South Sturgeon Lake

The LakeGrade rubric puts South Sturgeon Lake at a C: clarity at 2.5 ft, 20 µg/L of phosphorus, and a TSI of 56 signal an intermediate trophic state. Secchi readings are the weakest of the three parameters, suggesting suspended sediment or algal biomass dominates the optical signal.

Eutrophic conditions are the baseline here: clarity drops noticeably in late summer, and dissolved oxygen near the bottom can become a concern. The lake bottoms out at 43 ft — a moderate depth that supports a warm-water fishery without the year-round cold refuge a deeper basin provides. South Sturgeon Lake covers 204 acres alongside 3.7 miles of shoreline — a mid-sized water that supports a working fishery without being so large that conditions diverge between basins. Within St. Louis County's 187 graded lakes, South Sturgeon Lake ranks 135 — below the local median, though not at the bottom.

No invasive species are currently listed at South Sturgeon Lake — the lake remains off the Minnesota infested-waters roster. The fishery includes walleye alongside the lake's other 10 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 logged at South Sturgeon Lake more than two dozen times, putting the median around Apr 21 — 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.