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National Aquatic Resource Surveys

Temperate Plains Ecoregion - National Lakes Assessment 2012 Results

Key Results

A total of 15,045 lakes in the Temperate Plains ecoregion are represented in the National Lakes Assessment (NLA). Of these lakes, about 46% are natural and 54% 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 Temperate Plains, 35% of lakes are rated as most disturbed based on trophic state, 41% are eutrophic, 23% are mesotrophic, and 1% are oligotrophic.
  • The most widespread stressors assessed are phosphorus (46% of lakes), nitrogen (34%), and lakeshore disturbance (30%).

Trophic State

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

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Photo of a lake in the Temperate Plains ecoregion that was sampled during the National Lakes Assessment 2012Kansas lake sampled during the NLA 2012.

Human Use Condition

Cyanobacteria is one of three algal toxin related indicators presented 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, 34% of lakes in the Temperate Plains are in the most disturbed condition (i.e., pose a high risk of exposure to algal toxins).

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Change from 2007 (for lakes >4 hectares)*

  • For the Temperate Plains, the NLA reports a 29% decrease in the proportion of lakes in the most disturbed condition between 2007 and 2012 based on the lake drawdown exposure indicator.

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

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* 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.