Peterson Lake

Peterson Lake pulls a D on the LakeGrade rubric — phosphorus loading and limited clarity hold it below the Minnesota average. Clarity, phosphorus, and chlorophyll-a all rate similarly, so there is no obvious single lever to pull on watershed management.

Eutrophic conditions are the baseline here: clarity drops noticeably in late summer, and dissolved oxygen near the bottom can become a concern. The lake's 69 ft maximum depth is in the upper tier for Minnesota — deep enough for cold-water fish to find refuge in summer. Peterson Lake covers 2,540 acres alongside 14.8 miles of shoreline, large enough that conditions can vary meaningfully between bays. Within the 97 graded lakes of Otter Tail County, Peterson Lake sits at rank 91, near the bottom of the county list.

Zebra mussels have been documented at Peterson 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 16 documented species — a notable draw for Minnesota anglers. Public access is available — the lake is on the Minnesota PCA public-access list. Ice-out has been recorded 18 times at Peterson Lake, with a median around Apr 14. The grade is based on limited monitoring — fewer than three independent measurement years contribute, so future updates may shift the letter.