A crude oil spill from a pipeline operated by True Oil, LLC was reported on March 27.
The spill impacted Red Wing Creek, affecting roughly 1.5 miles of the creek.
The North Dakota Department of Environmental Quality (NDDEQ) says the spill has not yet been contained, and the amount of crude spilled has not yet been released.
The spill was reported on the same day.
The incident occurred about 17 miles southwest of Watford City, and the cause is still under investigation.
NDDEQ says it is inspecting the site and will continue to monitor the investigation and remediation.