Upper Hay Lake

On the LakeGrade scale Upper Hay Lake grades a B, with clarity at 10.0 ft and 20 µg/L of phosphorus placing it above the Minnesota median. 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.

Mesotrophic conditions dominate at Upper Hay Lake: enough nutrients for a healthy fishery, not so much that algal blooms become a chronic problem. The lake bottoms out at 42 ft — a moderate depth that supports a warm-water fishery without the year-round cold refuge a deeper basin provides. Upper Hay Lake covers 596 acres alongside 3.8 miles of shoreline — a mid-sized water that supports a working fishery without being so large that conditions diverge between basins. Upper Hay Lake sits at rank 82 of 120 in Crow Wing County, in the lower half of the local distribution.

Zebra mussels have been documented at Upper Hay Lake, which alters the filter-feeding balance and can paradoxically increase water clarity while disrupting the food web. Walleye are documented at Upper Hay Lake, one of 13 fish species on record for the lake. Public access is available — the lake is on the Minnesota PCA public-access list. 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.