A federal safety official says it will probably be months before investigators know what caused an ExxonMobil oil pipeline to rupture near Billings, Mont., spilling about 1,000 barrels of crude oil into the Yellowstone River.

Cynthia Quarterman, head of the safety agency that regulates pipelines, told a House committee Thursday that it will likely be August or September before water levels in the river are low enough to exhume the section of damaged pipe responsible. She said it would be about two months after that before investigators identify a cause.

She said investigators have not found any violations of federal safety regulations by Exxon related to the spill.

ExxonMobil Pipeline Company President Gary Pruessing said the company wants to lay a new pipeline 30 feet below the riverbed.

Associated Press