Karst Aquifers: Can They Be Protected?

Abstract

Karst aquifers are notorious for poor water quality, including the presence of microbial pathogens, chemical pollutants, and suspended sediment. Water flow in karst is primarily through conduits, allowing little time or surface area for processes to remove surface-derived contaminants. To meet drinking water standards, water often must be heavily treated; this treatment is sometimes beyond the capacities of domestic well owners in the United States and often unattainable in the developing world. This situation is exacerbated in urbanizing areas, where burgeoning development results in increasing numbers of septic systems, landfills, and industrial activities. Because ∼25% of the land surface of the world is karst, it is obvious that associated aquifers are critical resources for drinking water. But given the vulnerability of karst aquifers, is it worthwhile to expend resources to protect these aquifers? Or should resources be directed toward treatment? Even our best efforts will not keep karst aquifers in pristine condition. The likelihood of adequately protecting a karst aquifer is based on several criteria (Table 1). When there are multiple best-case scenarios, it is more likely steps can and will be taken to protect a karst aquifer. Without economics and associated water resources providing the incentive for protection, other criteria rarely lead to land-use change. In the short term, significant land-use change to protect recharge areas is usually not possible. However, actions can be taken to mitigate the impacts of current and historic land uses. Best management practices in agricultural areas can lessen the amount of contaminants reaching the aquifer. Regulations for developed areas can be enforced and/or changed to restrict potential sources of contamination of recharge areas. Unfortunately, accidental and illegal dumping of toxins and wastes into sinkholes is extremely difficult to prevent and to clean up. Ground water protection plans need to be long term. There are rarely any quick fixes to protecting a contaminated or threatened aquifer. However, immediate steps can be taken for many karst watersheds, including identifying the most vulnerable recharge areas and developing and enforcing regulations for private and municipal septic systems, and the handling, storage, and disposal of potential contaminants. While making significant changes in land use may not be practical in the short term, most businesses and manufacturing/storage facilities have a finite lifetime, and land-use change may become a viable option when businesses and facilities close. Geoscientists are critical in helping to plan for the long term. One of the most important tasks is to educate the public. The goal is to change the collective consciousness so that residents will realize the need to protect recharge areas and pressure governmental authorities to protect ground water in karst regions.