Koochiching County Lake Quality

The county-level average smooths over real differences — a single agricultural watershed near the southwest corner can pull the average down even if the rest of the county runs clean. 3 of those lakes carry recent nutrient and algae readings. The county-level summary describes that subset, not every water body listed. For Koochiching County the spread behind the average matters more than the average itself: a few nutrient-rich lakes among many clear ones produce the same figure as the inverse.

The county's lakes lean shallow, which makes the readings sensitive to wind, sediment-resuspension, and any nutrient inputs from the watershed. The cleanest measured lake is Battle Lake.