Blue Spring Lake

Blue Spring Lake sits at the top of the Wisconsin DNR grading rubric with an A, a mark reached by the cleanest lakes in Wisconsin. The three sub-grades — clarity, phosphorus, and chlorophyll-a — track close together, so no single parameter is dragging the average.

Mesotrophic conditions dominate at Blue Spring Lake: enough nutrients for a healthy fishery, not so much that algal blooms become a chronic problem. Blue Spring Lake reaches 27 ft at its deepest point — typical for Wisconsin mid-sized lakes, with seasonal stratification but limited cold-water refuge. The lake's 136 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. Blue Spring Lake ranks 4 of 8 in Jefferson County — solidly in the upper half of the local distribution.

Zebra mussels have been documented at Blue Spring Lake, which alters the filter-feeding balance and can paradoxically increase water clarity while disrupting the food web. The fishery is bass-led, with 3 documented species across the lake's records. 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.