The pilot of the float-equipped airplane reported that, during takeoff from a private lake, the float plane did not "climb as the day before." Upon reaching the end of the lake, he "pulled up hard" on the yoke to avoid power lines, but the "left wing [stalled]," and the float plane impacted the ground. The float plane sustained substantial damage to both wings and the fuselage. The pilot reported that there were no preaccident mechanical failures or malfunctions with the airplane that would have precluded normal operation. The pilot added that, about the time of the accident, the wind was from 190° at 12 knots, gusting to 21 knots. An automated weather observation station about 5 nautical miles from the accident site reported that, about the time of the accident, the wind was from 190° at 11 knots. The airplane departed the lake with a 180° heading.