Portland city officials are issuing a warning after Wednesday night’s heavy rains.

They caused a combined sewage overflow into the Willamette River.

“It’s sewage, bacteria-laden, so the main problem is a lot of bacteria, and it can make people sick if it gets into a cut. If somebody swallows it, it can make you sick,” said Linc Mann of the Bureau of Environmental Services.

Mann says the overflows will keep happening until the East Side Big Pipe project is finished.

“When that’s activated it will capture almost all of that combined sewage, so in the summer it’ll take a huge storm, much larger than the one last night, to cause the combined sewage to overflow,” added Mann.

Since the project won’t be completed until December of 2011, boaters Howard Collins, of Salem, have to be extra careful.

“I don’t want anybody jumping off the boat. There are some risks I don’t want to undertake,” said, Collins. “The best advice is to avoid contact with the water. If you do come in contact with the water, wash up, and after 48 hour, after the rain stops falling, it’s clear,” said Mann.

The Columbia River is not impacted by the overflow.

The warning on the Willamette should be lifted by Saturday morning.