On May 19, 2002, about 1720 Pacific daylight time, an Enstrom F-28C, N51716, collided with a water tower during takeoff about 10 miles northeast of Stockton, California. The owner was operating the helicopter on a local flight under the provisions of 14 CFR Part 91. The airline transport pilot, the sole occupant, sustained serious injuries; the helicopter was substantially damaged. Day visual meteorological conditions prevailed, and no flight plan had been filed. The pilot reported that he had been flying over an orchard to dry cherry trees. The winds were gusty and there were intermittent rain showers. He landed in a parking lot and refueled. The parking lot was surrounded by several high obstacles including power lines, lighting poles, and water tanks. All of these were within 15 feet of the rotor blades as the helicopter sat on the ground. Rain had accumulated on the windscreen, which reduced visibility. The pilot was unable to detect the current wind velocity at the location. During the takeoff sequence, a gust of wind pushed the helicopter into a water tower near the refueling pad. The main rotor blades struck the tank and the helicopter fell to the ground. The pilot stated that the helicopter had impacted in a flat attitude before rolling over on its side. Water from the breached tank poured onto the airframe. There was no post crash fire.