| Abstract/Description or Keywords |
We evaluated controlled, gradual reductions in flows (flow ramping) and a large-scale fish salvage program, conducted in the Bridge River, British Columbia, in August 1992, to assess the effectiveness of these methods to reduce fish mortality associated with large flow reductions in a regulated river. During a forced spill caused by an increase in snowmelt, juvenile salmonids moved upstream into areas that were previously dewatered. Many fish did not move to the main channel when flows receded and became stranded in side channels and depressions in the floodplain. We recovered over 18,000 fish in a salvage program during and after the rampdown. The costs of the recovery program were high, however, and an analysis of the monetary benefits of the salvage resulted in a benefit-cost ratio of 1: 10. We conclude that flow ramping alone was not sufficient to protect fisheries resources and that there is a need to develop cost-effective mitigation alternatives. salmonids, aquatic habitat, low flows, environmental flows |
