Produced by the Cave Conservancy of the Virginias, June 1997
Runoff: The water from rain or melted snow that does not infiltrate the soil but flows over the land surface; precipitation drainage.
Everything that goes into a storm drain, flows out into the groundwater, streams, lakes, or river. In karst areas, sinkholes are nature's storm drains, and the dissolved caves beneath are like nature's piping system. As groundwater moves through the earth, wide open spaces such as caves can carry thousands of gallons of water at a time. This groundwater reemerges on the surface as springs or through wells.
Each time trash, motor oil, anti-freeze, litter, pet waste, fertilizer, yard and garden debris, household chemicals, and road sand and salt are dumped on the ground or washed into storm drains, drinking water, groundwater, and aquatic life are endangered. With every rain or snow these pollutants can be carried into the groundwater/surface water system.
Roof runoff contains water pollutants such as bird droppings, chemicals from roofing materials, and heavy metals leached from gutter. In an EPA study, roof runoff was one of the most toxic samples collected.