In 2004, Reclamation’s Lower Colorado Region (LC Region) initiated a research and development program to investigate the use of new methods for projecting possible future Colorado River flows that take into account increased hydrologic variability and potential decreases in the river’s annual inflow due to a changing climate.

This program is focused on two key areas:

• collaboration with other federal agencies and universities to conduct research to gain knowledge and understanding of the potential impacts of climate change and climate variability on the Colorado River; and
  
  
• improvement of the Region’s decision support framework, including modeling and data handling capabilities, in order to utilize the new information when it becomes available.

As part of this effort and in conjunction with the development of the Colorado River Interim Guidelines for Lower Basin Shortages and Coordinated Operations for Lake Powell and Lake Mead Final Environmental Impact Statement (EIS), Reclamation empanelled a group of leading climate experts (Climate Technical Work Group) to assess the state of knowledge regarding climate change in the Colorado River Basin and to prioritize future research and development needs. Their findings and recommendations were summarized in a final report as Appendix U to the EIS. The Final Report and executive summary can be accessed at the links below: 

• Climate Technical Work Group Final Report – Review of Science and Methods for Incorporating Climate Change Information into Reclamation’s Colorado River Basin Planning Studies

• Executive Summary

This report acknowledges the considerable scientific uncertainty regarding the precise nature of how a changing climate may affect the Colorado River Basin. In addition, it recognizes further uncertainties due to differences in the methodological approaches and model biases used in projecting those potential impacts. In light of these uncertainties, the Climate Technical Work Group recommended that, for a decision time horizon of twenty years or less, hydrologic variability is likely to be the most important impact of climate change. Subsequently, the EIS included a quantitative sensitivity analysis using paleo-climate evidence deduced from tree rings (Appendix N), accompanied by a qualitative discussion of the potential impacts of climate change.

The report also provides recommendations for additional future research and development critical to the enable a quantitative discussion of the potential impacts of climate changes. These recommendations are listed below and in Section U.10 of the Final Report. We are currently pursuing research efforts aligned with these recommendations in our current on-going investigations:

1. Improve availability and temporal resolution of regional climate projection datasets
2. Improve ability to model runoff under climate change
3. Investigate paradigm for Colorado River Basin precipitation response
4. Diagnose and improve existing climate models before adding additional features
5. Investigate changes in modeled climate variability at multiple time scales
6. Improve understanding of surface water, groundwater and land cover interaction
7. Improve prediction of interdecadal oscillations
8. Investigate use of paleo-record to inform modeled streamflow variability
9. Interact with Federal Climate Change Science Program and other climate change research initiatives

Current On-going Investigations

Reclamation's LC Region has two groups that are pursuing climate change research and development on the Colorado River Basin. The Colorado River Hydrology Work Group (Hydrology Work Group) and the Colorado River Modeling Work Group (Modeling Work Group) further the original goals of the research and development program, which are to pursue climate change and climate variability research in a collaborative manner and to improve the decision support framework such that the new information resulting from our research efforts can be utilized. Generally, the Hydrology Work Group produces the research and the Modeling Work Group does the model development needed in order to apply the research in operations and planning models. 

The Hydrology Work Group is a group of academic and federal researchers conducting climate change research primarily funded by the LC Region. The group is overseen by the LC Region and includes a Review Committee that provides independent input and viewpoints. 

• Colorado River Hydrology Work Group Charter 

• Colorado River Hydrology Work Group Membership

• Summary of On-going Climate Investigations under the Colorado River Hydrology Work Group

The Modeling Work Group is a group of Lower Colorado and Upper Colorado Region modelers who maintain the Regions’ official long-term planning model (the Colorado River Simulation System or CRSS) and mid-term operations model (the 24-Month Study), work on new development, and perform modeling studies. 

• Colorado River Modeling Work Group Charter
• Summary of On-going Model Development under the Colorado River Modeling Work Group

Additional information, questions, and/or comments on climate research in the Colorado River Basin may be directed to CRBclimateresearch@usbr.gov.