University of Wisconsin - Extension

Twenty-two percent of the 100 well water samples tested by the University of Wisconsin-Extension specialists at 2001 Farm Progress Days indicated unsafe levels of nitrate.

¿Nitrate-nitrogen greater than 10 milligrams per liter (mg/L) of water is considered unsafe,¿ explained Chris Mechenich, University of Wisconsin-Extension groundwater educator. Samples were brought in from twenty Wisconsin counties as well as counties in Iowa and Illinois

Twenty-two samples were over the drinking water standard of 10 mg/L. The unsafe samples came from nine different Wisconsin counties. Eleven of 33 (33%) Rock County samples were over the 10 mg/L limit. Rock County was the host of this year¿s Farm Progress Days.

The average nitrate level found was 6 mg/L. The highest value found was 28 mg/L nitrate nitrogen, nearly three times the drinking water standard.

¿Some of the people testing their water were unaware that their nitrate levels were high,¿ said Mechenich. ¿Nitrate in drinking water cannot be tasted or smelled. In fact, some people with high nitrate water tell us their water is very good tasting,¿ she added.

High levels of nitrate in drinking water can cause "blue baby" disease in infants less than six months of age, according to Mechenich. Women who are trying to conceive or who are pregnant should not drink water with high levels of nitrate because some researchers believe this increases the risk of birth defects and miscarriages.

People without infants in their homes should also be concerned about elevated nitrate levels. Recent studies in Nebraska and Iowa have suggested links between high nitrate drinking water and cancer. High nitrate levels do not occur naturally in Wisconsin groundwater, so they indicate that some human activity is contaminating the water, Mechenich said.

Lawn and crop fertilizers, manure storage, compost piles, septic systems and feed lots can affect nitrate levels in groundwater.

"In Wisconsin, about 70,000-80,000 private wells may contain unsafe levels of nitrate," Mechenich adds.

Although information is incomplete about the long-term effects of high nitrate levels on adults, identifying nitrate in water should motivate homeowners to identify the source, and other possible groundwater contaminants from that source. In some cases, homeowners will need to repair or replace their well to solve nitrate problems.

In other cases, a water treatment device can bring nitrate down to acceptable levels. Mechenich urges homeowners to choose a device certified by the Wisconsin Department of Commerce to remove nitrate or any other contaminant identified in the water. ¿However, what we¿d really like to accomplish is to implement land management strategies that will prevent nitrate problems in the first place¿, she said.

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