On July 2, 1998, at 1245 Pacific daylight time, an amphibian Avid Mark IV, N4353D, registered to the pilot and operated as a 14 CFR Part 91 personal flight, collided with the water shortly after takeoff from Coeur d'Alene Lake, Coeur d'Alene, Idaho. Visual meteorological conditions prevailed and no flight plan was filed. The aircraft was substantially damaged. The commercial pilot, the sole occupant, was not injured. In a written statement, the pilot reported that he was about two miles from shore when he initiated the takeoff from the north end of the lake. The pilot stated that after lifting off, he initiated a left turn at approximately 300 to 500 feet above water level. The pilot stated, "I just barely applied pressure to the stick for a left turn... The next thing I know I am going into the water at a 45 degree angle." The pilot reported that he felt that he had adequate airspeed and altitude when he entered the turn, but couldn't say if it was a control problem or a stall. Witness statements were taken by a Deputy from the Kootenai County Sheriff's Department. The witnesses reported that "It (plane) was about 25-30 feet off the water when it seemed to stall and head nose first into the water, like a bird diving for fish." Another witness reported that he observed the small airplane banking into a turn at a low altitude and instead of leveling out, "he took a nose dive into the lake." Other witnesses reported, "saw plane climbing at approximately 300 feet and turn to the left and drop into the lake." "The plane took a left bank turning east. The plane stalled at about 200 feet." A Federal Aviation Administration Inspector from the Spokane, Washington, Flight Standards District Office inspected the flight controls after the aircraft was recovered from the lake. The inspector reported that there was no evidence found to indicate a control malfunction. The pilot reported to this inspector that the aircraft was functioning normally at the time of the accident. The weather reporting facility at the Coeur d'Alene Airport located 10 nautical miles north of the lake, reported that the wind conditions at 1235, were from 200 degrees at 14 knots, with gusts to 18 knots. The pilot indicated that the winds were from the northwest at 10 knots, gusting to 12 knots.