Gabbro Lake

Gabbro Lake earns a D — measurements through 2021 show persistent nutrient pressure that limits clarity through the summer. The three sub-grades — clarity, phosphorus, and chlorophyll-a — track close together, so no single parameter is dragging the average.

A TSI in the eutrophic range signals a lake doing what nutrient-loaded waters do — supporting an active algal community at the cost of clear water. The lake's 50 ft maximum depth is in the upper tier for Minnesota — deep enough for cold-water fish to find refuge in summer. The lake's 977 acres and 23.7 miles of shoreline put it in the mid-range bucket — large enough for varied use, small enough that watershed inputs reach the whole basin. Gabbro Lake ranks 133 of 142 in Lake County — at the lower end of the locally monitored distribution.

No invasive species are currently listed at Gabbro Lake — the lake remains off the Minnesota infested-waters roster. The fishery includes walleye alongside the lake's other 8 documented species — a notable draw for Minnesota anglers. The lake lacks a documented public access point, so visitor use is limited. 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.