Voters in three Colorado cities approved anti-fracking initiatives by wide margins this week, which could have an impact on the controversial drilling process that has propelled the nation's oil and gas boom.

The votes Tuesday in Boulder, Fort Collins and Lafayette are particularly significant, notes a report in The New York Times, as Colorado has long been a major oil and gas producer. Furthermore, fracking -- or hydraulic fracturing -- has enjoyed bipartisan political support, including from its governor, John W. Hickenlooper, a former geologist.

Colorado produced 49.3 million barrels of oil in 2012, a 26 percent increase from the 39.2 million barrels produced statewide in 2011, figures from the Colorado Oil and Gas Conservation Commission show.

Fracking involves pumping water, sand and chemicals deep underground into horizontal gas wells at high pressure to crack open hydrocarbon-rich shale and extract natural gas. The practice has fueled concerns about water contamination, unhealthy air emissions and earthquakes.

Sam Schabacker, a regional director of anti-fracking group Food & Water Watch, said Colorado voters may have been influenced by the floods that struck northern Colorado in September.

"There's no doubt that seeing tanks floating down the Platte River, seeing oil spills spread out across floodwaters as they traveled toward agricultural land, had a significant impact," Schabacker told the Times.

Opponents of fracking want to push for a statewide referendum in Colorado next year.

"This is totally a galvanizing moment for our movement," Russell Mendell, an organizer for Frack Free Colorado said of the results of Tuesday's vote, The Wall Street Journal reports.

"Statewide and even across the country, people are thinking we can defeat Goliath and win these local elections," he said.

More than 100 municipalities nationwide have passed fracking bans or temporary moratoriums, says non-profit industry monitor, FracTracker.

Ted Brown, a senior vice president at Houston-based Noble Energy Inc. acknowledged Tuesday's votes are a wake-up call on fracking.

"We have a lot more work to do informing the general public," he told the Journal. "Quite frankly, that void has been filled for quite some time without a response from the oil and gas industry."

Noble recently teamed with Anadarko Petroleum Corp. to form Coloradans for Responsible Energy Development, a non-profit organization aimed at educating the public about fracking.

Noble intends to spend $2 billion this year to drill 300 wells in the booming Niobrara play north of Denver, the Journal reports, with that expenditure increasing between $10 billion and $15 billion before 2018.