Jan 16, 2020

Study Investigates Nitrate Contamination in Minnesota Tap Water

A new study by the Environmental Working Group (EWG) has found that more than 500,000 Minnesotans are drinking nitrate contaminated water. 

drinking water

More than 500,000 Minnesotans are drinking water contaminated with nitrate, according to a study by the EWG

EWG analyzed finished-water nitrate test results from all public water systems in Minnesota between 2009 and 2018. The data came from public records requests fulfilled by the Minnesota Department of Health, reported EWG. There are 6,626 active groundwater systems in the state and of those, 6,566 tested for nitrate at least once between those years. 

According to the report, farm pollution is the primary cause for nitrate contamination, and it is particularly worse in areas of Minnesota where the types of soil and geology make it easier for nitrate in fertilizer and manure to get into groundwater.

This is likely not an intentional effort on the part of farmers, contended EWG senior analyst of economics and co-author of the group’s study Anne Weir Schechinger.

The legal limit for nitrate in groundwater is currently 10 milligrams per liter, reported EWG

“At this point, there’s been so much education and outreach that farmers are really aware of what they put on their farm fields, and that gets into drinking water,” said Weir Schechinger. “So while they’re not doing it on purpose, I think they do know that a lot of their practices really do contribute to this nitrate problem in drinking water.”

A survey given to farmers by the Minnesota Department of Agriculture a few years ago showed that 61% of farmers were applying nitrate nitrogen at rates higher than what is recommended, reported Winona Daily News.

Minnesota is implementing a Groundwater Protection Rule to reduce nitrate in drinking water, however, reported EWG. The rule is three years in the making and administered by the Minnesota Department of Agriculture. EWG’s analysis highlights that even full implementation of the new rule may be insufficient from unsafe levels of nitrate nonetheless. 

Minnesota’s Groundwater Protection Rule was finalized in June 2019 and will be implemented starting in 2020, according to EWG

“We’re seeing nitrate in groundwater at levels that are pretty high,” said fellow co-author and senior spatial analyst and project manager for EWG Sarah Porter. “The rule is a really good step forward, but it might not do enough to reduce the nitrate problem in the short term. Over time, yes, you can reduce nitrate levels in your groundwater. There’s certain practices to cover crops that you can do in the agricultural field that help to reduce nitrate that can leach down into the groundwater.”

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