Minnesota is adding another 511 lakes and river segments to its list of impaired waters and taking 13 water bodies off the list.
Every two years, the Minnesota Pollution Control Agency updates the list, based on intensive monitoring of parts of the state's 81 major watersheds.
The MPCA's Shannon Lotthammer said a notable recent success is the clean-up of the Credit River, which was impaired by sediment.
"There were citizens, Scott County, the city of Savage, the Pollution Control Agency, and other groups, agencies, individuals that worked to clean up that river by installing rain gardens and stabilizing eroding slopes to clarify the water and make sure there wasn't sediment coming into the water and creating problems," Lotthammer said.
In another case, Jewitts Creek had too much ammonia, until the Litchfield wastewater treatment plant was upgraded.
Lotthammer said the state is about half-way through assessing all its major watersheds, and on average finds 40 percent of waters are impaired — which means they don't meet state standards for swimming, boating, or fishing.
By 2018, Lotthammer said the state will have data on all the major watersheds in the state. She's hoping more waters can then be removed from the list.
"Because we'll be able to see fruits of all the labor that agencies, individuals, local governments are putting into restoring and protecting water quality," Lotthammer said.