A karst landscape develops when the limestone or dolostone bedrock underneath the soil dissolves and/or collapses due to weathering. A karst system can be recognized by surface features such as depressions, sinkholes, sinking streams, and caves. In karst systems, surface water and groundwater are interconnected: surface water runoff flows into sinkholes and sinking streams and recharges the groundwater; likewise, springs maintain stream flow in the dry season. Kentuckians living in karst areas need to be acutely aware that any pollutants that reach either surface water or any karst feature can pollute the entire groundwater system (also called an aquifer). In addition, the cave system that accompanies a karst aquifer can allow pollutants to contaminate miles of water resources in just a few hours.