Fourth Progress Report on Fisheries Engineering Research Program: 1966-1972

None supplied. From foreword: This is the fourth Progress Report covering the research accomplished during the years 1966 through 1972 under the Corps of Engineers\u27 North Pacific Division Fisheries Engineering Research Program. The general thrust of the research throughout this period was directed toward the improvement of operational procedures for the passage of upstream and downstream migrants. A start was made in isolating principal causes of delay and loss of adult salmonids below dams and within pools. The continued construction of upstream reservoirs and the increased peaking at the mainstem dams in the Snake and Columbia Rivers are changing the natural flow patterns, thus requiring a re-evaluation of operating procedures. The cause and effect of nitrogen supersaturation has been brought under study, along with suggested corrections to minimize gases. Downstream migrant passage was studied for suggested operational procedures to minimize losses and delays