Nitrate is one of the most common drinking water contaminants. And shallow rural wells are particularly vulnerable to nitrate contamination because they are more likely to receive water directly from the surface, and thus there is less time for soil chemistry to reduce the nitrate into other forms. We have been looking at nitrate contamination of shallow rural wells in Illinois and recently released a report on our findings.
A Lack of Data a Catalyst for the Report
Unfortunately, there was actually very little data available on shallow rural drinking water in Illinois. This is a big part of the problem. Unlike some of our neighboring states, Illinois has not completed a comprehensive survey of private drinking water wells. Also, private wells, unlike public water, are not required by the U.S. EPA to be tested. Therefore, maintaining the well, monitoring its water quality, and treating the water if contaminated are all the responsibility of the well owner. This means we do not know as much about the water quality well owners are experiencing.
In our report, we looked at a combination of what data was available and performed an analysis of our own. National studies conducted by the U.S. Geological Survey found some wells in Illinois to have exceptionally high levels of nitrate. In fact, the single most contaminated well in their study was from Illinois with nitrate levels at almost 8x the safe drinking water standard. West central Illinois and the Lower Illinois River Basin were singled out as areas where wells often have elevated nitrate levels. While Illinois has not conducted a statewide survey of rural wells, they did do a pilot study testing the methods they would use for such a study. The five counties they looked at had on average 18% of their rural wells over the safe drinking water standard.
Additionally, we found nitrate levels in untested private domestic wells by looking at nearby public shallow rural wells for which there is data. These wells can be used as a proxy to learn about the likely extent of nitrate contamination in private rural wells. We focused on well data from public sources outside of municipalities (e.g., restaurants, places of worship, campgrounds) which tend to be shallower than community water systems. Our findings show widespread nitrate contamination of wells throughout Illinois, with particularly high concentrations along major rivers like the Rock, Mississippi, and Illinois.
Farming Practices Key to Reducing Nitrates
Farmers, as rural residents, are some of the people most affected by nutrient pollution, but they are also the ones in the position to change it. Eighty percent of nitrate comes from our agricultural lands. There are both in-field and edge-of-field practices that can make our water cleaner, and these practices also make farms more resilient to a changing climate. They can help manage the more concentrated high intensity rain storms that have become commonplace.
Every farmer should be learning about farming practices that can keep nitrate out of our drinking water. We all depend on having access to clean water, and no one can do it alone.
This year we were able to, in cooperation with partners, get the first state funding for the IL Nutrient Loss Reduction Strategy effort to reduce nutrient pollution. As Illinois is in the process of updating the State Water Plan, PRN will continue to push for the state to conduct a comprehensive survey of our groundwater that includes nitrate, as our neighboring states have done. This will give our agencies the information they need to develop a long term plan for our water quality.
The report is available at: prairierivers.org/whats-in-your-well
Catie Gregg
Agricultural Programs Specialist
Catie coordinates projects to advance the adoption of regenerative farming systems in Illinois.
