North Long Lake

North Long Lake earns an A — water clarity, phosphorus, and chlorophyll-a all rate among the best monitored waters in Crow Wing County. Clarity, phosphorus, and chlorophyll-a all rate similarly, so there is no obvious single lever to pull on watershed management.

A TSI near 40 places North Long Lake in the mesotrophic band — moderate productivity, with seasonal swings between clearer spring water and richer late-summer conditions. North Long Lake is unusually deep for Minnesota at 97 ft, which buffers the lake against summer warming and helps the deep water stay oxygenated. North Long Lake covers 6,190 acres alongside 20.1 miles of shoreline, large enough that conditions can vary meaningfully between bays. Among the 120 graded lakes in Crow Wing County, North Long Lake sits at rank 49, above the county median.

Zebra mussels have been documented at North Long Lake, which alters the filter-feeding balance and can paradoxically increase water clarity while disrupting the food web. Walleye are documented at North Long Lake, one of 18 fish species on record for the lake. Public access is available — the lake is on the Minnesota PCA public-access list. The lake has a long ice-out record — 64 observations on file, with a median ice-out around Apr 18. 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.