PANTON — A Panton farmer was arrested Sunday evening after an incident in which, according to Vermont State Police, he was driving a boat on Lake Champlain and struck his sister-in-law, who was swimming. Police characterized the injuries sustained by Lydia Vorsteveld, 61, of Bridport as “life-threatening.”

At a few minutes before 8 p.m. on Aug. 13, troopers were called to a boating accident in the Arnold Bay section of Lake Champlain.

Lydia Vorsteveld was air lifted to the University of Vermont Medical Center for immediate treatment of her injuries.

Police investigated and said they determined that she was swimming in Arnold Bay when she was struck by a vessel being operated by Gerard J. Vorsteveld, 49, of Panton.

While speaking to Gerard, troopers observed indicators of impairment, so they took him to the Vergennes Police Department, where he was evaluated by a drug recognition expert. After receiving the DRE’s assessment, state police cited him for boating under the influence. Gerard Vorsteveld is scheduled to answer the charge in Addison Superior Court, criminal division, on Oct. 16.

Lydia Vorsteveld is married to Gerard’s brother Andre, a Bridport dairy farmer.

State police were assisted on scene by members of Vergennes Area Rescue Squad and Charlotte Fire and Rescue.