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Discussion of SWIGG study results and nitrate pollution
Less finger pointing, more finding solutions for water

DARLINGTON – Since the Southwest Wisconsin Groundwater and Geology Study (SWIGG) delivered their results from the testing done in November and April, many in the study area and in the region have been concerned with the state of their drinking water.

Scott Laeser, water program director of Clean Wisconsin and Kevin Masarik, groundwater education specialist from  UW-Stevens Point, addressed those issues at a meeting on Sept. 4, along with discussing the next steps that can be taken with the results from the study.

The study began in November when homeowners take 301 samples of water from Grant, Iowa, and Lafayette counties. In April, homeowners tested 539 wells for a total of 840 samples being randomly selected across the three-county region.

From those samples, 42 percent of the wells tested in November and 27 percent of the wells tested in April showed evidence of contaminated groundwater. In Lafayette County, 55 percent of the wells tested in November and 36 percent of the wells tested in April tested positive for high concentrates of nitrates, E. coli, and coliform.

Thirty-five wells were then randomly selected from those previously testing positive for coliform bacteria and/or nitrate exceeding the drinking water standard (10 mg/L) and were analyzed in April for “pathogens and non-pathogenic microorganisms capable of distinguishing human wastewater and livestock manure, also known as microbial source tracking”. The results were shared with homeowners the first week in August.

Of those 35 wells tested, 32 showed evidence of both human and livestock fecal contamination. Seventeen of those 32 had bovine and human and five of the 17 had all three.

Laeser stated it is concerning to find nitrate in water, and can be dangerous to ones health, especially infants, pregnant women or women who could become pregnant.

“At the end of the day this is about public health and making sure people have safe drinking water,” Laeser said.

The groundwater in Southwest Wisconsin is vulnerable to contamination from the surface. The geology shows that this region has a fractured limestone and dolomite bedrock, also known as karst.

The study will help residents understand if their wells are contaminated with unsafe levels of nitrate, coliform bacteria, and/or various pathogens. It will also clarify what species of animal is the source of any bacteria or pathogen contaminants. The second phase of the study will make clear if there are any links between well contamination and well construction or surrounding land use. What the study will not definitively show are the sources of nitrate contamination.

“This isn’t just about people in the future and having clean water, it is taking steps and making changes to our current system to reduce contamination getting onto the landscape,” Laeser added.

Masarik works for UW-Stevens Point and UW-Extension as a groundwater education specialist He helped meeting participants understand where the nitrates are coming from in the water and what can be done to help reduce the amount of nitrate getting into the ground water.

“Anything that happens on the land surface has an opportunity to impact the aquifer below the ground,” he commented.

Groundwater is water found underground in cracks and spaces in soil, sand and rock. It is stored in and moves slowly through geologic formations of soil, sand and rocks called aquifers. With the layer of soil above the aquifers located deep in the bedrock being very eroded and containing soft rock, it is easy to see how pollutants such as nitrates could penetrate it and be found in the water.

Nitrate is part of the nitrogen cycle. It is a limiting nutrient for plant growth, which is why it is added to agricultural crops to maximize their profitability. Farmers add nitrates via fertilizer, manure or other bio-solids as well as plant materials. Modern agriculture relies heavily on adding synthetic nitrogen to crops, and also utilizes nitrogen from livestock or animal manures, with the goal to get some nitrogen into the plant. Not all nitrogen added is taken up by the plant. Some is converted into nitrate, which is highly a leachable form of nitrogen.

Even though it seems likely that of the nitrates found in water come from agriculture, septic systems drain fields are also potential sources of nitrate to groundwater. All septic system drain fields will release nitrate to groundwater. They are designed to treat for bacteria and pathogens but not designed to completely remove pollutants.

Why should we be concerned with nitrates? Runoff from the Mississippi River basin travels down to the Gulf of Mexico and has been linked to gulf hypoxia, where a concentration of dissolved oxygen in the water column decreases to a level that can no longer sustain aquatic organisms.

In Wisconsin, 70-75 percent of people get their water from groundwater. Public wells are required to test their wells each year. Private wells are not required to be tested. As of 2014 all new wells are required to be tested for bacteria and nitrates, with the stipulation of nitrates only being added in 2014. The only requirement before 2014 was to test for coliform.

“The message here is you are your own water utility manager,” said Masarik. “It is up to you to determine how often you are going to test, what those results mean, and what is the steps you are or aren’t going to take if the results suggest issues.”

