Okauchee Lake-Site No. 4-at Okauchee

Okauchee Lake-Site No. 4-at Okauchee earns an A — water clarity, phosphorus, and chlorophyll-a all rate among the best monitored waters in Waukesha County. Clarity, phosphorus, and chlorophyll-a all rate similarly, so there is no obvious single lever to pull on watershed management.

A TSI near 45 places Okauchee Lake-Site No. 4-at Okauchee in the mesotrophic band — moderate productivity, with seasonal swings between clearer spring water and richer late-summer conditions. Okauchee Lake-Site No. 4-at Okauchee is unusually deep for Wisconsin at 90 ft, which buffers the lake against summer warming and helps the deep water stay oxygenated. At 1,210 acres, Okauchee Lake-Site No. 4-at Okauchee is one of the larger lakes in Waukesha County, with partial shoreline records supporting multiple distinct use patterns. Within Waukesha County's 48 graded lakes, Okauchee Lake-Site No. 4-at Okauchee ranks 29 — below the local median, though not at the bottom.

Zebra mussels have been documented at Okauchee Lake-Site No. 4-at Okauchee, which alters the filter-feeding balance and can paradoxically increase water clarity while disrupting the food web. The fishery includes walleye alongside the lake's other 6 documented species — a notable draw for Wisconsin anglers. Public access is available — the lake is on the Wisconsin DNR public-access list. The grade is based on limited monitoring — fewer than three independent measurement years contribute, so future updates may shift the letter.