Colorado River Basin “super models” evaluate future trends

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Colorado River in Winter and Spring

To determine current conditions and evaluate the future health of the reservoirs and our water supply, planners, analysts and operators use various “models.” The Bureau of Reclamation (Reclamation) has developed and maintained system models since the 1990s. Here’s a quick look at three Reclamation planning and operations models used to give us a glimpse into our water future in the Colorado River Basin.

Colorado River Mid-termModeling System Infographic

Near-term planning (two years)

Every month, Reclamation publishes the 24-Month Study, which provides a snapshot of current conditions in the Basin. Based on those conditions, it also provides Basin-wide operational updates for the upcoming two years. The August 24-Month Study is used to determine the annual operating conditions for Lake Powell and Lake Mead for the upcoming year, as stipulated in the 2007 Interim Guidelines. Our CAP Colorado River Conditions Dashboard is updated monthly with the latest 24-Month Study from Reclamation, which is also reported during monthly CAWCD Board Meetings.

Mid-term planning (two- to five-years)

For mid-term planning, Reclamation publishes two- and five-year projections of Colorado River Basin operations and conditions using Colorado Mid-Term Modeling System (CRMMS) in Ensemble Mode. Ensemble Mode means that the model is run using an ensemble (or group) of 30 possible hydrology futures, and then analyzes the outputs to develop probabilities of Colorado River Basin conditions in the next two- to five-year period. Recently, CRMMS Ensemble Mode was used for analyzing alternatives as part of developing the Supplemental Environmental Impact Process for Near-term Colorado River Operations, which is a supplement to the 2007 Interim Guidelines.  

Long-term planning (five to 50 years)

Lastly, as part of the National Environmental Policy Act (NEPA) process for the Post-2026 Operational Guidelines and Strategies for Lake Powell and Lake Mead, Reclamation will be using the Colorado River Simulation System (CRSS) to analyze alternatives. Arizona, California and Nevada worked collaboratively to develop and submit a Lower Basin States’ Alternative for consideration by Reclamation

Within Arizona, the Arizona Reconsultation Committee (ARC) is working to inform and communicate with Arizona stakeholders on the Post-2026 Operational Guidelines NEPA Process. ARC has convened a technical work group, the Modeling and Analysis Work Group (MAWG) which will use information from these planning and operations models to help inform ARC’s proposals and recommendations.

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