Gull Lake

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

A TSI near 40 places Gull Lake in the mesotrophic band — moderate productivity, with seasonal swings between clearer spring water and richer late-summer conditions. Gull Lake is unusually deep for Minnesota at 80 ft, which buffers the lake against summer warming and helps the deep water stay oxygenated. Gull Lake covers 10,010 acres alongside 46.1 miles of shoreline, large enough that conditions can vary meaningfully between bays. Among the 133 graded lakes in Cass County, Gull Lake sits at rank 59, above the county median.

Gull 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. Gull Lake's fishery is anchored by muskellunge, with 22 documented species in total — a destination water for muskie anglers. A documented public access point at Gull Lake makes the lake usable for shore fishing, paddle craft, and trailered boats. The lake has a long ice-out record — 98 observations on file, with a median ice-out around Apr 21. 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.