DERIVING WATER RISK: A COMPARATIVE ANALYSIS OF WATER SOURCE PORTFOLIOS IN THE WEST

Environmental stressors have increasingly threatened water supplies in the Western United States over the past few decades. In particular, population growth and climate change pose major challenges forming uncertainty around water supply and demand in many western areas. A number of regions in the West are attempting various strategies to conserve and reuse water in order to stretch water supplies to meet growing demands and mitigate water shortage risk. A comparative analysis of water source portfolios in the metropolitan areas of Las Vegas, Nevada; Phoenix, Arizona; Denver, Colorado and Southern California is performed in this report in an effort to better understand the different risks, and extent of risk, that these regions are facing. Water sources for the portfolios fall under surface water, groundwater and effluent categories. Each water source has its own set of risks in supply. The comparative analysis explores both short-term and long-term water risks for each region based on their water portfolios. The short and long-term risks are derived through determining water source usage rates, number of water sources available, certainty of supply based on projected years of source availability, and impacts from climate change. The water source portfolios and their associated risks and risk levels are used in a side-by-side comparison for each of the four regions. Water risk levels ultimately illustrate the degree of uncertainty that regions face when it comes to the varying severity of impacts that stem from the challenges plaguing these water sources in the West.