Climate Change Indicators in the United States: Tribal Connection: Trends in Stream
Temperature in the Snake River - www.epa.gov/climate-indicators - Updated August 2016
Tribal Connection: Trends in Stream Temperature in the Snake River
Climate change has challenged and will continue to challenge some of the traditional ways of life that
have sustained indigenous peoples for thousands of years. In the Pacific Northwest, warming river and
stream temperatures will threaten ecosystems and species, including salmon populations.1 Salmon play
a particularly important role in the diet, culture, religion, and economy of Native Americans in this
region.2
Salmon are sensitive to water temperature at many stages of their lives. They spend much of their adult
lives in the ocean, then migrate inland to spawn. Salmon need cold water to migrate and for their young
to hatch and grow successfully. Warmer water can negatively affect fish, making it more difficult for
them to swim upstream. It can also make fish more susceptible to disease.3 River and stream
temperatures in the Pacific Northwest are influenced by many factors, but are expected to rise as
average air temperatures increase (see the U.S. and Global Temperature indicator).4,5,6
The graph shows average August water temperatures at a site in the Snake River, in eastern Washington
near Nez Perce tribal lands. Several species of salmon use the Snake River to migrate and spawn.
Between 1960 and 2015, water temperature has increased by 1.4°F.
Figure 1. Average August Temperature in the Snake River, 1960-2015
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1960 1970 1980 1990 2000 2010 2020
Year
This graph shows average August water temperatures at a site along the Snake River in eastern
Washington.
Data source: USGS, 2016''
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Climate Change Indicators in the United States: Tribal Connection: Trends in Stream
Temperature in the Snake River - www.epa.gov/climate-indicators - Updated August 2016
Melillo, J.M., T.C. Richmond, and G.W. Yohe (eds.). 2014. Climate change impacts in the United States: The
third National Climate Assessment. U.S. Global Change Research Program, http://nca2014.globalchange.gov.
Dittmer, K. 2013. Changing streamflow on Columbia basin tribal lands—Climate change and salmon. Climatic
Change 120(3):627-641.
U.S. EPA. 2001. Issue paper 5: Summary of technical literature examining the physiological effects of
temperature on salmonids. EPA-910-D-01-005.
Caissie, D. 2006. The thermal regime of rivers: a review. Freshwater Biology 51:1389-1406.
Van Vliet, M.T.H., F. Ludwig, and P. Kabat. 2013. Global streamflow and thermal habitats of freshwater fishes
under climate change. Climatic Change 121:739-754.
Isaak, D.J., S. Wollrab, D. Horan, and G. Chandler. 2012. Climate change effects on stream and river
temperatures across the Northwest U.S. from 1980-2009 and implications for salmonid fishes. Climatic
Change 113:499-524.
USGS (U.S. Geological Survey). 2016. Analysis of data from the National Water Information System. Accessed
March 2016.
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