Background
The helicopter was being used for aerial observation of aquatic plants that had been previously sprayed. The mission involved flying at low level along a river.
Flight Details
The pilot executed a dawn takeoff and proceeded along the river at a low altitude. During the flight, he glanced at the observer and then looked forward again. He did not see any obstruction, but felt a bump, and the helicopter struck the river surface.
Post-Impact
Following the impact, the pilot and his passenger exited the helicopter while it was underwater. No further information regarding injuries, damage, or subsequent events was provided in the initial report.