Charleston County residents could be faced with three proposed tax hikes next fall, but that might be too many for voters to stomach.

Nothing is definite, but it's clear that three county agencies are looking at the same time frame to ask for more money.

School Superintendent Nancy McGinley has started talking about possibly extending beyond 2016 the 1 percent sales tax for school buildings.

Separate from that, county officials have been considering next fall as a time to request a potential half-percent sales tax hike for roads and green space projects. And library leaders have been eyeing that same time for a possible referendum for new buildings.

“If you put those three issues up separately, they likely won't be successful,” said Mary Graham, senior vice president for business advocacy at the Charleston Metro Chamber of Commerce. “We think there's a lot of merit in putting all three items together as a campaign.”

Grouping those projects would help the referendum appeal to a broader group of voters and give it more potential to successfully pass, she said.

The chamber's support is critical because it has been the force behind some of the successful referendum campaigns in the past. Public officials can't use public money, property or time to influence the outcome of an election, so the chamber has been one of the groups to take the lead to market the proposed tax increases and solicit county-wide support.

The Charleston Trident Association of REALTORS worked alongside the chamber to pass in 2010 the Yes4Schools campaign. That effort resulted in the 1 percent sales tax hike, which will generate an estimated $440 million for new school buildings across the county. Ryan Castle, government affairs director for the association, said he hasn't had any formal or informal discussions about extending the school tax, but the county needs to come together to talk about the direction it wants to go.

“Everyone needs to start engaging the groups they want to help pass (the referendum) so they have support,” he said. “You would hate to put something on a ballot and not have anyone help you pass it.”

The impetus for the current school building sales tax was tied partly to five schools with severe seismic deficiencies. Students and staff were moved from those buildings after the problems were discovered, and property taxes would have been raised to pay for new construction had the sales tax increase not passed.

This time, school officials are faced with needs in three areas: maintaining the $1.4 billion investment in school buildings since 1997; providing new buildings for growing communities; and ensuring equity in facilities across the district, said Bill Lewis, the district's chief operating officer who oversees capital projects.

McGinley made the first public mention of a potential November 2014 referendum on Wednesday night during a discussion about growth in Mount Pleasant, and she said Thursday morning her staff has been looking at the district's needs.

If this issue isn't on the November 2014 ballot, the district would have a gap between its current building program and the next one, she said. The current one percent sales tax expires Dec. 31, 2016, and referendums only can be on a ballot during a general election, which happens every other year.

“My point is unless we either get the extension of the sales tax or come up with another source of money, there isn't another pot of money,” she said.

The district could consider returning to bond sales, but that requires it to incur long-term debt. The sales tax is a pay-as-you-go concept, she said.

“(Sales tax) definitely is the more frugal and efficient way,” she said.

The board would have to make the call on whether to pursue a referendum, and McGinley said staff would need to have a potential project list identified by December. She wouldn't name any school that would be included or say how long the tax would be extended, but she said officials were looking at those kinds of issues.

Lewis rattled through a list of building needs across the county. Mount Pleasant could use another elementary school and potentially a second high school, while middle schools on James Island and in West Ashley would be focal points. West Ashley and the north end of North Charleston will need elementary schools to accommodate growth, and North Charleston will have to make some decisions about Garrett Academy, a county-wide magnet school known for its career and technology programs.

“(Trailers) are a good short-term solution, but it is not a long-term solution for growth,” he said. “And we can't modernize one community and leave another behind.”

The county has been extraordinary in its support for schools, and the district needs to be good stewards of the funding it has received, he said.

“If we waited until 2016 ... that's not being responsive, and it's not cost effective,” he said.

Reach Diette Courrégé Casey at @Diette on Twitter or (843) 937-5546.