Chetco River Protection Act of 2018 This bill amends the Wild and Scenic Rivers Act to make corrections to the segment designations for the Chetco River, Oregon, including revising segment lengths. The bill withdraws the federal land within the boundaries of a certain segment of the Chetco River from: (1) entry, appropriation, or disposal under the public land laws; (2) location, entry, and patent under the mining laws; and (3) disposition under laws pertaining to mineral and geothermal leasing or mineral materials.