Northern Plains Ecoregion - National Rivers and Streams Assessment Results

• In the Northern Plains ecoregion, biological condition was good in 38% of river and stream miles based on benthic macroinvertebrates. 
• The most widespread stressors assessed in the Northern Plains ecoregion were nitrogen with 43% of river and stream miles in poor condition, riparian disturbance with 38% of miles in poor condition, and phosphorus with 36% of miles in poor condition. 
• 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 8% of river and stream miles in the Northern Plains however, zero miles were above EPA’s recommended criteria.

Change from 2013-14*

• The percent of river and stream miles in good condition for phosphorus increased by 15 percentage points between 2013-14 and 2018-19 in the Northern Plains ecoregion.
• The percent of river and stream miles with microcystin detections decreased by 32 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.