Stony Lake

Stony Lake earns an A — water clarity, phosphorus, and chlorophyll-a all rate among the best monitored waters in Douglas County. The three sub-grades — clarity, phosphorus, and chlorophyll-a — track close together, so no single parameter is dragging the average.

A TSI value of 37 puts Stony Lake in the oligotrophic range, where biological productivity stays low and the water column remains clear. Stony Lake is unusually deep for Minnesota at 58 ft, which buffers the lake against summer warming and helps the deep water stay oxygenated. The lake is compact at 87 acres, with 2.0 miles of shoreline and little volume to buffer nutrient inputs. Within Douglas County's 51 graded waters, Stony Lake sits at rank 9, near the top of the local distribution.

Stony Lake is on the Minnesota infested-waters list for zebra mussels — boaters should follow clean-drain-dry protocols when moving gear to or from the lake. The fishery includes walleye alongside the lake's other 10 documented species — a notable draw for Minnesota anglers. The lake lacks a documented public access point, so visitor use is limited. The grade is based on limited monitoring — fewer than three independent measurement years contribute, so future updates may shift the letter.