Topaz Lake

On the LakeGrade rubric, Topaz Lake pulls an A: clarity at 17.5 ft and phosphorus readings still being added put it in the top bracket for Minnesota.

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. The lake's 110 ft maximum depth is in the upper tier for Minnesota — deep enough for cold-water fish to find refuge in summer. Topaz Lake covers 410 acres alongside 10.1 miles of shoreline — a mid-sized water that supports a working fishery without being so large that conditions diverge between basins. Among the 142 graded lakes in Lake County, Topaz Lake ranks 19 — in the top quartile locally.

Topaz Lake has no invasive species recorded in Minnesota state databases as of 2023, though prevention practices still apply at all access points. The fishery is bass-led, with 4 documented species across the lake's records. No formal public access is documented at Topaz Lake — most use is by shoreline residents and their guests. Monitoring depth is thin here: the LakeGrade rubric is applied to a small number of sample years, and the grade will be revised as more data accumulates.