Tetonka Lake

Tetonka Lake earns an F: 363 µg/L of phosphorus and clarity at 3.0 ft signal heavy nutrient loading from the surrounding watershed. clarity and phosphorus rate similarly, so there is no obvious single lever to pull on watershed management.

A TSI above 70 puts Tetonka Lake in hypereutrophic territory: visible blooms are common, and clarity rarely climbs even in early summer. The lake bottoms out at 35 ft — a moderate depth that supports a warm-water fishery without the year-round cold refuge a deeper basin provides. With 1,358 acres of surface and 11.6 miles of shoreline, Tetonka Lake is a large water by Minnesota standards — recreational pressure is spread across a long shoreline. Within the 14 graded lakes of Le Sueur County, Tetonka Lake sits at rank 11, near the bottom of the county list.

Eurasian watermilfoil has been documented at Tetonka Lake, requiring shoreline management to keep dense mats from crowding native vegetation. The fishery includes walleye among the lake's 19 documented species — a notable draw for Minnesota anglers. A documented public access point at Tetonka Lake makes the lake usable for shore fishing, paddle craft, and trailered boats. The lake has a long ice-out record — 76 observations on file, with a median ice-out around Apr 2. 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.