Groundwater If you dig a hole and water begins to seep in, you have hit groundwater. It is simply the area beneath the land’s surface where all the spaces between soil particles, or in rocks, are filled with water. Karst: Why be concerned? Where soils are shallow, karst conditions make it easier for groundwater to be contaminated with bacteria, nitrate and pesticides. Even wells that are hundreds of feet deep can be contaminated. Shallow Karst Potential Deep soils help filter out sediment and pollutants as water from rain and melting snow percolates downward. Shallow soils are not as effective and, in karst areas, surface water may flow into the groundwater with little or no soil filtration. In karst areas, groundwater can move 100 feet or more per day (in other areas, groundwater typically moves less than 1 foot per day). The water follow cracks in the limestone, moving deep and spreading out under the ground. Eventually this water returns to the surface at a spring, river or lake. It can also be held deep underground for thousands of years, only reaching the surface again when pumped out of wells. (less than 5 ft. below ground surface) Deeper Karst Potential (5 ft. to 300+ feet below ground surface) Help is available For more information about bedrock concerns, drinking water or cost-share programs, contact: County Land and Water Conservation Departments Public Health Departments University of Wisconsin -- Extension USDA Natural Resources Conservation Department Wis. Dept. of Natural Resources Service Centers Wis. Geological and Natural History Survey Wis. Dept. of Agriculture, Trade and Consumer Protection Or web sites: What can be done? Once contaminants enter the groundwater, little can be done to remove them. The best, easiest and cheapest thing to do is to prevent contamination in the first place. Specific suggestions can be found on the other side of this brochure. Avoid Avoid that that Sinking Feeling Feeling clean-water.uwex.edu/rockriver/groundwater www.uwex.edu/wgnhs/karst.htm Produced by the Rock River Coalition, Inc. and the University of Wisconsin-Extension, with funds through the Environmental Quality Incentives Program Educational Assistance funds of the USDA. Graphics design by Brooke Wentland, UW-Extension Environmental Resources Center. The RRC and UWEX prohibit discrimination in their programs and activities on the basis of race, color, national origin, gender, religion, age, disability, political beliefs, sexual orientation and marital or family status. Sinkholes, Limestone and Groundwater Contamination In karst areas, groundwater is threatened by: Contaminated water from What is it? ✔ Barnyards and other areas where manure accumulates. ✔ Cropland where chemicals and manure are applied. ✔ Septic systems and household waste disposal. ✔ Roads and other paved areas. Karst refers to an area where bedrock such as limestone is easily dissolved by water. Karst regions are generally characterized by connecting cracks and layers between rocks that easily transport water and pollutants to the groundwater. Sinkholes, shallow soils, sinking streams and springs are found in areas of karst bedrock. This is a typical karst spring, but not all springs bubble out of karst areas. Many springs in Wisconsin flow out of deep gravel and sand deposited by the glaciers. The fractures in the bedrock under shallow soil can be seen during a drought. The alfalfa was able to send deep roots down into the moist soil that had accumulated through the cracks. Sinkholes like the one above are often used to dispose of unwanted junk. Sometimes this junk can contaminate a well miles away. Caves such as this one can be an important home for bats and hibernating animals. Take action to prevent groundwater contamination in karst areas Bentonite being used to seal an unused well. In the community On the farm • Use care when planning and • Grow a grass buffer 10 - 200 feet wide, depending constructing roads and ditches to avoid runoff draining into cracks in the bedrock. • Provide “clean sweep” programs to properly dispose of home, business and farm chemicals. • Consider geology and groundwater in land use planning. Around the home • Properly seal unused wells. • Test wells annually for nitrate and bacteria. on site conditions, around sinkholes and crevices. • Do not apply manure, fertilizers, pesticides or other agricultural chemicals near sinkholes. • Any manure applied near sinkholes should be incorporated into the soil as soon as possible. See your NRCS or LCD office for site-specific guidelines. • Divert water away from sinkholes and crevices. • Do not dispose of chemical containers, dead animals, or anything else in sinkholes. • Pump your septic system at least every three years. The water along this ditch disappears into a sinkhole, carrying with it oils, lead, salt and other chemicals from roadways. A sinkhole without a protective berm before and during flooding. A berm would have prevented runoff containing fertilizers and pesticides from draining into the sinkhole.