Climate change is leading to a sizeable decrease in stream flows in the major river basins of the Southwest, declines that could impact recreation and wildlife in national parks such as Arches, Canyonlands, Grand Canyon, and Big Bend, according to an Interior Department report.

The report, which you can find at this page on the U.S. Bureau of Reclamation website, predicts an 8-20 percent decrease in average stream flow in those river basins. Additionally, it envisions a temperature increase of 5-7 degrees Fahrenheit in the Western United States.

The analysis also projects:

* 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, and;

* a decrease for almost all of the April 1st snowpack, a standard benchmark measurement used to project river basin runoff.

The report, which was sent to Congress as required under the SECURE Water Act of 2009, examines "climate-change risks and how these risks could impact water operations, hydropower, flood control, and fish and wildlife in the western United States."

“Water is the lifeblood of our communities, rural and urban economies, and our environment,” Interior Secretary Ken Salazar said Monday in announcing the report, “and small changes in water supplies or the timing of precipitation can have a big impact on all of us.  This report provides the 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."

"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.

From a recreational standpoint, climate influences could lead to changes in the operation of reservoirs and their dams that in turn could affect float trips on those rivers, the report noted.

Bureau of Reclamation staff is working with stakeholders across the West to achieve a sustainable water strategy to meet the country's water needs, a release from the Interior Department said, adding that, "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.

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.

The Bureau of Reclamation is the largest wholesaler of water in the country, providing water to more than 31 million people and to one out of five Western farmers for irrigation of more than 10 million acres of farmland.  Reclamation is also the second largest producer of hydroelectric power in the western United States with 58 power plants generating nearly a billion dollars in power revenues and producing enough electricity to serve 3.5 million homes.