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 is the limiting factor — phosphorus is reasonable but suspended particles or algal cells keep water transparency below Minnesota norms.

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. Green Lake reaches 32 ft at its deepest point — typical for Minnesota mid-sized lakes, with seasonal stratification but limited cold-water refuge. At 1,809 acres, Green Lake is one of the larger lakes in Chisago County, with 16.5 miles of shoreline supporting multiple distinct use patterns. Green Lake ranks 14 of 31 in Chisago County — solidly in the upper half of the local distribution.

Eurasian watermilfoil is established at Green Lake, which can dampen recreational access and pressure the native plant community. The fishery includes walleye alongside the lake's other 15 documented species — a notable draw for Minnesota anglers. Public access is available — the lake is on the Minnesota PCA public-access list. Ice-out has been recorded 13 times at Green Lake, with a median around Mar 31. The grade is supported by multiple sampling years from Minnesota PCA volunteers and partner agencies, giving the letter a reasonably stable foundation.