Forest Lake

Forest Lake sits at a C on the grading scale — not impaired, not pristine, with summer measurements that vary year to year. The three sub-grades — clarity, phosphorus, and chlorophyll-a — track close together, so no single parameter is dragging the average.

At a TSI of 59, Forest Lake reads as eutrophic — nutrient-rich enough that summer algal growth and reduced clarity are expected, not unusual. Forest Lake reaches 42 ft at its deepest point — typical for Minnesota mid-sized lakes, with seasonal stratification but limited cold-water refuge. At 90 acres, Forest Lake sits below the Minnesota median: a small water where shoreline activity has an outsized effect on water quality. Among the 95 graded lakes in Hennepin County, Forest Lake sits at rank 35, above the county median.

Zebra mussels have been documented at Forest Lake, which alters the filter-feeding balance and can paradoxically increase water clarity while disrupting the food web. The state fisheries records do not list documented species for Forest Lake, which usually reflects a lack of formal fisheries survey work rather than an empty lake. No formal public access is documented at Forest Lake — most use is by shoreline residents and their guests. The grade is based on limited monitoring — fewer than three independent measurement years contribute, so future updates may shift the letter.