ST. PAUL — Scientists have identified pollution in hundreds of additional Minnesota lakes and streams.
The new update comes as the state is part way through a 10-year project to monitor water quality in all 80 Minnesota watersheds. Every two years, the Minnesota Pollution Control Agency announces results from another round of monitoring.
With the new additions, there are just under 3,000 total lakes and stream segments marked as impaired in some way across Minnesota.
“It’s essentially a running accounting of where we’ve found problems across the state and the nature of those problems,” said Shannon Lotthammer, director of MPCA’s environmental analysis and outcomes division. “We need to identify them as impaired so we can come up with a plan for fixing the problem.”
Generally speaking, Minnesota’s waters are cleanest in the northeastern part of the state and are least clean in the southwest. Population density, development, industry and agriculture can all contribute to a lake’s or stream’s impairment.
MPCA is three-quarters of the way through its first 10-year cycle of assessments, paid for by the Legacy Amendment voters approved in 2008. Early next decade, scientists will start the cycle over again, revisiting waters they examined in past years.
The new additions for the 2016 update were concentrated in a few parts of the state: a cluster of watersheds in south-central Minnesota, another cluster in north-central Minnesota, and a cluster by the Red River in the northwestern part of the state.
It’s not all bad news for Minnesota’s waters. For one, a lake being marked as polluted doesn’t mean it’s a sewage dump. Instead, it just means that it falls short of being clean and healthy in some way. Some of the impaired lakes have dangerous toxic chemicals; others are perfectly safe to swim in but have damaged ecosystems.
“It can be an aesthetic problem, or it can be more of a human health issue,” Lotthammer said.
More than half of the newly added waters fall into that former category — they’re impaired because they “failed to support the number and quality of the fish and the bugs in the aquatic community that we would expect to see in a healthy stream,” Lotthammer said.
The new list of polluted water doesn’t necessarily mean pollution is getting worse. Rather, MPCA hadn’t surveyed most of these rivers and lakes before. Now that it has, it’s found pollution.
Additionally, while the latest update adds more than 300 new rivers and lakes to the polluted list, it also gave two formerly polluted waters a clean bill of health.
“We see more impairments and more problems being identified in the list,” Lotthammer said. “Over time we hope to see that tip from more water bodies being added to more water bodies being taken off.”
But these improvements won’t come quickly. One of the newly clean lakes, Lake Shaokatan in western Minnesota, has been the subject of cleanup efforts since the 1990s and was only just certified clean.