Groundwater and Surface Water Protection: Agricultural Chemicals

Why is it important the plan focus on this concern?

Agricultural chemicals may contribute to water pollution from runoff into surface waters or infiltration into groundwater. Contaminated groundwater and surface water can affect human health as well as ecosystem quality. The protection of drinking water is an important health issue as approximately 75 percent of Minnesotans obtain their drinking water from groundwater.

Groundwater contamination from nitrate presents a potential health risk to human populations that rely on it for drinking water. In areas with vulnerable groundwater, nitrate may exceed the drinking water standard. If elevated nitrate levels are detected in drinking water, there may be in an increased probability that other contaminants, such as bacteria or pesticides, may be present. Once the standard is exceeded, it may be difficult to reduce the levels of contaminants. Therefore, it is highly desirable to prevent contamination of groundwater from occurring through protective actions in areas with vulnerable aquifers.

Agricultural chemicals are also frequently a concern related to surface water impairments under the Clean Water Act. The most common agricultural sources of excess nutrients in surface water are chemical fertilizers and manure. Such nutrients contribute to eutrophication in surface water and have been identified as a source of hypoxia in the Gulf of Mexico.

What actions are needed?

  • Continue the sealing of abandoned wells in agricultural landscapes and prioritize efforts for subsurface sewage treatment system upgrades in sensitive areas. Utilize the MDA Ag BMP Loan Program and other cost-share programs to assist landowners in addressing these issues.
  • Promote the appropriate Nitrogen Fertilizer BMPs for Agricultural Lands
  • Promote crop irrigation water management (Ag Weather and Irrigation Management Resources)
  • Encourage the conversion of older irrigation systems to low pressure.
  • Develop and implement educational programs regarding water management in conjunction with nitrogen fertilizer management.
  • Promote the establishment and data access of local climate stations to irrigators for ET (evapotranspiration) estimates.
  • Promote the use and availability of irrigation scheduling software and record keeping.
  • Promote the use of the county soil survey and other localized soils information in determining soil moisture holding capacity on a field-specific scale.
  • Encourage the use of soil moisture sensors (moisture blocks, tensiometers, etc.) and other advanced tools for determining crop water stress.
  • Chemigation (nitrogen applied through the irrigation water) is an excellent option for irrigators to distribute small amounts of nitrogen (20-30 lb/acre).  Note that the MDA requires a chemigation permit and the proper backflow equipment.
  • Provide assistance in irrigation uniformity testing and nozzle calibrations.
  • Provide nitrate testing services on irrigation water to help promote nitrogen crediting concepts and environmental protection. MDA staff can help provide equipment and technical assistance.
  • Promote hybrid and crop selection that have lower water and/or nitrogen requirements.
  • In highly sensitive groundwater areas or areas where high nitrate concentrations already exist, explore Alternative Management Tools, such as cover crops, diversifying the rotation, conversion to perennial crop or retiring the land.
  • Conduct training sessions and workshops for farmers that have agricultural production activities within sensitive areas and drinking water supply management areas.
  • Encourage the use of the Nutrient Management Initiative plots and similar tools within these areas.
  • More resources regarding drinking water protection in agricultural settings.
  • Provide Minnesota Agricultural Water Quality Certification Program information and encourage participation to access technical and/or financial assistance to County landowners and operators to implement agricultural best management practices on working lands to reduce soil erosion, protect stream banks and improve water resources.

What area(s) of the county is high priority?

Sensitive areas where row crops and/or livestock are being produced, including Drinking Water Supply Management Areas.

What resources may be available to accomplish the actions?

The MDA prepares specific maps for counties to assist in local groundwater protection efforts. The maps should be used to prioritize groundwater BMP implementation, protection and restoration efforts. The Water Table Aquifer Sensitivity map classifies the county into three aquifer sensitivity ratings: low, medium and high. These reflect the likelihood that infiltrating precipitation or surface water would reach the water table possibly bringing surface contaminants with it. Priority should be given to the Drinking Water Supply Management Areas (DWSAs), Wellhead Protection Areas and to the areas given a high aquifer sensitivity rating.

Nitrate concentrations found in MDA monitoring wells and wells in the County Well Index (CWI) are also shown on the map. Concentrations greater than 3 mg/L indicate nitrate concentrations above background levels, while concentrations greater than 10 mg/L are above the nitrate drinking water standard. 

Programs to evaluate:

Programs to prevent: 

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Additional Priority Concerns

  • Livestock & Manure Management
  • Agricultural Land Management
  • Targeting BMPs, Aligning Local Plans, & Engaging Agriculture
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Introduction to the Nutrient Management Initiative

The Minnesota Nutrient Management Initiative (NMI) was develo

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