Living in the middle of a natural gas boom can be pretty unsettling. The area around the town of Silt, Colo., used to be the kind of sleepy rural place where the tweet of birds was the most you would hear. Now it's hard to make out the birds because of the rumbling of natural gas drilling rigs.
The land here is steep cliffs and valleys. But bare splotches of earth called well pads are all over the place.
"That's the one I'm worried about because it just went in," says Tim Ray.
In Pennsylvania, there's an industrial revolution going on. Battalions of drilling rigs are boring into the earth to extract natural gas from an underground layer of shale called the Marcellus formation.
And as the wells multiply all along the western end of the state, people worry they may be facing another toxic legacy.
The first one came from coal mining. All over the state, you can see bright orange rivers and streams. The aquatic life was killed by acidic runoff from abandoned mines.