Long Lake

Long Lake earns an A — water clarity, phosphorus, and chlorophyll-a all rate among the best monitored waters in Iron County. 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.

The lake's low TSI puts it in oligotrophic territory — the cleanest of the four trophic classes, but also the most vulnerable to nutrient-driven shifts. A maximum depth of 34 ft puts Long Lake in the middle of Wisconsin's depth distribution. The lake's 370 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. Long Lake ranks 1 of 34 in Iron County, putting it in the upper tier of locally monitored lakes.

Eurasian watermilfoil has been documented at Long Lake, requiring shoreline management to keep dense mats from crowding native vegetation. Walleye are documented at Long 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.