A 22-year-old man fell through the ice at the Twin Lakes Recreation Area after rescuing his dog Wednesday afternoon.The man's dog fell through the ice about 25 feet from shore, so the owner walked out to save him. After pulling the dog out of the water, the man fell through the ice into water deep enough to cover his head.Off-duty Columbia police officer Dustin Green, who was walking his own dog, saw everything and immediately went to help. Green crawled onto the ice and used his dog leash to reach the man and pull him to safety.The incident occurred a few minutes after 2 p.m. and was over in minutes. The Columbia Fire Department was on the scene by 2:09 p.m., by which time the man had been removed from the water. He was taken to University Hospital by ambulance for evaluation."Fortunately, this turned out to be a non-event" said Columbia Fire Captain John Metz. "It had all the makings of a tragedy. If the event hadn't been witnessed and the rescue hadn't happened so fast, the victim might have succumbed to hypothermia and drowned."Each year, the Columbia Fire Department responds to several ice rescues, many of which occur when a person falls through the ice while trying to rescue a pet."Never go out onto the ice to rescue a pet that has fallen through the ice," Metz said. "Call 9-1-1 and wait on shore for rescuers to arrive."Officials want to remind Columbia residents and visitors that ice skating is only allowed on Stephens Lake and that signs will be posted at the lake when ice skating is permitted.