Frances Lake

Frances Lake earns a C — middle-of-the-pack water quality, with one or two parameters dragging the average down from a stronger grade. The lake's weakest score is on Secchi depth — the water looks more turbid than its phosphorus number alone would predict.

A TSI in the eutrophic range signals a lake doing what nutrient-loaded waters do — supporting an active algal community at the cost of clear water. At 60 ft of maximum depth, Frances Lake stratifies reliably through the summer — the hypolimnion stays cooler and clearer than the surface layer suggests. The lake's 927 acres and 8.8 miles of shoreline put it in the mid-range bucket — large enough for varied use, small enough that watershed inputs reach the whole basin. Within Le Sueur County's 14 graded waters, Frances Lake sits at rank 3, near the top of the local distribution.

Eurasian watermilfoil has been documented at Frances Lake, requiring shoreline management to keep dense mats from crowding native vegetation. 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 logged at Frances Lake more than two dozen times, putting the median around Mar 29 — a useful baseline for tracking climate trends. The grade is based on limited monitoring — fewer than three independent measurement years contribute, so future updates may shift the letter.