Hundreds of Prince George’s County’s police officers have begun receiving pay raises — some as much as 12 percent — after an arbitrator ruled that the county must make up for four years of pay freezes stemming from the economic downturn.

The raises, which are expected to be formally funded by the County Council next week, come after months of sometimes-contentious negotiations between the union and the administration of County Executive Rushern L. Baker III (D). Baker resisted the pay increases and both sides eventually declared an impasse, sending the dispute to arbitration.

Although some of the county’s 1,580 officers will get raises of 12 percent, the average will be 8 percent as a result of the September ruling, which by law cannot be appealed.

The immediate cost to the county is about $8 million. Under the ruling, police officers would receive four payments, with the final one due in March.

The county, which has a $2.7 billion spending plan, already is expecting to face a budget gap of $125 million or more by December, said Tom Himler, a top budget official. The gap is similar to last year’s and is expected to prompt belt-tightening and spending cuts in the next proposed budget, due in March, he said.

“You start factoring in potential wage adjustments, several million dollars in teacher pension shifted to the county, it is going to be challenging,” Himler said.

But Arbitrator Seymour Strongin noted that the county’s Prince George’s reserve fund — now hovering between $70 million and $90 million — was available to pay for the increases, something county officials did not dispute. The cost of the raises, while not retroactive, will escalate in the annual budget as the increases are built into base pay and pension benefits.

The county had offered the police officers $2,250 in one-time bonuses, which it has paid to other county employees. Had the police union agreed to that, the cost to the county would have been about $4.5 million, Strongin noted.

Starting pay in the police department is $46,660, and top pay for a lieutenant is $104,400. Most of the increase will go to those at the lower and middle end of the pay scale. About 250 officers at the higher end of the scale will not receive any increase, officials said.

“No one is jumping up and down in this economy bragging about anything like this,” said Vince Canales, president of the Prince George’s police department union, which represents officers up to the rank of lieutenant. “We wanted to make sure we put a fair and responsible proposal on the table. We did not come after the county for anything they could not afford.”

The raises could put pressure on Baker to agree to increases for other county government employees, who have gone without in recent years. In the past year, the county government’s 4,500 non-police employees received two one-time payments totaling $2,250, instead of raises and step increases promised by union contracts.

“It was a huge victory for the Fraternal Order of Police,” said Gary McLhinney, a labor negotiator who represents police unions in the region but was not involved in the Prince George’s case.

Elsewhere in the region, police departments have received pay increases in recent years, though none as large as the Prince George’s award, McLhinney said. Many local governments have put in place pay freezes and unpaid furloughs for employees who are not employed in public safety or education.

Baker has repeatedly said he wants to boost public safety and school spending. Both are key elements of his plan to make the county a more appealing place to work and live. Recently, the school system’s 9,000 teachers won a 2 percent increase after union negotiations.

About half of the county $2.7 billion budget funds the 123,000-student public school system. The police department’s budget is about $267 million.

County Council Chairwoman Andrea Harrison (D-Springdale), who in recent years has pushed for raises for county employees, said she expected there to be more requests from other employee unions.

“You have to do what you have to do,” she said.

Although most county employees did not get a raise this year, the previous council had voted to increase current council members’ pay by $3,278, which brought their annual salaries to $99,695, among the highest in the region. Council members Mel Franklin and Eric Olson turned back their raises; Mary A. Lehman donated hers to a local charity.