(Multnomah County, OR)  --  A search is under way for a missing hiker in Multnomah County.  Authorities say 40-year-old Katherine Mckinnon was picking mushrooms with her boyfriend yesterday on Larch Mountain in the Columbia River Gorge when the couple became separated.  Mckinnon's boyfriend says she has minimal supplies and is inexperienced on the trail.  Meanwhile, authorities are also searching for a pair of lost hikers near Angel's Rest Trail near Bridal Veil.