Thunder Lake

Thunder Lake sits at a C on the grading scale — not impaired, not pristine, with summer measurements that vary year to year. Sub-grades cluster within a single letter of each other, which usually means the lake is in stable trophic balance rather than fighting one specific stressor.

Eutrophic conditions are the baseline here: clarity drops noticeably in late summer, and dissolved oxygen near the bottom can become a concern. Thunder Lake is a shallow lake at 12 ft maximum depth, which means it warms quickly, mixes constantly, and amplifies nutrient inputs. The lake's 182 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. Thunder Lake ranks 124 of 140 in Oneida County — at the lower end of the locally monitored distribution.

Thunder Lake has no invasive species recorded in Wisconsin state databases as of 2025, though prevention practices still apply at all access points. Walleye are documented at Thunder Lake, one of 6 fish species on record for the lake. The grade is based on limited monitoring — fewer than three independent measurement years contribute, so future updates may shift the letter.