Humboldt County Lake Quality

Humboldt County's 21 monitored lakes fall in the moderate-density bracket for Nevada. The county-level average smooths over real differences — a single agricultural watershed near the southwest corner can pull the average down even if the rest of the county runs clean. 3 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. 1 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 Onion Valley Reservoir @ Dam (C); the most-stressed is Knott Creek Reservoir (F).