RedactedNarrative: Operator advised that he had docked his watercraft (a pontoon boat) near the building structure portion of the power dam at Lake Zumbro and walked around on land for some time. The group boarded the pontoon and began driving away from that location. Operator advised that after a short period of time he noticed that they were on the edge of the dam. He attempted many maneuvers to exit the area, but realized that they were going to go over. He had the passengers stand on one side of the watercraft in an attempt to keep it from going over and had them put life jackets on. One passenger jumped off the watercraft before it went over and swam to a buoy. She was later rescued by a nearby boater. The rest of the occupants rode the watercraft over the dam. the watercraft stayed upright and came to rest on a shelf below the dam with the three occupants remaining in the watercraft. All three were rescued from the watercraft and brought to shore by first responders. All were checked out by ambulance personnel and one passenger was transported to the hospital. There was some damage to the boat. Alcohol was a factor.