As New Haven debates its budget for the next fiscal year, the city has already implemented cuts in some of its services, with more on the way pending negotiations with city unions.

While the service cuts have been limited thus far, city officials said further reductions may be necessary given $5.5 million in next year’s budget that must be resolved through union concessions or layoffs. But reductions in state aid have already resulted in service cuts in the city’s libraries, as well as its public works and parks departments.

Mayor John DeStefano Jr. said the service reductions are unavoidable for a city that receives over half its revenue from the state.

“I don’t think they’re dramatic,” DeStefano said. “I think people are aware of them and not necessarily pleased with them, but I think people understand the choices that have to be made.”

The city’s library system, which has cut its staff by almost one-third, has been the target of some of the most drastic service reductions. In February, the city reduced operating hours for all four of its libraries. New Haven librarian James Wellbourne said the city decided to close its four branches on Friday so it could afford to keep the libraries open on weekends.

But Karen DuBois-Walton, the city’s chief administrative officer, said the library would be able to provide many of its core services despite cutting its annual budget by almost 20 percent over the last two years.

“During the DeStefano administration, we’ve devoted a lot of resources and have been able to grow our library,” DuBois-Walton said. “We are scaling back some of that in terms of hours, but we’re still trying to do it in a way that provides services.”

Pierre Barbour, the chief fiscal officer for the city’s public works department, said his department has not made any significant changes in its operations. But he said further budgetary restraints may result in service reductions that will be phased in over time.

“We’re delivering services at a level that people expect even with the budget cuts, but it will be very difficult to maintain that level without something going by the wayside,” Barbour said. “It’s unfortunate, but it’s the nature of our economy right now.”

And while Barbour said services like street sweeping and bulk trash collection will remain at the current level in most areas, he said some neighborhoods might receive these services less frequently.

“Instead of getting swept twice monthly, they may be swept once monthly,” Barbour said.

Other city offices experiencing service reductions include the parks department, which is shortening its camp programs by a week this summer. Both the police and fire departments have made changes in administrative operations, although they are maintaining or even increasing the number of officers responding to emergencies, DuBois-Walton said.

But she also said city services could be more adversely affected if the city is forced to further cut its workforce, which has already been reduced by 8 percent in the past year.

“Departments are already cut so close to the bone right now, so there aren’t positions out there that are really extra,” DuBois-Walton said.

Ward 25 Alderwoman Nancy Ahern said she did not think service reductions would have as significant of an impact on her constituents as the mayor’s proposed tax increases. For the second consecutive year, DeStefano’s proposed budget includes an increase of the mill rate for city property taxes. If passed, the tax hike will result in an average tax increase of almost $150 per household.

“I hope we can adjust the budget and take the mill rate increase out of it,” said Ahern, one of two Republicans on the Board of Aldermen. “I don’t know if we’ll have support from the Democrats on that.”