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

North Mankato 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 effected 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.