MINNEAPOLIS (WCCO) — There’s something very unpleasant happening in Cambridge. Tens of thousands of gallons of raw sewage have leaked into the Rum River.

Monday evening someone spotted the sewage flowing into the river and called the sheriff’s department. A deputy arrived to find the mess oozing out of a man hole, 20,000 gallons total.

It’s now under control.

Unaware of the spill, Cambridge native Kristen Williams came Tuesday to soak in the river scene. It was hard to detect a half a day later.

“It doesn’t smell too bad down here,” she said. “It’s pretty much the normal smell down here.”

Cambridge Utilities director Todd Schwab says the smell was contained to the leak site by the Wastewater Treatment Plant. He says it wasn’t as bad as it sounds. The sewage made up 2 percent of the total water flow.

“It’s such a small part of what flows in the river that it’s diluted pretty heavily,” he said.

And that combined with the recent rain means it’s OK to frolic in the water or fish.

“At this point, it’s safe to do all of those things,” Schwab said.

But that doesn’t mean it’s preferable to everyone.

“I’ve never swam in the river, but I probably won’t be putting my feet in anytime soon,” Williams said.

The spokesperson with the state’s Pollution Control Agency says this does not constitute emergency clean up and the water should be safe.

It’s not clear what caused this leak, but there is a $12 million construction project going on at the plant to make the water cleaner, and that could have been the cause.