Clear Lake

Clear Lake earns a D — measurements through 2025 show persistent nutrient pressure that limits clarity through the summer. 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 only 12 ft deep, Clear Lake is shallow — wind keeps the water column mixed and sediment resuspension drives phosphorus levels harder to manage. At 77 acres, Clear Lake sits below the Wisconsin median: a small water where shoreline activity has an outsized effect on water quality. Clear Lake sits at rank 3 of 4 in Rock County, in the lower half of the local distribution.

Clear Lake carries an invasive watermilfoil record — boat-launch decontamination and shoreline care matter more here than at uninfested lakes. The fishery is bass-led, with 3 documented species across the lake's records. The grade is based on limited monitoring — fewer than three independent measurement years contribute, so future updates may shift the letter.