A 21-year-old woman was severely injured and may lose her arm after being hit by a projectile when North Dakota law enforcement officers turned a water cannon on Dakota Access pipeline protesters and threw “less-than-lethal” weapons, according to the woman’s father.

Sophia Wilansky was one of several hundred protesters injured during the standoff with police on Sunday on a bridge near the site where the pipeline is planned to cross under the Missouri river.

Graphic photographs of her injured arm with broken bones visible were circulated on social media.

“The best-case scenario is no pain and 10-20% functionality,” said Wayne Wilansky, Sophia’s father, who travelled to Minneapolis where his daughter underwent eight hours of surgery on Monday. He said his daughter had been hit by a concussion grenade thrown by a police officer and that the arteries, median nerve, muscle and bone in her left arm had been “blown away”.



Sophia will require additional surgery in the next few days and her arm may still have to be amputated, he added. “She’s devastated. She looks at her arm and she cries,” he said.

Sophia Wilansky is one of thousands of activists who have travelled to the Standing Rock Sioux reservation in North Dakota to attempt to halt the construction of the pipeline. Members of the Standing Rock Sioux tribe established a “spiritual camp” on the banks of the Missouri in April. The tribe fears the pipeline will jeopardise their water supply and say that construction has disturbed sacred burial grounds.

The activists, who call themselves “water protectors”, have faced a heavily militarised police force. More than 400 protesters have been arrested by law enforcement officers who have deployed pepper spray, teargas, rubber bullets, Tasers, sound weapons and other “less-than-lethal” methods.

Following Sunday’s confrontation 26 protesters were taken to hospital and more than 300 injured, according to the Standing Rock Medic & Healer Council. Most of the injured had hypothermia after being hit by a water cannon in below-freezing weather.

The Morton County sheriff’s department did not immediately respond to inquiries from the Guardian. In an interview with the Los Angeles Times, a spokeswoman for the department denied the agency had deployed concussion grenades and suggested the injury may have occurred while protesters were “rigging up their own explosives”.

The Standing Rock Medic & Healer Council refuted law enforcement’s claims in a statement, citing eye-witness accounts of seeing police throw concussion grenades, “the lack of charring of flesh at the wound site” and “grenade pieces that have been removed from her arm in surgery and will be saved for legal proceedings”.

The incident on Sunday began when about 100 activists attempted to remove two burned trucks from the bridge just north of the main encampment. The bridge has been barricaded for several weeks, blocking the most direct route to Bismarck, North Dakota, and raising safety concerns among residents of the camp and the reservation.

The barricade may have exacerbated Wilansky’s injury, her father said, by delaying her arrival at a hospital in Bismarck. She was subsequently airlifted to another hospital in Minneapolis.

Wilansky has received a massive outpouring of support online. A crowdfunding campaign established to help pay her medical bills raised more than $120,000 (£96,000) from more than 4,000 donors in the first seven hours.



Friends of Wilansky are planning a prayer vigil in Minneapolis on Tuesday.