There is a splash pad area where he would likely be able to ride under the sprayers, but that is at the bottom of a very long and steep hill so accessing the area would be doable but difficult.
From my personal experience I see people in wheelchairs all the time there. I know they have a one area where you can get up under the water and a little splash deal. It's pretty big and pretty cool. The Water Park section does not open until May 25th. If you will look up the Magic Springs website and get a phone number and call them I'm sure they will try to accommodate you the best that they can.
Thanks! Your answer is awaiting moderation.