Xeric Ecoregion - National Lakes Assessment Results
Key Results
An estimated 3,390 lakes in the Xeric ecoregion are represented in the National Lakes Assessment (NLA). Of these lakes, 44% are natural and 56% 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 Xeric ecoregion, 16% of lakes are rated as hypereutrophic while 37% are eutrophic, 39% are mesotrophic and 9% are oligotrophic.
- The most widespread stressors assessed are lakeshore disturbance, nitrogen, and degraded riparian vegetation cover with 39%, 36, and 28% 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 15% of lakes and no lakes are above the recreational benchmark.
Change from 2012*
- For the Xeric ecoregion, the NLA reports that the percent of lakes in poor condition based on the benthic macroinvertebrate indicator increased by 28 percentage points between 2012 and 2017.
- The percent of lakes that are in poor condition for nitrogen increased by 22%.
To access more ecoregional specific information, please visit the interactive NLA Dashboard.
* The change analysis is based on information from two points in time – 2012 and 2017.
![Image showing the dashboard results from the NLA Interactive Dashboard](/system/files/styles/large/private/images/2022-06/XER%202017%20Good.png?itok=lyuOVwKj)