The pilot of the hot air balloon planned for a local sightseeing flight that departed and returned to the same airport. During the flight, the pilot realized that the balloon would not be able to return to the airport as planned, so he selected a field for an off-airport landing. During the final portion of the landing approach, one of the passengers alerted the pilot to the presence of a previously unseen powerline. Due to the balloon’s close proximity to the ground and the powerline, the pilot elected to vent the envelope and allow it to drape over the power line rather than risk the parts of the balloon between the envelope and the basket contacting the powerline. After touchdown, the envelope and the upper portion of one (steel) riser cable contacted two wires. The pilot heard a pop and saw an arc, which ultimately resulted in substantial damage to the riser cable, a quick link connector, and the envelope. The pilot and passengers were not injured. The pilot reported that there were no preimpact mechanical malfunctions or failures of the balloon that would have precluded normal operation.