NR 151 Rule Changes

In late 2019, the DNR was approved to open up the administrative rule, NR 151 to include a targeted performance standard addressing nitrate contamination in groundwater. Over the last year, DNR and their Technical Advisory Committee of assembled experts and stakeholders (including three county representatives) drafted a rule aimed at reducing nitrate leaching from agricultural fields in targeted areas.

Why do we need a new rule?

Nitrate is needed to grow crops and applied to fields through commercial fertilizer and manure across Wisconsin. When rain is heavy and soils are sandy, the plants can miss the opportunity to grab the needed nutrient and seep straight to groundwater. Because nitrogen is readily available, it has long made sense to apply more fertilizer to ensure plants get what they need.

Unfortunately, this also makes nitrate the most widespread drinking water contaminant. Wisconsin communities have struggled to address elevating nitrate levels in both private and public wells in particularly susceptible areas due to high nitrate linked to birth defects, blue baby syndrome, thyroid disease, and certain types of cancer.

The purpose of this rule is to help reduce nitrate contamination to meet the federal drinking water and state groundwater standards of 10mg/l by creating targeted agricultural performances standards and prohibitions in most vulnerable areas of the state.

Who is affected by the draft rule?

The fields that are included in the targeted area are:

1. On Nitrogen Restricted Soils, as defined in NRCS 590 standard. Soils that are permeable, close to bedrock, wet or close to the water table are more likely to allow nitrate to seep past plant roots and reach groundwater. Restricted soils also include areas within 1,000 feet of a community well.

2. In DNR identified sensitive areas based on groundwater nitrate data. The list of areas is included in the rule and can be found in the mapping viewer. No new areas will be added or removed from the list without another revision of the rule.

3. In municipal wellhead protection areas (land around a well known to be contributing most of the water) with nitrate concentrations meeting or exceeding 5mg/l. This allows communities time to ensure they can deliver clean, safe drinking water to residents.

Use the mapping tool: https://wi-dnr.maps.arcgis.com/apps/webappviewer/index.html?id=fea5c014a9dd4a6f901140b05e317b6e

What is the draft performance standard?

Fields within the targeted area will need to account for all sources of nitrate in the nutrient management plan (commercial fertilizer, manure, irrigation water).

To achieve the groundwater standard of 10mg/l, fields will need to limit nitrate loss to under 2.2lb of nitrate/acre/inch of recharge over the crop rotation. The rule does not dictate specific ways to limit losses, but instead a range of approaches to achieve overtime.

What are the draft prohibitions?

All prohibitions apply after September 1 and limit application to fields that are not growing crops.

Commercial fertilizer: Applies to all fields within the targeted area.

Liquid manure: Only applies to fields with highly permeable soils (P soils) and soils close to bedrock (R soils), fields within 1,000 feet to a community well, and within identified Municipal Wellhead Protected Areas.

What are the exceptions to the prohibitions?

If there are crops growing or newly seeded and nitrogen will be used by the plant, manure and fertilizer can be applied after September 1. Rates need to be in accordance with NRCS 590 and included in the nutrient management plan.

There’s an additional exception for liquid manure. With approval by DNR to ensure application rates will still achieve the groundwater standard, liquid manure can still be applied at reduced rates in the prohibition areas after September 1.

How can I provide comments?

The DNR just wrapped up the public comment period for the Economic Impact Assessment. The draft rule will be open for public comment summer 2021.

For more information, visit https://dnr.wisconsin.gov/topic/nonpoint/nr151nitrate.html

Have questions or comments about the draft rule, how it will impact your county, or how you can impact the future of the rule?

Contact Christina: christina@ wisconsinlandwater .org