Under the Groundwater Protection Rule (Minnesota Rules 1573.0040 Subparts 2 and 3), the MDA determines the mitigation levels for public wells and their Drinking Water Supply Management Areas (DWSMAs) that have elevated levels of nitrate-nitrogen (nitrate). View the current list of DWSMAs with a mitigation level determination.
Mitigation Level Determination Process
The MDA uses monitoring data provided by the Minnesota Department of Health to begin the determination process. Wells that have nitrate levels greater than or equal to 5.4 mg/L (or part per million (ppm)) but less than 8 mg/L at any point in the previous ten years fall within the guidelines for a Mitigation Level 1 determination. Wells with nitrate at or above 8 mg/L at any point in the last ten years, or are projected to exceed 10 mg/L in the next ten years are within the guidelines for Mitigation Level 2. Nitrate levels are used to determine the mitigation level unless the MDA determines there is a point source causing the well to exceed these levels or the MDA delays the determination of a mitigation level decision for good cause.
Final mitigation level determinations are made after the MDA conducts a review of the quality of the monitoring data, the condition and vulnerability of the well, the hydrogeology and groundwater flow paths for groundwater flowing into the well, and potential point sources such as an agricultural chemical facility, septic system(s), feedlot(s) or a poorly constructed well that may be contributing significantly to nitrate levels in the well.
| Mitigation Level | Nitrate level used for determination* |
|---|---|
| Level 1 | 5.4 to less than 8 mg/L |
| Level 2 | 8 mg/L or greater; or are projected to exceed 10 mg/L in the next ten years |
*Based on monitoring data from the MDH. Nitrate values can be from any time in the previous ten years.
The MDA has completed this review for the monitoring data received from the Minnesota Department of Health by July 15, 2023 and determined the following:
| Mitigation Level 1 Drinking Water Supply Management Areas |
Mitigation Level 2 Drinking Water Supply Management Areas |
Mitigation Level |
|---|---|---|
| Becker | Adrian | Atwater |
| Bethany Water Company (new level 2024) | Altura | Battle Lake Mobile Home Park** |
| Chatfield | Cold Spring | Chandler |
| Isanti Estates** | Edgerton | Goodhue |
| Milan (new level 2024) | Elgin | |
| Pine River | Ellsworth | |
| Plainview | Glenwood | |
| Rice | Hastings | |
| Rosemount | Lincoln Pipestone Rural Water- Holland | |
| Valley Mobile Home Park** | Lincoln Pipestone Rural Water- North Holland | |
| Lincoln Pipestone Rural Water- Verdi | ||
| Melrose | ||
| Oak Grove Mobile Home Park** | ||
| Perham | ||
| Rock County Rural Water System | ||
| Rockwood Estates** | ||
| Roscoe | ||
| Saint Peter | ||
| Shakopee | ||
| Sundruds Court Mobile Home Park (new level 2024) | ||
| Utica | ||
| Verndale |
*In DWSMAs where the MDA has delayed the determination of a level decision for good cause, additional information is needed. View the details for current and past DWSMAs Delayed for Good Cause.
** Non-municipal DWSMAs are not subject to the fall and frozen soil nitrogen fertilizer application restrictions in Part 1 of the Groundwater Protection Rule. However, the restrictions may still apply if the land is located in a Vulnerable Groundwater Area. View the Vulnerable Groundwater Area map.
