ST. PAUL (AP) -- Minnesota cities are seeing an increase in emergency sewage discharges as they struggle with rainfalls that can overwhelm systems that collect and treat wastewater.

Cities like North Mankato are dealing with rising waters. The city has released more than 4 million gallons of untreated sewage into the stormwater system since a June flood.

Experts say these emergency discharges are happening more often, as cities grapple with a rise in extreme rainfalls.

The Minnesota Pollution Control Agency says that since 2010, wet weather has affected wastewater treatment operations an average of 143 times a year, which has resulted in raw or partially treated sewage overflowing or being discharged into the environment.

More than 140 cases have been reported so far this year.