Lake Denoon

On the LakeGrade rubric Lake Denoon fails the cutoffs — a TSI of 71 and persistent algal pressure put it in the bottom tier. The three sub-grades — clarity, phosphorus, and chlorophyll-a — track close together, so no single parameter is dragging the average.

A TSI above 70 puts Lake Denoon in hypereutrophic territory: visible blooms are common, and clarity rarely climbs even in early summer. The lake's 55 ft maximum depth is in the upper tier for Wisconsin — deep enough for cold-water fish to find refuge in summer. The lake's 167 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. Lake Denoon ranks 47 of 48 in Waukesha County — at the lower end of the locally monitored distribution.

Zebra mussel presence at Lake Denoon means the lake's clarity numbers carry an asterisk — filtered water is not the same as nutrient-poor water. The fishery includes walleye alongside the lake's other 4 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.