Chisago Lake

The LakeGrade rubric puts Chisago Lake at a C: clarity at 4.0 ft, 32 µg/L of phosphorus, and a TSI of 55 signal an intermediate trophic state. Clarity is the limiting factor — phosphorus is reasonable but suspended particles or algal cells keep water transparency below Minnesota norms.

At a TSI of 55, Chisago Lake reads as eutrophic — nutrient-rich enough that summer algal growth and reduced clarity are expected, not unusual. Chisago Lake reaches 34 ft at its deepest point — typical for Minnesota mid-sized lakes, with seasonal stratification but limited cold-water refuge. Chisago Lake covers 944 acres alongside 13.2 miles of shoreline — a mid-sized water that supports a working fishery without being so large that conditions diverge between basins. Chisago Lake sits at rank 18 of 31 in Chisago County, in the lower half of the local distribution.

Eurasian watermilfoil has been documented at Chisago Lake, requiring shoreline management to keep dense mats from crowding native vegetation. Walleye are documented at Chisago Lake, one of 14 fish species on record for the lake. The lake lacks a documented public access point, so visitor use is limited. The lake has a partial ice record — 6 observed ice-outs, centered near Apr 1. Multiple sampling years from Minnesota PCA volunteers and partner agencies back the grade, so the letter should hold steady absent a major watershed shift.