Wanganui Mayor Annette said the trust had shown "poor judgment" opening the pool without qualified lifeguards available, saying it did not meet council's requirements and that action breached its contract.
"We've been working closely with the trust for some time to ensure the pool had its full complement of staff before opening for the summer and I'm unhappy at the poor judgment shown," Ms Main said.
"People need to have confidence that our community facilities are safe to use.
"The Wanganui East pool is a very popular family activity and it is essential that everyone can continue to have access to it," she said.
Council officers had been working with the trust to ensure lifeguard training was achieved and met standard.
The trust had only just announced that it had achieved its fundraising target of $12,000, which would guarantee free swims for all primary and intermediate age children in the city this season.
Ms Main said the trust and council had jointly agreed that while the trust has a continuing role in supporting the viability of the pool, "It is in the best interests of both parties and the community that Sport Wanganui take over the operational day-to-day management of the facility".
She said every effort was being made to ensure that school and group bookings are able to proceed and that the pool is open for business at peak times until the full staffing complement had been achieved.
When that stage was reached the pool could open for its normal operating hours.
Details of when the pool will be open to the public were still being finalised but private group bookings for this week will go ahead.
Councillor Ray Stevens, who has been a strident critic of the trust's failure to maintain accepted safety standards, said he had continually flagged safety issues at the pool "but every time I was belted down".
"This council will not compromise the health and safety of any person just because we want to open something," he said.
