Long Lake

Long Lake sits at the top of the Minnesota PCA grading rubric with an A, a mark reached by the cleanest lakes in Minnesota. The two scored sub-grades — clarity and phosphorus — track close together, so neither one is dragging the average down.

Mesotrophic conditions dominate at Long Lake: enough nutrients for a healthy fishery, not so much that algal blooms become a chronic problem. At 73 ft of maximum depth, Long Lake stratifies reliably through the summer — the hypolimnion stays cooler and clearer than the surface layer suggests. At 767 acres, Long Lake fits the Minnesota median for monitored lakes, with 7.5 miles of shoreline. Long Lake ranks 28 of 97 in Otter Tail 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 among the lake's 17 documented species — a notable draw for Minnesota anglers. Public access is available — the lake is on the Minnesota PCA public-access list. The lake has a partial ice record — 6 observed ice-outs, centered near Apr 12. The grade is based on limited monitoring — fewer than three independent measurement years contribute, so future updates may shift the letter.