1120 SW 5th Ave, Suite 613, Portland, OR 97204
Overview: 94% reduction in combined sewer overflows (CSOs) to the Willamette River
99% reduction to the Columbia Slough
Before CSO control: An average of 50 Willamette River CSO events each year.
Today: An average of four CSO events each winter and one every third summer.
100%: Eliminating all CSOs, instead of 94%, would have doubled the $1.4 billion project cost
Lesley Stahl narrates Portland's CSO Program, a video overview of Portland's 20-year program to control combined sewer overflows. The overall program became known as the Big Pipe Project.
Cornerstone projects - downspout disconnections, sumps, stream diversions and sewer separations - removed millions of gallons of stormwater from combined sewers to allow construction of smaller CSO control facilities.
Big Pipes - one on the Columbia Slough, two on the Willamette River - intercept combined sewage and stormwater and direct it to the treatment plant.
See if a combined sewer overflow (CSO) or sanitary sewer overflow (SSO) advisory is in effect
Get e. coli and temperature information for the Willamette River in Portland
Information about Portland's combined sewer system and CSO control
CSO control tunnels on the Columbia Slough and Willamette River