Hydraulic fracturing is the process of extracting natural gas from the rock. In New York state natural gas is located under the Marcellus Shale. In order to extract the natural gas from the Marcellus Shale it must be fractured by pumping millions of gallons of water, proppants (small particles such as sand or synthetic beads), and chemicals into a well. The concoction is propelled down the well at an extremely high pressure in order to fracture the rock and release the natural gas that is trapping it.
There are various methods of fracking, however the one that may be used in New York, known as high-volume hydraulic fracturing, is the one causing intense concern. In this type of fracking millions of gallons of pure water is mixed with proppants, and a variety of toxic chemicals including friction reducing ones. Only a portion of this water is cleaned up out of the well and the rest is left to osmose through the ground where it will eventually end up in a river, lake, reservoir, or another body of water and pollute it.