The pilot reported that, before departing from a high altitude (6,830 ft mean sea level), 1,600 ft private, dirt airstrip, he set the wing flaps to 10° and trimmed the airplane. During takeoff, he advanced the throttle and the airplane "accelerated well". He anticipated becoming airborne near the first of the runway's "two step downs", which was about 1,000 ft down the runway. He further reported that during landing he noted the prevailing wind direction, and although light and variable he would be departing with a tailwind. At the step down, he observed that the airspeed was low, but felt that he had gone beyond a "safe shut down point", so he chose to continue the takeoff with the belief that he would be able to clear power lines near the departure end of the runway. The airplane became airborne near the departure end of the runway but was unable to maintain a climb rate enough to clear the power lines. The airplane struck two sets of power lines, impacted an embankment, and the main landing gear collapsed. The airplane sustained substantial damage to both wings, fuselage, and empennage. The pilot reported that there were no preaccident mechanical failures or malfunctions with the airplane that would have precluded normal operation. The automated weather observation station located 13 miles northeast of the accident site reported that, about 7 minutes before the accident, the wind was variable at 3 knots, clear skies, temperature 68°F, dew point 30°F, altimeter setting 29.96" Hg. The calculated density altitude was 8,985 ft. The pilot departed to the southeast.