Rep. Jackie Speier (D-California) said the president of Pacific Gas & Electric Co. told her that his staff cannot find them.
PG&E spokesman Brian Swanson did not immediately confirm or deny the congresswoman's statement.
Those records are needed to set safe operating pressures for nearly a third of the company's largest gas transmission lines.
Regulators have ordered PG&E and other California utilities to present reliable records for transmission lines.
The order came after PG&E admitted it had incorrect documents about the San Bruno pipeline that exploded on Sept. 9, killing eight people.
PG&E records showed the pipe was seamless, but investigators found the spine of the ruptured line had a type of weld that's now being examined in the search for a cause of the explosion.
Officials have not determined an exact cause but suspect the pipeline may have burst under high pressure.