Data collected from private well owners testing their wells suggests that 9 percent of private wells in the state of Wisconsin would show high levels of nitrate. In areas where more than 75 percent of the land is cultivated, that percentage would jump to 21 percent. This data can be found via the Wisconsin Well Water Quality Interactive Viewer, an educational tool to help people better understand Wisconsin’s groundwater quality. The viewer relies mostly on voluntarily submitted well water samples from homeowners and other well data collected by state agencies over the past 25 years. It can be found at

Scott Pedley, Lafayette County Board Supervisor for District #15, asked if there was research that would evaluate damage done to the groundwater from lawn care products.

Masarik said that research shows that most of the nitrates contaminating groundwater is coming from agricultural sources – 90 percent from agriculture, 9 percent from septic systems and 1 percent from lawn care. Lawn care might get a high dose but it is only a small portion of the landscape.

“Research tells us that most of the nitrates contaminating our groundwater are coming from agricultural sources,” Laeser said. “In Lafayette County we have 5,245 septic systems. Septic systems leach about 20 pounds of nitrogen per system per year. That adds up to 105,000 pounds of nitrogen that could pollute our groundwater each year. In 2017, we had 137,500 acres of corn grown in Lafayette County. A generally accepted application rate for nitrogen fertilizer on corn is about 160 lbs/year. That amounts to 22 million pounds of nitrogen spread on cornfields in Lafayette County each year. Using an estimated leaching rate of 32 lbs/acre leaves us with 4.4 million pounds of nitrogen from corn fields that could pollute our groundwater, about 42 times more than what comes from septic systems. That also does not account for nitrogen from any manure or other fertilizer spread on farm fields other than corn. There are parts of the state where septic systems, especially where they occur in higher densities, pose a greater groundwater pollution risk, but overall, we know about 90% of the nitrates in our groundwater come from agricultural sources.”

Studies suggest that in an annual or average year, about 32 pounds of nitrogen would be lost from an acre of corn. One septic system would lose about 16 to 20 pounds. Not many farms are only 1 acre of tillable landso for a septic system to equal that of an agricultural farm of 20 acres, there would need to be 32 septic systems.   

More nitrogen is used on corn and alfalfa crops compared to soybeans. After harvest in October, the soil is bare until the following year. During that time, there is snow and then snowmelt. That water can leach nitrogen into the groundwater. Studies show that continuous corn rotations leach the highest concentrations of nitrate to groundwater. If soybeans or even oats or alfalfa is added to the rotation, the nitrate impact is much less.

Perennial crops have the greatest impact to leaching of nutrients into the groundwater. Masarik stated it is easy to tell someone to grow crops like switch grass but there is not a large market for those types of crops.

“It is not all doom and gloom.” Said Masarik. “There are things to be optimistic about and nitrate reduction strategies for agricultural activities.”

Masarik discussed the potential cover crops have and studies showing that they have the potential to reduce nitrate to groundwater by 30 percent.

“I’m cautiously optimistic that cover crops will play an important role in improving nitrate loss to groundwater,” he added.

Masarik said it is not just the farmer’s job to fix these issues but the responsibility is on everyone.

“We need to do a better job in giving farmers more variety of things they can do on their landscape to make sure they have consistent profits year after year,” he said

Laeser agreed with Masarik’s statement, adding that everyone has contributed to the food system we find ourselves into today. Those that don’t farm need to invest in those who do to make changes in the system, working together to address these pollution issues.

“We need to focus less on the finger pointing and identifying the sources of contamination and more on using the science to find the causes and find solutions,” said Laeser.

There will be three more rounds of testing over the next year. One sampling was just taken in early August. Another will take place in November and another in the springtime. As the study is conducted, researchers will be able to dig deep in the construction of the wells and the geology of the area, which relate greatly to contamination of the wells.

Last year, Lafayette County was asked to pay $15,470 for the study. The Lafayette Ag Stewardship Alliance (LASA) contributed $7,000 and citizens of the county helped pay for the additional amount of the study. This year, LASA again is looking into providing some money and asking the county to contribute about $10,000.

Both Laeser and Masarik emphasized the importance of the study and what it can do for the people of Lafayette, Grant and Iowa counties.

“We hope one thing that we have accomplished with the study is more awareness of our water resources and that we shouldn’t take them for granted,” said Laeser.