Otter Tail Lake

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

The lake sits in the mesotrophic zone — the band where most well-managed Minnesota lakes fall. Otter Tail Lake is unusually deep for Minnesota at 120 ft, which buffers the lake against summer warming and helps the deep water stay oxygenated. At 14,079 acres, Otter Tail Lake is one of the larger lakes in Otter Tail County, with 23.7 miles of shoreline supporting multiple distinct use patterns. Otter Tail Lake ranks 39 of 97 in Otter Tail County — solidly in the upper half of the local distribution.

Zebra mussels have been documented at Otter Tail Lake, which alters the filter-feeding balance and can paradoxically increase water clarity while disrupting the food web. Walleye are documented at Otter Tail Lake, one of 17 fish species on record for the lake. A documented public access point at Otter Tail Lake makes the lake usable for shore fishing, paddle craft, and trailered boats. Ice-out has been logged at Otter Tail Lake more than two dozen times, putting the median around Apr 16 — 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.