A ballot measure that would require a vote on the annexation of the 308-acre CU South property is trailing, according to unofficial election results.

The latest available results, posted around 12:45 a.m. Wednesday, indicate 58% of Boulder voters voted no on the issue, while 42% voted for it.

If the ballot measure is approved, it would force a vote on the annexation agreement ahead of the provision of any city utilities aside from flood control facilities. The ballot measure also requires that the agreement include specific details such as a site plan for development on the university-owned property, though the University of Colorado Boulder has said it is years away from beginning its master planning process.

Supporters believe the measure’s success will require more specificity from the university about its plans for the site at U.S. 36 and Table Mesa Drive.

However, the full impact of the ballot measure remains unclear since Boulder City Council approved the annexation agreement in a 6-1 vote in September.

Brian Frey, from the opposition group Protect Our Neighbors, said the ballot measure jeopardizes the safety of the community by delaying flood protection by five to ten years for 2,300 residents. Frey said the delay could potentially be indefinite.

“If 302 fails, it will help ensure that the current annexation agreement moves forward without delay,” Frey wrote in an email. “This will ensure that flood protection is built for 2,300 residents, 119 acres of open space is protected and hundreds of housing units, including permanently affordable housing, are built.”

Frey said Protect Our Neighbors is thrilled with the early results that show how Boulder voters are in favor of critical flood protection.

Marki LeCompte, co-chair for measure proponent Save South Boulder, reiterated her support for the ballot issue.

“If the vote is ‘yes’ for Ballot Measure 302, we feel that Boulder residents will benefit from a chance to re-evaluate the annexation agreement passed by City Council in September,” LeCompte wrote in an email. “We’ll have a new City Council , and they’ll have to examine the weaknesses and flaws in the agreement signed by the former City council, and, we hope, to correct them.”

LeCompte said if the measure fails, then a “fully legitimated” referendum petition will go before the new City Council, which will call for the repeal of the annexation. Residents who oppose the project have submitted more than 6,000 signatures to place a ballot measure asking Boulder voters to repeal Council’s approval of the annexation agreement.

The City Attorney’s Office at one time stated that approval of the annexation agreement would make the ballot measure irrelevant. But this is not certain, particularly because campaign organizers have said they’d fight that determination in court.

Generally, the annexation agreement approved in September outlines a path forward for development and flood mitigation at the property. It proceeded well before the university was prepared to plan for development on the property because Boulder needs a portion of the land for the 100-year South Boulder Creek flood mitigation project, meant to protect 2,300 residents downstream from the property.

The area was among the hardest hit in the 2013 flood. The university offered Boulder land in exchange for the provision of city services such as water and sewer.

Opponents of the measure worry approval would significantly delay work on the flood mitigation project they’ve been pushing for the past eight years.

By the third update, 18,843 votes had been tallied. The Boulder County Clerk & Recorder’s Office will continue counting ballots on Wednesday. An update is expected by the evening.