In Minnesota, study finds drinking water tainted with nitrates

Hundreds of thousands of Minnesota residents are drinking water contaminated with elevated levels of nitrates, according to a new analysis from the Environmental Working Group. The state is rolling out new rules to regulate nitrogen fertilizer application and protect groundwater, but advocates say they may not go far enough to keep residents safe.

According to EWG’s analysis of federal and state data, nearly 500,000 Minnesotans are drinking water from public water systems or private wells that have logged elevated levels of nitrates within the past 10 years. Overwhelmingly, the affected residents live in rural communities. About half of the contaminated water systems were located in areas where the average income falls below the state median.

The nitrate contamination is caused by fertilizer runoff, researchers say. Millions of acres of corn and soybeans are cultivated in Minnesota and fertilized with nitrogen. Excess nitrogen can run off into waterways or seep into the groundwater, affecting the state’s drinking water.

Anne Schechinger, senior economic analyst at EWG and co-author of the report, says that farmers aren’t implementing conservation practices that could keep nitrogen out of drinking water sources. “When you have huge amounts of crop acres that are not receiving any conservation practices, that’s going to lead to these nutrient runoff issues.”

Consuming elevated levels of nitrates can introduce a range of health issues, including “blue baby syndrome,” a potentially fatal condition for infants. New research suggests that consumption of excess nitrates could be associated with a higher risk of cancer. Under the Clean Water Act, the federal legal limit for nitrates in drinking water is 10 milligrams per liter, yet research suggests lower levels could also expose humans to adverse health effects.

Minnesota’s Department of Agriculture is making an effort to address the state’s nitrate issues with its new Groundwater Protection Rule, which has been decades in the making and will go into effect on Jan. 15. The rule restricts application of nitrogen fertilizer in the fall in farming regions that have vulnerable groundwater or are near a public well. In areas with highly contaminated groundwater, it also introduces “a sliding scale of voluntary and regulatory actions” to prevent the nitrate levels from exceeding the legal limit.

Advocates have applauded the state for making an effort to address the groundwater issue. “This is a great step forward,” says Sarah Porter, senior GIS analyst at EWG and co-author of the report. “No other state has had this kind of rule go into effect that has regulatory enforcement.”

The rule has received support from the state’s agriculture industry. The Minnesota Corn Growers Association says it has been involved with developing the rule and agrees that the “overall quality of our groundwater is a legitimate concern.”

Yet experts also say the rule doesn’t go far enough. It only applies to 13 percent of farmland in the state, and it doesn’t apply to private wells. It also relies in large part on voluntary participation from farmers before regulation kicks in. One retired soil scientist in Minnesota told the Star Tribune in June that even after the rule goes into effect, “there won’t be any improvement in nitrate in the water.”

“The state isn’t doing enough to protect people on private wells or public water systems from these dangerous public health impacts,” says Schechinger. “The Groundwater Protection Rule is a good first step but it isn’t going to be enough to protect people who are drinking nitrate in their water.”

The state could better protect its residents by closely monitoring and testing private wells, Schechinger says. EWG’s analysis found that more than 3,000 private wells were at or above the legal nitrate limit; 164 wells tested at or above twice the legal limit.

Though it has its limitations, EWG’s researchers say that the Groundwater Protection Rule will likely serve as a model for other states that are dealing with groundwater contamination from fertilizer runoff. Iowa residents have struggled with polluted and contaminated waterways for many years. Wisconsin’s runoff has contributed disproportionately to “dead zones” in the Gulf of Mexico. Those and other states will be looking to the rollout of Minnesota’s rule for guidance on future efforts, the report’s authors say.