On March 31, 1998, at 1230 central standard time, a Robinson R22 Beta helicopter, N2628B, registered to and operated by Mesquite Helicopter Services, Inc., of Alice, Texas, was substantially damaged during a forced landing following a tail rotor ground strike while hovering near Riviera, Texas. The commercial pilot, the sole occupant, was not injured. No flight plan was filed and visual meteorological conditions prevailed for the Title 14 CFR Part 91 local business flight. The pilot reported that he was using the helicopter to herd cattle. With the helicopter "at an altitude of 3-5 feet AGL," he was attempting to move a bull towards a corral when the animal charged the helicopter. As the pilot maneuvered to avoid the bull, the helicopter's tail rotor contacted the water in a stock tank (pond), resulting in failure of the tail rotor drive shaft. The pilot performed an autorotation. The helicopter "spun twice" to the right, touched down in a level attitude in the stock tank, and rolled onto its right side. According to the pilot, the helicopter "came to rest on its right side in about 2 1/2 feet of water." He reported that the fuselage was dented, the main rotors were "severely bent," and the tail cone was "chopped."