Whanganui District Council chief executive Kym Fell has resigned.
Fell was appointed in 2016 and is leaving to take up a role at Wellington City Council after almost six years in Whanganui.
Mayor Hamish McDouall said Fell's contribution to the council and the district had been transformative.
McDouall said Fell had provided, "stable, level-headed leadership" to Whanganui during a time of great change.
"During Kym's time at the council has inherited some large projects, such as the rebuild of the wastewater treatment plant and has been part of the team leading the Sarjeant Gallery and port redevelopment.
"During his time here Whanganui has received many awards and we have seen a population increase, in part due to the council creating and promoting a liveable, creative and vibrant city.
"Personally, he has become a good friend and I've really enjoyed working with him."
McDouall said some of Fell's "management decisions were not popular with everyone".
"He has some scars but he leaves the council and Whanganui and Partners [the council's economic development agency] in great shape."
Fell initially brought in changes to the council's structure which saved ratepayers $625,000 a year but caused some pain with a number of job losses and changes to some roles.
McDouall said one of Fell's best attributes has been his ability to nurture the talents of council staff and identify individual strengths.
He said there was a time when taking on the role of chief executive with the Whanganui District Council would have seemed like accepting a "poison chalice" but Fell was leaving a good space for a successor to fill.
Fell said he had enjoyed leading the council "under the guidance of a very progressive elected council".
"In this role, working with other community leaders and organisations is key and no two days are the same.
"From day one, my focus was to make the council more user-friendly and accessible to the community.
"This involved transformational change and a shift towards a customer-centric approach and away from bureaucracy and resistance."
Fell had previously lived in the city for a time while studying at the Whanganui Polytech school of tourism and hospitality in the 1990s.
The mayor at the time of Fell's appointment, Annette Main, said she enjoyed working with him.
"I realise it must have been very hard for him as we were in the midst of dealing with the failed wastewater treatment plant and we were still recovering from the  floods," Main said.
"At the same time, he was going through the process of relocating and settling his family here."
Main said she had watched with interest as Fell worked through big Whanganui projects such as the Sarjeant Gallery and port developments and had been impressed with his management.
"He's done a great job and I wish him well," she said.
Fell said "there were a number of highly complex challenges" when he first joined the organisation, including a new wastewater treatment plant, the Sarjeant Gallery redevelopment and recalibrating council-controlled organisations.
"We now have a very effective organisation, which makes me immensely proud.
"The timing was right, as I made a commitment to mayor Hamish McDouall that I would see through the adoption of Whanganui's Long-Term Plan before exploring opportunities outside of the region," Fell said.
Whanganui District councillors have already begun the search for a replacement but Fell will remain as Whanganui District Council's chief executive until late October.
Fell has accepted the role of chief customer and community officer with Wellington City Council.