Replacing Hawaii’s largest jail might cost $673 million, although that price tag could be reduced by hundreds of millions of dollars if lawmakers and prison officials choose a less expensive, low-rise design, according to preliminary estimates in a report from consultants hired to plan and design the proposed facility.

State lawmakers for years have wanted to replace Oahu Community Correctional Center, arguing OCCC’s 16-acre site in urban Honolulu along the planned rail line ought to be redeveloped. The aging jail also has an outdated, sprawling design that requires high staffing levels, and the facility is both overcrowded and inefficient to run.

Prison officials Wednesday announced they have narrowed the search for a replacement site to four, including the current OCCC lot, the Halawa Correctional Facility site and the state Department of Agriculture’s Animal Quarantine Facility site in Halawa Valley.

Also included as a finalist site was “Lot 17” in the Mili­lani Technology Park. The quarantine facility was ranked highest out of the proposed sites, but the state will further evaluate each of those sites in an environmental impact statement before making a final selection.

However, it is not certain that any of the sites will end up being the actual location for a new jail.

House Public Safety Committee Chairman Gregg Takayama has repeatedly raised concerns that the consultant for the project considered only sites that were 20 acres or larger. Takayama said that approach might have eliminated potential sites where the state could erect a new high-rise jail similar to the Federal Detention Center at Honolulu Airport.

Department of Public Safety Director Nolan Espinda said the search for sites that are 20 acres or larger was aimed at developing a new campus-type facility that would be least costly to run. He acknowledged in a hearing last month that approach might have been a mistake.

“Honestly, if I could step back and say (the search should include) any site 4.5 acres or bigger from the very beginning, quite possibly that may have been a smart move to make. It was not,” Espinda said. “We will entertain any late-coming ideas.”

Other lawmakers, including House Finance Committee Chairwoman Sylvia Luke, have complained the consultants on the project didn’t listen to lawmakers’ ideas and requests, and suggested that might jeopardize the entire site selection process.

The consultant’s report submitted Wednesday noted that “while four finalist sites have been selected to undergo detailed engineering and environmental evaluations, the potential exists for other sites not selected at this time to be reconsidered during the EIS process.”

Lawmakers continued to float ideas for possible sites Thursday, including a proposal by Takayama to build on state land next to the federal detention facility.

Espinda said Thursday that the state needed to identify a list of promising sites to move the process forward, but “until we start construction, the search for the proper site is going to be ongoing, so any of the sites mentioned today as alternatives will be looked into and appropriately scored and considered. We don’t want to leave any rock unturned, but we had to start somewhere.”

Residents often reject proposals for correctional facilities in their neighborhoods. The consultants held a series of meetings in the communities where sites were being considered. Robert Nardy, senior vice president of consultant Louis Berger, told lawmakers there was no opposition to the Halawa sites, but not everyone agreed.

Halawa resident Sharlene Chun-Lum said she attended a neighborhood board meeting called to discuss the jail plan and that “there was opposition.”

She said residents were concerned that having both Halawa prison and a new jail there would cause property values to decline; others were worried that a major new facility would aggravate already severe traffic congestion. She said there were also safety concerns.

“There have been escapes from both the prisons and the jails, and you have a lot of elderly population there,” Chun-Lum said.

The consultant’s report listed preliminary cost estimates for the new jail ranging from $433 million for a low-rise facility to $673 million for a high-rise jail at the Halawa prison property.

The report also includes a jail population forecast that concluded the number of male detainees at OCCC will drop from 1,057 today to 959 in 2026. To house those inmates, the consultants proposed that the new facility have 1,044 detention beds.

The new OCCC is also expected to house low-security pre-release male inmates who are preparing to leave the prison system. The new facility will need 336 beds to house those inmates, according to the report.

OCCC currently costs $67.3 million a year to operate, and the state could save an estimated $4.8 million a year in reduced staffing costs by developing a more modern low-rise facility. A well-designed new high-rise facility would save the state about $3.8 million a year, according to the report.

The progress report on the project released Wednesday was prepared by a team that includes Architects Hawaii Ltd. and subcontractor Louis Berger U.S. under a $4.9 million planning and design contract with the state. Lawmakers were told at a briefing Thursday that the state so far has spent $1.5 million under that contract.