According to Wisconsin Department of Natural Resources (WDNR) well construction reports (http://prodoasext.dnr.wi.gov/inter1/watr$.startup, accessed 23 October 2017), residents within eleven northwestern Wisconsin counties obtain their drinking water from over 56,000 wells, including more than 48,000 private wells that are not regulated under the federal Safe Drinking Water Act and have no routine monitoring requirement. In reality, the number of public and private wells within these primarily rural counties is much higher, given that electronic records are only readily available for wells constructed after 1987. Although groundwater in northwestern Wisconsin aquifers may not be as impacted by anthropogenic contaminants as groundwater in other areas of the state, baseline data regarding naturally-occurring inorganic contaminants and metals is severely lacking. In addition, despite the high percentage of residents obtaining drinking water through public and private wells, many homeowners in the region are unaware that their private water supply should be tested on a regular basis (i.e., recommended annually to every three years). Therefore, this research aims to foster public awareness about the need for annual drinking water testing, and provide much-needed baseline data to residents of northwestern Wisconsin that will allow informed public health decisions to be made.
Fluoride and the metals arsenic, iron, and manganese are groundwater contaminants that may impact public health, and for which little is known regarding baseline concentrations present in northwestern Wisconsin aquifers. Fluoride is a naturally occurring inorganic ion, which has a narrow range of therapeutic concentrations. Fluoride is not a parameter that is typically analyzed in well water samples collected for Safe Drinking Water Act monitoring requirements, private property transfers, or private well installations. The American Dental Association recommends fluoride supplementation in drinking water containing less than 0.7 mg/L fluoride to prevent dental caries (Rozier et al., 2010). Conversely, drinking water fluoride concentrations greater than 1.5 mg/L can cause dental fluorosis and negatively impact bone health in children (Ozsvath, 2006 and 2008; Brindha and Elango, 2011). Fluoride concentrations in a small set of public and private well water samples collected from Douglas County range from <0.1 mg/L to 1.1 mg/L fluoride (a portion of these data were supplied by the WDNR). In the absence of publicly-available data on groundwater fluoride concentrations, homeowners are unable to make informed decisions about whether or not fluoride supplementation is necessary.
The Wisconsin Well Water Quality Viewer, developed by the Center for Watershed Science and Education at the University of Wisconsin-Stevens Point, is a tool that can be used by the public to determine concentrations of various drinking water contaminants that could be present in their private drinking water supply. Currently, fluoride is not a parameter displayed on the Well Water Quality Viewer. Arsenic, iron, and manganese are naturally-occurring metals that could be present in groundwater depending upon the underlying geology and water quality of the aquifer. In a recent study, these three metals were identified as having a relatively-high exceedance rate in samples collected from private drinking water wells in rural Wisconsin (Knobeloch et al., 2013). In northwestern Wisconsin, Douglas County in particular, baseline data on naturally-occurring arsenic, iron, and manganese are lacking. Although these parameters are displayed on the Well Water Quality Viewer, insufficient data exists for Douglas County and users are unable to determine a range of metals concentrations present in groundwater.
The objectives of this research are:
1. To identify naturally-occurring fluoride and selected metals in groundwater within northwestern Wisconsin.
2. To increase the data available to residents of northwestern Wisconsin by incorporating monitoring results into the Wisconsin Well Water Quality Viewer.
Data to support these objectives will be collected through a combination of public and private drinking water analyses. Public drinking water samples will be collected by the Douglas County Department of Public Health. Private drinking water samples will be obtained on a volunteer basis, through an outreach effort involving dental offices throughout northwest Wisconsin, through attendance at town hall meetings, and through citizen science. Volunteers will be supplied with a drinking water sampling kit, and will be instructed on how to collect well water samples. All samples will be analyzed for fluoride, and a randomly-selected subset of private drinking water samples will be analyzed for several naturally-occurring metals, including arsenic, iron, manganese, and aluminum plus lead, which is not naturally-occurring. At the end of the project, the findings from this study will be presented to the participating dental offices and town seats from which volunteers were recruited. Volunteers and the general public will be invited to attend one of four public seminars that will be offered to disseminate the results throughout the eleven counties in the study area. The data collected will be used by residents of northwestern Wisconsin counties, dental practitioners, county public health departments, well drillers, water industry professionals, and scientists involved in the development of groundwater models.