GRAND CANYON NATIONAL PARK, Ariz. -

Authorities are scaling back the search for a University of Montana student reported missing from a private river trip in Grand Canyon National Park.
    
Park rangers say 21-year-old Kaitlin Anne Kenney of Englewood, Colo., was last seen Friday night at her group's camp near Tapeats Creek on the north side of the Colorado River.
    
Temperatures dropped below zero that night.
    
Kenney was reported missing Saturday, and helicopter and ground crews searched the Tapeats and Deer Creek drainages, Surprise Valley and along the river all weekend.
    
Ground-based crews searched again Monday. Park spokeswoman Shannan Marcak said Tuesday that with no new clues, authorities have decided to scale back the search.

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