The incident occurred in New Haven County around 6:15 p.m., Thursday, Aug. 1, in Seymour, according to Will Healey of the state Department of Energy & Environmental Protection.
Healey said DEEP received reports of a paddleboarder in the Housatonic River, located by boaters in the region.
DEEP Environmental Conservation officers and the Seymour Fire Department responded.
The victim, identified as Fairfield County resident Alyssa Mackinnon, age 30, of Fairfield, was brought to shore, and medics began treatment, Healey said.
Healey said Mackinnon was transported to the hospital, where she was later pronounced deceased.
The State Office of the Chief Medical Examiner will determine the cause and manner of death.
The incident remains under investigation.
This remains a developing story. Check back to Daily Voice for updates.
Click here to follow Daily Voice Bloomfield and receive free news updates.