Drinking water quality in JDC

It’s worrisome to learn about nitrate contamination in the private wells of southwest Wisconsin and northeast Iowa. News flash: We have the same geology in Jo Daviess County. Do we also have elevated nitrate levels? While there’s still a lot of work to be done to provide a definitive answer, we have a base of good information to build on.

In 2013, the League of Women Voters of Jo Daviess County brought scientists here from the Illinois State Geological and Water Surveys for a program: “The Land and Water Beneath Us.” We asked them to tell us what they knew at that time about our geology and our hydrology, what they didn’t know, what we should try to find out, and how we should go about doing that. In the years between then and now, the League has worked with others in the county to come up with questions and then worked with the scientists to define and execute projects to help answer those questions.

The private wells in Jo Daviess County draw, almost exclusively, from the Galena-Platteville aquifer, a layer of carbonate rock hundreds of feet thick with fractures, crevices and bedding planes through which flows the groundwater many of us drink. How vulnerable is our groundwater to contamination from land surface activities?

To explore this question, Sam Panno (Illinois State Geological Survey) and Walt Kelly (Illinois State Water Survey) worked with the League and local landowners sampling wells and springs in the county and analyzing for a variety of constituents including Nitrate levels.

Given the open nature of our geology we are bound to see contaminants within our aquifer, but how much? Based on our research, the scientists were able to estimate pre-settlement levels of contaminants as well as current levels. The pre-settlement background level for nitrate nitrogen was 0.04 milligrams per liter (mg/L). Our current background level is up to 2.0 mg/L. While the U.S. drinking water standard is 10 mg/L, if your well-water sample analysis is over 2 mg/L, it is likely that you have a contamination source (e.g., septic effluent, livestock, N-fertilizers) affecting your water.

The well sampling that was done to establish background water quality specifically targeted wells of a certain age and depth.

Collecting data from a broader range of well sampling conditions would be a useful next step.

If you have a well in Jo Daviess County and are interested in participating in a project to collect data to determine if we have issues similar to those in southwest Wisconsin and northeast Iowa, contact Beth Baranski at beth@bhms-arch.com or 563-580-6192.