It's fracking obvious

Oil fracturing has been used for quite some time to get natural gas out of the ground. The principle is simple--just apply extra pressure to existing rock fractures to widen them further, and the gas comes up out of the ground. The gas itself is more or less harmless--harmless, anyway, until it is ignited. There have been several cases of water wells blowing up in Pennsylvania and one of a house blowing up in Ohio when gas from nearby pipes leaked into the wells and the basement of the house.
Now, mining natural gas should not be that big a deal. It isn't as environmentally destructive as other types of mining, and has even been endorsed by the Sierra Club. However, the problem comes in with what substances are used for fracturing. The companies who do the mining use several cancer-causing chemicals, including benzene, to create the pressure necessary to fracture the rock. When the gas comes out, the benzene stays where it is, at least until it finds other fractures and works its way to the surface. Many Pennsylvanians are now complaining about their well water being cloudy where it used to be clear. All of these wells are near fracing operations and test positive for chemicals used in the fracing process.
One of the arguments for oil fracking is that since the oil and natural gas is found at least a mile below the surface, groundwater cant reach it. The problem comes when the substances left behind work their way through other fractures and eventually reach areas where groundwater can carry it to less desirable areas, like water wells.
That being said, the mining companies take every possible precaution. Few companies want to be responsible for someone else's misery. However, this is one of those times where we need to decide whether it is more important to have oil and natural gas or clean drinking water. We can live without one, but we can't without the other.