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Well testing results show problems with nitrate and coliform
Driftless Area Water Study
Fractured Karst Bedrock
Fractured karst bedrock overlain by shallow depths of soil, such as is present in Crawford, Vernon and Richland counties, makes the area's world class sandstone aquifers very vulnerable to contamination from the surface.

DRIFTLESS - The second round results of the Driftless Area Water Study (DAWS) well testing results were reported to about 21 citizens on Thursday, June 8. 

The study of well water quality was undertaken jointly by Crawford, Vernon and Richland counties, and included two sampling events in October of 2020 and April of 2021. The April 2021 sampling event also included 25 samples from the Tainter Creek Watershed.

Kevin Masarik of the Center for Watershed Science and Education at UW-Stevens Point led the discussion and answered any questions participants had.

“The majority of the samples were quite good or pretty good,” Masarik said. “About 80 percent of the results showed that the water is very hard due to the underlying bedrock of the three-county area.”

Depth of Soil to Bedrock Map
Depth of soil to bedrock is a key indicator of susceptibility to contamination of the groundwater aquifers that supply water to private wells in the three-county area. According to crude, outdated maps of soils in the area, more than 70 percent have depths of soil to bedrock of less than five feet. This is more true of upland acres where manure is likely to be spread, and less true of the incised valleys that are the beneficiaries of decades of soil erosion, where depths of soil to bedrock can be 50 feet or more. The depths of soils in the valleys in the deeply incised hills-and-valleys terrain reflect generations of soil erosion off degraded slopes and ridgetop fields. Updated maps for the three-county area from Wisconsin Geological and Natural History Survey were due to be released in 2020, but the release was delayed due to COVID.

Masarik explained that much of the area in the three counties is characterized by shallow levels of soil over the bedrock – less than five feet. He said that more than 70 percent of the area has bedrock within five feet of the surface, with only eroded areas near the river bottoms having more significant depth of soil of 50 feet or more.

“Areas with shallow depths of soil to bedrock are areas where the groundwater is more vulnerable to contamination,” Masarik explained. “This can allow contaminants such as coliform bacteria and nitrate to infiltrate into groundwater from the surface relatively quickly.”

Nitrate results

In the most recent April 2021 water sampling, 54 of the 270 wells sampled had no detected nitrate (20 percent), and 84 of the wells had a nitrate result of less than two milligrams-per-liter (mg/L) (31 percent). Two mg/L nitrate is considered to be the naturally occurring level of nitrate in groundwater free of any human impacts such as septic systems or agriculture.

A total of 42 of the 270 tests had a nitrate result of between 2.1 and 10 mg/L. The threshold for nitrate in drinking water that is considered unsafe to drink is 10 mg/L. Sixty-two of the 270 wells tested showed nitrate results in the 2.1-5 mg/L level (23 percent), and 49 wells showed nitrate levels of between 5.1-10 mg/L (18 percent).

For public water utilities, if water from a municipal well tests higher than five mg/L, utility customers are still allowed to drink the water up to the 10 mg/L level, but the water utility is put on notice that there could be a problem with the well. 

At that point, given that public utilities are required to regularly sample their water, an evaluation will be made to see if there is an increasing trend over time for nitrate levels in the water. In some cases, a utility may be required to discontinue use of the well. 

For private well owners, there is most often no ongoing monitoring of the well to detect trends over time. If a problem is detected, the well owner is not required to correct the problem, and if they do take steps to correct it, the financial responsibility is theirs alone. 

Nineteen of the 270 wells tested (seven percent) showed a nitrate result of between 10.1-20 mg/L, and three wells showed a nitrate result of greater than 20.1 mg/L. Because of the level of nitrate contamination, the water from these wells is considered to be unsafe to drink.

“Nitrate in the water can be an indication that other contaminants such as pesticides may be present in the water,” Masarik said. “For this reason, if you have high nitrate in your water you may want to consider a further test to identify whether there are pesticides in the water.”

Masarik said that his lab has never found Roundup in groundwater, but they have found pesticides that were more commonly used in years past such as Alachlor, Metolachlor, Atrazine, Metribuzin and Cyanazine.

DAWS + TCWC+CSP well testing nitrate results
Overall, across all testing events from 2018 through 2021, 48 percent of wells tested showed nitrate levels below the naturally-occurring level of two milligrams-per-liter (2 mg/L); 42 percent of wells showed nitrate levels in the building, danger-zone level, of 2.1-10 mg/L; and nine percent of wells can be considered 'undrinkable' due to exceeding the federal (and state) drinking water standard of 10 mg/L.

Overall nitrate results

Since November of 2018, a total of five well water testing initiatives have taken place in the three-county area. The Tainter Creek Watershed Council tested wells in Crawford County Utica Township and Vernon County Franklin Township has tested wells on three occasions. Their first test was in November 2018 (44 samples), the second in November 2019 (39 samples), and the third in April 2021 (25 samples) in conjunction with the second round of DAWS testing.

DAWS well testing events occurred in October of 2020 (293 samples), and April 2021 (270 samples). In addition, Crawford Stewardship Project conducted a well water test in March of 2019 (53 samples).

