Environmental Matters in the Commonwealth of Kentucky

The technical definition of the term “karst” is a terrain, generally underlain by limestone or dolomite, in which the topography is chiefly formed by the dissolving of rock and which may be characterized by sinkholes, sinking streams, closed depressions, subterranean drainage, and caves. (Monroe, W.H., 1970, A glossary of karst terminology: U.S. Geological Survey, Water-Supply Paper 1899, 26 p.)  The term “karst” is derived from a Slavic word that means barren, stony ground.  The term “karst” describes the whole landscape, not a single sinkhole or spring.

Karst is a special type of landscape that is formed by the dissolution of soluble rocks, including limestone and dolomite. Kentucky is one of the most famous karst areas in the world.  Much of the state’s beautiful scenery, particularly the beautiful horse farms in and around Lexington, is the result of development of karst landscape. The karst topography of Kentucky is mostly on limestone, but also some dolostone.   According to the Kentucky Geological Society, Karst underlies about half of the state.  Kentucky is one of the world’s most famous karst areas. About 38 percent of the state has sinkholes that are recognizable on topographic maps, and 25 percent has obvious and well-developed karst features.

The Kentucky Bluegrass Region is a karst region.  Much of the region is drained by the Kentucky River and its tributaries.  Particularly near the Kentucky River, the region exhibits karst topography, with sinkholes, caves, and disappearing streams which drain underground to the river.  Caves of 1 or more miles of surveyed passage in Kentucky are listed at http://www.ksscaves.org/projects/Kentucky%20Long%20Cave%20List-2.html. Kentucky’s only national park and state jewel, Mammoth Cave, was formed by karst processes.

Groundwater in karst regions is particularly susceptible to contamination. Because of the nature of karst, water moves rapidly into the subsurface from discrete sites such as sinkhole drains and sinking streams, as well as in nondiscrete locations by moving through large pores in the soils. This rapid migration of water into the subsurface does not provide for the filtering of contaminants in the soils and rocks before arriving in the aquifer. Therefore, we need to be more diligent about protecting groundwater in these susceptible regions, including using best management practices, and following certain “Do’s and Don’ts” such as do not dispose of anything in a sinkhole.

According to the Kentucky Division of Water, about 2 million Kentuckians depend on groundwater for their source of drinking water, as well as a source of water for industry and irrigation. Because about half of the surface area underlain by shallow, unconfined aquifers in Kentucky is karstic, a significant percentage of the groundwater in Kentucky moves through karst aquifers. Most karst springs previously used for a public water supply have been abandoned because of groundwater contamination. Despite that, water from karst aquifers is vital to Kentucky because karst springs support the base flow of the streams to which they discharge. This means that most public systems in karst areas are still using water from a karst aquifer when they withdraw from a stream or reservoir.

An estimated 11 percent of karst springs in Kentucky are used for domestic water supplies: this affects over 10,000 homes. These people have a critical interest in protecting the quality of the water they are drinking. Most homes have no water treatment system, and those that homes that have water treatment only remove sediment and sanitize the water, but cannot remove organic compounds or metals