Abstract: On July 22, 2009, Employee #1 was working with a crew that was operating flow control valves in the River Valve Chamber (RVC) of the Hyatt Power Facility inside of Oroville Dam. The crew had been directed to open the river valves to 100. When the valves were opened to 85, the Break-Away wall was sucked downstream into the 35-ft river diversion tunnel. The suction eliminated the lights and sucked any loose materials or equipment in the access areas above the RVC toward the RVC. The suction knocked three workers off of their feet and toward the tunnel. It pulled two employees over the edge of the RVC concrete platform. Employee #1 was hanging over the edge of the RVC concrete platform, holding on to the bent rail, and was struck by various tools and equipment. He suffered head trauma, a broken leg, a broken arm and multiple bruises and cuts. He was hospitalized for four days.