Falling temperatures in Montana mean conditions are such that responders can return to oil recovery from a spill in the Yellowstone River, officials said.

The Poplar pipeline, operated by Bridger Pipeline, spilled oil into the Yellowstone River in mid January. A unified command responding to the spill said oil recovery continues for the estimated spill volume of 925 barrels.

Response efforts were scaled back as warmer temperatures in Montana meant the ice covering the Yellowstone River was too soft to support operations. Crews were able to return to full-scale operations Thursday as temperatures fell.

"Safety is a top priority and river conditions are constantly monitored," state responders said. "However, temperatures have cooled and river conditions have stabilized."

The National Weather Service forecast a high near 44 degrees Fahrenheit for Friday, but a cooler weather pattern is moving into the region. Temperatures in the low to mid teens are forecast for Sunday.

Responders found the Poplar pipeline was exposed at the site of the spill, with the river bottom measured at about 1 foot below the oil transit artery. The pipeline operating company in 2011 confirmed Poplar was buried about 8 feet below the river bed at its shallowest point.

River scour was identified as a leading cause in the 2011 oil spill from the Silvertip pipeline, operated by Exxon Mobil. That rupture spilled 1,200 barrels of oil into the Yellowstone River.