Franklin County Lake Quality

There are 26 monitored lakes in Franklin County. The mix is varied enough that the county-level average tells you the broad strokes, not the choose-this-cabin specifics. 4 of those lakes 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 Massachusetts. 4 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 Roaring Brook Lake (A); the most-stressed is Roaring Brook Lake (A).