More than 300 polluted lakes and rivers added to Minnesota's impaired waters list

Another 305 streams, lakes and rivers in Minnesota have become too polluted to meet federal water standards and will be added to the state's impaired waters list.

The list, updated Monday by the Minnesota Pollution Control Agency (MPCA), now includes about 3,000 bodies of water with more than 6,000 specific impairments.

"These are streams with degraded habitat or with too much sediment for fish to find food," said Peter Tester, deputy commissioner of the MPCA. "Many have high bacteria levels that make them unsafe to swim. Many have too many nutrients that grow algae. Some have more than one impairment. That's too many."

Every lake or stretch of river on the list tested too high for at least one pollutant that can harm swimmers, kill off aquatic life or make fish unsafe to eat. The most common problems in recent years have risen from pollutants that have many sources, including some from miles away or even from out of state, which makes them especially daunting to regulate.

Much of the Le Sueur River in south central Minnesota, for example, was added to the list because its fish now have too much mercury to be safe to regularly eat. The vast majority of that mercury has been building up slowly over time from air pollution originating outside of Minnesota, according to the MCPA.

The mercury is carried in by the wind and lands either directly on Minnesota's rivers and lakes through dust particles or washes into the water through erosion and runoff after collecting on the soil.

For the first time, the state added rivers and lakes that were impaired by two pollutants that are quickly becoming more of a health and environmental concern: sulfate and chemicals known as PFAS.

Sulfate pollution is high enough in 35 bodies of water, primarily in northeast Minnesota, to prevent wild rice from growing, according to the updated list.

That pollution likely is coming from mines and wastewater treatment plants, said Catherine Neuschler, who manages water assessment for the MPCA.

The agency is coming up with plans to reduce sulfate contamination in those lakes and streams, which could include new monitoring requirements from companies or cities that may be contributing to the problem, she said.

Polyfluoroalkyl substances — also called PFAS and PFOS — are a wide-range of chemicals that don't break down in the environment. They can accumulate in blood and have been linked to certain types of cancer and other health risks.

At least some PFAS pollution is now in virtually every body of water in the state. But it has built up in high enough numbers to cause special concern in 15 lakes and streams, all of which are downstream from known contamination or disposal sites, said Miranda Nichols, coordinator of the impaired water list.

"We looked at water across the state and found low levels of PFAS in just about all of them," she said.

The majority of PFAS impairments are near the Twin Cities, including the St. Croix River.

Three lakes and rivers downstream from the Duluth International Airport also were contaminated.

Phosphorus and other nutrients that are carried into streams from agricultural runoff and sediment from erosion continue to be problems throughout much of the state. More than 50 lakes and streams, including parts of the Chippewa and Buffalo rivers, were added to the list because of nutrient pollution, which can suck oxygen out of water and spawn toxic algae blooms that kill dogs and make swimmers sick.

The majority of additions to the list were made because the waters were so polluted that fish and other aquatic life has died off. "That has been true for the last ten years," Nichols said.

Greg Stanley • 612-673-4882