Grassroots Groundwater Quality Trend Data Program

About the Grassroots Groundwater Quality Trend Data Program

About the Tests

The following tests are included in the testing package that is run on participating samples:

Alkalinity is a measure of water’s ability to neutralize acid. It is generated by the dissolution of carbonate minerals common to Wisconsin. Groundwater alkalinity measurements are relatively stable from one year to the next. Testing for alkalinity would help in understanding if a particular sampling event was influenced by rainfall or snow melt because alkalinity should be relatively consistent under normal conditions. 

Like nitrate, chloride is a useful tool for understanding the impacts of land use. Major sources of chloride to groundwater include fertilizer, road salting and septic system drainfields. Potash is used to add potassium to soil. The most common form of potash is potassium chloride; the chloride is susceptible to leaching. Road salt (usually sodium chloride) helps in deicing roads, but is then washed off roads into ditches or other pervious areas where it soaks into the soil and can eventually leach to groundwater. Septic system drain fields dispose of wastewater which contains chloride from human waste and water softener salt. 

Conductivity is a measure of the ability of water to pass an electrical current. Because dissolved salts and other inorganic chemicals conduct electrical current, conductivity increases as salinity increases. Organic compounds like oil do not conduct electrical current very well and therefore have a low conductivity when in water. Conductivity is also affected by temperature: the warmer the water, the higher the conductivity. Conductivity is useful as a general measure of water quality. Each water body tends to have a relatively constant range of conductivity that, once established, can be used as a baseline for comparison with regular conductivity measurements. Significant changes in conductivity could then be an indicator that a discharge or some other source of pollution has entered the aquatic resource.   

Corrosivity describes how aggressive water is at corroding pipes and fixtures. Corrosive water can cause lead and copper in pipes to leach into drinking water and can eventually cause leaks in plumbing.  Surface water and groundwater, both sources of drinking water, can potentially be corrosive. 

Nitrate is a chemical commonly found in agricultural and lawn fertilizer. It is also produced when organic rich materials such as manure, bio-solids, septic system effluent, etc. decompose. Nitrate is a very soluble form of nitrogen and can easily leach past the root zone of plants into groundwater. Levels of nitrate in groundwater are generally less than 1 mg/L in natural or areas of little human influence. Elevated levels generally occur in areas of agricultural activity or areas of dense rural development (ie. small lot sizes with septic systems, lawn fertilizers, etc.). Soils and geology make certain areas more prone to nitrate losses to groundwater. For these reasons, nitrate is a good test to perform if trying to understand the impacts of land use on groundwater quality as well as trends over time.

Nitrate is an important test for private well owners. Levels greater than 10 mg/L nitrate-nitrogen should not be consumed by infants, or women who are / are trying to become pregnant.

pH is an expression of hydrogen ion concentration in water. The term is used to signify how basic or acidic a solution is on a scale of 0 to 14, where pH 7 is neutral. The more hydrogen ions are concentrated in water, the more acidic the water is (pH below 7). When pH is above 7, the solution is basic. 

Water hardness is the amount of dissolved calcium and magnesium, as well as other metals, in the water. Hard water is high in dissolved minerals, largely calcium and magnesium. Water systems using groundwater as a source are concerned with water hardness, since as water moves through soil and rock it dissolves small amounts of naturally-occurring minerals and carries them into the groundwater supply. Hard water can damage equipment, or even shorten the lifespan of fabric items such as clothes. Additionally, long-term movement of hard water through pipes can result in scale buildup. 

Where are Tests Occurring?

Figure 1.
Black triangles represent 770 well parcels that were mailed recruitment materials.

Yearly Results

Green County began tracking groundwater quality in 2019 through a project funded by the County. Multiple years of data give a more expansive picture of overall trend results throughout time. Here you can view the results summaries and other relevant information from past years.

Other Resources

For more information on understanding groundwater in Green County, check out these resources and educational centers to learn more!

Groundwater Resources

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Questions? Contact:

Jordyn Sattler, Regional Crops and Soils Educator, at (608) 328-9440 or jordyn.sattler@wisc.edu.