ALAMEDA — City officials are exploring raising the sales tax rate by a half-cent on the dollar.

The increase could pump an additional $4.9 million annually into the city’s general fund to help cover rising medical and pension costs. Alameda is estimating a $4.7 million shortfall over the next five years because of those cost increases.

“There’s no one silver bullet to fill that gap,” acting City Manager Liz Warmerdam said. “But (an increased sales tax) would be one way to help us balance our budget in five years.”

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The money also could be used to help pay for other city services. Because the money would be unrestricted and go into the general fund, the council could choose how to spend it.

A draft version of the measure said it could go toward helping pay for police and firefighters to respond to emergencies, easing traffic congestion, promoting pedestrian and bicyclist safety, maintaining city parks and storm drains, as well as programs that help young people, seniors and the homeless. However, there is no requirement the money be spent on those services.

On Tuesday, the City Council voted to have city staffers begin work on putting the tax increase before Alameda voters this November.

If it ends up on the ballot, the measure would need a simple majority vote to pass.

Mayor Trish Spencer cast the lone vote against going forward with tax, saying she believed the wording of the measure needed to underscore it would have no sunset date. A preliminary draft of the measure says the tax would last “until ended by voters.”

“I think it’s critical that we be transparent with the public and honest with them,” Spencer said. “If we are not willing to put in there that it has no end date, I think that’s a serious problem.”

The council is facing a July 24 deadline to approve the wording of the measure in order to meet an August deadline by the Alameda County Registrar of Voters to get on the November ballot.

The city’s current sales tax rate is 9.25 percent. The general fund makes up about $92 million of the approximately $200 million budget.

While the council moved forward with the possible sales tax increase, it rejected looking into putting a $95 million infrastructure bond on the ballot, which would require a two-thirds voter majority to pass.

Some of that money would have been earmarked to upgrade the drinking water system at the former Alameda Naval Air Station, where in September last year residents and workers were advised not to drink the water for four days because of possible harmful contaminants.

“I realize it’s a heavy lift,” Councilwoman Marilyn Ezzy Ashcraft, who supported the infrastructure bond, said about securing the two-third voter approval. “But our infrastructure is getting older by the day, deteriorating. Not only is the cost to address it more expensive, that maintenance is deferred.”

But Vice Mayor Malia Vella and Councilman Jim Oddie said more details about the projects the bond would pay for was needed before seeking voter approval.

“I think there’s a lot of work that needs to be done,” Vella said. “And there needs to be more clarity on how we are going to fund the projects that we are considering spending the money on.”