The purpose of the flight was to count geese as part of the Iowa Department of Natural resources water fowl program. The pilot reported that during the flight the pilot’s side door opened. The pilot stated he was unable to close the door due to the wind, so he decided to make an off airport landing to close and latch the door. He stated that when he initiated a turn the door opened due to the wind, so he continued the flight in a direction that the wind kept the door closed, believing this direction would result in a headwind. The landing sequence was “normal” with some turbulence and windy conditions. The pilot reported the helicopter lost all lift at an altitude of five to ten feet above the ground. The helicopter experienced a hard impact with the ground which resulted in a main rotor blade severing the tail boom. Ground scars indicated the helicopter was on a heading of 165 degrees when it impacted the terrain. The closest weather reporting station, 11 miles away, recorded wind from 20 degrees at 13 knots gusting to 19 knots. The pilot reported there were no mechanical failures/malfunctions of the helicopter.