The Groundwater Protection rule minimizes potential sources of nitrate pollution to the state’s groundwater and protects our drinking water. The rule restricts fall application of nitrogen fertilizer in areas vulnerable to contamination, and it outlines steps to reduce the severity of the problem in areas where nitrate in public water supply wells is already elevated.
*A number of web addresses in the rule have changed. Please view the Updated Links (PDF) to access the references listed.
Parts of the Rule
The rule contains two parts. Each part contains separate criteria and requirements. Depending on where you farm, you may be subject to one part of the rule, both parts, or none at all.
The rule is intended to promote appropriate nitrogen fertilizer Best Management Practices (BMPs) and to involve local farmers and agronomists in adopting the most current science based and economically viable practices that can reduce nitrate in groundwater. These other practices are called alternative management tools (AMTs).
- More information about nitrogen fertilizer best management practices (BMPs)
- More information about alternative management tools (AMTs)
Part 1 of the rule
Part 1 of the Groundwater Protection rule focuses on restrictions to fall application of nitrogen fertilizer if you farm in 1) an area with vulnerable groundwater or 2) those protection areas around a public well, known as a drinking water supply management areas (DWSMA), with high nitrate.
Vulnerable Groundwater Areas are determined by coarse textured soils, shallow bedrock, or karst geology and are designated by quarter sections. An entire quarter section is included if 50% or more of a quarter-section is considered vulnerable.
- To see if you farm in a vulnerable groundwater area, view the vulnerable groundwater areas map.
Notification of areas subject to fall application restrictions under Part 1 of the rule were posted in January 2020. Restrictions will take effect in September 2020.
View additional information on Part 1 of the Groundwater Protection Rule
Part 2 of the rule
Part 2 of the rule responds to DWSMAs which already have elevated nitrate. The goal is to take action to reduce nitrate in groundwater before a public well exceeds the health standard for nitrate. The rule is structured using a sliding scale of voluntary and regulatory actions based on the concentration of nitrate in the well and the use of the BMPs. The MDA will form a local advisory team with farmers, agronomists and other community members. This team will be involved in reviewing, considering and advising the MDA on appropriate practices or requirements to reduce nitrate in the DWSMA.
There are four mitigation levels used to determine voluntary and regulatory actions, two voluntary levels and two regulatory levels. All areas will begin at a voluntary level and move to regulation only if BMPs are not adopted or if nitrate contamination in the groundwater increases.
The earliest possible regulation under Part 2 of the rule could be three years after the rule takes effect and after a DWSMA is determined to meet the criteria for Level 2.
View additional information on Part 2 of the Groundwater Protection Rule
- MDH nitrate and methemoglobinemia factsheet
- Frequently asked questions (FAQs)
- Fertilizer as a source of nitrate in groundwater
- Nitrogen Fertilizer Management Plan, March 2015 (PDF)
- Rulemaking Process