PROVIDENCE — With Rhode Island’s prison population at an all-time high, lawmakers are asking whether the state can move some inmates into drug treatment programs to save money and address a social problem at the same time.

Nationally, half of all prison inmates have substance abuse problems and 60 percent of inmates committed their crimes to get money to buy drugs, according to Neil A. Corkery, executive director of the Drug and Alcohol Treatment Association of Rhode Island.

And in Rhode Island, 73 percent of female inmates said alcohol or drugs contributed to their criminal behavior and 70 percent of male inmates reported having “significant” problems with drugs or alcohol, according to A.T. Wall, director of the Department of Corrections.

“It’s quite clear to me that most of the people I deal with at the ACI … are there because of addiction,” Dr. Josiah D. Rich, a Miriam Hospital physician who visits the Adult Correctional Institutions every week to treat prisoners, told the House Finance Committee yesterday.

The committee invited testimony from professionals in corrections and substance-abuse treatment yesterday in a move to look at the bigger picture as discussions begin on next year’s state budget.

In 20 years, the annual budget for the Department of Corrections has gone from $20 million to more than $160 million, Rep. John Patrick Shanley Jr., D-South Kingstown, said yesterday. The enacted budget for this year was $162 million, but the department has asked the General Assembly to add another $17 million to that. The budget, as passed, was based on an average inmate population of 3,370. The population is “hovering near 3,800” on a daily basis and has gone as high as 3,830, Wall said yesterday.

It’s unlikely officials can stave off significant growth in next year’s corrections budget, but getting drug treatment for inmates who need it would save money in the long run.

It costs $20,000 a year for the state to reserve a bed in a residential drug treatment center — a bed that might be used by more than one person over the course of a year, noted Ellen R. Nelson, director of the state Department of Mental Health, Retardation and Hospitals. The average length of stay in such a facility is 126 days.

For intensive outpatient treatment, the annual cost of a slot is $11,500, and the average person stays 81 days in the program. For regular outpatient treatment, the annual cost is $3,800, and the average person stays 131 days. And for methadone treatment, the annual cost is $2,900, and the average person stays on the treatment for more than 5 years.

Compare that to an average per-inmate cost of more than $39,000 a year for incarceration at the ACI, and it looks as though the state could save nearly $20,000 a year for each person it transfers from the ACI into a residential drug treatment center, and much more for each person it transfers into outpatient drug treatment programs. But Wall said it’s not that simple.

Built into the annual per-inmate cost are expenses that don’t change when a person leaves, mostly staffing costs. In order to recover the total per-person cost, the state would need to close an entire cell block. In minimum security, that would mean closing a 115-bed dorm. If the dorm couldn’t close altogether, Wall said the Department of Corrections would save closer to $3,500 — the cost of food, clothing and health care for one inmate for a year — an amount that might not even cover the cost of addiction treatment for that person, depending on the type of treatment.

Were the state to try to transfer a large number of prisoners into substance-abuse treatment programs, it’s not clear treatment providers could meet the demand. In the past nine years, the number of certified substance-abuse professionals in Rhode Island has decreased from 380 to 300, Corkery testified. Nelson said it might not be possible for the state to buy additional slots in treatment programs — particularly a large number of new slots — because the programs are near capacity now.

If the state were to increase the rates it pays to providers, Nelson said, “I think that would improve the situation” by drawing more providers into the field.

House Finance Chairman Steven M. Costantino, D-Providence, said those rates are among the things the committee will examine. “If providers aren’t able to hire staff to provide the services, we’re not going to be able to accomplish what we’re trying to accomplish,” he said.