A short but heavy Monday storm caused a sewage overflow into the Willamette River. City officials are advising residents to avoid contact with the stretch of it from the Morrison Bridge downstream to the Willamettes confluence with the Columbia River near Kelley Point Park.
The Bureau of Environmental Services issued the following statement Monday afternoon.
A brief, intense rainstorm this afternoon caused Portlands combined sewer system to overflow to the Willamette River. Combined sewage overflowed through an outfall pipe near the Morrison Bridge on the east bank of the river. For the next 48 hours, the public should avoid contact with the river from the Morrison Bridge downstream to the Willamettes confluence with the Columbia River near Kelley Point Park.
The combined sewer overflow (CSO) event began shortly after 4:00 p.m. today and lasted for about 12 minutes. As a precaution, the public should avoid contact with river water until the afternoon of Wednesday, June 18.
It is especially important to avoid recreational activities, such as jet skiing or swimming, during which water could be swallowed. CSOs are contaminated with bacteria from untreated sewage. Environmental Services recommends these precautions to protect public health.
People who fish within 48 hours of a CSO event should wash their hands following contact with river water. Those who choose to eat fish caught in the Willamette River within 48 hours of a CSO event should cook the fish thoroughly to kill bacteria.
Portlands combined sewer system carries sewage and stormwater runoff in the same pipes. During very heavy rainstorms, the increased stormwater runoff can cause combined sewers to overflow into the Willamette River.
In December 2011, Portland completed a 20-year program to improve the sewer system and reduce Willamette River CSO events from an average of 50 per year to no more than four per winter and one every third summer.