WASHINGTON — Colorado’s ballot this November won’t include a question about fracking because opponents who want to restrict the practice failed to gather enough valid signatures to put a plan before voters, Secretary of State Wayne Williams announced Monday.

The setback represents a major blow to environmentalists, who tried in 2014 and again this year to use the Colorado ballot to put new limits on hydraulic fracturing — or fracking — a procedure in which water, sand and chemicals are pumped into the ground to extract oil and gas.

“It’s fair to say that everyone that participated in this (campaign) is feeling disappointed,” said Diana Best of Greenpeace, one of several groups that helped collect signatures.

Their goal was to put two proposals before Colorado voters: one that would prohibit energy companies from building new oil and gas facilities within 2,500 feet of homes or other occupied buildings, and another that would give more power to local governments to restrict fracking.

Neither measure, however, netted the requisite number of signatures. A minimum of 98,492 voter signatures are needed, and a random-sample test of the two petition efforts showed both proposals came up short.

The review by state officials also raised the possibility that some signatures may have been forged as part of the setback petition.

According to documents provided by the Secretary of State’s office, the signatures in question were gathered by a circulator named Elsadig Saeed Merghani, a Denver resident. At least three of the signatures collected by Merghani were marked as questionable. Reached for comment, Merghani declined.

Williams has forwarded the signatures in question to state Attorney General Cynthia Coffman for an investigation.

Overall, several organizations were involved in collecting signatures for the setback proposal. Among them: 350.org Action Fund, Colorado People’s Alliance, Food & Water Action Fund, Food & Water Watch, Greenpeace USA and Localized Strategies LLC.

A spokeswoman for the campaign behind the anti-fracking initiatives questioned the forgery claims and raised the possibility that they might challenge in Denver District Court the decision to leave the two measures off the ballot.

“We are reviewing the signatures that the (state) rejected in the voter database, and we’re already finding some discrepancies with their findings,” said Suzanne Spiegel of Yes for Health and Safety Over Fracking.

“Once we have a complete understanding of all of the issues of the (state’s) findings, we will make a determination of whether to file a challenge.”

They have 30 days to decide.

Opposition to the anti-fracking initiatives was fierce from the oil and gas industry. A group called Protect Colorado — which is funded by the energy sector as well as ranchers and other businesses — led an effort dubbed Decline to Sign that was intended to chill momentum for the anti-fracking effort.

The energy industry also was girding for a fight in case either measure made the ballot.

“Colorado voters recognized that these extreme measure would destroy the state’s economy and take away private property rights. The voters read the petitions and declined to sign them because they understood the devastating consequences these initiatives would have on all Coloradans,” said Karen Crummy of Protect Colorado in statement.

Leading up to Monday’s announcement, there were questions about whether the anti-fracking measures had garnered enough support — though an aide to Williams said a review of the petitions showed the signature-gathering effort had at least one bright spot.

“What is so interesting is that these measures actually had a really high validity rate,” said Lynn Bartels, a spokeswoman for the Secretary of State.

Random-sample reviews of the two anti-fracking measure showed that both had a valid signature rate of more than 70 percent. Comparatively, a petition to raise the Colorado’s minimum wage to $12 an hour sported a validity rate of about 58 percent.

The minimum-wage proposal made the ballot, however, because organizers submitted about 189,000 signatures — about double the 98,492 signatures required. That wasn’t the case for the anti-fracking measures, which both yielded about 107,000 signatures.

“They just didn’t have enough signatures,” Bartels said.

What happens next in Colorado’s fracking fight is an open question.

Supporters of new fracking regulations tried two years ago to get similar measures on the ballot — only to have those withdrawn as part of a compromise deal orchestrated by Gov. John Hickenlooper.

The effort this year was borne out of frustration from fracking opponents who say very little has been done to address the issue since then, though now it could be harder for them going forward.

One measure that did make the November ballot this year is a proposal that would make it more difficult to amend Colorado’s constitution through initiatives such as the anti-fracking proposals.

“This would be a huge hit for grassroots movement,” said Best of Greenpeace.

State Rep. Mike Foote, D-Lafayette, carried unsuccessful legislation in the last session to grant more local controls on fracking, but he said Monday that it’s too early to say what the next step will be.

“The issue is not going away,” he said. “It’s still a big issue, and it hasn’t been solved, so this isn’t the end of the conversation.”