According to the pilot, while on a cross country flight, he descended and overflew a lake along his route of flight. Flying into the setting sun at low level over the lake, the right main landing gear struck a marked power line, about 70 feet above the lake's surface, which separated the right landing gear and broke an engine mount on the airplane. The pilot turned "immediately" for a nearby airport and completed the forced landing which collapsed the left main landing gear and damaged the firewall. The pilot reported there were no mechanical anomalies with the airplane. A witness stated that the power lines were marked by orange balls, while the pilot stated that the balls were red and "dark." When asked how the accident could have been prevented, the pilot stated that "yellow or white balls would have been easier to see."