Junee Jail says prisoners will cope when a ban on smoking takes effect in all New South Wales prisons within 18 months.

General manager Andy Walker says smoking is already banned in parts of the jail.

The Department of Corrective Services says 80 per cent of the state's inmates smoke, but Mr Walker says in Junee it's around 60 per cent.

He says he welcomes the move to prevent the health hazard and smokers will be supported.

"I'm not concerned about it, let's face it they're not just thrown in and taken off the cigarettes," he said.

"There are programs to assist inmates to give up smoking, there's supply of nicotine patches all that sort of thing."

"So it's not just being thrown into jail and your cigarettes taken off you, it's managed very very well to stop disruption."

The general manager says the state wide ban on smoking in jails could fuel black market trade inside prisons.

Andy Walker does not think the changes will bring drastic consequences, but says the prison will deal with repercussions as they come.

He says the health initiative is a positive step which staff will also have to comply to and it is up to prisons to control the trade of contraband.

"I suppose everything that's not allowed in jail always has a chance to be contraband or trafficked into a jail like mobile phones, like drugs," he said.

"It's not going to stop and people are going to try."

"It's just how you manage your perimeter security and how much effort you out into trying to stop it."

The Junee Jail manager says it's normal for the jail to run at its full capacity of almost 800, after a prisoner was refused a bed over the weekend.

Andy Walker says prisoners are discharged daily and the inmate from Temora was kept in Wagga Wagga on Saturday night and was back in Junee the next day.

"Every now and again we peak at 790, it's not unusual, it's not out of context for the prison," he said.

"What happens then if the police have someone in the cells that's got to come in they probably need to wait until the next day til we've got a vacancy."

"You've got to remember we take inmates as far as Griffith, Temora, Albury so it covers the Riverina."

Andy Walker says the Correctional Centre is operating efficiently with a high turnover of inmates and having many spare beds would be a waste.

"We generally discharge four to five prisoners each day, so we don't stay full day after day after day," he said.

"We've got an arrangement with the local police and we work very well together."

"What happened on Saturday is not unusual and it's certainly not a problem between the two parties."

The adult jail full capacity is in contrast to the Riverina's youth jail in Wagga Wagga which has suffered over-crowding for many years, but after a $10 million expansion, is shutting two units.