West-wide Climate Risk Assessments
Identification of Impacts
SECURE Water Act Section 9503(c) — Reclamation Climate Change and Water 2011
Secretary of the Interior Ken Salazar has released a report that assesses climate change risks and how these risks could impact water operations, hydropower, flood control, and fish and wildlife in the western United States.
The report to Congress, prepared by Interior's Bureau of Reclamation, 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, which responds to requirements under the SECURE Water Act of 2009, shows several increased risks to western United States water resources during the 21st century.
Specific projections 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.
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.
Last updated: 10/31/12