None supplied. Introduction: When John Day Dam is Completed, one of the last primal reaches of the Columbia River channel will be inundated. A substantial number of chinook salmon (Oncorhynchus tshawytscha) is reported to use this section of river for spawning and it is generally held that flooding from the John Day pool will take this area out of production. The responsible fishery agencies have proposed that the stock now spawning in this area be separated from other salmon populations bound for more distant upriver spawning grounds. Fish would be separated in the fishways at John Day Dam, the segregation being based on external coloration of the fish. Bright, silvery fish would be returned to the river to continue their upstream migration, whereas dark-colored fish, generally considered lower river spawners) would be collected for artificial propagation. A mechanical separator would be used to shunt the fish into appropriate channels following visual inspection for determination of the fish stock. The following is a report of laboratory study to determine the feasibility of separating salmonids in the manner described above.