When a faulty storage tank flooded West Virginia’s Elk River with a coal-processing chemical last Thursday, it left more than 300,000 people without access to water they could safely use to drink, cook, bathe—anything other than to flush the toilet. Sixteen percent of the state’s population was stranded. But just a decade ago, the number would have been far smaller.

The coal industry, which is behind the spill, is also responsible for the scope of its impact: The Elk River branch of the state’s largest water utility, West Virginia American Water, has gained up to 100,000 customers since the mid-2000s, according to the estimate of environmental consultant Rob Goodwin. That’s because mountain top removal and the disposal of coal mining waste (buried underground in a muddy form called slurry) have contaminated local water sources throughout the state’s southern and central regions, driving more and more West Virginians to board up their wells and lay pipe to the Elk River.

“It’s really an extra smack in the face to these community members, when they already did not have safe water due to this same chemical and others being leaked from coal slurry,” said Johanna de Graffenreid, coordinator for the CARE Campaign.

The state’s dependence on the Elk reveals the dark side to its reliance on the energy industry. “The coal industry holds sway over elected politicians,” said Bill Price of the Sierra Club. “They just push the legislature around.” Companies with expansive holdings in the state poured hundreds of thousands of dollars into politics in the off-year of 2013 alone, as the Center for Responsive Politics has documented. (Alliance Resource Partners: $424,000; Alpha Natural Resources: $244,975, and so on.) There are currently 17 coal industry lobbyists registered in West Virginia, according to the Sierra Club.

It’s almost impossible to pass safety regulations that would cut into the industry’s profits, creating a political climate in which the facility holding the ruptured tank had gone without inspection since 1991—without breaking the law. The West Virginia Department of Environmental Protection said the company in question, Freedom Industries, didn’t even need a permit because it stores chemicals rather than producing them.