Managing instream flows for salmonid spawning habitat

Detrimental sediment related effects on aquatic habitat for anadromous fisheries include (1) deposition of excessive amounts of fine sediments in spawning gravels, and (2) mobilization of the streambed during high stream flows thus destroying spawning redds or alevin. These effects can be managed by utilization of upstream reservoirs to modify instream flows to minimize negative impacts on the fishery. That management in some cases may be a tradeoff with other alternate uses of water such as water supply or power. In other cases, however, it can be a win-win alterative for all parties. This paper presents methods for assessing detrimental impacts on salmonid habitat which are directly related to instream flows