Winnebago County Lake Quality

Winnebago County has 7 monitored lakes — a thin enough sample that one or two stressed lakes can move the county average noticeably. Use the per-lake pages below for what actually matters. 1 of those lake carry an A–F grade. The county-level summary describes that subset, not every water body listed. The county's average grade is A — among the cleanest in Illinois. 1 lakes pull an A on their own, and almost none fall into the D or F brackets.

The county's lakes lean shallow, which makes the grades sensitive to wind, sediment-resuspension, and any nutrient inputs from the watershed. The cleanest lake on the books is Baumann Park Lake (A); the most-stressed is Baumann Park Lake (A).