Minnesota’s new Groundwater Protection Rule may not be enough to protect residents from exposure to nitrates in the drinking water supply, says a report from the Environmental Working Group (EWG).

The report applauds the implementation of Minnesota’s Groundwater Protection Rule, but adds, “Even full implementation of the new rule may be too little, too late to protect Minnesotans – especially those drinking water from private household wells – from unsafe levels of nitrate.”

The application of nitrogen fertilizer in the fall or on frozen soils will be restricted in areas with a soil type that is vulnerable to nitrate infiltration. (Minnesota Dept. of Agriculture)
The application of nitrogen fertilizer in the fall or on frozen soils will be restricted in areas with a soil type that is vulnerable to nitrate infiltration. (Minnesota Dept. of Agriculture)

The EWG, a non-profit organization based in Washington, D.C. involved in research, advocacy and education, reported on Jan. 14 that an estimated 500,000 Minnesotans are drinking tap water contaminated with unsafe levels of nitrate, a chemical associated with cancer and other serious health problems.

“Many years of unaddressed nitrate from farm pollution have brought Minnesota to the brink of a public health crisis,” said Sarah Porter, a geographic information systems analyst who is one of the report’s authors. She attributed the elevated nitrate levels to “the state’s failure to hold farmers accountable for not keeping fertilizer and manure out of the water supply.”

According to data from the Minnesota Department of Health (MDH), more than 150,000 Minnesotans drink water from groundwater-based public water systems containing nitrate at or above the legal limit of 10 milligrams per liter (mg/L).

That limit was set by 1962 federal legislation to guard against blue baby syndrome. More recent research suggests that half that amount, 5 mg/L, or even less is associated with higher risks of colorectal cancer and neural tube birth defects. EWG researchers recently released a study finding that nitrate pollution of U.S. drinking water may cause up to 12,594 cancer cases a year.

More than 300,000 Minnesotans get water from systems with nitrate levels at or above 5 mg/L, the report says. Another 200,000 people drink tap water with 3 mg/L or more of nitrate, according to tests conducted by tap water utilities under federal guidance between 2009 and 2018.

The report notes that nitrate is found in many foods and occurs naturally in soil at low levels. However, a nitrate level of 3 mg/L or higher indicates a human cause, according to the MDH.

The EWG’s analysis also shows nitrate contamination in private wells in the state. Tests by the MDH and the Minnesota Department of Agriculture between 2009 and 2018 found more than 3,000 households drink from private wells with nitrate contamination of 10 mg/L or higher; more than 7,600 wells tested at least once at or above 3 mg/L; and 6,000 wells had nitrate levels of at least 5 mg/L.

As a result, the report says, one in eight Minnesotans whose water comes from groundwater-based public water systems are affected by concerning nitrate levels, as are tens of thousands who drink from private wells.

The most contaminated systems and wells are located in southeastern, southwestern and central Minnesota, where the soil and geology make it easier for nitrate to seep into groundwater. The most vulnerable areas comprise one-quarter of the state, including 2.5 million acres of cropland and 6,287 livestock feedlots.

“Minnesota’s new nitrate rule is a necessary, important first step, but much more needs to be done – and soon,” said Anne Weir Schechinger, an economic analyst and the report’s co-author. “As written, this rule has too many loopholes allowing for continued contamination of tap water from farms.”

In 2017, the EPA began to review its legal limit for nitrate, but halted the process in April 2019, saying it was no longer a priority for the agency.

Nitrates in Hubbard County

In local data provided with the EWG report, at least one test taken between 2009 and 2018 showed nitrate levels at or above 10 mg/L in private wells within 10 Hubbard County townships.

During that 10-year period, 2,933 tests on private wells yielded 208 results with nitrate levels at or above 10 mg/L, 347 results with at least 5 mg/L and 476 results with at least 3 mg/L.

Townships that had 10 or more private well tests showing nitrate levels of at least 10 mg/L included Badoura (11), Crow Wing Lake (35), Henrietta (17), Hubbard (90), Straight River (21) and Todd (30).

During the same ten years, 693 tests of groundwater-based public drinking water systems in the Hubbard County area yielded 44 results with nitrate levels of at least 10 mg/L, 118 results of at least 5 mg/L and 202 results of at least 3 mg/L.

Locations where multiple private well tests revealed high nitrate levels included Bergen’s Nursery (5), the dental office of Dr. David Anderson (5), Evergreen Church (12), Lake George Bible Chapel (2) Sundsruds Court (10) and Y Steakhouse (8).