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Joseph Zachmann, Ph.D.Research Scientist
Pesticide & Fertilizer Management Division
Pesticides & Risk
Pesticides control insect pests, weeds and diseases andmay pose risk to human health and the environment
Some pesticides leach to groundwater
People are concerned about exposure risks
Are there pesticides in my drinking water?
How high are the concentrations relative to known risk?
Even if concentrations are low, what about unknown risks likeexposure to pesticides in mixtures, endocrine disruption and
other concerns?
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Groundwater Monitoring for Pesticides
MDA monitoring networks aredesigned for agricultural pesticides
Wells are located adjacent tooperating farm fields
Central Sand Plainmonitoring well nest
Far from non-agricultural contaminant sources; intersect water
table to represent worst-case scenario
Southeast karst bedrock aquifers are monitored viasprings
Extremely rare long-term data set entering 29th year
Statewide Network
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What are we looking for?
In 2011 276 groundwater samples
From 171 wells/sites
CWF helped purchase state-of-the-art LC/MS-MS equipment to:
Find pesticides at lower concentrations
Increase number of pesticides & samples analyzed
Each sample analyzed for 110 different pesticides ordegradates = 30,000 analyses annually
As new pesticides are registered they are reviewed forrisk and may be added to the analytical list
What do we find?
40 pesticides or degradates detected
Most are found in fewer than 4% of samples
Commonly detected in vulnerable areas:
Acetochlor
Alachlor
Atrazine
Metolachlor
Metribuzin
No pesticide concentrations exceeded MDHdrinking water risk levels
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Metolachlor in Central Sands
Atrazine and its degradates are frequently detected, but concentrationshave decreased significantly in recent years
Atrazine and degradate concentrations: 2000-2012
Atrazine and its Degradates in Central Sands
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Atrazine in Southeast Karst
Uncertainties and Groundwater Risks
Possible changes in pesticide use patterns &groundwater impacts due to:
New pesticide-resistant crop technologies
Weed resistance to current pesticides
Invasive species control
Climate change effects (warming) on economic croppests
Climate change effects on increased precipitationintensity and greater leaching and runoff
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All MDA monitoring data is:
Reviewed, compiled and reported annually Submitted to MDH, MPCA and EPA for evaluation
Available and stored long-term in MPCAs EQuISdatabase
QUESTIONS?
Joseph Zachmann, Ph.D.
Research ScientistPesticide Management Unit
Minnesota Department of [email protected]
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Nitrates in Groundwater within
Agricultural Regions of Minnesota
Senate Legislative Briefing:Environment and Energy Committee
April 9, 2013
Bruce MontgomerySection Manager
Fertilizer Non-Point Section
Pesticide and Fertilizer Management DivisionMN Department of Agriculture
A groundwater/drinking watercontaminate of major concern
NitrateNO3-N
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Potentially Lost to Groundwater,Surface Water or Tile Drainage
Nitratemovement togroundwater,springs, andtile drainagewaters can be
appreciable
The ManyEscape Routesof Nitrogen
Whats Grown on the LandStrongly Influences Nitrate
Loss to the Aquifer
Groundwater Stressors
Cropping Systems areNOT created equal
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Crops with Low N Loss Leaching Potential
Alfalfa and CloverVegetated Pasture
Native Prairie/CRP Plantings Perennial Crops
Acreage Trends in Minnesotas Legume Crops(All Hay and Soybeans)
SoybeansAlfalfa,Clover, etc
The Last 90 Years..
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Acreage Trends for Minnesotas Major NitrogenDemanding Crops
All Small Grain Crops
Corn
The Last 90 Years..
Crops with High N Loss Leaching Potential
Potatoes
Edible Beans
Grain Corn
Silage Corn
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Data Source: MDA, TVA, and AAPFCO
Commercial Nitrogen Fertilizer SalesTrends in U.S.& Minnesota: 1965-2011
1960s 1970s 1980s 1990s 2000s 2010s
MN Farmers Continue to Increase Efficiencyfrom Their Nutrient Inputs
Bushels of Corn Produced perLb of N Fertilizer
1992 to 2011
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County Well Index DataNitrates in Private Drinking Wells
Most elevatedconditions are found inthe Central Sands regionand Washington/DakotaCounties;
(Note that only wells with nitrate-N> than 3 mg/L are illustrated here)
Two Home Owner Nitrate Monitoring Networks havebeen Recently Established
Networks have beendesigned to provide low-cost nitrate trendinformation;
Private wells selected ona pre-determined grid;
Multi-Agency support;
SWCD and/or LocalEnvironmental Healthshoulder much of work
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Homeowner Participation is the Cornerstone ofthe Design
Nitrates in Private Drinking Wells in theCentral Sands
Home Owner NetworkApproach included1,555 Minnesotafamilies;
This recent data(2011) suggests that
about 5% > HealthStandard (10 mg/L);
Approx. 500-600wells will be used forlong-term trends
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Southeast Nitrate Monitoring Network
2008 to 2011
Data Source: MDH
This Type of Information will be ExtremelyValuable to Future Generations
Recent AnalysisSuggests that
between 200-300Agricultural
Townships Are atPotential Risk
(based upon GIS layering ofsensitive surficial geologyand row crop density)
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Nitrates in PublicWater Supplies
Nitrates in Public Water Supplies
Based upon MDHdata, less that 1% ofMinnesotas publicwater supplies exceedthe MCL;
(Note that only wells with
nitrate-N > than 3 mg/Lare illustrated here)
Figure 10. Distribution of public water supply wells in the County Well Index
with nitrate-N greater than 3 mg/L
Data Source: MDH
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Roughly 20-25 Public Water Suppliers in AgriculturalAreas are Dealing with Nitrate Issues
y = 0.0012x - 40.114
R = 0.688
0
2
4
6
8
10
12
14
Jan-93 Oct-95 Jul-98 Apr-01 Jan-04 Oct-06 Jul-09
Nitrate-N(mg/L)
PARK RAPIDS WELL 4
Rapidly Increasing Nitrate Levels Are NotUncommon in These Highly Sensitive Landscapes
1993 1998 2003 2008
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Whats at Stake for Community WaterSuppliers Dealing with Nitrate Problems?
Nitrate removal systemstypically cost more than $3Million for upfront constructioncosts and also maintenance costs
Costs of drilling new and/ordeeper wells;
Costs of blending multiplewells to achieve get acceptablewater quality;
Consumer costs are 2-6 times
higher than non-impacted watersupplies
LESSONS LEARNED: MDA, MDH, and our
partners have tools and case studies to share
http://www.mda.state.mn.us/protecting/waterprotection/drinkingwater.aspx
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