A synthesis of published and unpublished literature on the upstream migration of adultsalmon and steelhead (Oncorhynchus mykiss), with particular reference to passage throughreservoirs and over dams, was prepared as part of an evaluation of fish passage through thelower Snake River. Most of the information on adult migrations in the Snake and Columbia riverswas collected on Chinook salmon (O. tshawytscha) and steelhead. The amount of flow,temperature and turbidity of the water, and partial barriers are natural factors that affect the rateof migration and survival of upstream migants. Human-caused alterations in flow, temperatures,and turbidities through the construction of dams and creation of reservoirs may be beneficial ordetrimental to migrants, depending on the amount of change from natural and the fishes\u27 ability toadapt. Dams and reservoirs placed in the migration path of adult salmon and steelhead usuallycreate unique passage problems because the structures and discharges differ and the stocks offish involved change from one section of the river to the next
