Lower Snake River Weekly Report 5/2/17

Steelhead (hatchery and wild) movements in the lower Snake River, over Lower Granite Dam are as follows:

Totals on 4/30/17.

2017:  7141

2016:  5306

10-yr avg:  8611

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Wild Steelhead:

2017:  2953

2016: 2995

10-yr avg:  3297

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Flows are still very high in the lower Snake River, averaging about 125,000 cfs for the past week.  All 4 lower Snake dams are currently spilling water to help the juvenile salmon return to the ocean quicker.  Prior to dam construction, juveniles could make the journey from Idaho to the Pacific Ocean in a matter of days.  After dam construction, that trip took weeks because the reservoirs behind the dams slowed the river velocity.  Juvenile mortality increases as their travel time increases.   Mortality also increases if the juveniles pass through the turbines.  Spilling them over the top of the dam, while still causing trauma and death to many fish, is the preferred method of fish passage.