The Minnesota Pollution Control Agency is advising people to avoid swimming or skiing in Lake Minnetonka and two other nearby lakes, after heavy rains forced the city of Mound to release untreated sewage into the storm water sewer system Sunday morning.
The MPCA gave Mound permission to release the sewage in order to keep waste water from backing up into the basements of around 1,000 homes in the city. The city has since stopped releasing the water.
"The heavy rainfall has caused a great deal of just groundwater infiltration into the sewer system," said Mound City Manager Kandis Hanson.
Mound began releasing the waste water onto six sites near Lake Minnetonka, Dutch Lake and Lake Langdon.
The MPCA says the waste water will likely make its way into surrounding lakes.
"Much of what was siphoned off the system over the weekend was nearly clear. However, it had been contaminated, because it had been part of the sewer system. It was filtered. There were no solids that went into our lakes. If you were to look at it, it virtually ran clear," Hanson said.
Hanson says the sewage is being filtered as it is put into the stormwater system.
But The MPCA says the sewage will increase the amount of E. coli bacteria in the lakes.