Diamond Lake

On the LakeGrade rubric, Diamond Lake pulls an A: clarity at 42.7 ft and 11 µg/L of phosphorus put it in the top bracket for Wisconsin. The three sub-grades — clarity, phosphorus, and chlorophyll-a — track close together, so no single parameter is dragging the average.

A TSI value of 31 puts Diamond Lake in the oligotrophic range, where biological productivity stays low and the water column remains clear. At 83 ft of maximum depth, Diamond Lake stratifies reliably through the summer — the hypolimnion stays cooler and clearer than the surface layer suggests. Diamond Lake covers 322 acres alongside partial shoreline records — a mid-sized water that supports a working fishery without being so large that conditions diverge between basins. Within Bayfield County's 55 graded waters, Diamond Lake sits at rank 13, near the top of the local distribution.

An invasive species record — Banded Mystery Snail — has been logged at Diamond Lake; Wisconsin DNR maintains the official infested-waters list. The fishery includes walleye alongside the lake's other 5 documented species — a notable draw for Wisconsin anglers. A documented public access point at Diamond Lake makes the lake usable for shore fishing, paddle craft, and trailered boats. 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.