Fire crews in full biohazard suits rescued a dog from a sewage pond. (Calgary Fire Department)

A pair of three-legged dogs impounded after an unusual rescue at a Calgary sewage treatment plant will be reunited with their owners.

Calgary firefighters in full biohazard suits rescued a German shepherd-cross from the Bonnybrook sewage plant at Sixth Street S.E. on Sunday.

The dog was clinging to a skimming arm in a fenced, nine-metre-deep settling pond, part of the system that cleans raw sewage. The trapped dog climbed into a rescue dingy, according to the department.

"The dog was very co-operative, fortunately," said fire department spokeswoman Deb Bergeson.

The dog, which didn't seem harmed, and the fire crews were given thorough baths. The rescued animal — along with another three-legged dog captured at the sewage plant — were taken to the city pound.

Bergeson called it an unprecedented rescue.

The captured dogs, which were taken to the pound, will be reunited with their owners. (CBC)

"The fact that it was a three-legged dog, the fact that we were operating in sewage, the fact that there was another three-legged dog on scene … everything about this situation was unique," she said.

Bill Bruce, head of the city's animal bylaw services, said the dogs were examined by a veterinarian and are unharmed.

The animals were obviously well cared for and will be reunited Monday with their out-of-town owners, who told bylaw services the dogs escaped during a visit to Calgary, Bruce said.