Why are high nitrate levels concerning?

We know, through years of study and research, about the harmful effects of drinking water with high nitrate levels (over 10 mg/L). Most specifically, exposure to these concentrations can lead to methemoglobinemia, or blue baby syndrome. Alarmingly, newer studies show that consuming nitrate at much lower concentrations is associated with decreased liver function, thyroid disease, some types of cancer and birth defects in newborns, including limb deficiency and spina bifida. While most of the homes and businesses in the area of the known nitrate contamination are served by a tested community water system, that’s not always the case. Several people rely on the groundwater for drinking. According to the EPA, nitrates cannot be removed by carbon filters (like Brita filters) or by boiling the contaminated water. In addition, the community water system has a limited ability to expand or allow new connections due to water rights limitations. This means the likely water supply option for proposed new development in Seeley will be the already contaminated aquifer.

The groundwater study shows that the nitrate-laden groundwater moves through the community, accumulating sewage discharge, and eventually intercepts Seeley Lake and the Clearwater River outlet. While the influence of groundwater on the lakes and rivers in the area has not been studied, we can observe the impacts to the lakes and rivers by the fast growth of aquatic vegetation along their shorelines.