North Carolina Lake Water Quality

149 of the 395 North Carolina lakes in this index carry a recent clarity, phosphorus or algae reading, spread over 83 counties. Those readings come from the North Carolina Department of Environmental Quality, alongside federal programs and volunteer monitoring networks. The rest are listed for their size, depth and location, with no recent nutrient or algae sampling behind them. Low nutrient readings are less common among North Carolina's measured lakes. The smaller, agricultural-watershed lakes that dominate the measured set tend to carry persistent phosphorus loads.

By surface area the largest lake here is Lake Mattamuskeet, at about 26,110 acres, and 63 of the lakes in this index cover more than 500 acres. Size is worth knowing before you go: a large deep basin buffers nutrient inputs by sheer volume, while a shallow one warms quickly and can turn over its whole water column in a single summer storm. Eutrophic conditions dominate the measured set: nutrient-loaded, productive, with algal pressure that shows up most years in late summer. These lakes tend to be shallow, in agricultural watersheds, and over-warmed by the time July ends. The county with the lowest nutrient and algae readings on average is New Hanover. The gap between counties is large enough that a single figure for North Carolina lake water quality hides real local variation.