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Home > Ag Chemicals & Fertilizers > Pesticides > Monitoring & Assessment for Agricultural Chemicals in the Environment > Surface Water Pesticide Water Quality Monitoring

Surface Water Pesticide Water Quality Monitoring

The primary goal of the Minnesota Department of Agriculture's surface water monitoring is to provide detailed information on the occurrence and concentrations of pesticides in Minnesota's surface waters. Protection of Minnesota's citizens and water resources from agricultural chemicals is the fundamental purpose of this goal. The program focus is monitoring of streams and rivers in the agricultural and urban areas of the state.

2016 and historic Minnesota Department of Agriculture surface water monitoring locations throughout the state of Minnesota.


In 1987, the Minnesota Legislature amended the Minnesota Pesticide Control Law (MN Statute 18B.04). It directed the Minnesota Department of Agriculture (MDA) to determine the impact of pesticides on the environment, including the impacts on surface water and groundwater.

In response to this charge, the MDA initiated a pesticide groundwater monitoring program in 1987. In 1991, surface water monitoring began. MDA also conducts edge-of-field water quality monitoring for nutrients and sediment. The MDA has one of the most comprehensive pesticide monitoring programs in the country.


In 2015, there were 82 sampling locations, 1,010 pesticide samples collected and over 52,000 individual analyses.

  • 1,016 pesticide samples were collected from 82 river, stream, or wetland monitoring locations
    • 138 pesticide compounds were analyzed; 62 pesticide compounds were detected
      • 39 of the 62 detected pesticide compounds were found in less than 10 percent of the samples
      • 10 of the 62 detected pesticide compounds were found in greater than 50 percent of the samples
      •  Degradates of atrazine, metolachlor, and acetochlor were the four most frequently detected pesticide compounds in Minnesota surface water
      • The three most detected pesticide parent compounds were 2,4-D, atrazine, and metolachlor, which were detected in 71,67, and 63 percent of the samples respectively
      • Glyphosate was detected three times, and its degradate AMPA was detected once, out of 81 samples. The maximum glyphosate detection was 1.34 percent of its lowest water quality reference value.
      • Four neonicotinoid pesticides (clothianidin, dinotefuran, imidacloprid, and thiamethoxam) were detected in one of 19 samples, at concentrations well below applicable water quality reference values.
    • Of the 62 detected pesticide compounds, acetochlor (five samples from four locations) and chlorpyrifos (seven samples from seven different locations) exceeded water quality reference values
  • 32 pesticide samples were collected from three rainfall monitoring locations and 12 pesticide compounds were detected

For additional information view the yearly monitoring reports and other resources.

Bar graph illustrating the number of pesticide target analytes and detections found from 2000 to 2015 in surface water.

The MDA's pesticide analysis has become more comprehensive in recent years.

  • The number of pesticides analyzed in water samples has grown from 28 in 2000 to 138 in 2015 due to an increase in laboratory analysis capability.
  • Since 2010, the number of detected pesticide compounds in Minnesota surface water has remained relatively stable.




Surface Water Pesticides of Concern

Three pesticides have been designated as "surface water pesticides of concern" by the Commissioner of Agriculture. Acetochlor and atrazine (herbicides) were designated in 2012, and chlorpyrifos (insecticide) was designated in 2012. Designation as a "surface water pesticide of concern" initiates chemical specific best management practices (BMP's) and increased water quality analysis. The designation as a "surface water pesticide of concern" evaluates both detection of the pesticide in Minnesota surface waters and the concentration relative to water quality standards and/or reference values.

Surface Water Pesticide ImpairmentsPesticide impairments for currently registered pesticides. Proposed acetochlor in Silver Creek 2016; Acetochlor delisted in Beauford Ditch and LeSueur River, 2014; Chlorpyrifos impairment Seven Mile Creek, 2012; Chlorpyrifos proposed impairment Grand Marais Creek and Dry Weather Creek, 2016

All data collected by the MDA are evaluated by the Minnesota Pollution Control Agency (MPCA) to determine if pesticide water quality impairments occurred. While MDA detects pesticides in surface water across the state, rarely do pesticide detections violate the water quality standards developed by the MPCA and or the United States Environmental Protection Agency to protect aquatic life.

There are currently 5 waterbodies in Minnesota proposed or designated as impaired on the USEPA 303(d) Impaired Waters List for currently registered pesticides as a result of MDA surface water pesticide monitoring:

  • Acetochlor (violation of the chronic (3,600 ng/L) Minnesota water quality standard)
    • Silver Creek (Carver County, proposed on 2016 Impaired Waters List)
  • Chlorpyrifos (violation of the acute (83 ng/L) Minnesota water quality standard)
    • Dry Weather Creek (Chippewa County, proposed on 2016 Impaired Waters List)
    • Grand Marais Creek (Polk County, proposed on 2016 Impaired Waters List, previously designated in 2014)
    • Seven Mile Creek (Blue Earth County, designated on 2012 Impaired Waters List)
    • Tamarac River (Marshall County, designated on 2014 Impaired Waters List

The 2015 and 2016 MDA pesticide water quality data will be assessed as part of the 2018 USEPA 303(d) Impaired Waters List. The Le Sueur River and Beauford Ditch were designated as impaired for acetochlor on the 2008 USEPA 303(d) Impaired Waters List, and were removed on the 2014 USEPA 303(d) Impaired Waters list due to improved acetochlor water quality conditions over several years and outreach conducted by the MDA.

Visit the MPCA Minnesota Impaired Waters List for more information.

Future Work

The MDA will continue to improve its program to expand monitoring to new locations and to include additional pesticide analytes, if resources are available. Finally, MDA is committed to maintaining its long-term data record to allow for continued trend analysis.

MDA Contact

Bill VanRyswyk
Hydrologist Supervisor