McHenry County Lake Quality

There are 15 monitored lakes in McHenry County. The mix is varied enough that the county-level average tells you the broad strokes, not the choose-this-cabin specifics. 5 of those lakes carry an A–F grade. The county-level summary describes that subset, not every water body listed. The county-wide average grade is D — water quality issues are persistent across most of the monitored basins. 2 lakes fall into the F bracket outright.

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 Silver Lake (A); the most-stressed is Pistakee Lake (F).