On October 20, 2005, about 1630 mountain daylight time, a Cessna A185F amphibian airplane, N7377H, sustained substantial damage when it impacted a canyon wall during an aborted water takeoff from the surface of Lake Powell, Utah. The private pilot, the sole occupant and registered owner and operator of the airplane, was not injured. Visual meteorological conditions prevailed and no flight plan was filed for the local personal flight conducted under 14 CFR Part 91. The flight was originating when the accident occurred. According to the pilot, he was making a water takeoff from a finger of the lake that extended into a narrow canyon. During the takeoff run, he was almost on the step when the right float struck a submerged object. He aborted the takeoff by reducing power. The airplane drifted to the right, and the right wingtip contacted the canyon wall. The airplane pivoted to the right, the right float contacted the canyon wall, and the airplane came to a stop. The right wing sustained structural damage.