Tennessee Lake Water Quality

82 {{stateName}} lakes carry a grade. Most of the input data flows through monitoring run by {{agency}}, which feeds state, federal, and volunteer measurements into the EPA Water Quality Portal. Only about 6% of {{stateName}}'s lakes pull an A grade — the smaller, agricultural-watershed lakes that dominate the dataset tend to carry persistent nutrient loads. 41% of lakes fall in the D or F brackets.

Eutrophic conditions dominate — nutrient-loaded, productive, with algal pressure that shows up most years in late summer. These lakes tend to be shallow, agricultural-watershed, and over-warmed by the time July ends. The cleanest county on average is Clay (grade A); the most-stressed is Maury. The gap between the top and bottom counties is large enough that "{{stateName}} lake water quality" hides real local variation.