Rain that fell early Tuesday morning also caused Portland's combined sewers to overflow into the Willamette River.
The city's Bureau of Environmental Services is asking the public to avoid the river for 48 hours after the rain has stopped because of possible contamination from untreated sewage.
In many areas of Portland, sewage mixes with stormwater runoff in a combined sewer system. When the combined sewers receive too much runoff, they overflow into the Willamette River.
Portland is in the final year of a 20-year program to improve the city's sewer system. Until the program is complete in December, overflows of untreated sewage and stormwater will occur during some rainstorms.
After all the city's combined sewage overflow projects are complete in December, the sewers are expected to overflow only an average of four times each winter and once every three summers, instead of an average of 50 times each year.