Natural gas has been touted as a cleaner alternative to other fossil fuels, but it seems the recent boom in hydraulic fracturing is striking nerves instead of oil.

The technique—known as fracking—has sparked debates over possible air and groundwater contamination. Those threats have led at least one community to put its foot down about the well next door.

The city of Longmont, Colorado, is in a tooth-and-nail fight to turn the tables on the oil and gas industry. Voters recently passed a ban on fracking and wastewater disposal within city limits, despite ongoing lawsuits and $500,000 spent by opponents at the polls, according to the New York Times.

The ban was a big win for public opinion, but city leaders are already bracing for a slew of lawsuits from a cast of characters that ranges from the State to individual lease holders. And lost in that back and forth is a point yet to be fully realized in Colorado—earthquake risk.

Although contaminated air and ground water are likely good enough reasons to fear fracking, a U.S. Geological Survey study last week added the Mountain States to the many regions that can link disposal of fracking waste to seismic activity.

The study, presented at the 2012 American Geophysical Union conference last week, indicated a connection between disposal wells and earthquakes in the Raton Basin of Southern Colorado and Northern New Mexico.

“The majority, if not all of the earthquakes [which have occurred in the Raton Basin] since August 2001 have been triggered by the deep injection of wastewater related to the production of natural gas from the coal-bed methane,” the report stated, according to MSNBC.

The study found that from 1970 to July 2001, the region recorded just five magnitude-3 or higher earthquakes. Between August 2001 and December 2011, that number jumped to 95.

These recent findings fall in line with similar studies linking injection wells to earthquakes in Texas, Oklahoma, Arkansas, Ohio, and internationally. Even so, Colorado officials aren’t convinced the USGS report has much merit.

“I don't think they're nuts. I just think it is premature,” Colorado Geologic Survey chief Vince Matthews told The Denver Post. “We're gathering data that is going to help us understand what is going on down there.”

While studies linking earthquakes and wastewater injection are relatively new, the phenomenon isn’t. The link was identified as early as the 1920s and gained visibility in the 1960s when the Army dumped contaminated water at Rocky Mountain Arsenal east of Denver. But since earthquakes that can be definitively tied to injection wells are rare and of a relatively small magnitude, uneasiness remains. Even a recent National Academies report seems to come down on the side of a tenuous connection.

“About 35,000 hydraulically fractured shale gas wells exist in the United States; only one case of felt seismicity (Oklahoma) has been described in which hydraulic fracturing for shale gas development is suspected but not confirmed as the cause," the report stated.

The idea that industry pipe dreams could turn to nightmares isn’t lost on all U.S. decision makers, though. Growing concern over earthquake swarms led the Arkansas Oil and Gas Commission to not only shut down wastewater wells, but also ban the drilling of any new disposal wells. In Colorado, regulators are incorporating seismic risk into the disposal well permit review process—even while they say more study is needed, according to the Associated Press.

Some might call those measures a start, but USGS report author Justin Rubinstein would take the same better-safe-than-sorry approach as Longmont voters.

“I don't think blowing this off is a good idea,” he told the Post. “It's a problem we need to understand. There's been millions of dollars of damage. If you trigger bigger earthquakes, there's a possibility of worse outcomes.”