Portland celebrated a big achievement this week: Going a whole year without sending poop and other sewage into the Willamette River.
Portland is one of about 800 U.S. cities with a combined sewer system — meaning stormwater and sewage move through the same pipes. It rains a lot in Portland — enough that this system sometimes overflows into the river that cuts through the city.
But a pricey infrastructure overhaul completed almost 14 years ago has helped stem much of that pollution, reducing the amount of E. coli bacteria in the river — making it cleaner for Portlanders wanting to take a dive.
FILE: A man jumps into the Willamette River in Portland in 2015.
Christina Belasco / OPB
Some Portlanders celebrated this week’s achievement with a cold plunge, along with toasty saunas and campfires organized by a river advocacy group, Human Access Project.
The two-decade-long sewer overhaul known as the Big Pipe Project cost about $1.4 billion by the time work finished in 2011. Before this system was installed, sewage overflowed into the river an average of 50 times annually, according to the Portland Bureau of Environmental Services. Now about four overflows occur in a typical rainy season. The city also reduced overflows into the Columbia Slough by 99%.
The bureau estimates it would have spent twice as much money on a system that stopped overflows entirely.
This isn’t the first time the city celebrated a year with no overflows: Portland went 499 days without overflows between August 2019 and December 2020.
As part of the Big Pipe Project, Portland installed three massive pipes with diameters measuring up to 22 feet that could handle larger water inflows.
The city also shifted its focus to what’s called "green infrastructure" — like trees, plants and soils that absorb and filter water naturally. It installed rain gardens between sidewalks and streets, where grasses and rock streams slowly filter water.
The city also encourages residents to disconnect their roof downspouts from sewer pipes, instead of directing water into their yards. This has helped redirect an estimated 1.2 billion gallons of stormwater out of sewers.
The bigger pipes have allowed the city to take in more sewage. The bureau is now expanding its wastewater treatment facility on Columbia Boulevard, a $515 million project.
