SACRAMENTO — Officials Monday announced an overhaul of California prisons that would cut spending by billions of dollars, cancel some construction projects, close one lockup and bring back 9,500 inmates housed in other states — all while meeting court orders to reduce crowding and improve medical care.

If state lawmakers and federal judges sign off on the proposals, California’s long-troubled prison system would look significantly different by 2016 — smaller, cheaper and more autonomous.

“It’s a massive change,” said Matthew Cate, secretary of the California Department of Corrections and Rehabilitation, touting the plan at a Capitol news conference.

Inmate numbers are already shrinking as low-level offenders are kept in local jails rather than sent to state prisons, part of officials’ effort to comply with federal judges’ orders. But prisons still weigh heavily on California’s bursting budget, increasing from 3% of general-fund spending just over three decades ago to a proposed 9.4% in the next fiscal year.

If the new plan is successful, prisons will fall to 7.5% of spending in the 2015-16 budget.

“California is finally getting its prison costs under control and taking the necessary steps to meet federal court mandates,” Gov. Jerry Brown said in a statement Monday.

Besides their impact on the state’s bottom line — currently about $9 billion — prisons have been the subject of costly and embarrassing lawsuits that have left medical, dental and mental healthcare under federal control. Cate said Monday that he hopes all of those operations will be back under state direction next year.

Because of concerns about inmate care, judges have told California to reduce its inmate population to 110,000 by June 2013. Cate conceded Monday that the state probably won’t hit that goal and will ask the court to raise the limit by up to 6,000 prisoners.

The Prison Law Office, an inmate advocacy group that sued the state because of overcrowding, said it would oppose that request. Rebekah Evenson, an attorney at the organization, noted that California’s 33 prisons were designed for 80,000 inmates, so even fully complying with the court order would leave the state close to 40% over capacity.

“It’s still quite crowded,” Evenson said. “The court felt that was the absolute maximum the prisons could have and still provide constitutional care.”

Still, Cate said the new plan would allow California to roll back some expansion projects and end out-of-state incarceration contracts.

Construction pegged at $6 billion would be cut to $2.7 billion for new beds and medical facilities. In addition, the California Rehabilitation Center in Norco would close by June 2016, saving $160 million a year.

Cate said the prison is one of the state’s oldest and least efficient, and its 1,200 employees could face layoffs or transfers if they don’t retire.

The inmates now in private facilities in other states would come back to California by 2016, saving $318 million a year, Cate said.

The politically powerful public prison guards union has long opposed the use of private institutions, including those in other states. But the group reacted skeptically to Monday’s announcement.

Ryan Sherman, a spokesman for the California Correctional Peace Officers Assn., said that if the court declines to increase the inmate population limit, officials may continue to rely on private facilities.

In recent years, California has steadily increased the number of inmates it sends away. It has 4,600 inmates at two facilities in Arizona, 2,400 at one in Mississippi, and 2,600 at one in Oklahoma.

Some activists said Monday that the new plan isn’t enough.

It is “not really a bold vision in any way,” said Emily Harris of Californians United for a Responsible Budget, which opposes heavy prison spending.

She said the state should be paroling more inmates and easing criminal sentences, which would help lower the prison population further.

chris.megerian@latimes.com