RIVERSIDE -- Shoppers could be picking up a portion of the tab on construction of new jails, sheriff's stations and law enforcement offices in the next 15 years if county officials move ahead with a proposal to increase the sales tax a quarter-cent per dollar.

In a 53-page report to be delivered to the Board of Supervisors today, a county consultant says that it could cost as much as $2.4 billion to build the 26 criminal justice facilities the county will need to keep up with projected growth in the next decade and a half.

A countywide sales tax increase, which would have to be approved by two-thirds of voters, might be needed to help pay for part of the construction, the report states. The current sales tax is 7.75 percent.

Supervisor Marion Ashley, a member of a task force asked to come up with a plan to address the county's growing criminal justice needs, said Monday that voters would only be asked to approve such an increase if other alternatives fail to provide enough money for the building program.

He said increasing the sales tax would be the last on a list of financing options that would include using existing revenues as construction goes along, a developer fee on new housing and a voter-approved bond issue.

"It would be the last resort and it would have to be for very specific facilities and programs," Ashley said.

While the method of paying for the facilities promises to be a highly debated topic in county government in coming months, that the county needs them likely won't be.

Last year, the county released about 3,000 inmates before their sentences were completed and Sheriff Bob Doyle said Monday that the practice would have to continue if more jails aren't built. The lack of beds is straining the entire criminal justice system, from the jails to the courts, he said.

"This isn't a sheriff's issue," he said. "This is a county issue."

While the county is working on a long-term solution to the county's jail needs, Doyle said, something has to be done in the short term. Adding another 480 beds to the Larry D. Smith Correctional Facility in Banning would be a step in that direction, he said.

"If we don't act on this, we're just going to have to compound the problem with early releases, which isn't good," he said. "It's a production of our growth and we need to deal with it."

Presently, the county has only about 3,500 jail beds, and according to the consultant's report, it will need about 6,500 by 2020 to keep up with growth.

The long-term plan calls for the construction of three "hub" jails -- facilities that aren't attached to courthouses, as all the county's jails currently are. Those would provide about 3,000 beds and would cost about $1.6 billion to build, according to the consultant's report.

The plan also calls for four new juvenile correction centers, more offices for the district attorney and new sheriff's patrol stations.

Projected county revenues won't be able to pay for all of the facilities, the report states, so county officials will have to seek alternative financing. The sales tax increase would be one option, it states.

County officials aren't considering the measure for the November ballot. In fact, they say, it would probably be June 2008 at the earliest.

Ashley acknowledged that asking for an increase would be a difficult thing to do in a county known for its conservative leanings. And if the recent election is any indication, he added, voters aren't in the mood to approve added taxes.

"The last thing anybody wants is another tax," he said. "That's the last thing. Having said that, you have to be realistic and look at everything."

Contact staff writer Jose Carvajal at (951) 676-4315, Ext. 2624, or jcarvajal@californian.com.