Walking Through Shadows by Sheri Lewis Wohl

Molly Williams is a powerful hereditary witch who manages to keep her powers under control as she tries to be normal. Most of the time, it works.An invitation from friends Winnie and Angus is just the diversion she needs right now, and she jumps at the offer to go backpacking along the Umatilla River in northeast Oregon. When a freak storm forces them to take shelter in a secluded, crumbling cabin, their trip takes an unexpected turn. The moment Molly touches a leather-bound book discovered in the floorboards, they're transported back in time.Only with the help of the mysterious and beautiful Native American woman Aquene do they stay one step ahead of a band of witch hunters. Will Molly find the right magic to get them home before the hunters find her? Or will she risk it all to stay at Aquene's side?