On July 23, 1998, about 1432 Alaska daylight time, a float equipped Cessna 206 airplane, N206F, sustained substantial damage during takeoff from Campbell Lake, Anchorage, Alaska. The airplane was being operated as a visual flight rules (VFR) personal flight under Title 14, CFR Part 91, when the accident occurred. The certificated airline transport pilot was not injured. The pilot-rated passenger aboard received minor injuries. Visual meteorological conditions prevailed, and no flight plan was filed. The flight was en route to Telequana Lake, Alaska. During an on scene interview with the National Transportation Safety Board investigator-in-charge, on July 23, the pilot reported that he started the takeoff run with 10 degrees of flaps, and once on the step, he extended the flaps to 20 degrees. He stated that once airborne, the airplane would not climb. As the airplane neared the end of the lake, the pilot said that the airplane would not maintain altitude, forcing him to land on a road in a housing development adjacent to the departure end of the lake. During the interview the pilot said: "I just hit a downdraft at the end of the lake. I just couldn't climb out." The pilot noted that there were no preaccident mechanical anomalies with the airplane, and that the engine was producing sufficient power. During the landing, the airplane struck a tree and a pickup truck with two occupants inside. The two occupants of the pickup truck were not injured. The pilot stated the wind conditions at the time of the accident were from the southeast at 10 knots, with peak gusts to 15 knots.