Temperate Plains Ecoregion - National Lakes Assessment Results
Key Results
An estimated 35,100 lakes in the Temperate Plains ecoregion are represented in the National Lakes Assessment (NLA). Of these lakes, 22% are natural and 78% 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 Temperate Plains, 31% of lakes are rated as hypereutrophic while 59% are eutrophic, 8% are mesotrophic and 1% are oligotrophic.
- The most widespread stressors assessed are atrazine detections, phosphorus, and nitrogen with 77%, 44% and 34% 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, 1% of lakes are above the recreational benchmark.
Change from 2012*
- For the Temperate Plains, the NLA reports that the percent of lakes in good condition for nitrogen increased by 30 percentage points between 2012 and 2017 and for habitat complexity by 25 percentage points.
- The percent of lakes in poor condition based on the benthic macroinvertebrate indicator increased by 33 percentage points between 2012 and 2017.
- The percent of lakes with microcystins detections decreased by 23 percentage points.
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.