The owner of two-and-a-half year-old Springer Spaniel Milo called 999 after the dog fell into the water during a walk at the reserve at Wyndham Crescent.
He slipped through the ice and was in the water for around 25 minutes before he managed to climb up onto an island in the middle of the pond.
When firefighters arrived, they used an inflatable walkway to reach the island and two firefighters walked across to Milo. They were able to get a lead on him and walked him back to safety, where he was reunited with his owner. He was unhurt, just cold and wet.
An Avon Fire & Rescue Service spokesperson said: “We would like to remind people to take when outside during the cold weather. Never venture onto frozen water. It may look solid but can break easily and anyone falling in will quickly feel the effects which could lead to hyperthermia or worse.
“Always dial 999 and ask for the fire and rescue service. We have the equipment and training to deal with incidents of this nature.”