Nitrates in Sauk County

Due to local geography and widespread agriculture in Sauk County, residents may be at an increased risk of consuming nitrate-contaminated water. Nitrate data was recently analyzed for residential and transient non-community (TN) well systems between 1999 and 2015. TN well systems refer to those that serve at least 25 people at least 60 days of the year, but do not serve the same 25 people over 6 months of the year. This designation includes restaurants, motels, parks, gas stations, and taverns.

Results showed:

• Residential wells (red) had higher nitrate concentrations than TN wells (blue) for all years
• Residential wells were significantly increasing in nitrate concentration
• Both residential and TN well nitrate averages were above 2 mg/L, or parts per million, for all years. This suggests that the nitrates are not naturally occurring and may indicate the presence of other water pollutants, such as bacteria or chemicals used on lawns or fields.

We recommend that all residents sample their wells for nitrates annually or if there is a change in color, taste, or smell.