Diamond Lake

Diamond Lake earns an F: 96 µg/L of phosphorus and clarity readings still being added signal heavy nutrient loading from the surrounding watershed.

A TSI in the eutrophic range signals a lake doing what nutrient-loaded waters do — supporting an active algal community at the cost of clear water. A maximum depth of just 6 ft means sediment-bound phosphorus releases back into the water column whenever wind stirs the bottom — a classic shallow-lake dynamic. Diamond Lake is small — 52 acres alongside 1.2 miles of shoreline — which makes it sensitive to even modest changes in watershed runoff or recreational pressure. Within Hennepin County's 95 graded lakes, Diamond Lake ranks 70 — below the local median, though not at the bottom.

No invasive species are currently listed at Diamond Lake — the lake remains off the Minnesota infested-waters roster. The fishery is panfish-dominated — bluegill, crappie, and sunfish among the 7 species documented for the lake. The lake lacks a documented public access point, so visitor use is limited. Ice-out has been recorded 10 times at Diamond Lake, with a median around Mar 26. 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.