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A Review and Synthesis of Effects of Alterations to the Water Temperature Regime on Freshwater Life Stages of Salmonids, with Special Reference to Chinook Salmon

Feb 22, 1999


Despite the great significance of the Columbia River Thermal Effects Study (a joint publication of the USEPA, NMFS, and AEC) and a compilation of temperature criteria and methods by the National Academy of Sciences in the 1970s that has been key EPA guidance on water temperature, too little attention has been placed on the key role of thermal pollution of river systems in reducing fish survival and production. The current review and synthesis of effects of water temperature on salmonids is an attempt to update important aspects of these earlier works in light of current ecological understanding. This revision is in terms of numeric criteria by species and life stage but, more importantly, is an explanation of the concepts that must be considered to fully protect salmonids from thermal effects under the Endangered Species Act.

Regulation of water temperature in salmon-bearing streams of the Pacific Northwest involves selection of appropriate biologically-based temperature standards and then creation of implementation procedures that insure that the biological intent is effected on necessary spatial and temporal scales. Selection of standards involves a thorough review of the effects of temperature on key life stages of species, variation in response among species and stocks, and an ability to estimate immediate and delayed biological responses from temperature statistics. Implementation involves consideration of problems such as where, when, and how to monitor water temperature in a watershed and developing a process for responding to violations of standards. This report deals primarily with a review of biological aspects of temperature in the environment, but the best understanding of the influence of temperature will not be effective unless implementation procedures are also meaningful. The tight interconnection between these two elements necessitated a broader review that incorporated a wide variety of spatial and temporal issues in fish ecology. In this context, full protection was viewed in terms of entire life cycle effects, single and multiple species, variation among stocks of a species, multiple environmental gradients, watershed to reach scales, and multiple biological responses (survival, growth, preference, fitness, reproduction, migration, swimming, feeding, etc.).




McCullough, D.A. 1999. A review and synthesis of effects of alterations to the water temperature regime on freshwater life stages of salmonids, with special reference to Chinook Salmon. Seattle, Wash, U.S. Environmental Protection Agency, Region 10. 291p.



Report No.


Media Type

Inter-Agency Report