Hart Lake

On the LakeGrade rubric, Hart Lake pulls an A: clarity at 70.5 ft and phosphorus readings still being added put it in the top bracket for Wisconsin. The three sub-grades — clarity, phosphorus, and chlorophyll-a — track close together, so no single parameter is dragging the average.

Trophically, Hart Lake reads as oligotrophic — nutrient-poor, clear, and ecologically more sensitive to disturbance than richer lakes. Hart Lake is unusually deep for Wisconsin at 54 ft, which buffers the lake against summer warming and helps the deep water stay oxygenated. Hart Lake covers 257 acres alongside partial shoreline records — a mid-sized water that supports a working fishery without being so large that conditions diverge between basins. Within Bayfield County's 55 graded lakes, Hart Lake ranks 30 — below the local median, though not at the bottom.

Eurasian watermilfoil has been documented at Hart Lake, requiring shoreline management to keep dense mats from crowding native vegetation. The fishery includes walleye alongside the lake's other 6 documented species — a notable draw for Wisconsin anglers. The grade is based on limited monitoring — fewer than three independent measurement years contribute, so future updates may shift the letter.