On October 28, 2007 about 1330 eastern daylight time, a twin-engine Piper 601P airplane, N717SB, sustained substantial damage during a ditching in a freshwater lake, following a loss of power in both engines during normal cruise, about 7 miles east of Penn Yan, New York. The airplane was being operated by the pilot as a visual flight rules (VFR) personal cross-country flight under Title 14, CFR Part 91, when the accident occurred. The solo private certificated pilot was not injured. Visual meteorological conditions prevailed. The airplane departed the Rochester Airport, New York, about 1310. According to information received from an aviation safety inspector who spoke with the pilot, the pilot landed in Rochester, and refueled the airplane for the continuation of the cross-country flight. After departure, the pilot reported climbing to 5,000 feet where both engines began to run rough. The pilot turned the airplane toward what he thought was the nearest airport at Penn Yan, and descended below the clouds to about 1,500 feet. The pilot reported that he did not think the airplane would make it to the airport, and that due to the rugged terrain, he felt it was better to ditch the airplane in the large lake he was flying over. After ditching, the pilot was able to deploy a life raft he had aboard the airplane. The depth of the lake is estimated to be about 600 feet. The pilot reported there were no mechanical anomalies prior to the loss of engine power. In a written statement dated October 28, the pilot reiterated what he had told the FAA inspector. He said he felt that fuel contamination was the cause of the engine problem, and that not fueling during heavy rain might have prevented the problem. Fuel samples were taken from the fuel supply where he added fuel, and the equipment used to fuel the airplane. No other instances of fuel contamination were reported, and according to the FAA inspector, the fuel samples were tested, and found to be clean. The airplane was not recovered from the lake, and has not been examined by the NTSB.