Underground coal mining can affect wells and springs used as water supplies. Subsidence caused by underground mining is generally acknowledged to be a primary cause of groundwater resource effects. In coal producing regions of Virginia and neighboring states, many rural residents depend on groundwater as their primary water source.

Although it is well known that underground mines can impact groundwater supplies, guidelines for determining if a specific mining operation will be likely to affect a particular water supply have not been developed for the Virginia coalfield area. Complicating factors include variations in mining methods, depth of mining, and geology among locations within the Virginia coalfield area, and between the Virginia coalfield and mining areas in other states. Throughout central Appalachia, contested allegations of water supply impacts have been the subject of disputes between mining firms and residents.

The costs associated with disruptions of groundwater supplies in rural areas can be substantial. When a household's water supply is disrupted, an alternative supply must be developed or the property must be abandoned. One way or the other, somebody must pay. When the cause of a water supply disruption is disputed, both sides must bear costs to resolve that dispute, through litigation or other means. Rational resource management requires that clear guidelines be available for determining cause-and-effect relationships. Such guidelines are not currently available for application to potential water supply impacts of underground mining operations in Virginia.

The purpose of this paper is to report the results of an analysis of water supply impacts of underground mining in Virginia. We analyzed reports of 73 water supply investigations conducted by the Virginia Division of Mined Land Reclamation (VDMLR). These investigations were conducted between 1981 and 1987 for the purpose of resolving disputes between surface residents and underground mining firms.

The results of the VDMLR investigations were analyzed with reference to guidelines for identifying the zone of subsidence influence on groundwater supplies which were prepared by geologist Henry Rauch (1989). based on research which he and his students conducted in the northern West Virginia - western Pennsylvania area. Rauch's "rules of thumb" are the most complete and explicit published guidelines for determining subsidence impacts on water supplies in Appalachia.

This research addresses a subject that is relevant to recently enacted legislation. Section 2504 of the federal Energy Policy Act of 1992 requires mining firms to replace water supplies damaged by underground mining. Virginia House Bill 1687 (1993) also requires water replacement. In developing regulations to implement these laws, federal and state agencies must develop guidelines for determining whether or not alleged water supply impacts are, in fact, mining related.