Surface Water Monitoring Results

2018 Water Quality Monitoring Report January – December 2018 Minnesota Department of Agriculture 625 Robert Street North, Saint Paul, MN 55155 www.mda.state.mn.us Published June 2019 In accordance with the Americans with Disabilities Act, this information is available in alternative forms of communication upon request by calling 651-201-6000. TTY users can call the Minnesota Relay Service at 711. The MDA is an equal opportunity employer and provider. Authors and Contributors Monitoring and Assessment Unit Hydrologists – Heather Johnson, Michael MacDonald, Scott Matteson, Katie Rassmussen, Matt Ribikawskis, Brennon Schaefer, Dylan Timm, and David Tollefson. Monitoring and Assessment Unit Supervisor - Bill VanRyswyk Editor – Heather Johnson Minnesota Department of Agriculture Pesticide and Fertilizer Management Division Monitoring and Assessment Unit Acknowledgements The following personnel and cooperating organizations were critical to the collection of much of the data presented in this report: MDA Laboratory Water Analysis Unit MDA Staff: Stefan Bischof, Russ Derickson, Ryan Lemickson, Jeff Paddock, and Luke Stuewe. Chippewa River Watershed Project, Carver County Water Management Organization, Fillmore County SWCD, Hawk Creek Watershed Project, International Water Institute, Martin County SWCD, Metropolitan Council Environmental Services, Minnesota Department of Natural Resources, Minnesota Pollution Control Agency, Minnesota State University – Mankato, Mower County SWCD, Redwood Cottonwood River Control Area, U.S. Geological Survey, Vermillion Community College and Weck Laboratory. Pursuant to Minn. Stat. § 3.197, the cost of preparing this report was approximately $26,867. Executive Summary Minnesota Department of Agriculture 2018 Annual Monitoring Report* Groundwater 684 pesticide samples were collected from 171 routine groundwater monitoring sites (monitoring wells, springs and private drinking water wells). o Forty different pesticides or pesticide degradates were detected out of 155 pesticide analytes that were analyzed by the MDA Laboratory. o Metolachlor ESA was the most frequently detected analyte (81%). o Glyphosate, and its degradate AMPA, were not detected in the 180 samples that were analyzed. Samples for glyphosate and AMPA were collected at least once from every groundwater site. o Six neonicotinoid insecticides, and two neonicotinoid insecticide degradates, were analyzed in the groundwater samples. There were no detections of neonicotinoids in urban monitoring wells. Detection frequencies of clothianidin, imidacloprid, and thiamethoxam ranged between 10 to 19%. o Isoxaflutole DKN was detected for the first time in MDA’s groundwater monitoring program. o Five pesticides were analyzed for the first time in 2018. Two of these pesticides (fomesafen and sulfentrazone) were detected in 15% and 6% of the samples collected statewide, respectively. o A total of four fomesafen detections exceeded 50% of the human health-based drinking water reference value, including one detection that was greater than the reference value. These samples were collected from three different wells. No other pesticide detections exceeded 50% of an applicable reference value. Private Well Pesticide Sampling 1,589 pesticide samples were collected in 2018 from private wells and analyzed by a contract laboratory. o At least one pesticide was detected in 84% of wells sampled. Eleven percent of the total wells sampled had one pesticide or pesticide degradate detected. Fifty-one percent of the total wells had between two to six pesticide compounds detected. o As many as 16 different pesticide compounds were detected in a single well. o Metolachlor ESA was the most frequently detected pesticide compound (72%). o Four neonicotinoid insecticides were detected infrequently: clothianidin (3%), dinotefuran (<1%), imidacloprid (<1%), and thiamethoxam (<1%). o No pesticide detections were above an applicable human health reference value. Surface water 1,050 pesticide samples were collected from 56 river or stream monitoring locations. o 155 pesticide compounds were analyzed; 72 pesticide compounds were detected. Forty-two of the 72 detected pesticide compounds were detected in less than 10% of the samples. Nine of the 72 detected pesticide compounds were detected in 68% or more of the samples. o A degradate of atrazine (hydroxyatrazine) was the most frequently detected pesticide compound in Minnesota surface water. o The three most detected pesticide parent compounds were 2,4-D, atrazine, and metolachlor. These were detected in 80, 75, and 75% of samples, respectively. o Chlorpyrifos was detected in 11 samples, including 10 detections over the Minnesota chronic standard (41 ng/L) and one detection over the Minnesota maximum standard (83 ng/L). o The neonicotinoid clothianidin was detected 65 times, including 29 detections equal to or over the USEPA benchmark (50 ng/L). o The neonicotinoid imidacloprid was detected 38 times. All imidacloprid detections were over the USEPA benchmark (10 ng/L). o Glyphosate was detected in 9% of samples. The maximum glyphosate detection was <1% of the lowest water quality reference value. o Fomesafen was first analyzed by the MDA in 2018 and was detected in 43% of samples. o Ninety-one detections were above the numeric applicable water quality reference value, including detections of acetochlor (8), atrazine (2), bifenthrin (2), chlorpyrifos (10), clethodim sulfoxide (1), clothianidin (29), diazinon (1), and imidacloprid (38). The MPCA will assess these detections, as well as the duration of concentration, for any applicable violation of water quality standards. 12 pesticide samples were collected from two lake locations. o Chlorpyrifos was detected in one lake sample over the Minnesota chronic standard (41 ng/L). The MPCA will assess this detection along with the duration of concentration to determine if there was a violation of a water quality standard. Rain Monitoring 35 pesticide samples were collected from three rain monitoring locations, and 16 pesticide compounds were detected. *Citation: Minnesota Department of Agriculture 2018 Water Quality Monitoring Report: https://www.mda.state.mn.us/pesticide-fertilizer/water- monitoring-reports-and-resources Table of Contents Table of Contents ............................................................................................................................i List of Figures .................................................................................................................................iv List of Tables ..................................................................................................................................viii List of Appendices ..........................................................................................................................xi Abbreviations ..................................................................................................................................xii Definitions.......................................................................................................................................xiii SECTION 1: Introductions ....................................................................................................... 1-1 1.1 Program history ................................................................................................................ 1-1 1.2 Overall program purpose ................................................................................................. 1-2 1.3 Program elements............................................................................................................. 1-2 1.4 Pesticide Monitoring Regions .......................................................................................... 1-2 1.5 Changes to program activities .......................................................................................... 1-4 1.5.1 Groundwater .......................................................................................................... 1-4 1.5.2 Surface water ......................................................................................................... 1-4 1.6 Recent precipitation patterns............................................................................................ 1-6 1.7 Chemical analytes and 2018 detection summary ............................................................. 1-6 SECTION 2: Groundwater Monitoring Results ..................................................................... 2-1 2.1 2018 Groundwater pesticide sampling summary ............................................................. 2-3 2.1.2 2018 Quality Assurance/Quality Control Summary ........................................... 2-12 2.2 Trend analysis ................................................................................................................ 2-12 2.3 Analysis of the common detection pesticides ................................................................ 2-15 2.3.1 Acetochlor results ................................................................................................ 2-17 2.3.2 Alachlor results .................................................................................................... 2-25 2.3.3 Atrazine results .................................................................................................... 2-32 2.3.4 Metolachlor results .............................................................................................. 2-44 2.3.5 Metribuzin results

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