In total, from these sampling events, 699 wells were tested in the three-county area between November of 2018 and April of 2021. Of those tests, 127 wells showed no nitrate detected (18 percent), and 206 wells showed a nitrate result of two mg/L or less (30 percent).

In the mid-range of between 2.1-10 mg/L, 169 wells showed a nitrate result of between 2.1-5 mg/L (24 percent), and 128 of the wells showed a nitrate result of between 5.1-10 mg/L (18 percent).

Total tests in the three counties across all the testing events showing nitrate levels above the naturally-occurring level of 2 mg/L were 361 (52 percent).

In the ‘unsafe to drink’ range of 10.1 mg/L or greater, a total 65 wells (nine percent) showed this result. Nineteen wells showed a nitrate result of between 10.1-20 mg/L (three percent), and seven wells showed a nitrate result of 20.1 mg/L or greater (one percent).

Problems with nitrate

Nitrate in drinking water has been linked to health effects such as Methemoglobinemia or ‘Blue Baby Disease,’ possible links to birth defects and miscarriages in both humans and livestock, and can be an indicator of other contaminants. Other research has begun to link elevated levels of nitrate in drinking water with certain types of cancer or thyroid problems.

Sources of nitrate in drinking water are agricultural fertilizer, lawn fertilizer, septic systems and animal wastes. To stop nitrate from reaching well water, the well owner must eliminate the contamination source or reduce nitrogen inputs. 

In the short-term, the well owner has a short list of options to address the problem. Those include changing the well depth or relocating the well, carrying or buying water, or a treatment device that will remove nitrate from the water. Treatment options include reverse osmosis, distillation and anion exchange. These solutions present an ongoing maintenance requirement and expense to the well owner.

DAWS+TCWC+CSP well testing coliform results
Results for well testing across well testing initiatives conducted between October 2018 to April 2021 for wells in Crawford, Vernon and Richland counties showed that positive E.coli results exceeded the statewide average of two percent in March of 2019 and October of 2020. In the March 2019 testing event, the samples that showed the highest levels of contamination were obtained from wells just below the Roth Feeder Pigs hog CAFO operation in Wauzeka Township in Crawford County.

Coliform bacteria

In the latest round of DAWS sampling in the three counties, 20 of the 270 wells sampled tested positive for coliform bacteria (seven percent). Of those wells one tested positive for E.coli, a particularly dangerous coliform bacteria (0.04 percent).

The presence of coliform bacteria itself is in no way an indication that the water is unsafe to drink. It is, however, an indication that a pathway exists for bacteria, viruses or pathogens to enter the well. 

“The presence of coliform bacteria in well water may be an indication that other pathogens such as salmonella, campylobacter, listeria or giardia could be present,” Masarik said. “For this reason, well owners are encouraged to become sleuths to identify the possible source of any coliform bacteria entering their well and takes steps to eliminate it.”

Masarik also explained that evaluating the well for any structural or construction problems may be just as significant for preventing well contamination as identifying the source of the contamination. He said that factors such as other old, unused wells on the property, cross connections with hoses that may allow backflow, whether the well head cap is in good condition, and the depth of casing on the well and whether it is below the water table.

Well owners who received a positive test result for coliform bacteria are encouraged to re-test as soon as possible, but also to investigate what the pathway in and source of the bacteria might be, and make efforts to mitigate those things.

Some coliform bacteria do present an immediate health threat that would make the water unsafe to drink. Premier among those is Escherichia coli (E. coli) bacteria. Some forms of E. coli can make you sick. Some kinds of E. coli can cause diarrhea, while others cause urinary tract infections, respiratory illness and pneumonia, and other illnesses, according to the Centers for Disease Control (CDC).

Well owners whose wells tested positive for E. coli would have been notified by the lab in Stevens Point within 48 hours of receiving the result. 

Well owners whose wells tested positive for E. coli are encouraged to reach out to the lab in Stevens Point or their county Public Health Department to discuss next steps for their well, and their family’s health and safety.

In the first round of DAWS sampling in the three counties, 293 samples were collected. Of those, 24 percent tested positive for the presence of coliform bacteria. Three percent of wells tested in the three counties tested positive for E. coli. This is higher than the statewide average of one-to-two percent.

Overall, with all of the 699 well water samples tested in the county through DAWS, Crawford Stewardship Project, and the Tainter Creek Watershed Council, 123 wells tested positive for coliform bacteria (18 percent). Of those wells, 12 tested positive for E.coli (two percent).

Next steps

Masarik recommended next steps for well owners concerned about their well water quality. Those steps include:

Testing the well annually for bacteria, or if the water changes color or clarity

Consider testing annually for nitrate, particularly if levels in your water are approaching 10 mg/L

If your nitrate level was greater than 5 mg/L, consider testing for pesticides

If you have never checked for arsenic, consider testing.

The Center for Watershed Science and Education laboratory at UW-Stevens Point offers a ‘DACT Test’ which will detect any contamination in well water from Triazine pesticides (mainly atrazine used on corn crops). The test only measures the diaminochlorotriazine (DACT) residue levels of triazine-type pesticides (atrazine, simazine, propazine, cyanazine, etc…) and does not account for the parent compound or other breakdown components.

The drinking water limit for atrazine and its three breakdown components is three parts-per-billion.