Lake Beulah

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

A TSI value of 34 puts Lake Beulah in the oligotrophic range, where biological productivity stays low and the water column remains clear. Lake Beulah is unusually deep for Wisconsin at 58 ft, which buffers the lake against summer warming and helps the deep water stay oxygenated. Lake Beulah covers 812 acres alongside partial shoreline records — a mid-sized water that supports a working fishery without being so large that conditions diverge between basins. Among the 34 graded lakes in Walworth County, Lake Beulah ranks 8 — in the top quartile locally.

Zebra mussels have been documented at Lake Beulah, which alters the filter-feeding balance and can paradoxically increase water clarity while disrupting the food web. Bass fishing is part of the appeal: the species list runs to 3, anchored by largemouth and/or smallmouth bass. 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.