At a special council meeting on Thursday night, councillors backed a recommendation to provide an additional $3.29m to the project.
More than half of that will be handed over to LandCorp after land preparation blew out from $3.95m to $5.66m.
The figure is now fixed and any increase will be absorbed by LandCorp.
Close to $500,000 was also needed to redesign a car park and the facility�s western elevations after a major optic fibre owned by Optus was found running through the site.
An additional $1.1 million will be used to ensure three feature waterslides are included in the build, a move the City says will ensure the project meets forecasted patronage numbers contained in the project business plan. The final cost is now estimated at $108.42m, with the City contributing $72.08m of that.
Central ward councillor Bart Houwen, the lone voice against providing the extra funding, said a smaller facility would mean less financial risks and allow a better spread of money across other City projects.
�I urge council to reject tonight�s request for extra funding and to instruct the officers to downscale appropriately the size and design of the project� thus immediately reducing the risk profile for the project,� he said.
�The value engineering methodology used to squeeze the desired design into the existing budget has surely compromised the design and for me this is a sign of measured panic.�
But Mr Cain rejected concerns about future cost blowouts saying the City would enter into a guaranteed maximum price contract, which councillors are scheduled to consider in June.
�This form of contract requires the builder to accept any risks with regard to escalation in costs, etc,� he said.