A woman who fell into the fast-flowing River Usk in Brecon clung onto a branch until firefighters rescued her.
Fire crews were called to the town's Promenade around 3am on Thursday, February 20.
Mid and West Wales Fire and Rescue Service said 20 firefighters were involved in the rescue.
Water levels are high on the river in the aftermath of Storm Dennis but the woman was able to stay afloat by hanging onto a branch.
Crews used ropes and a thermal imaging camera in the operation. She was put on a spinal board and handed over to ambulance crews. The operation ended at 4.06am.
Experts have warned the weather for flood-hit communities will get worse before it gets better in the aftermath Storm Dennis.
Natural Resources Wales has four flood warnings and seven flood alerts in place across the country.
Roads have already been forced to close and hundreds of people have been evacuated from their homes in the worst-affected areas.
