New Orleans voters will be asked this year to raise property taxes to provide more money to the struggling New Orleans Public Library system.

The City Council voted Thursday to put a 25-year, 2.5-mill tax before voters in a special election on May 2. The tax increase is expected to raise $8.25 million a year for library operations, according to a resolution adopted by the council.

The tax would be in addition to the 3.14 mills now dedicated to the library. That tax expires at the end of 2021.

The money would be used “for the purpose of adequately funding” the library system’s continued operations.

The library request could be accompanied on the May 2 ballot by a proposal to increase special property taxes that help pay for police and fire protection.

The library system’s executive director told the City Council in November that, without more money, the system will exhaust its reserves by the middle of 2016. Charles Brown said the system’s financial situation was so dire that it might have to close one or more of the 14 branches it operates.

City Council members offered their full support of the tax increase Thursday, voting 7-0 to call the election and offering to help promote the request.

“A good library system is good crime prevention,” Councilman Jason Williams told Library Board Chairman Bernard Charbonnet. “And closed doors on a library are closed minds, so we will be with you all the way on this.”

The library needs $18 million a year to be properly funded, Brown told the council last year as he presented the operation’s $12 million 2015 budget.

About a quarter of the library’s funding for this year will come from the last bit of the surplus it accumulated when many of the city’s libraries were closed after Hurricane Katrina. The balance, $9.2 million, will come from the existing millage. As has been the case in recent years, the library will not receive any money from the city’s general fund in 2015.

Voters statewide and in Orleans Parish last year gave the city permission to put a request on a future ballot doubling the maximum authorized rate for special taxes for police and fire protection to 10 mills each. The two taxes are now capped at 5 mills each. They are not subject to the homestead exemption that covers all other municipal tax millages in New Orleans.

Increasing both public-safety taxes to 10 mills would generate an additional $31.6 million a year for the police and fire departments. The new revenue would have to be used for services that directly contribute to residents’ safety.

The City Council has not voted on whether to include those measures on the May 2 ballot or, if so, how large an increase in each tax the city would seek.

The ballot will definitely include a second attempt by Orleans Parish Sheriff Marlin Gusman to allow his office to use money from an existing property tax to pay for expensive reforms at Orleans Parish Prison. Gusman’s request, which voters rejected on Nov. 4, would not increase the current millage rate, but it would allow the sheriff to use the money in more ways.

The money is now dedicated solely to paying off bonds for construction projects. If the ballot measure is approved, the sheriff also could use the money to pay for costs associated with a federal consent decree mandating reforms in how the jail is managed. About $4.4 million a year could be redirected to cover such expenses if voters approve the measure.