Nitrate Information

What are nitrates? Why would an area have increased nitrates?

Nitrate (NO₃^-) is a chemical compound that occurs when nitrogen, a common fertilizer additive, combines with oxygen in water. Nitrates can pass easily through the soil and into the groundwater, which many people ultimately consume as drinking water.

While nitrates occur nearly everywhere, certain areas are more susceptible to enhanced groundwater nitrate concentrations due to land use and geological makeup. Agricultural sources, like fertilizers, and leaky septic systems can cause nitrates to enter the groundwater. Additionally, characteristics such as soil cover and water table depth influence the ability for nitrate runoff to contaminate groundwater.

Sauk County residents should be aware of nitrate contamination in their private well systems because Sauk County is agricultural and contains many areas designated as highly susceptible to groundwater contamination, according to the United States Geological Survey.

What are the health risks of high nitrates in drinking water?

While low concentrations of nitrate in drinking water are considered safe, nitrate levels exceeding 10 ppm have adverse health effects in certain people. Most notably, infants under 12 months of age may develop methemoglobinemia, or “blue baby syndrome”.  Blue baby syndrome occurs when red blood cells cannot transport oxygen to body tissues. Affected infants may have blue-tinted skin, fatigue, and shortness of breath. In serious cases, this condition can lead to shock, seizures, or death.

Adults may also experience poor health from prolonged high nitrate exposure, and evidence suggests that drinking contaminated water may be linked to esophageal and stomach cancers. The Wisconsin Division of Public Health recommends that everyone avoid prolonged consumption of drinking water above 10 ppm nitrate.