Bureau of Reclamation Publishes Columbia River Basin Climate Impact Assessment

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Impact Assessment finds warming temperatures will continue and precipitation timing will change significantly

This impact assessment is only the starting point – an initial analysis of conditions. This serves to establish a foundation for in-depth studies that will include more detailed climate adaptation strategies.

The Bureau of Reclamation released the Columbia Basin Climate Impact Assessment today, which projected climate change impacts on water resources in the Pacific Northwest, including Idaho, Nevada, Montana, Oregon and Washington.

The study found that warming temperatures will continue across the basin, and although there will not be significant changes in the mean annual precipitation, precipitation timing will change significantly, with more precipitation during the winter and less during the summer. This assessment supports earlier findings on Columbia River Basin projections for the 21st century.

"This climate impact assessment for the Columbia River Basin will give water managers new information to plan for sustainable water supplies now and into the future," Reclamation Commissioner Estevan López said. "This impact assessment is only the starting point – an initial analysis of conditions. This serves to establish a foundation for in-depth studies that will include more detailed climate adaptation strategies."

The assessment used five climate scenarios to simulate temperature, precipitation and runoff. They were separated into four future periods and were centered on the 2020s, 2040s, 2060s and 2080s. The five climate scenarios were less warming wetter, less warming drier, median, more warming wetter and more warming drier.

Future climate change inflow data was calculated at 157 locations across the Columbia River Basin. With the warming temperatures and increased precipitation in the winter, runoff is expected to increase in the winter and decline in the summer. Three areas were specifically studied, the Columbia River above The Dalles, Snake River at Brownlee Dam and the Yakima River at Parker. At these three points the mean snow water equivalent is projected to decline at all locations. The assessment projected a trend that indicated there would be an increase in runoff from December to March and a decrease in runoff (in most projections) from April to July.

This assessment is part of the West-wide Climate Risk Assessments, which is included in WaterSMART. The WaterSMART program focuses on improving water conservation, sustainability and helping water resource managers make sound decisions about water use. It identifies strategies to ensure that this and future generations will have sufficient supplies of clean water for drinking, economic activities, recreation and ecosystem health. The program also identifies adaptive measures to address climate change and its impact on future water supply and demand.

This report is being released in conjunction with the first White House Summit on Water in observance of World Water Day. During the White House Summit, the Administration announced new efforts and commitments from the federal government and more than 100 external institutions to enhance the sustainability of water in the United States. For more information, click https://www.whitehouse.gov/blog/2016/03/22/working-together-build-sustainable-water-future.

The Columbia Basin Climate Impact Assessment is available online at http://www.usbr.gov/watersmart/wcra/. Information about the Department of the Interior’s WaterSMART program is available at http://www.usbr.gov/watersmart/.

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Peter Soeth
Bureau of Reclamation
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