"We won, and we are so thrilled," said Kay Fissinger, a volunteer with Our Health, Our Future, Our Longmont.
Hydraulic fracturing, or "fracking," is a process used by oil and gas drillers to crack rock deep below ground.
It's a practice that hundreds of volunteers worked to get banned, according to those with Our Health, Our Future, Our Longmont. The time and effort over months to get people to the polls and vote for the ban was worth it, they say.
"It's a health hazard. It's a safety hazard," Fissinger said.
Opponents of the ban also mobilized a group called Main Street Longmont.
"Oil and gas development, and the process of hydraulic fracturing, is proven over the last 40 years to be an environmentally sound and important economic driver in our state and our nation's pursuit of domestic energy," Bill Ray, the group's spokesperson, said.
He says the ban is unfair to mineral lease holders in Longmont.
"That is not something that The City of Longmont can do. It's an issue that the state regulates," Ray said.
Governor Hickenlooper has long supported fracking operations in Colorado, with environmental safeguards.
When asked about Longmont's ban Wednesday morning, he said he expects private companies to file suit against the ban.
But for now, the votes are in and supporters of the ban say they won over a well-funded industry campaign.