She was made redundant when former principal Annette Joyce was in the role. According to the Authority's decision, "for reasons that still remain unclear, Mrs Joyce and Mrs Hughes did not get on well".
In 2010 and 2011 the Ministry of Education informed the school it would need to reduce staff numbers because of its falling roll.
Seven full-time teacher positions were to go for the 2012 school year and five of the seven positions were found by way of voluntary offers, meaning two full-time positions needed to be cut.
The Authority found Mrs Hughes was off work with a serious injury during the time that decision was being made, and she was never told her position was at risk.
The board made the decision to make Mrs Hughes' position redundant on the basis it needed a photography teacher, following incorrect advice from Mrs Joyce that Mrs Hughes could not teach photography, it said.
"The Board clearly unfairly selected Mrs Hughes for redundancy because it had been given the wrong information that Mrs Hughes was not prepared to teach photography and could not do so.
"The facts are entirely otherwise and in a matter relating as much to procedure as substance, Mrs Hughes was never given the opportunity to correct the Board's error made as a result of Mrs Joyce's advice."
Mrs Joyce could not be reached for comment.
Board of Trustees chairman Chris Nairn told the Rotorua Daily Post he could not comment about an individual employee's employment circumstances or whether Mrs Hughes had yet been reinstated.
"Rotorua Girls' High School has a new principal and the current board were elected or co-opted in 2013," he said.
Mr Nairn said the board was proud of the traditions of the school and valued and respected staff and students.
"The board and staff are committed to crafting remarkable leaders of the future."
Mrs Hughes could not be reached for comment.
