McLean County Lake Quality

There are 43 monitored lakes in McLean County. The mix is varied enough that the county-level average tells you the broad strokes, not the choose-this-cabin specifics. 2 of those lakes carry an A–F grade. The county-level summary describes that subset, not every water body listed. With an average grade of B, McLean County sits comfortably above the North Dakota median.

Most of the county's monitored lakes are shallow — under 50 feet — which means wind keeps the water column mixed all summer and sediment-bound phosphorus releases back into the surface layer whenever the bottom is disturbed. Lake Audubon (B) is the cleanest in the county.