The larger population would likely continue to put more pressure on the state system, which already uses private Mainland prisons to house more than one-third of its prisoners.

The increased numbers, the 13th-largest expected prisoner growth of any state, would force the state to decide whether to add more detention facilities in the Islands or send even more inmates to other states. Some officials and lawmakers are considering options for setting up treatment centers or minimum security facilities.

The state currently has 3,490 inmates in Hawai'i facilities and 158 in the Federal Detention Center in Honolulu. On the Mainland, there are 2,114 Hawaii inmates, each costing the state $62.05 per day, or about $48 million a year, said Department of Public Safety spokeswoman Louise Kim McCoy.

Nationally, state and federal prison populations will swell by 13 percent, or 192,000 additional inmates, to 1.7 million over the next five years, according to the report by The Pew Charitable Trusts' Public Safety Performance Project. Nationwide, the report said, one in every 178 Americans will live in prison by 2011.

Montana leads the expected growth with 41 percent, while nine of the top 10 states with the fastest projected inmate population growth rates are in the West.

A rise in crystal methamphetamine arrests, increased penalties for sex crimes, tougher sentencing, and more difficult prison-release requirements have contributed to the increases, said Dr. James Austin, a criminologist and one of the report's authors.

For the past 12 years, island prisons have overflowed with inmates, and to solve the population problem Hawai'i pays to have other states house the prisoners.

While adding additional facilities has been debated for the past few years, Gov. Linda Lingle backed off a 2002 campaign pledge to build two new prisons in Hawai'i last year.

Lingle said in July that no community in the state would show a willingness to have a new prison built in its neighborhood.

Critics say the governor shouldn't wait for a community to come forward.

"It's inappropriate for the governor to say those advocates or supporters for a new facility need to come up with a location," said Sen. Clayton Hee, D-Kahuku-Kane'ohe, chairman of the Senate Judiciary and Labor Committee. "She's the governor. She should make that decision or suggest who should."

Instead of building new prisons, the state plans to refurbish and repair existing facilities and community correctional centers. Lingle also wants to invest in more residential-based facilities to treat nonviolent inmates and those soon to re-enter society, Lingle spokesman Russell Pang said.

The Mainland prisoners are currently spread out among privately run correctional centers in Arizona, Oklahoma, Mississippi and Kentucky, but the state plans to consolidate them at three Arizona facilities. Arizona ranked second in the nation for prisoner growth, with its prison population expected to rise from 35,965 this year to 48,381 in 2011, the report found.

More people are behind bars because the state Legislature has continued to approve stricter penalties, including mandatory minimum sentences for crimes especially drug offenses, Hee said. Parts of Hawai'i, especially Honolulu, have become more urbanized, which tends to attract more crime, he said.

Hee said sending inmates to the Mainland is a short-term solution but the state needs to take care of its own people.

"It does not make sense," he said. "This will eventually come to a tipping point when other states will no longer support it."

A bill in the Legislature calls for the state to study where in the islands a minimum security prison could be located to house at least 500 inmates and an intensive mandatory substance-abuse treatment program. More than 40 percent of prisoners are classified minimum security.

State Rep. Cindy Evans, who recently toured several of the prisons, said the state lacks separate minimum security facilities and programs to prepare those incarcerated to re-enter society. Evans, a Democrat, said the prisons seem inefficient because each facility houses inmates of all different custody levels, causing a need for extra guards.