Pontoon was heading upstream to go home. Two passengers were sitting in the front of the pontoon under a towel because it was raining.  They felt the boat hit a wave and got splashed; they came out from under the towel and saw the jet ski sitting perpendicular to them.  They told Operator1 to watch out for the jet ski, but she didn't hear them.  They then yelled at Operator1.  She heard them that time and then slowed down.  They said by that time they were too close and couldn't stop. 

Prior to the accident the jet ski had flipped the jet ski and got back on it , started it, drove a short distance and then it stalled.  At that point is when they began drifting downstream and were struck by the pontoon.
Missouri River
Mandan                        