CALGARY -- First responders are conducting a search of the Bow River Thursday in an attempt to bring closure to many families who have been searching for their lost loved ones.

The sixth annual search includes officers from the Calgary Police Service (CPS), the Calgary Fire Department (CFD), Calgary Search & Rescue (CALSARA), Alberta RCMP and Cochrane Fire Service.

Crews deployed in the morning from the Bearspaw Dam area in northwest Calgary and plan to move south beyond the city limits. The teams expect to cover the span of about 50 kilometres.

Staff Sgt. Martin Schiavetta with the CPS Homicide Unit and Missing Person Team says while no one has been found during the past five years of the search, it’s still a worthwhile effort for the family and friends of missing Calgarians.

“Obviously we want to do everything we can to provide closure for our families,” Schiavetta said. “We can’t imagine the tragedy and the stress of not knowing where their loved ones would be.”

CPS confirmed to CTV News that its teams are actively searching for four people that are believed to have entered the city’s waterways this year and still remain unaccounted for.

One of those individuals is 20-year-old homicide victim, Shane Smith, who was last seen on June 6 in the southeast community of Maxkenzie Towne. Police believe he was killed after he met with a group of three men sometime that same evening.

Smith’s abandoned vehicle was found parked on Deerfoot Trail near the Bow River where extensive searches have been conducted on the waterway all the way from Calgary to Carseland, Alta.

Three men have been charged in connection with Smith’s death, despite the fact that his body has yet to be found.

Brad Maxwell, a team leader with CASARA, says finding answers to unsolved cases is just one reason why he and 50 other volunteers on the search and rescue unit come together.

“It matters,” Maxwell said. “In dealing with our tasking agents, but then seeing the impact it has on the families that were able to assist and not always with regard to locating a specific individual, but with regards to finding a crucial piece of evidence or something along those lines that helps our judicial system to close a case so it’s really beneficial.”

Roughly 5,000 missing people are reported to Calgary police annually. Just a small number of those individuals who have voluntarily or involuntarily gone into the Bow River are unaccounted for.

If anyone is found on Thursday’s search, police will work with the Medical Examiner’s office to determine their identity and ensure no criminal offence has been committed.

The search is conducted around this time every year because water is typically clear and at its lowest point.

Anyone with information about the disappearance of a missing individual is asked to contact the Calgary police non-emergency line at 403-266-1234 or give an anonymous tip through Crime Stoppers at 403-262-8477.