Green Lake

Green Lake earns a C — middle-of-the-pack water quality, with one or two parameters dragging the average down from a stronger grade. Clarity, phosphorus, and chlorophyll-a all rate similarly, so there is no obvious single lever to pull on watershed management.

A TSI in the eutrophic range signals a lake doing what nutrient-loaded waters do — supporting an active algal community at the cost of clear water. A maximum depth of 28 ft puts Green Lake in the middle of Minnesota's depth distribution. At 833 acres, Green Lake fits the Minnesota median for monitored lakes, with 4.6 miles of shoreline. Green Lake sits at rank 11 of 19 in Isanti County, in the lower half of the local distribution.

Eurasian watermilfoil is established at Green Lake, which can dampen recreational access and pressure the native plant community. Walleye are documented at Green Lake, one of 15 fish species on record for the lake. Public access is available — the lake is on the Minnesota PCA public-access list. Ice-out has been recorded 10 times at Green Lake, with a median around Apr 10. Multiple sampling years from Minnesota PCA volunteers and partner agencies back the grade, so the letter should hold steady absent a major watershed shift.