There are two main reasons why karst landscapes are vulnerable to groundwater pollution, and therefore why we have to be aware of how our actions on the surface impact what’s down below.

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1.  The surface and subsurface are more connected in karst areas than most other landscapes. Karst has natural openings on the surface and throughout the underground bedrock that can become connected networks of sinkholes, springs, caves, underground rivers and aquifers. After every rainfall, trash and chemicals on the surface can easily enter through natural and man-made openings in the ground and rapidly travel throughout these networks. In fact, water and pollutants which flow into injection wells, curb inlets, sinkholes, cave entrances, or other stormwater drains does not travel to water treatment facilities where harmful chemicals or trash can be removed.  Instead, the water flows directly into natural underground voids and passageways without being cleaned, and then flows to caves, springs, or surface water bodies such as the Barren River. Therefore, human actions on the surface, such as over applying fertilizers/pesticides or disposing of trash into sinkholes, can quickly and easily pollute both the water resources flowing below ground and the water bodies on the surface.

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2.   The bedrock that karst forms in (often limestone) does not filter pollution from water. Surface water can quickly move underground through the natural karst features (sinkholes, cave openings, or sinking streams) or man-made features (injection wells, curb inlets, stormwater drains), and then can continue to travel for long distances through underground rivers or small cracks in the rock. To picture how fast this water can travel below ground, think about how a surface stream or river flows… underground rivers and surface rivers often look very similar. This flowing underground water can carry pollutants over long distances throughout the entire karst system. Therefore, what we do on the surface can impact our groundwater supply almost immediately. Groundwater may be out of sight temporarily, but because we live on a karst landscape, it may eventually resurface with all of the pollution it has been carrying. This pollution could be trash, debris, or even harmful chemicals from agricultural fields, home lawns, pet waste, sediment, and urban streets and parking lots.