Intamin Rapids Ride in Theme Parks, Roller Coasters, & Donkeys! Posted August 27, 2016 The following is based on Thunder Canyon at CP. There are two pumps on each side of the lift conveyor, so in your pictures you're only seeing half of the total pumps. The ride only needs 3 pumps on to run. Thunder Canyon only uses 3 and they rotate which ones are on day by day. If you turned on all 4 at the same time the river would just flow faster because you're trying to push a higher volume of water through the same space. That doesn't necessarily mean that you'll get wetter though. It's also a waste of energy to run all 4 if the ride only needs 3 to run with proper water levels. The likely scenario in your first pic is that the pump not being used that day was on the other side of the lift and not visible. On the other day in your second pic the pump not being used was on the side closest to the queue, and therefore visible.