Auckland's Supercity council spent about $30 million on fill-in staff during its first year.
The council said the cost was mainly due to a large number of information technology staff attempting to merge the region's seven former councils' IT systems, although the money also included maternity cover, casual librarians and park workers.
The figures, released to the Herald on Sunday under the Local Government Meetings and Official Information Act, covered staffing from the day the council was formed, November 1, last year to October 1.
During that time, the council hired 2224 such workers, with 996 falling under the "casual temporary" category; 747 under "agency" workers and 481 on "fixed contracts".
Council spokesman Glyn Walters said the council employed "8000-odd staff" at a total cost of about $400m and was comfortable with its level of contract workers as it allowed flexibility. He said it was an industry standard for 5-8 per cent of a large organisation's wages bill to go on such workers.
"We are in the process of merging all the rates, financial and IT systems.
"We are slowly switching off old systems and building a new one. It's a long programme, it will probably take five years to merge the infrastructure."
On October 1 the council was recruiting to fill 647 vacancies.
Deputy mayor Penny Hulse said she wasn't surprised by the figures and agreed the "state of flux" would continue for years.
"I was sceptical about talk of savings and, sadly, that has been borne out," she said.