Jefferson County Lake Quality

Only 1 lakes in Jefferson County carry an active grade. The county-level summary is therefore representative of those specific lakes, not necessarily of every water body in the county. Jefferson County averages to a C. The distribution behind that average matters more than the letter: a few stressed lakes versus many decent ones can produce the same average as the inverse.

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. French Broad River Lake (C) is the cleanest in the county.