CALGARY — A major search operation remains underway in Waterton Lakes National Park as emergency crews work to locate an 81-year-old man who disappeared while hiking.Bob Toothill, of Golden, B.C., was last confirmed at the Rowe Lakes trailhead on July 19 after beginning a multi-day hike through Section A of the Great Divide Trail. He had been expected to complete the route and arrive in Coleman, Alberta, by July 22 but never arrived.According to a post on Facebook, Parks Canada said team search efforts are focused on the western portion of Waterton Lakes National Park after Toothill's backpack was located in the Tamarack Basin area.The search involves Parks Canada visitor safety specialists, the RCMP, Southwest Alberta Regional Search and Rescue (SARSAR), RCMP Police Dog Services (K9), helicopters, and other specialized resources. .Toothhill's daughter, Natalie Neustaedter, told Shootin' the Breeze that on July 17, he phoned family to say hikers ahead of him had been charged by a grizzly and that he’d seen a sow and cubs himself. He added that he was heading down into a meadow to get around the bears but did not ask to be picked up at that time. It is unknown if he camped on the trail that night.Neustaedter said Toothhill arrived at the Waterton townsite campground on July 18 before checking out the following day. On the morning of July 19, at about 11 a.m., he was dropped off at the Rowe Lakes trailhead by shuttle alongside two other hikers, where he was captured on a trail camera.Toothhill told fellow hikers he might try to flag down the shuttle again to continue toward the Tamarack Trail. He had planned to reach Lone Lake that evening, but hikers who were in the area later reported that he never arrived..The Great Divide Trail spans more than 1,100 kilometres through the Canadian Rockies, crossing Alberta and British Columbia and passing through some of Canada's most remote backcountry. Much of the route takes hikers through rugged mountain terrain where weather can change quickly and access for emergency responders is limited.Parks Canada is urging members of the public not to conduct independent searches, warning that the park's rugged backcountry presents significant hazards, and added anyone who was hiking in the area between July 19 and July 22 or who may have information about Toothill's whereabouts is asked to contact the RCMP.