An official website of the United States government.

This is not the current EPA website. To navigate to the current EPA website, please go to This website is historical material reflecting the EPA website as it existed on January 19, 2021. This website is no longer updated and links to external websites and some internal pages may not work. More information »

National Aquatic Resource Surveys

Coastal Plains Ecoregion - National Lakes Assessment Results

Key Results

A total of 24,928 lakes in the Coastal Plains ecoregion are represented in the National Lakes Assessment (NLA). Of these lakes, 26% are natural and 74% are man-made.

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

  • In the Coastal Plains, 28% of lakes are rated as most disturbed based on trophic state, 49% are eutrophic, 21% are mesotrophic, and 1% are oligotrophic.
  • The most widespread stressors assessed are phosphorus (50% of lakes), lake habitat complexity (37%), and nitrogen and riparian vegetation cover (both 33%).

Trophic State

National Lakes Assessment 2012 Bar Chart of the Trophic State of Lakes in the Coastal Plains Ecoregion

Indicator with the Highest Percentage of Lakes in the Most Disturbed Condition: Phosphorus

National Lakes Assessment 2012 Bar Chart of the Condition of Total Phosphorus in the Coastal Plains

Top of Page

Photo of a lake in the Coastal Plains ecoregion that was sampled during the National Lakes Assessment 2012Lake sampling in Texas for the NLA 2012. Photo: Texas crew.

Human Use Condition 

Cyanobacteria is one of three algal toxin related indicators assessed in the NLA (see also chlorophyll a and microcystins). It serves as a proxy for the presence of algal toxins.  

  • Based on cyanobacteria cell counts, 23% of lakes in the Coastal Plains are in the most disturbed condition (i.e., pose a high risk of exposure to algal toxins).

Top of Page

Change from 2007 (for lakes >4 hectares)*

  • For the Coastal Plains, no indicators showed a significant change in most disturbed condition between 2007 and 2012

To access more indicator graphics please visit the interactive NLA Dashboard.

Top of Page

* The change analysis is based on information from two points in time – 2007 and 2012.  The change in condition analysis only considers lakes 4 hectares and larger because smaller lakes were not sampled in 2007.