On threats to the aquifer:

"As more scientific evidence becomes available about karst it is becoming increasingly apparent that its unpredictable GW [groundwater] supply and movement and its high potential for contamination call for a high level of awareness and diligence on the part of those who inhabit karst terrain (which is most of us who live in Shenandoah County)."

- from a USGS report on water in the northern Shenandoah Valley (between Winchester and New Market, in simplest terms -- but including Basye and Orkney Springs, because the "karst" honeycomb extends to the west of Rt 81, the main N/S artery of the valley). To be noted, the same structures effect all of the Shenandoah Valley. Karst topography accelerates both the rate at which groundwater from precipitation and surface run-off is collected into the aquifers, and the rate at which the aquifers can be contaminated. 

In other words, the same circulatory system that makes the Shenandoah Valley so verdant and beautiful, renders it susceptible to poisoning by pollutants. 

Resources and Advocacy

A Primer on Shenandoah Valley Water Supply

Friends of the Shenandoah River

Shenandoah Valley Pure Water Forum

Potomac Watershed Partnership

USGS: "What is groundwater?"