 The refuge also includes the <unk> scablands created by the Missoula Floods to the southeast of the river . These scablands were scoured of the top layers of soil , leaving a marsh @-@ filled valley . There is also the Wapato Lake Unit approximately 15 miles ( 24 km ) to the west . Located along the Pacific Flyway for migratory birds , this habitat includes seasonal wetlands , streams , forested wetlands , savanna , riparian zones , forested uplands , and the Tualatin River and portions of its floodplain . 
