On February 9, 1994, at 1630 Pacific standard time, an amphibian equipped Cessna A185F, N4833C, landed in a lake near Valley Springs, California, with the wheels extended and nosed over onto its back. The aircraft was owned and operated by the pilot. Visual meteorological conditions prevailed at the time and no flight plan was filed. The aircraft incurred substantial damage. The certificated airline transport pilot, the sole occupant, was not injured. The flight originated at the San Andreas, California, airport on the day of the mishap at 1600 hours as a local area flight to the lake. In a telephone interview, the pilot said he had just recently purchased the aircraft and had completed 5 hours of instruction in it just before the accident flight. The pilot reported that before he left for home he wanted to make one more water landing and flew to the New Hogan Lake Reservoir. The pilot said he forgot to raise the wheels when he departed the San Andreas land airport, and on touchdown in the lake, the aircraft nosed over.