Managing the Columbia River: Instream Flows, Water Withdrawals, and Salmon Survival (2004)Water Science and Technology Board
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The State of Washington issues water withdrawal permits from the portion of the Columbia River that flows within Washington. Decisions regarding the granting of permits must be balanced with the state's obligation to protect and enhance environmental quality, including salmon habitat. Relations between instream flows, salmon mortality rates, and water withdrawals have been investigated by scores of scientists for decades, yet clear scientific answers to these issues remain elusive. Given these scientific uncertainties, tensions have arisen between groups who either support or protest the granting of additional permits.
- Allowing for additional withdrawals during the critical periods of high demand, low flows, and comparatively high water temperatures identified in this report would increase the risks of survivability to listed salmon stocks and would reduce management flexibility during these periods.
- Decisions regarding the issue of additional water withdrawal permits are matters of public policy, but if additional permits are issued, they should include specific conditions that allow withdrawals to be discontinued during critical periods.
- Sound, comprehensive Columbia River salmon management strategies will depend not only on science but also on a willingness by elected and duly appointed leaders and managers to take actions in the face of uncertainties.
- The conversion of water rights to uninterruptible status will decrease the flexibility of the system during critical periods of low flows and comparatively high water temperatures. Conversions to uninterruptible rights during these critical periods are not recommended.
- Within the body of scientific literature reviewed as part of this study, the relative importance of various environmental variables on smolt survival is not clearly established. When river flows become critically low or water temperatures excessively high, however, pronounced changes in salmon migratory behavior and lower survival rates are expected.