(Radio Iowa) – The Department of Natural Resources has advised against swimming in 11 lakes across the state again this week. The D-N-R’s Jason Palmer in the Water Quality division says the return of wildlife and agricultural runoff toward the end of the season has created an elevated risk for all types of harmful bacteria. They look first for E-coli.

Palmer says birds in the water around the beaches have elevated the concern of possible bacteria.

The D-N-R held over last week’s advisories as they says the heatwave made it unsafe for workers to take new samples.