Alleghany County Lake Quality

Alleghany County has 2 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. Every one of those lakes carries an A–F grade, so the county-level summary covers the full set rather than a monitored subset. The county's average grade is A — among the cleanest in Virginia. 2 lakes pull an A on their own, and almost none fall into the D or F brackets.

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. Dam Lake (A) is the cleanest in the county.