Long Lake

On the LakeGrade rubric, Long Lake pulls an A: clarity at 11.2 ft and 10 µg/L of phosphorus put it in the top bracket for Minnesota. Clarity, phosphorus, and chlorophyll-a all rate similarly, so there is no obvious single lever to pull on watershed management.

A TSI value of 40 puts Long Lake in the oligotrophic range, where biological productivity stays low and the water column remains clear. Long Lake is unusually deep for Minnesota at 135 ft, which buffers the lake against summer warming and helps the deep water stay oxygenated. At 1,926 acres, Long Lake is one of the larger lakes in Hubbard County, with 18.9 miles of shoreline supporting multiple distinct use patterns. Long Lake ranks 30 of 77 in Hubbard County — solidly in the upper half of the local distribution.

Zebra mussels have been documented at Long Lake, which alters the filter-feeding balance and can paradoxically increase water clarity while disrupting the food web. The fishery includes walleye alongside the lake's other 14 documented species — a notable draw for Minnesota anglers. A documented public access point at Long Lake makes the lake usable for shore fishing, paddle craft, and trailered boats. Ice-out has been logged at Long Lake more than two dozen times, putting the median around Apr 23 — a useful baseline for tracking climate trends. 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.