Monitoring for Pesticides in Wyoming's Water

Science Center Objects

Wyoming's groundwater and streams are routinely monitored for pesticides. In order to balance the use of pesticides (herbicides, insecticides, and fungicides) with the protection of water resources, the Wyoming Department of Agriculture began a project to sample groundwater in 1995, in cooperation with the U.S. Geological Survey. Since the project's inception, more than 750 samples from groundwater and, recently streams, have been collected across Wyoming and analyzed for up to 165 pesticides and their breakdown products. No sample collected has had a pesticide detected at a concentration exceeding drinking-water standards.  

Groundwater sampling results:

Locations of wells sampled 1995-2006 and notation of pesticide detected (red dot)

Locations of wells sampled for baseline sampling during 1995-2006. Well locations are shown in red when pesticide detected.(Public domain.)

 

  • Nearly 700 groundwater samples from nearly 350 wells have been collected since 1995.
  • Samples have been collected from wells in every county in Wyoming.
  • Baseline samples were collected at sites where groundwater was deemed to be the most vulnerable to human activities, so results from this project describe the groundwater where pesticides are most likely to be detected.
  • Two-thirds of the pesticides or breakdown products that were screened for were never detected.
  • Herbicides were detected more often than insecticides, and fungicides were not detected in groundwater. 
  • Four of the nearly 165 pesticides analyzed for were found more frequently in groundwater: prometon (trade name Pramitol), atrazine (trade name Aatrex), simazine (trade name Princep), tebuthiuron (trade name Spike).
  • Water from wells that were located in urban areas tended to have pesticides detected more frequently than wells located in agricultural areas.
  • Water from wells in agricultural areas tended to have a wider variety of pesticides detected.

Surface-water sampling results:

  • Around 60 samples from 19 different streams and rivers have been collected since 2006.
  • Three-quarters of the pesticides or breakdown products that were screened for were never detected.
  • Herbicides were detected more often than insecticides or fungicides. 
  • Four of the nearly 140 pesticides analyzed for were found more frequently in surface water: glyphosate (trade name Roundup), 2,4-D (trade name Dacamine), 2,4-DB (trade name Butoxone), and prometon (trade name Pramitol)
  • Streams and rivers in areas with agricultural activities tended to have pesticides detected more frequently than in areas with other land uses.