The Environmental Protection Agency on Tuesday released a long-awaited report on water temperatures in the Columbia and Lower Snake Rivers. Warm water temperatures in rivers–specifically, over 68 degrees Fahrenheit–are particularly harmful for salmon and steelhead. The federal report validated what conservation groups and advocates have been saying for years: dams are playing a major role in rivers warming, adding to the lengthy list of their negative impacts on wild salmonids.
Climate change and warm-water discharges also contribute to warming water temperatures. The report, however, noted “that the dam impoundments have a greater temperature impact than point sources and tributaries” (page 43).
The negative impacts of dams are numerous, wide-ranging, and well-documented. Whether it is the physical barring of upstream or downstream migrations, predation, destruction of habitat, affecting water quality, or mortality-inducing warm water temperatures, dams are the primary culprit for the precipitous declines of wild salmon and steelhead.
For more on this report, read this Lewiston Tribune article, as the report is immensely complex.