I doubt it will happen. I have been to every City of Scottsdale General Meeting and Design Review Meeting in the last five years and have heard/seen nothing on this. The project would have to go through both meetings before getting approval.
Personally, I wouldn't swim in that water either, it just north of the North Indian Bend Wash NPL and is on the same water system... there is a reason why none of that wash has been developed or why you can't swim or drink that water... A couple years ago during the boom a condo/townhouse developer bought a vacant parcel from a church that back that wash. After doing a little investigation he found the water problem is a lot worse than what is generally noted. He let the site go into foreclosure and walked away from a site he paid four million for.
A cable park on Tempe Town Lake seems a lot more feasible to me, although I wouldn't swim in that water either. They have had several wakeboarding events on that lake (one with boats) though and the City of Tempe appears to be generally receptive to the idea. I actually talked to the Hugh Hallman, the Mayor, about the idea and he liked it.