The Department of Interior has released a report to Congress, which represents the first consistent and coordinated assessment of risks to future water supplies across eight major Reclamation river basins, including the Colorado, Rio Grande and Missouri river basins. The report notes that projected changes in temperature and precipitation are likely to impact the timing and quantity of stream flows in all western basins, which could impact water available to farms and cities, hydropower generation, fish and wildlife, and other uses.
Among several increased risks, specific projections include: a temperature increase of 5-7 degrees; a precipitation increase over the northwestern and north-central portions of the western United States and a decrease over the southwestern and south-central areas; a decrease for almost all of the April 1 snowpack, used to project runoff; and an 8 to 20% decrease in average annual stream flow in several river basins, including the Colorado, the Rio Grande, and the San Joaquin.
The report was prepared by Interior's Bureau of Reclamation using original research and a literature synthesis of existing peer-reviewed studies. Projections of future temperature and precipitation are based on multiple climate models and various projections of future greenhouse gas emissions, technological advancements, and global population estimates. Reclamation will develop future reports to Congress under the authorities of the SECURE Water Act that will build upon the level of information currently available and the rapidly developing science to address how changes in supply and demands will impact water management.
Secretary of the Interior Ken Salazar says this report provides the foundation for understanding the long-term impacts of climate change on Western water supplies and will help identify and implement appropriate mitigation and adaptation strategies for sustainable water resource management.
"Water is the lifeblood of our communities, rural and urban economies, and our environment, and small changes in water supplies or the timing of precipitation can have a big impact on all of us," Salazar said.