Heavy rains over the past few days have caused a sewer overflow into the Willamette River at several locations, Portland's Bureau of Environmental Services announced Monday. People are being urged to avoid contact with the river.

Officials say that because of increased bacteria in the water, people should avoid contact with the river until 48 hours after the overflow event ends. As of 1 p.m. on Monday, the event is still going on so the 48-hour clock can't even begin.

The overflows begin at the outfall near the Ross Island Bridge and extend downstream, according to the city. Several outfalls are affected.

The bureau says that this is just the third sewer overflow event of the 2016-2017 winter season with the previous ones having occurred on Jan. 18, 2017 and Thanksgiving Day.

The city says while they would prefer no overflows, the situation is much better than it used to be.

Before the city completed the Combined Sewer Overflow control program, combined sewers overflowed an average of 50 times a year. Today, the combined system overflows to the Willamette River an average of four times per winter and once every three summers.

Portland's combined sewer system carries sewage and stormwater runoff in the same pipes. In December 2011, Portland completed a 20-year program of sewer improvements, including constructing big pipes on both sides of the Willamette River and along the Columbia Slough. The improvements eliminate 99% of CSOs from the slough and 94% from the river.

The bureau says that during heavy storms, the big pipes store large quantities of stormwater and sewage while pumping it to the Columbia Boulevard Wastewater Treatment Plant. During very heavy storms, some combined sewage can overflow. A combined sewer overflow is about 80% stormwater and 20% sanitary sewage.

Photo Colin Miner