PNAS: Environmental Catastrophe in Twin Cities Lakes in 3 Decades
Star Tribune: Rising salt levels threaten Twin Cities lakes by 2050
Twin Cities is a hot spot in a national study of lakes and road-salt runoff. It showed that salt concentrations in the Mississippi, mostly from road salt, have increased 81 percent since 1985.
Many lakes around the Twin Cities are becoming so salty from winter road maintenance that, within three decades, they will no longer support native fish and plants.
The lakes were included in the first study of freshwater chloride contamination across the northern region of the country, an area that has one of the highest density of lakes on earth. The researchers found that lakes showed steadily rising concentrations of chloride even with just one percent impervious land cover around their perimeters.
The Twin Cities turned out to be among the saltiest.
“One of the most impacted areas is Minneapolis and St. Paul, where you have dozens of small lakes,” said Hilary Dugan, the lead researcher and a limnologist at the University of Wisconsin, Madison. “The smaller the lake, the more easily you load it with salt.”
Altogether, researchers analyzed the salt histories of 371 lakes in 10 northern states and Ontario, Canada — 62 of which were in the Twin Cities metro area. The study was published Monday in the Proceedings of the National Academies of Science.
The study could provide new guidance for environmental campaigns in many northern states, including Minnesota, to use less salt. While many of those efforts focus on road and street agencies like MnDOT, Dugan said homeowners and private businesses are to blame for about half the salt used each winter. And no one knows how much they are using.