A list of nitrogen best management practices (BMPs) and alternative management tools (AMTs) to protect groundwater within the Rockwood Estates Mobile Home Park Drinking Water Supply Management Area (DWSMA) has been approved by the MDA and published in July 2025.
The list of practices was developed by the MDA in consultation with the Local Advisory Team (LAT). The BMPs that apply to cropland will need to be adopted on at least 80% of cropland (excluding soybean acres) within the DWSMA. AMTs can be voluntarily adopted and used to replace BMPs. A summary of the information used by the MDA to develop the list is also available. Both documents can be found under "Forms + Resources".
The BMP list identifies practices for coarse and fine textured soils. An interactive map of the Rockwood Estates DWSMA is available to illustrate where coarse soils are present.
Note that Part 1 of the Groundwater Protection Rule restricts the application of nitrogen fertilizer in the fall and on frozen soils in this DWSMA unless producers are following the exceptions to the rule.
After no less than three growing seasons following the publication of this list, the MDA will conduct an evaluation to determine if the BMPs or AMTs have been adopted in the Rockwood Estates DWSMA. If during this evaluation less than 80% of the cropland acres within the DWSMA have adopted the BMPs or AMTs listed, the DWSMA may be designated a Mitigation Level 3 and the adoption of the BMPs will be required.
DWSMA Details
Due to elevated levels of nitrate-nitrogen, the Rockwood Estates Mobile Home Park Drinking Water Supply Management Area (DWSMA) has been listed at a Mitigation Level 2 under the Groundwater Protection Rule. To learn more about the determination process visit Mitigation Level Determination.
- Designated a Mitigation Level 2 on January 15, 2023 using the following criteria
- Nitrate levels in the public well were projected to exceeded 10 mg/L nitrate within the next 10 years
- No point source of nitrate found to be the cause of the elevated nitrate level
(i.e., ag chemical incidents, animal feedlots, improperly sealed wells, etc.)
- The DWSMA is approximately 838 acres (high vulnerability area)
- There are two cropland owners and operators within the DWSMA
- Located in Benton County
Local Advisory Team
The MDA established a Local Advisory Team (LAT), consisting of a local farmer, and the public water supplier.
The primary functions of the LAT are to:
- Advise the MDA on the appropriate nitrogen fertilizer best management practices (BMPs) for the project area.
- Explore opportunities to use Alternative Management Tools (AMTs) in targeted high-risk areas.
- Provide the MDA with guidance on the most effective methods to communicate with the agricultural community in the local project area.
- Support the implementation of the BMPs and AMTs at the local level.
Throughout 2023 and 2024, MDA staff met with the Rockwood Estates LAT reviewing agronomic information and the MDA’s analysis of nitrogen loss below cropland within the DWSMA. Below is a list of milestones that were met during this process. The LAT will continue to meet once annually to review new public well nitrate data and discuss ongoing implementation of BMPs and AMTs within the DWSMA.
Status of the Rockwood Estates Mobile Home Park DWSMA LAT
- Formed a local advisory team
- The team is actively meeting
- Interviewed local farmers to gather information on the current nitrogen fertilizer management practices within the DWSMA
- Mapped the boundaries of cropland within this DWSMA
- Completed computer modeling of nitrate loss below the crop rooting zone within this DWSMA
- In consultation with the LAT, a list of BMPs and AMTs that are practicable and appropriate for protecting groundwater within this DWSMA was developed and approved by the MDA.
