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Drinking Water Protection
Environmental Health Division
Nitrate and Source Water Protection
On this page:
Guidance for Mapping Nitrate Concentrations
Nitrate Probability Maps and Reports
Nitrate Links
For More Information
Guidance for Mapping Nitrate Concentrations
Guidance for Mapping Nitrate in Minnesota Groundwater (PDF: 720KB/43 pages)
A Nitrate Work Group formed by the Minnesota Department of Health (MDH) produced this guidance in 1998, using funds provided by the United States Environmental Protection Agency. The guidance was developed for use by state, county, and local government units in mapping nitrate contamination. It is intended to help identify areas with nitrate contamination and to identify hydrogeologic and well construction factors that control nitrate distribution in groundwater. This document presents guidance on: how to collect samples for nitrate analysis; database development; criteria to identify well construction, maintenance, or well location concerns; aids to data interpretation; and a three-tiered approach for mapping nitrate-impacted areas.
Additionally, Section 2 of this report provides background information on nitrate, including: health concerns related to nitrate, the nitrogen cycle, sources of nitrate, ranking of the influences of land use on nitrate concentrations, site-specific considerations, and trend analysis. Section 2 also lists references that can be used to understand the effects of land use on nitrate concentrations, such as estimated amounts of nitrogen introduced into the environment by various land uses.
Nitrate Probability Maps and Reports
Listing of Available Nitrate Probability Maps and Reports |
The MDH has also developed nitrate-nitrogen (nitrate) probability maps to assist in state and local water quality planning efforts. These maps identify areas of a county with relatively high, moderate, and low probability of having elevated nitrate concentrations in ground water. The goal of nitrate probability mapping is to help protect public and private drinking water supplies and to help prevent further contamination. |
Example Nitrate Probability Map |
Wells with elevated nitrate concentrations probably will be located in areas ranked as high or medium probability; however, wells in these areas also may provide drinking water without nitrates. Note also that localized problems - such as poor well construction, improper drainage, or onsite wastewater contamination - can lead to elevated nitrate levels and cannot be predicted using the probability maps.
Each probability map is accompanied by an explanatory report which describes the data layers used to develop the map. The data layers used to prepare the map may vary between counties, as different databases are available for various counties.
Nitrate Web Links
MDH: Environmental Laboratory Accreditation Program - Search for Accredited Laboratories
Minnesota Department of Health, Well Management Section: Nitrate in Well Water
Minnesota Department of Agriculture: Drinking Water Protection