Health officials are warning people not to swim in two south Alabama rivers.

The Mobile County Health Department is advising no one to swim in Dog River and Fowl River due to poor water quality.

Local health officials and the Alabama Department of Environmental Management routinely collect water samples from 25 coastal recreational sites throughout Mobile and Baldwin Counties to test water quality, Al.com reported. The testing process looks for enterococci bacteria.

State officials say an increase in bacteria in Dog and Fowl Rivers could be due to recent rainstorms, which cause overflowing sewage, malfunctioning septic systems and storm water runoff.