It wasn't the semi-trucks rumbling down country roads, or the dust, or the natural gas wells that popped up around their homes that finally got to residents of Azle and Reno, Texas. It was the earthquakes.
These weren't major quakes, magnitude 3.6 was the biggest, but no one in those North Texas towns had ever felt tremors before. Now in just three months, between last November and January, 34 quakes large enough to be felt shook homes, cracked walls and foundations, scared horses and pets, and opened a few sinkholes.
The ones you can feel have since stopped, but smaller ones continue: some 300, in addition to a 1,000 or so tiny tremors, says Heather DeShon, a Southern Methodist University seismologist leading a team studying the outbreak in the area about 20 miles northwest of Fort Worth.
Locals, and their elected leaders, are convinced the quakes are due to the nationwide drilling boom sparked by a process called hydraulic fracturing, or fracking. The process forces a mix of water and chemicals into underground rocks to free trapped oil or gas.
Once used, the mix of water and chemicals is typically gotten rid of by injecting it into a disposal well. It's that step, not the oil or gas production itself, that can trigger quakes by loosening seismic plates, studies in other areas of the country have concluded.
The industry and Texas regulators say that hasn't been proven in the Azle-Reno area and are asking locals for patience while DeShon's team comes to a conclusion. Azle Mayor Alan Brundrett had other thoughts, telling MSNBC's Rachel Maddow Show last January that "we definitely need to get the wells shut down."
Reno Mayor Lynda Stokes says it's not right to ask for patience when residents are on edge, fearing another outbreak and worse damage. "There are studies out there" showing the connection, she tells NBC News. "I feel they are dragging their feet."
The bad blood in Reno and Azle has happened elsewhere in Texas and across the country.
"Of all the problems with fracking, fixing earthquakes is one of the easier ones."
How did it get to this, especially in a pro-energy state like Texas?
"Fracking came so quickly, much more quickly than we could figure out how to do it right," says Russell Gold, author of "The Boom: How Fracking Ignited the American Energy Revolution and Changed the World".
Thousands of disposal wells were approved "without asking if there were active faults nearby," adds Gold, whose full-time job is reporting on energy issues for the Wall Street Journal. The fracking boom has brought "energy to our backyard," he adds, and sometimes that creates fear. "Earthquakes are a very palpable example of that."
As a result, communities are getting more vocal, even in Texas.
"Without question, local governments are demanding a say in regulating oil and gas," says Gold. "That's setting up a rather intense arm wrestling match between local and state governments."
The industry is regulated by the Texas Railroad Commission, which has stood its ground, saying it needs to wait for the scientific report before taking any action.
"There has been no scientific proof that a specific disposal well or wells have caused the Azle-area earthquakes," says commission spokeswoman Ramona Nye.
At a public forum last Wednesday, residents made clear they disagree.
The dozens in attendance broke out into applause and cheers when Stokes, asked what residents want, was blunt: "I think they want to shut those wells down."
Residents also didn't like hearing from DeShon that her team's study could take a year to complete.
For all the tension, the issue is one that can be resolved, says Gold.
"Of all the problems with fracking, fixing earthquakes is one of the easier ones," he says, citing options like reducing injection pressure, recycling the wastewater and not placing disposal wells near fault lines.
Azle Mayor Brundrett agrees. "It's not that all injection wells are bad," he told MSNBC. "You do research before you choose a location for an injection well."
Gold says "the trickier issues" raised by fracking include air emissions, methane leaks and protecting aquifers from wastewater.
The range of issues has led to anti-fracking, or at least more regulated fracking, movements across the country. Bans or restrictions by dozens of local governments and even some states are being challenged in court by the industry.
Gold takes the view that the U.S. needs energy and so it might as well produce it here where it can better control the health and safety impacts, rather than import it from countries with laxer regulations.
"Let's figure out how to produce it in a way that's environmentally acceptable," he says. "That's our challenge. We're meeting it, but it takes time."