On August 9, 1998, at 1130 central daylight time, a Piper PA-18- 150, N9044D, operated by a private pilot was substantially damaged following a loss of control while landing on Crawling Stone Lake, Lac Du Flambeau, Wisconsin. The pilot was not injured. Visual meteorological conditions prevailed at the time of the accident. The 14 CFR Part 91 personal flight was not operating on a flight plan. The flight departed Lake Du Bay, Mosinee, Wisconsin, at 0930 cdt. The pilot reported he made a low downwind pass over the lake prior to landing. He stated that after the pass he gained altitude and began a left turn to the base leg at which time the "aircraft then stalled." The airplane descending with the left wing impacting the water first, followed by the right float. The airplane came to rest inverted in approximately four feet of water.