The airplane sustained substantial damage when it struck a power line during cruise flight at about 1830 Mountain time. Following the collision, the flight continued to its destination and landed without further incident. The Commercial pilot and single passenger were not injured. Visual conditions prevailed. The pilot later reported that he decided to descend from cruising flight at 8500 feet msl to about 100 feet agl to follow the Snake River. Although he checked a chart and didnt observe any charted power lines crossing on the segment of the river that he was flying, he subsequently saw three wooden poles and a crossbeam along the edge of the river and pulled up. He heard a loud bang as the airplane struck the wires. The airplanes pitot mast was torn from the right wing tip, the leading edges of both outer wing panels were damaged, and there were two puncture holes in the fabric of the left aileron.