North Fork Umatilla Wilderness is a protected area in the Blue Mountains of northeastern Oregon within the Umatilla National Forest and, at 20,144 acres, the smallest wilderness in that part of the state. Its terrain rises from about 2,000 to 5,400 feet, ranging from gentle hills to steep forested canyons below a high plateau, with plant life shifting from juniper and sagebrush to ponderosa pine, fir, spruce, lodgepole pine, and western larch. The North Fork Umatilla River and smaller streams support bull trout, steelhead, and native trout, while elk, deer, and grouse inhabit the area. Hiking, camping, hunting, fishing, and horseback riding are major uses.