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Moving Forward with Imperfect Information 443Case Study 1: Denver Water: Addressing Climate Changethrough Scenario PlanningBox 19.2Denver Water serves a growing population ofcustomers and prepares long-range plans formeeting future water needs. Historical streamflowand weather records plus paleohydrologicdata have been key information in projectingfuture water supply and demand conditions.Climate change fundamentally challenges theconcept that the weather and hydrologic patternsof the past are the best representation of futureconditions (Milly et al. 2008). But, there is a lotof uncertainty about how the climate will change.In addition to climate, other key uncertaintiesin long-range water planning include possibleeconomic, regulatory, social, and demographicchanges. Denver Water now uses scenario-planningtechniques to try to prepare for these futureuncertainties.The “cone of uncertainty” (Figure 19.3) illustratesthe growing uncertainty of futureconditions over time. Scenarios are created totry to represent a plausible range of future conditions.Plans are created to meet each scenario,and common near-term strategies across plansare identified. “Decision points” note when strategydiverges from the common path. The goalis to take actions today that prepare for a rangeof future conditions. Maintaining flexibility andadaptability as well as identifying and preservingoptions are key elements in successfully preparingfor future uncertainties such as climatechange.As a first step in climate change adaptation,Denver Water is testing the implications of a simple5°F (3°C) temperature increase. Initial resultsshow major supply losses and demand increases.Additional climate change conditions will beevaluated in an effort to develop a robust adaptationplan.Figure 19.3 Cone of uncertainty used in Denver Water Scenario Planning Initiative. Uncertainties,due to knowledge or communication gaps or imperfect information increase as time progresses from presentto future. The increase in uncertainties related to scientific understanding of the distant future (around 100years hence), has prompted many resource managers and planners to consider multiple scenarios of the future,which can be evaluated at key decision points in the near or medium term (roughly 10-50 years into the future).Adapted from Waage and Kaatz (2011).