Mr Hughes' report indicated that council staff knew there were problems with the plant well before councillors were made aware of it.
He noted a report by Cardno BTO in November 2011 which reviewed the plant and prepared an upgrade plan.
In response to a question from Councillor Michael Laws, Mr Hughes said he understood councillors had never been made aware of this report.
"A review of the plant should have been done well before 2011, and a plan to address the plant's shortcomings should have been done earlier," he said.
Mr Laws said councillors had been told in 2009 that the plant "was operating well".
He later introduced a motion that the council commission an independent review of the process of the design and operation of the wastewater treatment plant, including the advice provided to the council governance.
"I really think we do need to review how we got to this point. We also need to look at the quality of advice provided to the council. I had assumed our internal processes were robust enough to alert us, and they weren't," Mr Laws said.
The only other councillor who supported him was Councillor Hamish McDouall, who made a impassioned plea to his colleagues to support the motion.
"This [the review] has to happen because we are responsible to ratepayers. We've paid a lot of money for this plant and we could be left with a brown elephant on our hands.
"Mistakes have been made; I want to know how they happened," Mr McDouall said.
But there was no other support around the council table for the motion.
Mayor Annette Main questioned the cost of such a review and said she believed the council had "learned many lessons" from the situation.
Councillor Rangi Wills said finding out who was to blame would not fix the problem. "Let's put all our efforts into fixing the problem."
Mr Laws said if the council made a "stuff-up", they shouldn't run away from that. "I'd like to know where we went wrong as council," he said.
Mr Laws and Mr McDouall were the only councillors to vote for the motion and it was defeated.
