The primary goal of the Minnesota Department of Agriculture's (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.

In 2017 the MDA’s ambient monitoring program sampled over 200 river, stream and lake locations throughout the state for pesticides and/or nutrients.

Map showing surface water monitoring locations
 

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. 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 2017

  • 1,218 pesticide samples were collected from 208 river, stream, or lake monitoring locations.
    • 150 pesticide compounds were analyzed; 70 pesticide compounds were detected.
      • 48 of the 70 detected pesticide compounds were detected in less than 10% of the samples.
      • Nine of the 70 detected pesticide compounds were detected in greater than 50% of the samples.
    • A degradate of atrazine (hydroxyatrazine) was detected in 89% of samples collected and was the most frequently detected pesticide compound in Minnesota surface waters.
    • The three most frequently detected pesticide parent compounds were 2,4-D (74%), atrazine (63%), and metolachlor (63%).
    • The MDA detected the insecticide chlorpyrifos more times in 2017 than any previous year, including the first detection in a lake.
    • Twenty-two percent of river and stream samples had glyphosate detected, and no detections occurred in lakes. The maximum glyphosate detection was less than one percent of the lowest water quality reference value.
    • Eleven, one, and nine percent of river and stream samples had clothianidin, imidacloprid, and thiamethoxam (neonicotinoid insecticides) detected, respectively.
      • All three imidacloprid detections were greater than the USEPA chronic water quality reference value
      • All clothianidin and thiamethoxam detections were below the USEPA water quality reference values
    • Thirty-nine detections were above the numeric applicable water quality reference value including detections of acetochlor (13 detections), atrazine (2 detections), bifenthrin (4 detections), carbendazim (1 detections),
      chlorpyrifos (15 detections), dichlorvos (1 detection), and imidacloprid (3 detections). The MPCA will assess these detections, including the duration of concentration, for violation of water quality standards, if applicable.

 

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 2002, 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 Impairments

There are ten waterbodies in Minnesota that are either designated, or proposed, by the MPCA as impaired on the USEPA 303(d) Impaired Waters List for currently registered pesticides. These listings are a result of the MPCA assessment of the MDA collected surface water pesticide data. The 2017 and 2018 MDA pesticide water quality data will be reviewed by MPCA as part of the 2020 USEPA 303(d) Impaired Waters List assessment process.
Pesticide Impairment map through 2017 for MN.

 

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

2016

Dry Weather Creek

Chippewa

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

 

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 has been proposed for removal from the proposed 2018 Impaired Waters List. Removal from the USEPA 303(d) Impaired Waters List followed several years of water quality monitoring without elevated pesticide detections.

Visit the MPCA Minnesota Impaired Waters List for more information.

Data Availability and Future Work

All of the pesticide data collected as part of MDAs ambient monitoring program is publicly available through the Water Quality Portal or by contacting 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.