The damaged section of a pipeline that leaked oil into the Yellowstone River in Montana in January had a 1.5-inch crack at a weld seam, responders said.

About 1,000 barrels of oil spilled from the Poplar Pipeline near the Yellowstone River in Glendive, Mont. About half of the oil released had been recovered before weather forced a suspension of response operations in late February.

With response efforts back in full swing, crews pulled an 8-foot section of the pipeline out of the river to examine the cause of the incident.

"The breach in the line is about 1.5 inches at its widest point and wraps about halfway around the 12-inch diameter pipe," a unified command responding to the incident said in a Wednesday statement. "A cause of the breach has not yet been determined."

Survey crews found the ruptured section of the pipeline exposed above the bed of the Yellowstone River. A 2011 spill into the river from the Silvertip pipeline, operated by Chevron, was blamed on river scour.

Area residents were forced to use bottled water in the immediate aftermath of the spill. That order was lifted Jan. 22.

Federal regulators were on hand to monitor extraction of the damaged section of the Poplar pipeline, operated by Bridger Pipeline. The ruptured section is on its way to a lab in Oklahoma for metallurgical testing.