Oconomowoc Lake Site

On the LakeGrade rubric, Oconomowoc Lake Site pulls an A: clarity at 39.4 ft and 14 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.

Trophically, Oconomowoc Lake Site reads as oligotrophic — nutrient-poor, clear, and ecologically more sensitive to disturbance than richer lakes. Oconomowoc Lake Site is unusually deep for Wisconsin at 60 ft, which buffers the lake against summer warming and helps the deep water stay oxygenated. The lake's 818 acres and partial shoreline records put it in the mid-range bucket — large enough for varied use, small enough that watershed inputs reach the whole basin. Within Waukesha County's 48 graded lakes, Oconomowoc Lake Site ranks 25 — below the local median, though not at the bottom.

Zebra mussels have been documented at Oconomowoc Lake Site, which alters the filter-feeding balance and can paradoxically increase water clarity while disrupting the food web. Walleye are documented at Oconomowoc Lake Site, one of 5 fish species on record for the lake. 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.