The latest test results are showing that surface passage, combined with refined spill operations, has reduced the percentage of fish that go through powerhouses, turbines and bypass facilities, decreased fish travel time through the system and increased overall dam survival. Read more here.
Juvenile fish pass the dams by many routes: through juvenile bypass systems, spillways and turbines, or by collection and transport in barges or trucks. Adult fish migrate back to their spawning grounds using fish ladders, also called fishways.
Today, major improvements have rendered the lower Columbia and lower Snake River dams more fish friendly for juvenile and adult fish. Juvenile survival through all eight dams and reservoirs is higher than when there were four dams. Adult survival through the dams is similar to a natural river.
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Tests at Lower Monumental Dam on the lower Snake River in 2012 estimated that almost 80 percent of the juvenile spring chinook passed the dam through spill (surface weir or spillway), 16 percent through the bypass system, and 5 percent through the turbines. Overall survival through all routes was 98.7 percent. See findings from similar tests at all eight lower Snake and Columbia River dams. |
The FCRPS BiOp includes dam survival performance standards (through all passage routes) of 96 percent for spring migrating fish and 93 percent for summer migrating fish. Juvenile dam survival estimates of 86 to 99 percent have been demonstrated at all Snake and Columbia River dams.
The Corps has invested over $1.8 billion in fish passage improvements at the FCRPS dams since 2001, resulting in significant survival improvements.