Published: 1993
Total Pages: 50
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The premise for flow augmentation is based on the argument that increasing water velocity increases smolt migration speed, which in turn improves smolt survival through reservoirs and at ocean entry. The purpose of this document is to examine key technical issues regarding the benefits of flow augmentation as a strategy for improving survival of downstream migrants. Reservoir drawdown, an altemative strategy for increasing water velocity through the mainstream Snake and Columbia rivers will also be examined. Data sets and analyses that pertain to Snake River stocks will be emphasized, particularly those stocks currently listed as threatened or endangered. This document focuses on treating two smolt responses that can be useful in reflecting the effects of flow augmentation, or increased water velocity; travel time or migration speed, and survival. Although there has been recent interest in using migrational timing as a measure of flow effects that response reflects principally the temporal initiation of the migration event and does not provide a performance measure once fish are in transit between two locations.