Blackwater Lake

Blackwater Lake carries a solid B grade — strong on most parameters, with measurements that hold up well across the summer season. The three sub-grades — clarity, phosphorus, and chlorophyll-a — track close together, so no single parameter is dragging the average.

Mesotrophic conditions dominate at Blackwater Lake: enough nutrients for a healthy fishery, not so much that algal blooms become a chronic problem. The lake's 67 ft maximum depth is in the upper tier for Minnesota — deep enough for cold-water fish to find refuge in summer. Blackwater Lake covers 771 acres alongside 7.7 miles of shoreline — a mid-sized water that supports a working fishery without being so large that conditions diverge between basins. Within the 133 graded lakes of Cass County, Blackwater Lake sits at rank 100, near the bottom of the county list.

No invasive species are currently listed at Blackwater Lake — the lake remains off the Minnesota infested-waters roster. Walleye are documented at Blackwater Lake, one of 16 fish species on record for the lake. A documented public access point at Blackwater Lake makes the lake usable for shore fishing, paddle craft, and trailered boats. Ice-out has been recorded 22 times at Blackwater Lake, with a median around Apr 17. The grade is based on limited monitoring — fewer than three independent measurement years contribute, so future updates may shift the letter.