Southern Appalachians Ecoregion - National Lakes Assessment Results

An estimated 36,934 lakes in the Southern Appalachians ecoregion are represented in the National Lakes Assessment (NLA). Of these lakes, 1% are natural and 99% are man-made.

The NLA uses trophic state as an important indicator of lake condition and assesses the extent of biological condition and key stressors in the nation’s lakes.

• In the Southern Appalachians, 36% of lakes are rated as hypereutrophic while 47% are eutrophic, 5% are mesotrophic and 8% are oligotrophic.
• The most widespread stressors assessed are nitrogen and phosphorus with 83% and 73% of lakes in poor condition respectively.
• Cyanobacteria are one-celled photosynthetic organisms that normally occur at low levels. Under eutrophic conditions, cyanobacteria can multiply. Not all cyanobacterial blooms are toxic, but some may release toxins, such as microcystins. For information about risks at specific locations, recreational water users should check with state, tribal or local governments.
  • Based on microcystins, detections occurred in 47% of lakes and 3% of lakes were above the recreational benchmark.

• For the Southern Appalachians, the NLA reports the percent of lakes in good condition based on the zooplankton indicator increased by 25 percentage points between 2017 and 2022. 
• The percent of lakes with microcystin detections increased by 37  percentage points between 2017 and 2022.

To access more ecoregional specific information, please visit the interactive NLA Dashboard.

* The change analysis is based on information from two points in time – 2017 and 2022.