Prison Officers' Association general secretary John Clinton said the minister was coming up with new ideas all the time when speaking about the future of the prison service to the media.
Recently, Mr McDowell was talking about closing Spike Island, now he is talking about building a bridge and moving Cork Prison there, said a bemused Mr Clinton yesterday.
As for the minister's plans for a centralised criminal courts complex, Mr Clinton did not think that was a runner at all.
He asked how were remand prisoners to have their exercise and medical needs met when they were being held in cells underneath the courts.
The minister believes having a suite of cells in a criminal court building is a good idea, because taking a prisoner to and from court over a three-week period posed a security risk.
Mr McDowell said his plans for a centralised criminal courts complex could also reduce the wage bill for prison staff.
Escorting prisoners to courts every day accounts for some €25 million of the €60m annual prison overtime bill, said Mr McDowell.
Mr Clinton said the POA had already put forward proposals on the centralisation of prisoner escorts to every court they had no difficulty with that issue because they wanted to bring down the number of extra hours worked to a minimum.
"The POA wants to bring down the cost of running the prison service to get our people time off and get their family life on a level where it should be."
The POA did not object when a new court was attached to Castlerea Prison in County Roscommon or to Cloverhill Prison in Dublin. That resulted in cost-cutting and they had no difficulty with that.
The minister, however, was talking about having cells under the courts and keeping remand prisoners there. Mr Clinton had no idea who advised him on that.
"An awful lot of people in custody have severe drug problems. Are they going to have the medical care available for them?" he asked.
Mr McDowell, who intends presenting his prison reform plans to Government early next year, also wants to sell off Mountjoy Prison for between €50m and €60m.
"If they move Mountjoy out of Dublin they are also moving a major prison away from the courts, instead of closer to them," said Mr Clinton.
Even with all their faults, Wheatfield, Cloverhill and Mountjoy prisons were all situated within easy access to a major acute hospital.
He also pointed out that around €60m had been invested in Mountjoy in recent years.
Now the minister was talking about knocking it down for around the same price. That made no sense to Mr Clinton at all.
"Every time we hear the minister speaking about the prison service going forward into the future, he seems to be coming up with different ideas.
"Less than eight weeks ago the minister was talking about closing Spike Island. Now, he is proposing to build a bridge to the island and moving Cork Prison there. I would have to ask what kind of forward planning, if any, was involved in all of that," he said.