Altered Flood Control, Climate Change, and Rebuilding Pacific Northwest Salmon Stocks
The Columbia Basin salmon evolved in an environment of annual high water cycles and fast-moving water–two conditions that the modern hydrosystem has sought to erase. Not only is this detrimental to the salmon’s migration, but it is harmful to the surrounding ecosystem that was defined by rivers, not lakes. The Columbia River Inter-Tribal Fish Commission would like to see the Corps of Engineers alter its operations to move the mainstem Columbia and Snake Rivers back toward natural conditions. CRITFC hydrologist Kyle Dittmer has developed a model that accomplishes this goal. With this operation plan, there will be water available to simulate the spring flooding that is so important to juvenile salmon. With specialized modeling, this operation plan can provide a more natural river cycle while still protecting downriver communities from the risk of uncontrolled flooding.
Given the size of the Columbia River, these changes have huge impacts. Under the CRITFC model, water is passed through the dams during the springtime when rivers normally experience high water. The current operations model holds water back, creating an unnatural ‘trough’ in the water cycle. Juvenile salmon, depending on the high water that the springtime brings, will greatly benefit from the 2.9 million acre-feet of water passed through the dams during their migration from April to June. That same water, passed through the system slowly over the course of April to August diminishes the benefit to the salmon and the riparian ecosystem along the Columbia River. The strategy takes into account global warming, compensation for the effects of lighter snow pack accumulation and decreased likelihood of spring flooding.
This dam operation model can achieve immediate benefits to depressed salmon populations and may be a relatively easy measure to implement while the region debates the issue of bypassing the four Lower Snake dams.
Dittmer, K. 2006. Altered flood control, climate change, and rebuilding Pacific Northwest salmon stocks. Columbia River Inter-Tribal Fish Commission Presentation March 24, 2006. Portland, Oregon.