Blackwater Lake

Blackwater Lake earns an A — water clarity, phosphorus, and chlorophyll-a all rate among the best monitored waters in Cass County. Clarity, phosphorus, and chlorophyll-a all rate similarly, so there is no obvious single lever to pull on watershed management.

Trophically, Blackwater Lake reads as oligotrophic — nutrient-poor, clear, and ecologically more sensitive to disturbance than richer lakes. 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 Cass County's 133 graded lakes, Blackwater Lake ranks 68 — below the local median, though not at the bottom.

Blackwater Lake has no invasive species recorded in Minnesota state databases as of 2024, though prevention practices still apply at all access points. The fishery includes walleye alongside the lake's other 16 documented species — a notable draw for Minnesota anglers. 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. 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.