The two entities are currently working through an agreed transition period ensuring continuity of operations and service with as little disruption as possible.
Splash Centre staff were advised of the change in June and all current staff would be retained.
Jonas said a new area of focus for Sport Whanganui was the Whanganui Boys & Girls Gym Club.
"We took over management of that around 18 months ago, so there's some energy required to go into that to get the facility up to a level that we're happy with," he said.
He said the long-term desire for the gym involved expanding and upgrading the facility to promote activity in young people.
"It's been an iconic venue for Whanganui for many years, so we're really excited for what we can do in this space," he said.
Whanganui District Council property and open spaces general manager Sarah O'Hagan said the contract for the Splash Centre was worth $750,000 annually, with an additional $45,000 for the Whanganui East pool.
The $750,000 was the cost to run the whole facility, and Sport Whanganui would get a management fee.
O'Hagan said the council brought the management in-house to continue providing the service to Whanganui.
Whanganui District Council's chief executive David Langford said the council recognised and appreciated Sport Whanganui's 20-year contribution as the contract holder for Whanganui's community pools, which included a period managing the Whanganui East pool.
"We look forward to continuing to work in collaboration with Sport Whanganui on current and future initiatives that contribute to the wellbeing of the community," Langford said.
