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Future Streamflow and Climate Conditions Are Key

• Vulnerable conditions arise in a majority of scenarios where streamflows are lower than historical averages and where drought conditions persist for eight years or more.
• Depending where the shortages occur, problems will arise for delivery obligations for the upper river basin and the lower river basin. The lower river basin is vulnerable to a broader range of plausible future conditions.
• If future hydrologic conditions develop in a manner consistent with the more pessimistic current projections, the Basin is increasingly likely to face vulnerable conditions. The region may need to consider additional management options.

Additional Investments in Infrastructure and Efficiency Could Improve Performance and Reduce Risk

• Different portfolios of water-supply and demand-reduction options offer performance trade-offs.
• Different types of options in the portfolios, such as conservation, desalination, or water banking, would affect future outcomes and costs of implementation.

Other Solutions May Be Required

• Analysis of all the portfolios identified important near-term, high-priority options that should be implemented in the near future, including municipal, industrial, and agricultural conservation.

The U.S. Bureau of Reclamation and water management agencies representing the seven Colorado River Basin States initiated the Colorado River Basin Study in January 2010 to evaluate the resiliency of the Colorado River system over the next 50 years and compare different options for ensuring successful management of the river's resources. RAND was asked to join this Basin Study Team in January 2012 to help develop an analytic approach to identify key vulnerabilities in managing the Colorado River basin over the coming decades and to evaluate different options that could reduce this vulnerability. Using a quantitative approach for planning under uncertainty called Robust Decision Making (RDM), the RAND team assisted the Basin Study by: identifying future vulnerable conditions that could lead to imbalances that could cause the basin to be unable to meet its water delivery objectives; developing a computer-based tool to define "portfolios" of management options reflecting different strategies for reducing basin imbalances; evaluating these portfolios across thousands of future scenarios to determine how much they could improve basin outcomes; and analyzing the results from the system simulations to identify key tradeoffs among the portfolios. This report describes RAND's contribution to the Basin Study, focusing on the methodologies used to identify vulnerabilities for Upper Basin and Lower Basin water supply reliability and compare portfolios of options. The report provides a useful resource for other planners wishing to replicate or expand on the methodologies used for other studies.

• Chapter One

  Introduction

• Chapter Two

  Long-Term Water Planning and Management Under Uncertainty

• Chapter Three

  Developing Robust Management Strategies for the Colorado River Basin

• Chapter Four

  Future Vulnerabilities to Colorado Basin Water Deliveries

• Chapter Five

  Reducing Vulnerabilities Through New Management Options

• Chapter Six

  Implementing a Robust, Adaptive Strategy for the Colorado River Basin

• Appendix A

  Vulnerability Analysis Example and Additional Results

• Appendix B

  Basin Study Options Included in the Portfolios