More than £227,000 is needed to complete ongoing works at the NSC.
Tynwald will be asked to approve the funds for the flumes at this month's sitting - taking place next week.
The Department of Education, Sport and Culture says the overspend is because of ongoing problems regarding the leisure pool and flumes.
The facility has been closed since August 2018.
Are Manx-produced F-35 parts being exported to Israel?
Is the Isle of Man exporting advanced aircraft parts to Israel as the war in Gaza continues?
Yellow weather warning for rain and possible flooding
Ronaldsway Met Office has issued a yellow weather warning for today.
Minister apologises for police video showing fatal TT crashes
The Island's justice minister has apologised over a TT road safety video which featured footage of racers dying in crashes
Island's first EV filling station plans turned down
The Island's first dedicated charging station for electric vehicles has been rejected by planners.
Scandinavian therapy hut plan for Braddan's Roundhouse
Braddan Commissioners have applied for planning permission for a therapy hut near the Roundhouse.
56 babies born on the Island in May
The Isle of Man welcomed 56 brand new residents last month!
14 benefits claims exempt from residence conditions in past year
14 people have been allowed to claim benefits on the Island in the past year, despite not living here long enough.
Warning over scam manx.net emails
Beware of scam emails targeting manx.net users.
