Smith River National Recreation Area Expansion Act This bill expands the Smith River National Recreation Area in California into Oregon and designates specified segments of the North Fork Smith River as components of the National Wild and Scenic Rivers System (NWSRS). The management emphasis for any portion of the recreation area in Oregon shall be on roadless backcountry and white-water recreation. The Department of Agriculture (USDA) shall study the additions to the recreation area, including inventories and assessments of water features (e.g., streams and lakes). USDA shall modify any applicable management plan to protect the resources inventoried. USDA shall seek to enter into a memorandum of understanding with applicable Indian tribes to (1) provide them with access to the portions of the recreation area in Oregon to conduct historical and cultural activities; and (2) develop interpretive information to be provided to the public on the history of, and use of the area by, those tribes. On the adoption of a resolution by the State Land Board of Oregon, USDA shall acquire the 555 acres of land known as the Cedar Creek Parcel in Oregon. A streamside protection zone in which timber harvesting is prohibited (with exceptions) shall be established for each of the designated North Fork Smith River segments.