Colorado River Basin Water Supply and Demand Study Releases Updated Technical Reports

Media Contact: Rose Davis, 702-293-8421
Carly Jerla, 303-735-1729

For Release: February 03, 2012

BOULDER CITY, NEVADA - The Bureau of Reclamation today updated two technical reports titled “Technical Report B - Water Supply Assessment” and “Technical Report D - System Reliability Metrics”. Initially published in June 2011 as part of Interim Report No. 1, they were updated to reflect comments on Interim Report No. 1, technical developments, and the ongoing input of stakeholders.

Reclamation’s Colorado River Basin Water Supply and Demand Study is part of the Department of the Interior’s WaterSMART program under the 2009 SECURE Water Act (P.L. 111-11).

Technical Report B provides a quantified assessment of four water supply scenarios. These include scenarios based on historical observed and paleo-reconstructed streamflow records as well as future climate projections from global climate models. Updates to this report include the adjustment of streamflow projections under the scenario informed by future climate projections from global climate models to account for hydrologic model biases. In addition, the report describes further analysis of the evaluation of the sensitivity of streamflow projections to greenhouse gas emission scenarios.

These adjustments and additional analyses do not change the finding reported under Interim Report No. 1 indicating that under the climate change scenario, the mean natural flow of the Colorado River as measured at Lees Ferry, Arizona is projected to decrease by approximately nine percent over the next 50 years.

Technical Report D describes metrics developed for assessing the Colorado River system’s future reliability under the four water supply and demand scenarios. Updates to this report include the addition of metrics, particularly under the water deliveries, recreational and ecological resource categories.

The updated reports, along with a complete description of the updates and additional information on the Study can be found online at:

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Reclamation is the largest wholesale water supplier and the second largest producer of hydroelectric power in the United States, with operations and facilities in the 17 Western States. Its facilities also provide substantial flood control, recreation, and fish and wildlife benefits. Visit our website at and follow us on Twitter @USBR.