Bruce McCorkindale tendered his resignation in a letter to Clutha District Council chief executive Charles Hakkaart on Wednesday.
His resignation was accepted by the council at its short meeting yesterday.
Mr McCorkindale was elected as a councillor for the Bruce ward in 2007, and was re-elected last year.
When contacted by the Otago Daily Times yesterday he said he could no longer serve on the council due to his new role as agri manager at the National Bank. Mr McCorkindale began the job on Monday, working from an office in Mosgiel.
He was self-employed as a farm consultant, and while he was excited about his new role at the National Bank, he was sad to miss a number of "interesting" projects in the district.
"The council has been dealing with a few difficult issues this year - especially the Benhar and Tokoiti sewerage proposals.
It would have been interesting to be involved with the Milton 2060 project, and working with the Otago Regional Council."
The Milton 2060 project is a joint venture between the Clutha District Council and the Otago Regional Council and would look at the strategic direction of Milton and its surrounding areas over the next 50 years. It would identify how and where Milton might grow in a managed way, where growth could happen without risk from flooding and what measures needed to be put in place to avoid or reduce the risk of flooding for those already living in the town.
"There's a very positive environment in at the council and it's been a privilege to serve on it for the last four years," he said.
Clutha Mayor Bryan Cadogan said the council had enjoyed Mr McCorkindale's positive attitude and the valued member would be "sadly missed".
A by-election will be held in February and the elected representative will join Crs Bruce Vollweiler and Gaynor Finch as Bruce ward representatives.
Mr Hakkaart said the by-election would cost about $10,000. Under local government legislation the by-election would take place 82 days from November 20. Nominations will close by December 23, and voting will close on February 10.
