The Buller District Council says the final count of votes has altered the outcome in the Seddon ward.
Emily Miazga has replaced Robyn Anderson, while Martin Hill retains his place as the other ward councillor.
Buller electoral officer John Rodger said he did a provisional count before the last voting papers were received on Saturday.
There were no other changes in other wards, or to the Buller district representatives on the West Coast Regional Council and the Development West Coast Trust.
Voter turnout fell at this year's local elections and the government says it will have another look at online voting.
Analysis - Auckland's new mayor and council will be named today after a low-turnout election and, writes Todd Niall, the region's voting patterns make the winner's margin hard to call.
With just two days to go until votes are counted in the local body elections, voter turnout remains low in Auckland, Wellington and Christchurch. Audio
The New Zealand Electoral Commission says more Pacific people working in the election will help boost low voter participation numbers in the country.
Young people believe they're locked out of local government politics and campaigning is out of touch. Video
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