Skip to main content
LakeQuality

Big Mcdonald Lake in Otter Tail County, Minnesota has nutrient and algae measurements on record from state and federal monitoring. A water-quality reading is not a swimming clearance. The state water agency and county health departments post current advisories; check them before you swim.. Water clarity: 17.4 ft visibility. Phosphorus: 12 µg/L. Chlorophyll-a (algae): 3.2 µg/L. Always check local health department advisories before swimming.

Key Metrics

MetricValue
Water Clarity (Secchi Depth)17.4 ft
Phosphorus12 μg/L
Chlorophyll-a (Algae)3.2 μg/L
Maximum Depth46 ft
LocationOtter Tail County, Minnesota

How does Big Mcdonald Lake compare?

With an overall water-quality readings of , Big Mcdonald Lake matches or beats the Minnesota state average. It ranks #13 of 66 lakes in Otter Tail County by water quality score.

Water clarity (Secchi depth) sits at 17.4 feet. That counts as exceptional clarity — sunlight penetrates deep, supporting submerged plants and limiting algae. Algae levels (chlorophyll-a) measure 3.2 µg/L — low and well within safe swimming guidelines.