Authorities on Monday defended their decision to douse protesters with water during a skirmish in subfreezing weather near the Dakota Access oil pipeline, and organisers said at least 17 protesters were taken to the hospital - including some who were treated for hypothermia.

Protesters trying to push past a long-blocked bridge on a state highway late Sunday and early Monday were turned back by authorities using tear gas, rubber bullets and water hoses.

At least 17 protesters were injured severely enough to be taken to hospitals, said Dallas Goldtooth, an organiser with the Indigenous Environmental Network.

"Hypothermia, a number of head injuries from being shot with rubber bullets, one individual had a heart attack," he said.

Daniel Kanahele, 64, a native Hawaiian who joined the protest last week, said he was hit with tear gas, water spray and a rubber bullet in a leg, and "it took me off my feet." He was treated at the scene but said many other protesters suffered more serious injuries.