Authorities have arrested more than a dozen protesters during demonstrations against the Dakota Access oil pipeline this weekend.
Police arrested 14 protesters at three protest sites on Saturday.
The Morton County Sheriff's Department says pipeline workers were evacuated from sites near the protests by 9 a.m. All pipeline workers were back at work by 2 p.m.
About 100 officers converged with 150 protesters southeast of St. Anthony.
Protesters sang and beat drums in the middle of a gravel road for about an hour. No one was arrested.
Texas-based Energy Transfer Partners is trying to wrap up construction on the $3.8 billion, 1,200-mile pipeline from North Dakota to Illinois.
Opponents of the pipeline worry about potential impacts on drinking water on the Standing Rock Sioux reservation.