On October 2, 2007, about 1000 mountain daylight time, a Robinson R44 II N644BS, rolled over at a watercraft landing zone in Lake Powell, Utah. The pilot was operating the helicopter under the provisions of 14 CFR Part 91. The private pilot and one passenger sustained minor injuries; the helicopter sustained substantial damage. The local personal flight was departing Lake Powell with a planned destination of Page Municipal Airport, Page, Arizona. Visual meteorological conditions prevailed, and no flight plan had been filed. In a written report to the National Transportation Safety Board, the pilot stated he was distracted during the preflight inspection and neglected to remove the left rear tie-down strap. Upon departure, he sensed the helicopter had a tendency to turn to the left. He noted that the helicopter was reacting in an uncontrolled manner. During an attempt to return from hover to the landing zone, the helicopter rolled and came to rest on its left side. The helicopter sustained substantial damage to the main rotors, tail boom, and cabin.