That was another nice thing about working Everest. Our evacs (with only 3-4 trains running at a time) could be done entirely in-house, letting us get back up and running even faster.
Evacs and downtime - I know that people don't want to hear this- were treasured as a change of pace by a significant number of cast members. We always wanted to get back up and running ASAP, but sometimes, just sometimes, it was nice to do something different for a change.
At that point, cast members can enter the water (always outside the ride flumes!) and push the boats back or forward to the nearest designated emergency exit point. These are the points in the ride where the ride flume comes right up against the walkways and show scene floors around the building, so that riders can step out of the boat without getting into the water.
Once everyone's out - riders and CMs in the water - then maintenance and address the problem and turn over the ride to attractions personnel to restart when ready.