Mccarthy Lake

Mccarthy Lake earns an F: 195 µg/L of phosphorus and clarity at 1.0 ft signal heavy nutrient loading from the surrounding watershed. Clarity, phosphorus, and chlorophyll-a all rate similarly, so there is no obvious single lever to pull on watershed management.

A TSI above 70 puts Mccarthy Lake in hypereutrophic territory: visible blooms are common, and clarity rarely climbs even in early summer. A maximum depth of 19 ft puts Mccarthy Lake in the middle of Minnesota's depth distribution. The lake is compact at 12 acres, with 0.6 miles of shoreline and little volume to buffer nutrient inputs. Within the 36 graded lakes of Dakota County, Mccarthy Lake sits at rank 32, near the bottom of the county list.

No invasive species are currently listed at Mccarthy Lake — the lake remains off the Minnesota infested-waters roster. The fishery includes walleye alongside the lake's other 6 documented species — a notable draw for Minnesota anglers. No formal public access is documented at Mccarthy Lake — most use is by shoreline residents and their guests. Monitoring depth is thin here: the LakeGrade rubric is applied to a small number of sample years, and the grade will be revised as more data accumulates.