Groundwater Quality

COOPERATIVE EXTENSION SERVICE UNIVERSITY OF KENTUCKY COLLEGE OF AGRICULTURE, FOOD AND ENVIRONMENT, LEXINGTON, KY, 40546 AEN-120 Groundwater Quality Ashley Bandy, Earth and Environmental Sciences, and Carmen Agouridis, Biosystems and Agricultural Engineering G roundwater is an important water source for activities such as drinking, bathing, cooking, and crop irrigation. Keeping our groundwater sources clean is becoming more challenging with an ever growing population. In watersheds underlain with karst, such as many of those in Kentucky, the groundwater is more susceptible to contamination. his is because surface waters, such as runoff and in some cases streamflow, travel into the subsurface of karst by way of fractures, sinkholes, swallow holes, conduits and caves (Figure 1). Such direct paths into the groundwater mean that pollutants reach the aquifer much more quickly with little to no iltration (Figure 2). hus, while waters from springs and wells may look clean, they may actually contain unsafe levels of pollutants such as bacteria and nitrogen. Figure 1. Flow from a small stream enters into the ground by way of a large swallow hole. Sources of Pollution Pollution is classiied as either point source or nonpoint source. Point source pollution is defined as pollution that originates from a speciic location and is discharged through a pipe. Nonpoint source pollution (NPS) is pollution generated from many difuse or widespread sources. Examples of NPS include sediments from agriculture, construction or timber harvesting operations; oils and grease from urban areas; and pathogens and nutrients from livestock, human and pet wastes (Figure 3). Figure 2. In granular aquifers (left), water is iltered by lowing through tortuous paths around sand and gravel. In karst aquifers (right), water is not iltered because of direct low paths through fractures or sinkholes. Karst Watersheds Karst is prominent in Kentucky with 55 percent of the Commonwealth underlain by karst-prone rocks (Figure 4). Karst landscapes are characterized by springs, caves, sinkholes and sinking streams (Figure 5). Although typically found in regions underlain by limestone, karst can originate in other types of soluble rock such as evaporites, dolomites, and Figure 3. Uncontrolled livestock grazing adds pathogens and nutrients to water bodies, such as streams, ponds, lakes, and groundwater. Agriculture and Natural Resources • Family and Consumer Sciences • 4-H Youth Development • Community and Economic Development EXTENSION marble (Table 1). These soluble rocks are dissolved when acidic water, such as rain, lows through fractures and other openings, dissolving the rock and widening void spaces into larger conduits and caves. Rainwater becomes slightly acidic (pH of 5.5 to 6.0) when it interacts with carbon dioxide in the atmosphere and soil. Table 1. Types of soluble rocks in which karst is formed. Limestone (calcite). Many types of limestone exist. In Kentucky, limestone is gray or tan and has interlocking crystals. It may contain fossils. Protecting Groundwater Quality here are a number of ways to protect the quality of our groundwater. At home, be sure to properly dispose of all household waste. Trash and other debris should not be placed in sinkholes. If you have a septic system, inspect it regularly to ensure it is working properly. Be sure to pick up after your pet. In rural areas, protect sinkholes from runof from livestock or crop operations. Fence-of sinkholes so that livestock cannot enter. Doing so will not only protect the livestock from injury, but will help protect groundwater quality. Vegetated bufers, which are areas of thick vegetation such as grasses, shrubs or trees, can be established around sinkholes. hese bufers help ilter sediments, pathogens, nutrients and other pollutants from runof before it enters the sinkhole. Dolostone (dolomite) is granular (like sugar) or crystalline (interlocking crystals) and comes in a variety of colors. Gray and tan/yellow are the most common colors. Gypsum (gypsum) is soft and can be scratched by your ingernail. It is usually white or colorless. Additional Information Refer to the following Kentucky Cooperative Extension Service publications for more information: • AEN-106 Reducing Stormwater Pollution • AEN-109 Sinkhole Management for Agricultural Producers • FOR-67 BMP No. 4: Sinkholes • AGR-166 Maintaining Conventional Septic Systems Rock Salt (halite). Although salt can have color, it is typically colorless. Rock salt breaks into cubes, and as the name implies, it tastes salty. 2 Figure 4. Karst areas in Kentucky. Darker areas are more likely to have springs, sinkholes, and caves. Source: J.C. Currens, Kentucky Geological Survey. Inner Bluegrass karst area Area of high potential for karst Area of less potential for karst Area of no potential for karst Louisville Frankfort Georgetown Paris Lexington Lawrenceburg Versailles Winchester Nicholasville Fort Knox Elizabethtown Mt. Vernon Munfordville Princeton Somerset Bowling Green Hopkinsville Monticello Russellville Western Pennyroyal karst area References Currens, J.C. 2002. Kentucky is Karst Country: What You Should Know about Sinkholes and Springs. Kentucky Geological Survey, Information Circular 4, Series XII. Accessed at: http://kgs.uky.edu/kgsweb/olops/ pub/kgs/ic04_12.pdf. Halite. 2013. he Mineral and Gemstone Kingdom. Accessed at: http://www. minerals.net/mineral/halite.aspx. Kentucky Geological Survey. 2005. Sulfates. Accessed at: http://www.uky. edu/KGS/rocksmn/sulfates.htm. Taylor, B., Burns, S., Greb, S. 2006. Geology of Fayette County. Kentucky Geological Survey. Accessed at: http:// www.uky.edu/KGS/geoky/county/ fayette.htm. U.S. Environmental Protection Agency. 2012. What is nonpoint source pollution? Accessed at: http://water.epa. gov/polwaste/nps/whatis.cfm. Eastern Pennyroyal karst area Pine Mountain karst areaa U.S. Environmental Protection Agency. 1996. Managing Nonpoint Source Pollution from Agriculture. Pointer No. 4. EPA841-F-96-004F. Accessed at: http://water.epa.gov/polwaste/nps/ outreach/point6.cfm. U.S. Environmental Protection Agency. 1996. Managing Nonpoint Source Pollution from Households. Pointer No. 10. EPA841-F-96-004J. Accessed at: http://water.epa.gov/polwaste/nps/ outreach/point10.cfm. Acknowledgement Funding for this publication was provided in part by an Urban Waters grant from the U.S. Environmental Protection Agency. Figure 5. Common features found in karst landscapes. Source: J.C. Currens, Kentucky Geologival Survey. Educational programs of Kentucky Cooperative Extension serve all people regardless of race, color, age, sex, religion, disability, or national origin. Issued in furtherance of Cooperative Extension work, Acts of May 8 and June 30, 1914, in cooperation with the U.S. Department of Agriculture, M. Scott Smith, Director of Cooperative Extension Programs, University of Kentucky College of Agriculture, Food and Environment, Lexington, and Kentucky State University, Frankfort. Copyright © 2013 for materials developed by University of Kentucky Cooperative Extension. This publication may be reproduced in portions or its entirety for educational or nonproit purposes only. Permitted users shall give credit to the author(s) and include this copyright notice. Publications are also available on the World Wide Web at www.ca.uky.edu. Issued 1-2014