Split Rock Reservoir

Split Rock Reservoir grades an F: water clarity, phosphorus, and chlorophyll-a all rate poorly, placing it among the most stressed lakes monitored in Minnesota. 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.

Hypereutrophic conditions mean the lake is operating at the upper end of the productivity scale, with all the bloom risk that implies. Split Rock Reservoir reaches 16 ft at its deepest point — typical for Minnesota mid-sized lakes, with seasonal stratification but limited cold-water refuge. At 96 acres, Split Rock Reservoir sits below the Minnesota median: a small water where shoreline activity has an outsized effect on water quality.

Split Rock Reservoir has no invasive species recorded in Minnesota state databases as of 2023, though prevention practices still apply at all access points. The fishery is panfish-dominated — bluegill, crappie, and sunfish among the 12 species documented for the lake. A documented public access point at Split Rock Reservoir makes the lake usable for shore fishing, paddle craft, and trailered boats. The grade is based on limited monitoring — fewer than three independent measurement years contribute, so future updates may shift the letter.