Report shows increased water supply risk from climate change in western US

WASHINGTON, DC, Apr. 26, 2011 -- A report released by Secretary of the Interior Ken Salazar assesses climate change risks and potential impacts on water resources in the western United States...

WASHINGTON, DC, Apr. 26, 2011 -- A report released by Secretary of the Interior Ken Salazar assesses climate change risks and potential impacts on water resources in the western United States. Prepared by the Bureau of Reclamation, the report represents the first consistent and coordinated assessment of risks to future water supplies across eight major river basins.

"Water is the lifeblood of our communities, rural and urban economies, and our environment," said Secretary Salazar, "and small changes in water supplies or the timing of precipitation can have a big impact on all of us."

Salazar said the new report, which responds to requirements under the SECURE Water Act of 2009, provides a "foundation for understanding the long-term impacts of climate change on Western water supplies and will help us identify and implement appropriate mitigation and adaptation strategies for sustainable water resource management."

The report indicates several increased risks to western United States water resources during the 21st century. Specific examples include:

  • a temperature increase of 5-7 degrees Fahrenheit;
  • 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 1st snowpack, a standard benchmark measurement used to project river basin runoff; and
  • an 8 to 20 percent decrease in average annual stream flow in several river basins, including the Colorado, the Rio Grande, and the San Joaquin.

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 such as recreation.

"Impacts to water are on the leading edge of global climate change, and these changes pose a significant challenge and risk to adequate water supplies, which are critical for the health, economy, and ecology of the United States," added Reclamation Commissioner Mike Connor.

Reclamation is already working with stakeholders across the West to achieve a sustainable water strategy to meet our nation's water needs. Through the WaterSMART Basin Studies Program, Reclamation is developing and evaluating options for meeting future water demands in river basins where water supply and demand imbalances exist or are projected.

Reclamation is also continuing to implement actions to mitigate and adapt to changing climate. For example, at Hoover Dam, new wide head range turbines are being installed that will allow more efficient power generation over a wider range of lake levels than existing turbines. In addition, through the WaterSMART program, Reclamation continues to work with water users across the West to implement conservation and recycling measures and promote the efficient use of finite water resources. The Department of the Interior has also established Landscape Conservation Cooperatives and Climate Science Centers to help assess vulnerabilities to the natural and cultural resources management by the Department, and spearhead activities to adapt to the stresses of climate change.

"The WaterSMART program provides a strong foundation for the Department's efforts to improve water conservation and help water-resource managers make sound decisions about water use," said Assistant Secretary of the Interior for Water and Science, Anne Castle. "As climate change adds to the challenges we face in managing our water supply, meaningful engagement between the River Basin states and the Department of the Interior will continue to be essential."

To develop the report, Reclamation used 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.

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