On July 28, 2006, at approximately 1230 mountain daylight time, a Cessna TU206G, was substantially damaged during a hard landing at Deadwood Reservoir Airstrip (ID86), near Lowman, Idaho. The commercial pilot and his passenger were not injured. The airplane was being operated under contract to the USDA Forest Service by Pioneer Aviation, Inc., Boise, Idaho, as a public use flight. Visual meteorological conditions prevailed for the cross-country flight that had originated from Boise, Idaho, at approximately 0900. U.S. Forest Service personnel stated that the purpose of the flight was for an aerial survey for forest pest detection. The pilot said that the wind sock at the top of the hill, at the east end of the runway, was not moving, and there was no wind sock at the approach end of the runway. He said the approach was made over the lake and "there is always a sinker" where the runway meets the water. This approach is to runway 06, which has an uphill 6 percent grade. As the airplane went from over water to over the end of the runway, the pilot said the airplane was "really slammed down," and even with full takeoff power the airplane hit the ground hard. The pilot said the airplane bounced about 20 yards to the right where the right wheel went into a ditch about 2 feet deep. He applied full left aileron, full left rudder, and full left brake. The wheel came out of the ditch, but the empennage "whacked" the ditch berm fairly hard. Postaccident examination of photographs and parts replacement list by a Federal Aviation Inspector resulted in a Form 337 (major repair) being requested for the required repair. This form documented the replacement of the following parts: two skin pieces; two stringers; two frame bulkheads; one access door; and one tailcone assembly doubler.