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17 Twin Cities metro-area lakes receive failing grades for water quality

Lakes like Nokomis and Bde Maka Ska weren't included in the findings.

Don't eat yellow snow and try to avoid a sudden rush of warm lake water. Both are excellent rules to live by, but sometimes a dirty lake is more than, well, you know. 

According to a 2018 Metropolitan Council lake water quality study, Carver County has the dirtiest lakes in the metro area, followed closely by Dakota County and then Washington County. 

Of the 159 lakes given a grade in the seven-county metro area, 37 percent of them received an "A" or "B," meaning they had "relatively good water quality," the study says. 

Thirty percent got a "C" and the remaining 33 percent were given a "D" or "F," meaning they had "relatively poor water quality." 

Before you jump up with worry that a third of metro lakes are dirty, do know that there are 950 lakes in the metro area, and only 159 of them had a sufficient amount of data to be given a grade. 

Here's a breakdown of grades by number of lakes. 

  • A: 34 lakes
  • B: 25 lakes
  • C: 47 lakes
  • D: 36 lakes
  • F: 17 lakes

According to the Star Tribune, deeper lakes tend to grade better because dirty materials find ways to the bottom rather than settling at the surface. 

Which lakes failed?

  • Bone Lake, Washington County
  • Downs Lake, Washington County
  • Goose North Lake, Washington County
  • Northwood Lake, Hennepin County
  • Big Woods Lake, Carver County
  • Hazeltine Lake, Carver County
  • Goose Lake, Carver County
  • Benton Lake, Carver County
  • Meuwissen Lake, Carver County
  • Maria Lake, Carver County
  • Augusta Lake, Dakota County
  • Scout Lake, Dakota County
  • Long Lake, Dakota County
  • East Lake, Dakota County
  • Chub Lake, Dakota County
  • Cedar Lake, Scott County

Anoka and Ramsey counties didn't have any failing lakes, according to the Met Council's data. 

The study took into account total phosphorus (key nutrients), algae abundance and water clarity to determine which were the dirtiest.

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