Improved Nitrate Stats Credited To Non-Point Sources

Officials in Dane County, WI, have had success in lowering the level of nitrates in the drinking water supply, but that doesn’t mean their work is over.

“A sophisticated study blending 35 years of well contamination tests shows high levels of toxic nitrate is turning up a little less frequently in Dane County-area drinking water,” the Wisconsin Center for Investigative Journalism reported.

“But because the substance is so widespread and hazardous to human health, scientists from five state and local agencies who conducted the study are urging broader efforts to limit farm fertilizer use that is the primary source of contamination,” the report said.

The study by government experts gave the region a mixed grade when it comes to nitrate control. It said the prevalence of nitrates in Dane is not surprising due to the scope of the agriculture industry there.

“More than one in five tests of wells providing water to homes, churches, schools, bars and restaurants exceeded the safe limit from 2010 through late 2014. That’s down from 30 years ago when more than one-third showed unsafe levels, but still more than twice the statewide rate,” the report said.

The study gave farmers credit for the improvements:

The results of this study suggest that in some aspects, groundwater quality in Dane County is slightly improving — likely due in large part to improvements in agricultural nutrient management. Most notably the area of the county where average nitrate concentrations exceed the Maximum Concentration Limit (MCL) of 10 mg/L is declining, and wells with high nitrate concentrations appear to be decreasing. However, results also indicate that wells with low nitrate concentrations (far below the MCL) are increasing. This suggests that the groundwater system is not at steady state with respect to nitrate, and areas or geological strata with older water are being increasingly impacted by nitrate contamination.

Nitrates in drinking water are a threat to infant health, according to the Wisconsin Department of Natural Resources.

“In infants under 6 months of age, ingestion of nitrate can reduce the blood’s ability to carry oxygen. In severe cases it can cause a condition that doctors call methemoglobinemia. The condition is also called ‘blue baby syndrome’ because the infant’s skin appears blue-gray or lavender in color. This skin color change is caused by a lack of oxygen in the blood,” the department said.

For more stories on nitrogen contamination and prevention, visit Water Online’s Nutrient Removal Solutions Center.