Gurno Lake

Gurno Lake comes in at a B on the grading rubric — a respectable showing for a Wisconsin lake of its size and depth. 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.

A TSI near 45 places Gurno Lake in the mesotrophic band — moderate productivity, with seasonal swings between clearer spring water and richer late-summer conditions. The lake bottoms out at 27 ft — a moderate depth that supports a warm-water fishery without the year-round cold refuge a deeper basin provides. Gurno Lake is small — 76 acres alongside partial shoreline records — which makes it sensitive to even modest changes in watershed runoff or recreational pressure. Within Sawyer County's 50 graded lakes, Gurno Lake ranks 26 — below the local median, though not at the bottom.

Gurno Lake has no invasive species recorded in Wisconsin state databases as of 2024, though prevention practices still apply at all access points. Walleye are documented at Gurno Lake, one of 5 fish species on record for the lake. Multiple sampling years from the Wisconsin DNR Citizen Lake Monitoring Network back the grade, so the letter should hold steady absent a major watershed shift.