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Those giant steel towers rising all across the United States — they aren’t sucking oil from the ground. They’re pumping water into it, building enough pressure to break the rock and release 10-million-year-old fossil fuel. This is hydraulic fracturing, better known as fracking, and fighting it has become the cause célèbre of filmmakers, politicians, movie stars, and activists.

For good reason: The Environmental Protection Agency has found that fracking chemicals can contaminate drinking water supplies, gas companies have laid waste to rural landscapes, fracking can release methane, a powerful greenhouse gas, into the atmosphere, and scattershot state and federal regulations allow drillers to keep the ingredients of their chemical cocktails secret. Fracking has even been linked to earthquakes.