The primary goal of the MDA's surface water monitoring program is to provide detailed information on the occurrence and concentrations of agricultural chemicals, including pesticides and nutrients, 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.

Public Notice

New Draft Clothianidin and Imidacloprid BMPs are available for public comment

The MDA is seeking public comment on draft water quality best management practices (BMPs) for agricultural use of two neonicotinoid insecticides, clothianidin and imidacloprid. The BMPs were developed by the MDA in consultation with the University of Minnesota Extension and others to address impacts from clothianidin and imidacloprid on water resources. 

DRAFT Water Quality Best Management Practices for Agricultural Use of Clothianidin & Imidacloprid (PDF)

Notice for public comment was published in the November 21, 2022 Minnesota State Register. The comment period is open through January 19, 2023. Comments can be submitted to Theresa Cira by email or letter.

Theresa Cira
Pesticide and Fertilizer Management Division
Minnesota Department of Agriculture
625 Robert Street North, Saint Paul, MN, 55155

651-201-6237
Theresa.Cira@state.mn.us  

New “Surface Water Pesticides of Concern” Designated

The Commissioner of the MDA has determined that the neonicotinoid insecticides clothianidin and imidacloprid are “surface water pesticides of concern” in accordance with the state Pesticide Management Plan (PMP). For more information on this designation and the supporting resources for the determination visit the surface water pesticides of concern page.


Monitoring

In 2019 the MDA’s ambient monitoring program sampled 55 river, stream and lake locations throughout the state for pesticides and/or nutrients.
State of Minnesota map showing the surface water monitoring locations for 2019.
 

History

In 1987, the Minnesota Legislature amended the Minnesota Pesticide Control Law (MN Statute 18B.04). It directed the 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. The 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.

 

Surface Water Monitoring Results for 2019

The MDA’s ambient surface water monitoring focuses on pesticide sample collection from rivers and streams around the state.

In 2019, 1,161 pesticide samples were collected from 55 river or stream monitoring locations for up to 166 pesticide analytes.

  • 69 different pesticides or pesticide degradates were detected.
    • 39 were detected in 10% or less of the samples.
    • 12 were detected in 50% to 97% of the samples.
  • The most commonly detected parent pesticide compounds were the herbicides 2,4-D, metolachlor, and atrazine detected in 85%, 79%, and 67% of samples, respectively.
  • 3 neonicotinoid insecticides, clothianidin, imidacloprid, and thiamethoxam, were detected in 30%, 27%, and 11% of samples, respectively.
  • 138 detections were above an applicable numeric water quality reference value, including acetochlor (11), atrazine (2), chlorpyrifos (3), clothianidin (62), dichlorvos (1), imidacloprid (58), and metolachlor (1).
    • Where state water quality standards are available, the Minnesota Pollution Control Agency (MPCA) will assess these detections, as well as the duration of concentration, for any applicable violations of standards.
    • Pesticides without state standards in the above list (clothianidin, dichlorvos and imidacloprid) are compared to U.S. Environmental Protection Agency (USEPA) aquatic life benchmarks.
  • Glyphosate was detected in 10% of samples, and the maximum glyphosate detection (5,880 ng/L) was <1% of the lowest water quality reference value.
  • Acifluorfen and deethylcyanazine acid were detected for the first time in Minnesota surface water in 3% and 15% of samples, respectively.
  • 6 pesticide samples were collected from one lake and eight pesticide analytes were detected at concentrations well below the applicable water quality reference values.
  • 43 pesticide samples were collected from four rainfall monitoring locations, and 20 pesticide compounds were detected.
  • 3 pesticides are designated as "surface water pesticides of concern" by the Commissioner of Agriculture.

 

Surface Water Pesticide Impairments

There are fourteen waterbodies in Minnesota that are either designated, or proposed to be designated, by the MPCA as impaired on the USEPA 303(d) Impaired Waters List for currently registered pesticides. These listings result from the MPCA assessments of the MDA surface water pesticide data. The 2019 and 2020 MDA pesticide water quality data will be reviewed by MPCA as part of the 2022 USEPA 303(d) Impaired Waters List assessment process.
 
Map of Minnesota illustrating the fourteen waterbodies that are designated as impaired or proposed to be designated by the MPCA. Ten are located in the southwest, 2 in south central, and 2 in the northwest.See Table 1 for more information.

 

Table 1. Minnesota pesticide impairments for currently registered pesticides.

Pesticide Impaired Waters List Year Stream County Violation that Resulted in Impairment
Acetochlor 2016 Silver Creek Carver chronic (3,600 ng/L) Minnesota water quality standard
Chlorpyrifos 2018 Beauford Ditch Blue Earth maximum (83 ng/L) Minnesota water quality standard
Chlorpyrifos 2018 Beaver Creek Murray maximum (83 ng/L) Minnesota water quality standard
Chlorpyrifos 2018 Chetomba Creek Renville maximum (83 ng/L) Minnesota water quality standard
Chlorpyrifos 2020 Double Lake Cottonwood chronic (41 ng/L) Minnesota water quality standard
Chlorpyrifos 2016 Dry Weather Creek Chippewa maximum (83 ng/L) Minnesota water quality standard
Chlorpyrifos 2020 Dutch Creek Martin maximum (83 ng/L) Minnesota water quality standard
Chlorpyrifos 2014/2016 Grand Marais Creek Polk maximum (83 ng/L) Minnesota water quality standard
Chlorpyrifos 2018 Jack Creek Jackson maximum (83 ng/L) Minnesota water quality standard
Chlorpyrifos 2018 Lac qui Parle River Lac qui Parle maximum (83 ng/L) Minnesota water quality standard
Chlorpyrifos 2018 Sleepy Eye Creek Redwood maximum (83 ng/L) Minnesota water quality standard
Chlorpyrifos 2014 Tamarac River Marshall maximum (83 ng/L) Minnesota water quality standard
Chlorpyrifos 2020 Three Mile Creek Lyon maximum (83 ng/L) Minnesota water quality standard
Chlorpyrifos 2020 Yellow Medicine River Yellow Medicine maximum (83 ng/L) Minnesota water quality standard

Three waterbodies have been removed from the USEPA 303(d) Impaired Waters List for currently registered pesticides. The Le Sueur River and Beauford Ditch were designated as impaired for acetochlor in 2008 and were removed from the USEPA 303(d) Impaired Waters List in 2014. Seven Mile Creek was designated as impaired on the 2012 Impaired Waters List for chlorpyrifos and was removed from the USEPA 303(d) Impaired Waters List in 2018. Removal from the USEPA 303(d) Impaired Waters List typically occurs after several years of water quality monitoring without pesticide detections above the applicable standards.

Visit the MPCA Minnesota Impaired Waters List for more information.

Chlorpyrifos Response Plan: This plan was developed in response to continued detections of chlorpyrifos in rivers, streams and lakes and the determination of chlorpyrifos water quality impairments of rivers and streams in agricultural areas of Minnesota.

Data Availability and Future Work

All of the pesticide data collected as part of the MDA's ambient monitoring program is publicly available through the Water Quality Portal or by contacting the MDA. The MDA will continue to improve its program to expand monitoring to new locations and to include additional pesticide analytes, as resources and needs permit. The MDA is committed to maintaining its long-term data record to allow for continued assessment of the impacts of pesticides on surface water from routine use.