A $157 million Super City computer system has a potentially "catastrophic" risk, says Auditor General Lyn Provost.
The NewCore system, the cost of which has blown out from $71 million to $157 million, also carries an "almost certain" risk with a "major impact", she said.
Last night, the council's chief information officer Dean Kimpton said Ms Provost was commenting on information supplied in May and the computer system had improved significantly since then.
In the past few days, Ms Provost told the council's leadership and councillors the NewCore programme is an area of significant cost and risk to the council.
NewCore is considered key to delivering the promised savings of the Super City. It is designed to consolidate the outdated operating systems of the former eight councils, which merged in 2010 to become the Auckland Council.
Last year, the Herald revealed the budget blowout of the new system, which is due to start in June next year, a year later than originally planned.
In an audit of the council's books, Ms Provost said, at the end of July this year, council officers assessed NewCore's overall status as "Red - Critical".
The top seven risks were assessed as still high, one as "almost certain" with a "major" impact and another as "possible" with a "catastrophic" impact, she said.
Ms Provost recommended council management review the risks. She also recommended management update the business case justifying continued investment in NewCore.
"Benefits are now forecast to total $58 million by 2022, whereas the original business case had benefits reaching $75 million by 2022," Ms Provost said.
Mr Kimpton said the "catastrophic impact" risk had been addressed, but the risk level had been kept at "possible" to ensure the potential issue was monitored.
The other "almost certain" risk with a "major impact" was around building a property file viewer. This relied on other programmes to gather data which were not in place in May.
Mr Kimpton said that risk level was now "possible".
He did not give the updated impact level for the two risks.
A report to councillors in May made no mention of a "catastrophic" risk with the data issue, only that the "issues are being prioritised and addressed".
Last week, council managers gave councillors an upbeat progress report on NewCore, saying it was progressing well and forecast to be completed on time and on budget.
Councillor Cameron Brewer said the pointed references from the Auditor-General were a timely wake-up call following a pretty gung-ho impression given by officers last week.
• Possible catastrophic risk to NewCore system, says Auditor-General.
• System already blown out in cost from $71m to $157m.
• Auditor-General calls for an updated business case.
• Council boss says steps taken to reduce risks.