PHILADELPHIA spends more on prisons - $231 million last fiscal year - than it does on libraries, parks, Council, the District Attorney's Office, the Board of Ethics and Licenses & Inspections. Combined.

It seemed as if that was changing last year. The prison population had finally dropped below 7,700 inmates - after quadrupling from 1980 to 2008 - because of reforms to the city's criminal-justice system. That helped save the city more than $7 million in overtime costs, according to the Pew Charitable Trusts.

Deputy Mayor Everett Gillison even discussed the ultimate money-saver: tearing down a prison.

But by last week, the prison population had soared to 9,170, and costs are up as well. The prisons were built to hold 6,500 people.

The uptick raises questions about whether violence-plagued Philadelphia has the will, or ability, to lock up fewer people.

The inmate population is up because of two new crime-fighting measures that Mayor Nutter's administration says are badly needed in a city where someone is killed almost daily. First, At Nutter's behest, the courts cracked down on suspects found with illegal guns by imposing higher bail. Second, the First Judicial District created a Bench Warrant Court to get tough on people who skip trial.

But critics say the overpopulated prisons create additional, more costly problems. They argue that the city should use more alternatives to jail, especially because many inmates are awaiting trial and have not been convicted.

"Per capita, we lock up more people in our city jails than any other major city in the United States," said civil-rights lawyer David Rudovsky. "And the more people you put in, the more we don't have for parks, education and libraries."

In fiscal year 2012, taxpayers spent $4 million more on prisons than budgeted. The department's total bill included $85 million in salaries, $104 million in purchased services, $29 million in overtime and $13 million in supplies and other costs.

"We've seen increased overtime. We've had to staff areas that formerly we didn't have to occupy," Prisons Commissioner Louis Giorla said. "You do more intake medical screenings; you do more mental-health evaluations. Across the board, all of our costs have increased."

Understaffing is also an issue. Thanks to a recent rush of retirements, Giorla said, the system is short about 300 officers. So the city pays out more overtime to plug the gaps.

Last fiscal year, the city spent $7 million more on prisons overtime than budgeted. A few correctional officers have done so much extra work since January that, by July 29, their overtime already exceeded their annual salaries, according to data from the City Controller's Office.

"The city has a choice: Either employ more people or use overtime. And employing more people is a more costly option because you have to pay benefits," said Angus Love, executive director of the Pennsylvania Institutional Law Project. "I don't know how alert a guy is after a 16-hour shift."

Giorla denied that the prison system is trying to pinch pennies through overtime and said that the city has given him the OK to hire 100 more officers.

Gillison said he believes both of the get-tough initiatives instituted by City Hall and the courts will lower the prison population and costs over time. In the past, there were no real consequences for suspects who didn't show up for court and paraded through the streets with illegal guns, he said.

But for public defender Tom Innes, there's no evidence that the stiffer punishments - like contempt charges and higher bail for those who duck court - have been effective. He said the court should deal with no-shows in cheaper ways, like house arrest.

"What the court system has decided is to choose one way," he said. "That way is costing them."

Gillison said that although it's too early to judge the impact of the Bench Warrant Court, the city will work with the courts to consider other options if the population continues to rise. But he's hoping that the new policies will have their intended effect and that the head count will drop.

"My goal has been the same since the day I took this office," he said. "I need to blow up a prison."