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Karst features and their effect on your water

Karst features and their effect on your water

BILL BATTON, a geologist from the Wisconsin Geological & Natural History Survey, talks to those present about rock features in the BARD Materials’ quarry outside of Darlington.

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POSTED April 6, 2017 10:21 a.m.

LAFAYETTE COUNTY - Several people concerned with the water quality in Lafayette County and to learn more about karst features met at the Darlington Country Club on Thursday, March 30 to hear presentations from specialists on that subject.
Steve Carpenter, local farmer that operates at Red Rock View farms outside of Darlington, stated that he was like a lot of people in the area and had no idea was karst was and that Lafayette County has several karst features.
“We need to educate not only us but our community about things like this,” Carpenter stated.
He and a few other producers in the area put together a group called the Lafayette Ag Stewardship Alliance with the goal to educate people on how to improve water quality and the environment.
“We as producers on this, are going to set high expectations for ourselves, and others, to show what we do to make the environment better,” Carpenter added.
Kriss Marion, Lafayette County Board and Lafayette Ag Stewardship Alliance member, first heard about karst last year in Iowa County and brought the information into Lafayette County to help those in this area learn about the issues karst can have on the land and the groundwater.
“I have been walking around with a map for about a year looking at our county saying, ‘do we know about this?’ ‘Is anybody concerned about this?’ I want to learn about this,” Marion said.
She helped establish Pecatonica Pride, a producer lead group that also does some of the same things as the Lafayette Ag Stewardship Alliance, informing people about water quality.
Madeline Gotkowtiz, a hydrogeologist at the Wisconsin Geological & Natural History Survey helped define what karst is. Karst is a type of landscape that is formed when soluble rocks, such as limestone and dolomite, dissolve. When it rains, the rain has a pH of 5.7 and that dissolves the rock.
There are several well-developed karst features around the United States, like Mammoth Caves in Kentucky, Carl’s Bad Caverns in New Mexico and here we have Cave of the Mounds.
Most of the karst features in Wisconsin are small, like sinkholes or enlarged fractured networks, essentially cracks in the rock. Gotkowtiz said how they are concerned about how well those networks are connected to each other and they can lead to very fast flowing rainwater down to the water table.
Twenty percent of the United States land surface is karst. About 1/3 of Wisconsin is covered by carbonate rocks that can develop karst features. Karst features are made when the rainfall makes it way through the soil and it percolates and dissolves the rock and a void can begin. Soil then can fill up the hole and a karst or sinkhole is created. Sometimes the soil and rock can have a void in them for several years, it is only after a large rainfall or snowmelt that the sinkhole is created.
Gotkowtiz showed a map they have at the Wisconsin Geological & Natural History Survey, of the mining industry here in Lafayette County. These man made features can act in the same way geologically as a natural feature. Abandoned mines can be conduit for water to reach the water table. Sand and gravel help filter out the water before it reaches the water table but with the carbonate bedrock only within 50 feet of the land surface in Lafayette County the water can run right down the fractured networks in the rock and directly into the groundwater aquifer.
Bacteria and viruses can travel through the large cracks in the rock, into the water table and can make people sick. Contaminates from manure runoff, septic systems, chemical spills and runoff from road salts can seep into the water. One family in Iowa County was very sick. The casing on their well was only at 85 ft. and contaminated water was seeping into the well from fractures in the rock. They drilled a new well at placed the casing at 220 ft. to insure no more water could flow in from the cracked rock.
Paul Ohlrogge, UW-Extension Community Resources Development in Iowa County, discussed that in the country, water in a typical private well originates from about a two-mile radius of the well. Lafayette County has an abundance of water. Ohlrogge talked about water rich counties need to learn how to manage it. In Wisconsin there are 700,000 private and municipal wells. More than 70% of people in Wisconsin drink ground water.
Iowa County has done water testing for several years now. Ohlrogge said they have tested 1,318 wells. They distribute 10 to 12 bottles to test water a week and do town-by-town testing. Close to 13% of wells in Iowa County have tested high for nitrates. Lafayette County had 1,123 tested and 17% were over the safe drinking water standards for nitrates, or ten parts per million. Four percent are over the safe drinking levels for arsenic with only 156 wells tested. Forty-one percent tested for having coliform. Ohlrogge said a scary one was ten percent tested had e-coli.
The Lafayette County Health Department with the Lafayette County Land and Conservation are doing a program will be doing two townships every year. Letters will go out and residences will test their water. If the water comes back with problems, the Health Department will go to the homes and do some education on it. They are working with UW-Stevens Point and it will be mapped. It will take some time. They are thinking about six years. Marion added that the Lafayette County Board will be paying for 25% of the testing and they are looking into some funding so it will not take as long.
Another hydrogeologist from the Wisconsin Geological and Natural History Survey, David Hart, explained why people should care about the depth to bedrock. The DNR uses this information for data land planning. When creating a Nutrient Management plan, the DNR and the farm requesting to spread manure need to know the depth to the bedrock to make sure that the manure being spread does not seep into the ground water. Manure cannot be spread on bedrock less than 24 inches or 60 inches if the ground is frozen.
Hart showed how anyone could find karst features or sinkholes by using Google Earth or GIS. Fractures in the rock can be found in alfalfa fields or hay fields in the striation throughout the field. Sinkholes are easy to spot and can be near carbonate rock formations. Swallets, an opening in the ground where a stream can descend down, can be found in ditches.
Kevin Erb from the UW-Extension gave recommendations from the Northeast Wisconsin Karst Task Force. Based in Green Bay, he does training around the state. The reason for putting together the task force was for events that happened in Northeast Wisconsin with contaminated water; issues with sinkholes being formed and 86 wells contaminated over two weeks. The geology in Northeast Wisconsin is different from down here in Southwest. In the northeast, it is flatter and water flows for a lot longer distance picking up contaminations and southwest has more slopes. They had documented proof that water would flow into the cracks ¼ a mile every 20 minutes. Karst is different because the glaciers scraped off a lot of what southwest Wisconsin has.
They figured out if they got rid of every cow and person, there would still be groundwater contamination issues. There can be steps taken to greatly reduce the impact that is has. Karst features tend to appear in areas. Structures such as manure pits and sewage treatment plants should be at least 400 ft. away from a known sinkhole because other features could be hidden. They look at where the rain runs off to make sure they don’t flow to sink holes.
There are things towns, townships and farmers can do that don’t cost any money that can help contain sinkholes. Homeowners should physically inspect their wells and make sure dirt is built up around it rather than a low point in the landscape. Farmers should have a winter manure-spreading plan. Landowners can identify karst features and have it mapped so if the land changes hands, that information can be passed on. Everyone in the community can be educated on these features to enhance citizen awareness. Training farmers, nutrient management plan writers and manure applicators on how to find these features may cost some money but it is good in the long run.
“You are here today as a proactive first step. You are learning about this situation. But it is really up to the Land and Conservation Committees, the farmers, the elected representatives to come together, to figure out what a solution is to this. Education and changes in practices are all going to lead to better quality,” Erb said passionately.

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