Xeric Ecoregion - National Rivers and Streams Assessment Results
NRSA 2018-19 Ecoregional Results
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Key Results
An estimated 66,540 river and stream miles are represented in the Xeric region in the National Rivers and Streams Assessment (NRSA).
- In the Xeric ecoregion, biological condition was good in 24% of river and stream miles based on benthic macroinvertebrates.
- The most widespread stressors assessed in the Xeric region were riparian disturbance, nitrogen, and phosphorus with 48%, 36% and 28% of river and stream miles in poor condition respectively
- Cyanobacteria are photosynthetic microorganisms that occur at low levels. Under the right conditions (elevated nutrients and increasing temperature), cyanobacteria can grow at elevated rates producing blooms. 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.
- Microcystins detections occurred in 5% of river and stream miles and no miles were above EPA’s criterion recommendation in the Xeric ecoregion.
Change from 2013-14*
- For streambed sediments, there was a significant decrease of 16 percentage points in river and stream miles in good condition between 2013-14 and 2018-19 in the Xeric Region.
- The percent of river and stream miles with microcystin detections decreased by 27 percentage points.
To access more ecoregional specific information, please visit the interactive NRSA Dashboard.
* The change analysis is based on information from two points in time – 2013-14 and 2018-19.
