It happened Saturday morning when she fell backwards from her horse while riding near Culver.
The Jefferson County Shierff's Office says the horse started walking backwards downhill and Dianne Lomeli of Estacada, fell backwards. She continued downhill and stopped when she struck a tree.
A man attempted to do CPR, but was uanble to revive Dianne.
By the time law enforcement arrived, Dianne was deceased.