Crews are in the air, out on the water and along the banks Tuesday searching the Bow River for any bodies that might have ended up in the waterway.

The Calgary Police Service is using its HAWCS helicopter to do an aerial search while officers and fire crews — along with members of the Calgary Search and Rescue Association — conduct ground and water searches of the river and its banks.

"In Calgary, we receive approximately 3,500 missing person reports each year. Most of those people are found, but there have been cases where people have voluntarily or involuntarily entered our waterways and have not been able to get out," said CPS major crimes section acting Inspector Paul Wozney.

"The search is part of our due diligence to try to provide answers to families that may be missing their loved one."

The third annual search began at the Bearspaw Dam in the city's northwest and will move downstream to the southern city limits.

The Alberta RCMP's missing persons and unidentified remains unit is deploying its helicopter along the Bow River from the southern city limits and east to the Saskatchewan border.

If anything notable is spotted, the Calgary Fire Department's aquatic rescue divers and police officers will be sent to investigate further, said the department's spokesperson, Carol Henke.

If any bodies are recovered, police will work with the medical examiner's office to determine the person's identity and if the death was the result of a crime.

The search is being done now because water levels on the Bow River are at their lowest and the water is the clearest at this time of year.