Public health investigators are testing portions of the Arkansas River after raw sewage backed up at a prison in Canon City and spilled into a nearby creek.

The water quality tests are expected back later this week after a sewage line for the East Canon City Prison Complex was clogged Sunday morning, sending sewage spilling into an unused waste water lagoon and then a creek that flows into the Arkansas River, according to the Colorado Department of Corrections.

The blockage was discovered Tuesday.

The city of Florence occasionally draws from the river, but it hadn’t done so for nine days, the corrections department said.

Investigators haven’t found any evidence that the raw sewage has affected life in the river.

While investigators await test results, people are asked to stay out of the river near the complex.