The pilot reported that during the takeoff run, just before liftoff from a frozen, snow-covered lake, the ski-equipped airplane bounced over a snow drift. The pilot applied corrective action; however, rudder control inputs were momentarily unresponsive and the airplane's left wing tip contacted the snow covered lake. The pilot regained rudder authority and continued the takeoff. After the airplane became airborne the pilot learned that his rear seat passenger's foot (boot) inadvertently interfered with the rudder control pedal. The pilot continued the flight to his planned destination and landed without further incident. After landing, the pilot noted damage to the left wing, which was later classified as substantial damage. The pilot reported that there were no preaccident mechanical malfunctions or failures that would have precluded normal operation.