Lower Kelly Lake

Lower Kelly Lake grades an F: water clarity, phosphorus, and chlorophyll-a all rate poorly, placing it among the most stressed lakes monitored in Wisconsin. Clarity, phosphorus, and chlorophyll-a all rate similarly, so there is no obvious single lever to pull on watershed management.

The hypereutrophic status — TSI 77 — reflects sustained heavy nutrient loading from the surrounding watershed and frequent algal pressure. The lake bottoms out at 36 ft — a moderate depth that supports a warm-water fishery without the year-round cold refuge a deeper basin provides. Lower Kelly Lake is small — 3 acres alongside partial shoreline records — which makes it sensitive to even modest changes in watershed runoff or recreational pressure. Within the 48 graded lakes of Waukesha County, Lower Kelly Lake sits at rank 48, near the bottom of the county list.

Lower Kelly 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 2 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.