While downstream passage over tall dams for some species and life history stages has been achieved to a limited degree, much improvement in downstream juvenile fish passage is still needed. Anadromous fish such as salmon and steelhead are hatched in fresh water and migrate downstream to the ocean where they spend most of their lives before migrating upstream to their natal stream to spawn. Adult salmon swimming upstream to spawn can migrate hundreds of miles and may have to pass a number of natural barriers and man-made structures on their journey. Juvenile fish hatched in freshwater tributaries must pass the same natural and man-made barriers on their way downstream to the ocean.
