Fish Bypass

Dam fish bypass

Our goal is to ensure that 86 percent of juvenile salmon (smolts) pass through both Wanapum and Priest Rapids dams safely. Our fish bypass projects allow downstream migrating juvenile salmon to pass our dams without going through a turbine, thus increasing their chance of survival.

Each fish bypass project was preceded by years of research, model studies and testing to determine where smolts travel through the river as they approach our dams. The final design for the bypass offers migrating smolts the safest possible downstream passage route.

Wanapum Fish Bypass:

Construction Cost $35 million
Operating Schedule Juvenile salmon migration season - typically April through August
Construction Completed 2008
Bypass Dimensions • A single 290-foot chute
• Opening of 18.5 feet
• Exit width of 90 feet

Priest Rapids Fish Bypass:

Construction Cost $27.4 million
Construction Completed April 2014 (anticipated)
Bypass Dimensions • Three 204-foot chutes (using existing spill gates)
• 40-44-foot openings in each chute
Operation Schedule When Complete Juvenile salmon migration season - typically April through August
Design Features Retained and modified 3 existing spillways and raised the crest height just over 35 feet in each spillway

Innovative Technology with Results

Most juvenile salmonids stay in the upper portion of the water column as they migrate downstream to the ocean. This fact influenced the design of each bypass. Each fish bypass system is engineered to provide migrating salmonids the safest possible passage route while also maximizing water-use efficiency. Water flowing through the bypasses is designed to minimize harmful total dissolved gas (TDG), which at high levels can cause gas bubble trauma to fish.