The Kansas Department of Health and Environment issued a stream advisory for part of the river near Bowersock Dam.
The City of Lawrence issued a statement saying a pump failed at the wastewater pump station near the dam. The problem caused untreated wastewater to spill into the Kansas River.
Workers repaired the pump late Wednesday morning and stopped the water from flowing into the river.
City leaders plan to work with the KDHE to test the water for high levels of bacteria, if needed.
Anyone living near the Bowersock Dam is warned to stay out of the river. Experts say pets also need to stay out of the water, as a precaution, until bacteria levels return to normal.
Lawrence leaders said the wastewater issue did not impact the drinking water system and it is still safe to use.