That troubles organizations on both sides of the political spectrum. Sheriff Keith Royal of Nevada County, the president of the California State Sheriffs’ Association, said members were worried about their capacity to provide “adequate treatment” in jails and about “litigation at the location level.” The American Civil Liberties Union warned that instead of making fundamental improvements to the criminal justice system, many counties risked simply repeating the state’s mistakes by reflexively putting people behind bars.

Criticized for its overemphasis on jails, a local committee overseeing realignment in Fresno recently approved using $848,000 from its state total of $20.8 million this year to expand drug rehabilitation programs for people released from jail. But even that relatively small amount is facing deep skepticism from the county’s Board of Supervisors, which will vote on the plan in September.

“Some people, you’re not going to change their behavior until they’re incarcerated and they have to pay the consequences,” said Debbie Poochigian, the chairwoman of the Board of Supervisors. “I believe we’re keeping our community safer because they’re not out there looking for their next victim.”

The county has used about 40 percent of its state money so far to reopen two of three jail floors that were closed a few years ago because of budget cuts. The priority, Ms. Poochigian said, should be to finance the reopening of the third floor. If Fresno runs out of space, she added, inmates could be transferred to jails in other counties or to private jails.

According to the Board of State and Community Corrections, the population in county jails rose by about 4 percent from an average of 71,293 in last year’s third quarter to 73,957 in the first quarter of 2012, the latest figures available. In Fresno, like elsewhere, about two-thirds are inmates awaiting trial.

Allen Hopper, a lawyer with the A.C.L.U. who co-wrote a study on the shift to jails, said the population at county jails could be significantly reduced by overhauling pretrial procedures. Many inmates, who present no risk, remain in jail simply because they cannot afford bail, he said, adding that alternatives like electronic monitoring and day reporting could free up jail space and save counties money.