Water Management and Climate Change in the US- Mexico Border Region Robert Lempert Senior Scientist RAND September 27, 2008

climate -2 Climate Change Poses Significant Challenge for Resource Planning the US-Mexico Border Region “Stationarity is dead” –Many organizations already include climate (often implicitly) in their decisions –Amidst all the uncertainty one thing we do know for sure -- tomorrow’s climate will not be like the past’s Changes in West are likely to include: –Increased temperatures –Changes in precipitation patterns –More intense storms –Declining snow pack and summertime river flows Without proper planning: –Supply expectations may not be met –Demand may grow faster than can be accommodated –Infrastructure may fail

climate -3 Planners in S. California, for Instance, Face a Range of Possible Future Climate Conditions Summer-time temperature change ( )‏ +.1C +2.1C 0 Likely range Results based on statistical summary of 21 of the world’s best Global Climate Models No change Hotter Wetter Winter-time precipitation change ( )‏ +8% -19% 0 Likely range Much drier Water managers also face many similar, if not more, disruptive uncertainties

climate -4 Our Work With California Water Agencies Suggests Lessons for US-Mexico Border Region Resource managers can no longer assume future climate will be like the past Despite deep uncertainty, sufficient information exists to support prudent action today Effective response options are available Legislatures may have to help ensure: –Access to appropriate data and information –Funding for demonstration projects and new infrastructure – Appropriate incentives and perhaps some regulatory changes

climate -5 Conducted Vulnerability and Options Analysis for Inland Empire Utilities Agency (IEUA)‏ –IEUA currently serves 800,000 people May add 300,000 by 2025 –Water presents a significant challenge

climate -6 –Current water sources include: Groundwater 56% Imports32% Recycled1% Surface8% Desalter2% Conducted Vulnerability and Options Analysis for Inland Empire Utilities Agency (IEUA)‏ –IEUA currently serves 800,000 people May add 300,000 by 2025 –Water presents a significant challenge

climate -7 –Current water sources include: Groundwater 56% Imports32% Recycled1% Surface8% Desalter2% Focus of IEUA’s 20 year plan Conducted Vulnerability and Options Analysis for Inland Empire Utilities Agency (IEUA)‏ –IEUA currently serves 800,000 people May add 300,000 by 2025 –Water presents a significant challenge

climate -8 Our Research Focused on Two Key Questions Are IEUA’s plans vulnerable to assumptions about uncertain future conditions, including climate change? Which actions should IEUA do now and which can they defer to later to address the threat of climate change?

climate -9 We Identified Three Types of Assumptions That Could Impact the Performance of IEUA Plans Imported supplies Water use efficiency Costs of Future Supplies and Management Activities Development of aggressive waste-water recycling program Implementation of groundwater replenishment Performance of Management Strategies Future temperatures Future precipitation Changes in groundwater processes Natural Processes

climate -10 We Identified Three Types of Assumptions That Could Impact the Performance of IEUA Plans Imported supplies Water use efficiency Costs of Future Supplies and Management Activities Development of aggressive waste-water recycling program Implementation of groundwater replenishment Performance of Management Strategies Future temperatures Future precipitation Changes in groundwater processes Natural Processes

climate -11 We Identified Three Types of Assumptions That Could Impact the Performance of IEUA Plans Imported supplies Water use efficiency Costs of Future Supplies and Management Activities Development of aggressive waste-water recycling program Implementation of groundwater replenishment Performance of Management Strategies Future temperatures Future precipitation Changes in groundwater processes Natural Processes

climate -12 IEUA Faces a Wide Range of Possible Future Climate Conditions Summer-time temperature change ( )‏ +.1C +2.1C 0 Likely range No changeHotter Wetter Winter-time precipitation change ( )‏ +8% -19% 0 Likely range Much drier

climate -13 Model Performance of plans IEUA Plans System data & climate forecasts Our Simulation Model Assessed Performance of IEUA Plans in Different Future States of World Temp: +1.6 o C Precip: -10% Scenario B Plan suffers shortages in adverse future climate Year Annual supply (taf)‏ Recycled Groundwater Local Supplies Imports Dry-year yield Surplus Shortage Temp: +0.7 o C Precip: +3% Scenario A Plan generates surpluses in benign future climate Year Annual supply (taf)‏ Recycled Groundwater Imports Surplus Local Supplies

climate -14 IEUA’s Ability to Implement Its Plan and The Agency’s Future Costs are Also Uncertain Estimates of agency’s likelihood of achieving its recycling and ground water goals Future costs of alternative sources of supply

climate -15 Simulation Suggests that Climate Change Exacerbates Other Risks to IEUA’s Plan Factors considered Performance towards recycling goal Performance towards replenishment goal Future climate Amount of new conservation Amount of groundwater infiltration Effect of climate on imports Ran simulation 1,000 times for many different combinations of uncertain factors In 656 cases IEUA’s plan has low cost In 344 cases IEUA’s plan has high cost What factors explain these high cost cases? Key Vulnerabilities to IEUA Plan Miss recycling goal Adverse future climate Any reduction in groundwater infiltration

climate -16 Our Research Focused on Two Key Questions Are IEUA’s plans vulnerable to assumptions about uncertain future conditions, including climate change? Which actions should IEUA do now and which can they defer to later to address the threat of climate change?

