EPA’s letter to state on nitrate levels, how it will affect local area

The bluffs and extensive cropland of Southeast Minnesota sit on a geologic terrain called karst. In Southeast Minnesota, karst is made up of limestone and dissolves easily to form fractures, and holes below the surface. The porous qualities of karst allow water to travel underground quickly and its limestone dissolves easily which prevents the filtering of groundwater. This leads to karst being extremely vulnerable to contamination, according to the US Geological Survey (USGS). Contaminants, such as nitrates from fertilizers and manure through runoff, travel easily through the limestone and end up in groundwater and rivers.
The Karst Region of Southeast Minnesota consists of Dodge, Fillmore, Goodhue, Houston, Mower, Olmsted, Wabasha, and Winona counties. In this region, over 300,000 people rely on public water supplies and over 94,000 rely on private wells for drinking water. High nitrate levels in karst aquifers resulting from agricultural production have caused many public water suppliers to pursue additional water treatment or to dig deeper wells. Minnesota Department of Agriculture nitrate monitoring suggests over 9,200 Karst Region residents are at risk of consuming water that contains over 10 milligrams of nitrate per liter. Those tests showed 12.1% of private wells in the region exceeded that limit. Such levels can lead to colorectal cancer, thyroid disease, neural tube defects, and a sometimes fatal condition in infants called methemoglobinemia.
Because of the nitrate contamination found in many wells in Southeast Minnesota, eleven Minnesota environmental groups sent a petition to the Environmental Protection Agency (EPA) in April 2023. They urged the EPA to use its emergency authority to address the danger that nitrate in the Karst Region poses to human health.
On November 3rd, 2023, the EPA sent a letter to Minnesota state commissioners of the Agriculture and Health Departments and the MN Pollution Control Agency requesting immediate plans be implemented to ensure the nitrate contamination crisis does not get worse. By early December, the EPA requests the state develop a plan on how to identify, contact, conduct drinking water testing, and offer alternate water to impacted persons in the Karst Region. The letter mostly regards immediate actions but also insists the state develops a long-term solution to lowering nitrate concentrations in drinking water supplies.
Debra Shore, the EPA Region 5 Administrator, suggested that Minnesota adopt more “protective permits for wastewater and large animal feedlots, and stronger guidelines for applying manure and fertilizer to fields.”
Minnesota’s 1st District Congressman Brad Finstad has slammed the EPA, claiming it’s “targeting Minnesota family farmers at the behest of environmental extremists.”
However, farmers already implement, and can continue to implement, practices that reduce nitrate runoff. One such practice is planting perennial cover crops. Cover crops lower the erosion rate of soil and nutrients out of fields and can decrease nitrogen runoff by 70% according to a study done by agronomists at Iowa State University. Cover crops also build back organic matter in soil and improve crop yields over time, according to Sarah Carlson, an agronomist for Practical Farmers of Iowa, making them a more attractive option for decreasing nitrate runoff.
The EPA lists other farming practices that also reduce nitrogen runoff, including minimum tillage practices and woodchip bioreactors in drainage ditches. Among the most effective is buffer stripping. By adding grass buffer strips between cropland and water sources, nutrients are filtered and absorbed thus reducing sediment, nutrient, and pollutant runoff into waterways.
According to the USDA, one acre of buffer land stops 2.5 tons of soil, 6.4 pounds of nitrogen, and 1.1 pounds of phosphorus from being lost to runoff. When farmers implement buffer strips through the Conservation Reserve Program (CRP), they even receive financial benefits and a continuous acre rental rate from the program. Fields next to CRP land also lose less fertilizer so farmers won’t have to buy as much fertilizer in the years following CRP implementation.
Since Governor Mark Dayton created a buffer strip mandate in 2015, compliance with that mandate has increased from 87.2% in 2017 to 99.6% in 2023. The hard work that farmers and government officials have done at local levels to follow the mandate led to its overall success. However, nitrate contamination is still a problem in Southeast Minnesota. The success of the buffer mandate shows that the Minnesota state government and farmers can take the lead again in setting guidelines to further stop nitrates from contaminating groundwater in the Karst Region. Though it is not yet known how the state will tackle nitrate contamination, in early December the state will reveal plans to improve drinking water for Southeast Minnesota and will likely focus on agricultural solutions.