Geneva Lake

On the LakeGrade rubric, Geneva Lake pulls an A: clarity at 19.0 ft and 13 µg/L of phosphorus put it in the top bracket for Wisconsin. Clarity, phosphorus, and chlorophyll-a all rate similarly, so there is no obvious single lever to pull on watershed management.

A TSI value of 38 puts Geneva Lake in the oligotrophic range, where biological productivity stays low and the water column remains clear. Geneva Lake is unusually deep for Wisconsin at 135 ft, which buffers the lake against summer warming and helps the deep water stay oxygenated. With 5,401 acres of surface and partial shoreline records, Geneva Lake is a large water by Wisconsin standards — recreational pressure is spread across a long shoreline. Within Walworth County's 34 graded waters, Geneva Lake sits at rank 1, near the top of the local distribution.

Geneva Lake is on the Wisconsin infested-waters list for zebra mussels — boaters should follow clean-drain-dry protocols when moving gear to or from the lake. The fishery includes walleye alongside the lake's other 6 documented species — a notable draw for Wisconsin anglers. A documented public access point at Geneva Lake makes the lake usable for shore fishing, paddle craft, and trailered boats. 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.