A 20-foot long oil sheen found on the Whitefish River was investigated by Burlington Northern Santa Fe on Wednesday.
The railroad's Maia LaSalle says they are working with the Montana Department of Environmental Quality to determine the origin of this oil.
Originally, BNSF’s environmental team was able to stir the water and oil was brought back to the surface.
Crews worked for several hours on Wednesday morning gathering samples to determine the cause of the oil.
The oil was found in a popular recreation spot and LaSalle has some advice for those still wanting to enjoy the water.
"People have been continuing to recreate in that area," she told MTN News. "But, always best to use precaution when something like that is found.”
LaSalle says the crew’s next step is to have the samples analyzed.
She says right now, the time line for identifying the source of the oil is unknown.