Once tickets are purchased, is there any other fee that will need to be paid to get on the water rides?

No

No fee.

If you have seasonal passes which I recommend everyone to get the parking would be free.Food and drinks as Mr.David provided would be an additional fee.but there's no hidden fees when u buy the tickets tax would already have been included.

Not to get on the rides. However you will have to pay for food and drink on the inside and the only other cost that you may take into consideration is the $10 parking fee