Groundwater Protection Rule

Beginning September 1, 2020, the application of nitrogen fertilizer in the fall and on frozen soil will be restricted in areas vulnerable to groundwater contamination. This will also apply to Drinking Water Supply Management Areas (DWSMAs) with elevated nitrate levels.

Vulnerable groundwater areas include coarse textured soils, karst geology, and shallow bedrock. A map showing the vulnerable groundwater areas as well as a list of exceptions to the restrictions are outlined on the Groundwater Protection Rule website.

The nitrogen fertilizer restrictions are part of the Groundwater Protection Rule, which minimizes potential fertilizer sources of nitrate pollution to the state’s groundwater and works with local farmers to prevent public water supply wells from exceeding the drinking water standard for nitrate contamination.

Why is Nitrogen Fertilizer a Concern?

Nitrate is one of the most common contaminants in Minnesota’s groundwater. The majority of MN households have access to safe drinking water supplies. However, in areas vulnerable to groundwater contamination, some public and private wells have nitrate levels that exceed the health risk limit for nitrate. While elevated levels of nitrate in groundwater can result from several factors, a major contributor in rural MN is nitrogen fertilizer that leaches past the crop root zone.

Need Help?

The WCD offers technical assistance and cost share payments to help implement nitrogen fertilizer best management practices. For more information or questions related to the Groundwater Protection Rule, please contact Angela Defenbaugh at adefenbaugh@mnwcd.org or 651-330-8220 x23.