Tennessee Lake Water Quality

Tennessee lists 277 lakes across 75 counties, 60 of them with a recent water-quality reading. Most of that sampling flows through monitoring run by the Tennessee Department of Environment and Conservation, which feeds state, federal, and volunteer measurements into the EPA Water Quality Portal. The remainder are here because they are real named lakes, not because anyone has sampled them recently. Low nutrient readings are less common among Tennessee'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 Kentucky Lake, at about 22,907 acres, and 22 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 Rhea. The gap between counties is large enough that a single figure for Tennessee lake water quality hides real local variation.