Prisoners being locked in their cells for up to 26 hours at a time, and illicit alcohol contributed to the riot at Spring Hill prison in 2013.
Police blocked the road near the prison at the time of the riot. Photo: RNZ
Waikato prison's high-security unit had 27 prisoners uncontrollable for almost a day in June 2013, including some drunk on home-brewed alcohol, damaging property and lighting fires.
The prison, surrounded by a high concrete fence, covers 215ha and can house just over 1000 men of minimum to high security status.
Corrections has released its report into the circumstances of the riot.
Contributing included dysfunctional management and the fact some prisoners were locked in cells for up to 26 hours at a time.
The department's chief custodial officer, Neil Beales, said all of the report's recommendations had been put in place and Spring Hill was now a very different prison.
"This was, for the department, was quite a watershed moment," he said.
"We've taken a lot of lessons from that and we've applied those lessons."
"This was the most significant type of this event for a considerable period of time - you know, [it's been] well on 15 years that we haven't seen an event of this nature."
Mr Beales said there had been no riots since.
