Another day of searching Thursday failed to turn up any clues in Glacier National Park as to what happened to an angler who had planned to be gone for a few hours but never was seen again.

Michael William Sloan, 30, of nearby Hungry Horse, Montana, failed to return from an afternoon fishing trip Tuesday, according to park officials. Two days of searching on the ground, from the air, and on the water in and around Upper McDonald Creek has failed to turn up any sign of the man, the officials said.

After rangers searched the banks of the creek and portions of nearby Lake McDonald on Tuesday afternoon and evening, they redoubled their efforts Wednesday with help from the Flathead County Search and Rescue, North Valley Search and Rescue, the Flathead County Dive Team and a contracted helicopter from Minuteman Aviation of West Glacier.

The search did turn up a fishing pole where the creek pours into Lake McDonald that Mr. Sloan's family believes was his, park officials said.

"Based on the location of the fishing pole and all other evidence the search has been focused in this area, which is extremely treacherous due to a steep drop-off accompanied by very powerful down-flowing currents," a park release said. "The water surface temperature is currently about 57 degrees Fahrenheit."

Aiding searchers is a sonar unit from Flathead County that was being used to scan the bottom of Lake McDonald. "Members of the Flathead County Dive Team are on scene and are ready to assist should the sonar spot something at a depth and location that is safe for the divers," the park release said. "These efforts are constantly being monitored and evaluated to ensure everyone stays safe."

Glacier officials noted that the search "serves as a reminder to anyone recreating near water to be extremely careful. The swift, cold streams and rivers, moss-covered rocks and slippery logs can all be dangerous. Children, boaters, photographers, swimmers and anglers have been victim to these sometimes rapid, cold streams and deep glacial lakes in and around Glacier National Park. Visitors should pay close attention when wading or swimming in area lakes as drop-offs are common and seldom easy to see. Never walk, play or climb on slippery rocks and logs, especially around waterfalls. When boating, don’t stand up or lean over the side, and always wear a lifejacket."