On September 3, 2007, about 1431 Pacific daylight time, a float equipped Aeronca S15AC, N1118H, impacted the water following a loss of control during a water takeoff from Mason Lake, near Shelton, Washington. The float plane was owned and operated by the pilot, and it was substantially damaged. Neither the commercial pilot nor passenger was injured during the personal flight. Visual meteorological conditions prevailed at the time, and no flight plan had been filed. The flight was performed under the provisions of 14 CFR Part 91, and it was commencing at the time of the accident. The pilot reported to the National Transportation Safety Board investigator that during takeoff on the lake the front portion of the left float caught the wake from a boat. Thereafter, the airplane swerved left. The pilot attempted to, but was unsuccessful at, correcting the flight path, and directional control was lost. The airplane's right wing tip impacted the water. The airplane swerved farther left and was damaged. Following recovery of the airplane, an estimated 2-foot-long span of the right wing's leading edge, outbound section, was found crushed in an aft direction. Also, the inboard, aft portion of the right wing was buckled. About 1/3 of the forward portion of both floats was bent upward.