climate -17 Response Options May Help IEUA Address These Vulnerabilities Efficiency reduces demand but imposes costs on customers and requires customer participation Improved groundwater management increases resilience to shortages but requires significant cooperation and faces unknown costs Recycled water use is a drought-proof supply but requires significant public support Each Option Has Benefits and Costs

climate -18 Should IEUA Act Now or Later to Reduce Potential Climate Vulnerabilities? Act now to augment 2005 Plan? NO Monitor, and take additional action if supplies drop too low In 2015, 2020, 2025, …. YES Implement additional efficiency, recycling, and replenishment In 2015, 2020, 2025, …. Monitor, and take additional action if supplies drop too low

climate -19 We Evaluated Nine Strategies Under 200 Scenarios Reflecting Key Uncertainties Number of Scenarios (PV Costs > $3.75 billion)‏ Current Plan Forever UWMP + DYY and recycling UWMP + replenishment UWMP with updates UWMP + replenishment with updates UWMP + efficiency UWMP + efficiency with updates UWMP + DYY and recycling with updates UWMP + all enhancements Static options Update options

climate -20 Just Allowing the Current UWMP to Update Reduces Vulnerability Substantially Static options Update options From 120 Down to 30 Number of Scenarios (PV Costs > $3.75 billion)‏ Current Plan Forever UWMP + DYY and recycling UWMP + replenishment UWMP with updates UWMP + replenishment with updates UWMP + efficiency UWMP + efficiency with updates UWMP + DYY and recycling with updates UWMP + all enhancements Still vulnerable to: Precipitation declines Declines in imports Costs of imports

climate -21 Implementing Efficiency and Other Options Now Reduces Future Vulnerabilities Even More Static options Update options Number of Scenarios (PV Costs > $3.75 billion)‏ UWMP with updates UWMP + replenishment with updates UWMP + efficiency UWMP + efficiency with updates UWMP + DYY and recycling with updates UWMP + all enhancements Implementation becomes more challenging

climate -22 Implementing Efficiency and Other Options Now Reduces Future Vulnerabilities Even More Static options Update options Number of Scenarios (PV Costs > $3.75 billion)‏ UWMP with updates UWMP + replenishment with updates UWMP + efficiency UWMP + efficiency with updates UWMP + DYY and recycling with updates UWMP + all enhancements IEUA should make more near-term efficiency investments; monitor performance and adapt as needed down the road Implementation becomes more challenging

climate -23 US-Mexico Border Region Can and Must Begin Adapting to Climate Change Resource managers can no longer assume future climate will be like the past –Impacts of climate change may create significant vulnerabilities in agencies’ operations and plans Despite deep uncertainty, sufficient information exists to support prudent action –New planning methods may prove necessary –Key is identifying near-term actions that are robust over a wide range of plausible futures Effective response options are available –Inland Empire Utilities Agency should increase investment in near- term conservation, monitor carefully, and prepare to take further actions –Other agencies may require additional near-term responses

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climate -25 Analysis Suggests Three Such Driving Forces Conducted statistical, cluster-finding analysis over all the model runs to identify the factors most strongly associated with shortages in 20 Year Plan Meet recycling goal Meet replenishment goal Future climate New conservation Reduced groundwater infiltration Climate on imports MissExceedMeet MissExceedMeet DrierWetter -5%+20% -20%0% WeakStrong Explains 127 (of 180) low surplus cases

climate -26 Simulation Model Evaluated IEUA’s Current Plan Under Many Different Scenarios IEUA Water Management Options Uncertainties Simulation Model Option Performance

climate -27 Scatter Plots Summarize Supply and Shortage Costs for Each Scenario for Current Plan PV shortage cost ($ billions)‏ PV supply cost ($ billions)‏ Current Plan Forever

climate PV shortage cost ($ billions)‏ PV supply cost ($ billions)‏ Scenario A Modest warming and minimal precipitation decrease $3.3 billion in supply cost $0 in shortage cost Current Plan Forever Scenario B Significant warming and precipitation decrease $3.4 billion in supply cost $1.9 billion in shortage cost Scatter Plots Summarize Supply and Shortage Costs for Each Scenario for Current Plan

climate PV shortage cost ($ billions)‏ PV supply cost ($ billions)‏ Current Plan Forever (200 Scenarios)‏ Scatter Plots Summarize Supply and Shortage Costs for Each Scenario for Current Plan

climate -30 The Current Plan Performs Poorly Under Many Possible Future Conditions PV shortage cost ($ billions)‏ PV supply cost ($ billions)‏ Current Plan Forever $3.75 billion cost threshold (120 of 200 Scenarios)‏

climate -31 Statistical Analyses Suggested Three Major Vulnerabilities to the IEUA Plan PV shortage cost ($ billions)‏ PV supply cost ($ billions)‏ Current Plan Forever $3.75 billion cost threshold (120 of 200 Scenarios)‏ 1. Strong declines in precipitation 2. Reductions in imported supply 3. Changes in groundwater replenishment