CRAWFORD COUNTY - On a snowy Saturday, April 27, about 30 local residents gathered to hear Dr. Kevin Masarik, UW-Extension Groundwater Education Specialist, discuss high level results of a recent round of well testing. 

The testing was facilitated by the Crawford Stewardship Project. It involved a sample size of 53 wells. The cost of the tests were paid for 80 percent by CSP and 20 percent by the well owner.

“Most of the tests conducted were from the northern part of the county,” Masarik told the group. “Although it is generally a rule of thumb that water will flow from the highest point to the lowest point, your county’s complicated topography makes it hard to understand how your groundwater flows. However, you can most likely assume that the water in your well is coming from an area one-half-mile to one mile around you.”

Masarik told the group that all wells sampled showed that the water in the county is very hard. The nitrate and chloride results relate mainly to land use. 

The groundwater specialist said that 66 percent of wells sampled showed nitrate results of less than two milligrams per liter (mg/L), which is the naturally occurring level of nitrate in groundwater throughout the state. Four percent of the sampled wells showed results above the 10 mg/L federal safe drinking water standard. Masarik said that 85 percent of the samples showed a low chloride result, and in 80 percent of the samples there was a ‘no arsenic present’ result.

Health concerns

Masarik told the people present at the meeting that just because well testing results may have shown the presence of coliform bacteria does not mean their well is contaminated.

“Coliform bacteria generally do not cause illness, but do indicate that there is a pathway for potentially harmful microorganisms to enter your water supply,” Masarik told the group. “If a well test showed the presence of coliform, then it would have automatically been also checked for the presence of the dangerous coliform bacteria e.coli.”

Masarik explained that the presence of e.coli will confirm that the bacteria in your water originated from a human or animal fecal source. E.coli, he said, is often present with harmful bacteria, viruses and parasites that can cause serious gastrointestinal illnesses, and any detectable level of e.coli means that the well water is unsafe to drink.

“Nitrate generally comes to be present in water as a result of agricultural activities, especially agricultural chemicals,” Masarik said. “Levels of nitrate in water above the 10 mg/L federal standard are particularly dangerous for pregnant mothers and fetuses, and for young children. They can also pose a risk for developing other illnesses such as certain forms of cancers.”

Arsenic is most often found in water as a result of naturally occurring mineral deposits. In Crawford County, CSP’s Forest Jahnke pointed out, the area around the Orchard Ridge could also potentially show elevated arsenic levels because of historical use of arsenate pesticides in the orchards. Fortunately, the results of this round of testing did not show the presence of arsenic in wells. Arsenic in water can make drinkers potentially vulnerable to developing skin, lung, liver, bladder, kidney and colon cancers.

Problems with copper and lead in the water, though posing health hazards, are almost exclusively caused by the plumbing in the house that delivers the water from the well. These are some of the most easily fixed problems with well water quality.

What Masarik referred to as ‘aesthetic problems’ with water included hardness,  iron, and chloride, which can be fixed and do not pose health concerns. 

Geology matters

Masarik explained to the group that an area’s underlying geology dictates how easily water moves from the surface into aquifers, and how easily groundwater can become contaminated. He explained that Crawford County has a thin layer of soil overlaying a fractured karst bedrock of layered sandstones and dolomites. He noted that the  shallow depth to bedrock can make the county’s aquifers more vulnerable to surface contamination, but that the loam soil type most prevalent in the county is somewhat protective at filtering out contaminants from the surface.

“Wisconsin’s geology is like a layered cake. Underneath all of Wisconsin lies crystalline bedrock which is very dense, and does not hold much water,” Masarik said. “All groundwater sits on top of this foundation, with the layers of sandstone and dolomite in this area layered on top of that. The most common top layer in the county is a dolomite formation which is very prone to cracks and permeability.”

Masarik told the group that the county is fortunate that the challenging terrain limits the kinds of land uses that would be most likely to be potential sources of contaminants. High amounts of the county’s land surface is covered in forests and steep hillsides, leaving only certain areas on the ridgetops and in the valley floor that are suitable for human habitation with septic systems, and agricultural uses.

Water utility managers

Masarik explained that with municipal wells, there is a requirement for annual testing to ensure that the water quality is safe for human consumption. This, however, is not the case for private well owners.

“If you own a private well, then you need to be your own water utility manager,” Masarik said. “As of 2014, any new well drilled is required to be tested for bacteria and nitrates, and when you have work done on a well pump, there is also a requirement to test.”

Most homeowners don’t test annually as is recommended, but if they do test and find problems with their water, the solutions are both short term and longer term. Short term, residents with unsafe water will need to bring water into their homes from another source. There are filtration systems that can be installed to take contaminants out of the drinking water, but they are labor intensive to operate effectively and also require a long-term commitment of financial resources.

The first and most obvious method to detect the source of problems with a well is to obtain information on well construction, especially the depth of the well casing, and also to inspect the wellhead to make sure that it is not damaged.

After that, the longer-term solution will involve identifying potential sources of the contaminants in the water from nearby sources, and looking at changes in land use on your property that could be protective of your well water quality.

“Many people assume that they can solve their water quality problems simply by drilling a deeper well,” Masarik said. “Given what we know about how groundwater moves, it is difficult to say that this would or would not actually be a solution. Sometimes, when you drill a deeper well, you can cause a situation where contaminants in a shallower aquifer can be introduced through the well into a deeper aquifer.”