Drought in Utah: learning from the past - preparing for the future

Drought in Utah is a common occurrence and has given rise to various issues, from environmental to societal stresses. This natural phenomenon brings with it impacts that may take years to fully develop and similarly years to recover from. Water in Utah is a limited resource and drought only amplifies this truism. Water development projects and wise management practices are an integral part of Utah's burgeoning growth and appeal. As the population continues to grow, so too does the demand for water. This growth can potentially increase the state's vulnerability to drought and result in economically upsetting consequences. In many cases, current management of drought is based upon a responseoriented methodology, which can be a rather costly and sometimes ineffective approach. Management of drought, in general, needs to change from a response- oriented methodology to one of mitigation.

DROUGHT IN UTAH: LEARNING FROM THE PAST- PREPARING FOR THE FUTURE April 2007 By: The Utah Division of Water Resources U T A H S T A T E W A T E R P L A N Table of Contents ii Table of Contents iii ACKNOWLEDGEMENTS The Utah Division of Water Resources prepared this document with important contributions from the following staff: Dennis Strong - Director Eric Millis - Deputy Director Todd Adams - Assistant Director Todd Stonely - Section Chief, River Basin Planning Eric Klotz - Section Chief, Water Conservation, Education and Use Dave Cole - Section Chief, Hydrology and Computer Applications Eric Edgley - Section Chief, Technical Services Ken Short - Senior Engineer, River Basin Planning Mike Suflita - Senior Engineer, River Basin Planning Russ Barrus - Engineer, River Basin Planning Brian King - Engineer, River Basin Planning ( Primary Author) Gay Smith - Secretary, River Basin Planning The Utah Division of Water Resources also wishes to express gratitude to the following individuals who provided valuable input during the review process: Donald Wilhite - Director, National Drought Mitigation Center Michael Hayes - Associate Director, National Drought Mitigation Center Mark Svoboda - Climatologist, National Drought Mitigation Center Cody Knutson - Water Resource/ Social Scientist, National Drought Mitigation Center Stephen Gray - Director, Water Resources Data System and Wyoming State Climatologist Connie Woodhouse - Department of Geography and Regional Development, Univ. of Arizona Robert Gillies - Director, Utah Climate Center and Utah State Climatologist Mark Andersen - Assistant General Manager, Weber Basin Water Conservancy District Randall Julander - Snow Survey Supervisor, National Resources Conservation Service Brian McInerney - Hydrologist, National Weather Service Mike Wilson - General Manager, Metropolitan Water District of Salt Lake and Sandy Nancy Barr - Emergency Preparedness Planner, Utah Division of Homeland Security Mike Lowe - Geologist, Utah Geological Survey Ben Everitt - Geologist, Utah Division of Water Resources ( Retired) Mark Eubank - Meteorologist, Channel 5 News ( Retired) Table of Contents iv Table of Contents v PREFACE One of the responsibilities of the Utah Division of Water Resources is comprehensive water planning. Over the past decade and a half, the Division has prepared a series of documents under the title " Utah State Water Plan." This includes two statewide water plans, an individual water plan for each of the State's eleven major hydrologic river basins and " special studies" ( such as this document). Preparing these documents involves several major data collection programs as well as extensive inter- agency and public outreach efforts. Much is learned through this process. State, local, and federal water planners and managers obtain valuable information for use in their programs and activities, and the public receives the opportunity to provide meaningful input in improving the state's water resources stewardship. This document is the latest in the " Utah State Water Plan" series and is intended to provide information regarding drought in Utah. It describes drought of the past century ( instrumental record) and compares these droughts with pre- instrumental droughts of the not- so- distant past and ancient times, in an attempt to more fully describe drought variability in Utah and the West. It encourages discussion among water managers and decision makers regarding the potential for drought more severe than has been experienced in the past 100 years and strongly promotes a mitigation- based methodology of drought planning and management. It presents and discusses mitigation and response strategies that are currently used, or can be employed, to manage drought and minimize its impacts. This document also makes recommendations that will assist the water community in planning and employing drought mitigation strategies. In addition to the printed form of this document, the Utah Division of Water Resources has made a " pdf" version available on the Internet. This can be accessed through the Division's home page at: www. water. utah. gov. Such access facilitates better planning and management at the state and local level. It also provides a convenient mode for readers to provide comment and feedback to the division regarding its water planning efforts. Reader comments regarding this publication are welcome. Table of Contents vi Table of Contents vii TABLE OF CONTENTS APPENDICES ............................................................................................................................... .................... ix LIST OF FIGURES ............................................................................................................................... ............. x LIST OF TABLES......................................................................................................................... .................... xi BOXES ............................................................................................................................... ............................... xi EXECUTIVE SUMMARY ............................................................................................................................. xiii Chapter Page 1 INTRODUCTION: DROUGHT, INDICES AND IMPACTS...................................................................... 1 Purpose of this Report......................................................................................................................... ... 2 What is Drought? ............................................................................................................................... .... 2 Meteorological Drought ................................................................................................................... 2 Agricultural Drought ........................................................................................................................ 3 Hydrologic Drought ......................................................................................................................... 3 Socioeconomic Drought ................................................................................................................... 4 Sequence of Drought in Utah ........................................................................................................... 4 Drought Indices........................................................................................................................ .............. 5 Palmer Drought Severity Index........................................................................................................ 5 Palmer Hydrologic Drought Index ................................................................................................... 5 Surface Water Supply Index............................................................................................................. 6 Comparison of Drought Indices ....................................................................................................... 6 Standardized Precipitation Index...................................................................................................... 8 Drought Impacts ............................................................................................................................... ..... 8 Drought Vulnerability.................................................................................................................. ........ 10 2 HISTORICAL DROUGHT EVENTS FROM THE INSTRUMENTAL RECORD .................................. 13 Utah Droughts Within the Instrumental PDSI Record.......................................................................... 13 Identification of Utah Droughts ..................................................................................................... 14 PDSI Parameters- Temperature and Precipitation.................................................................. 16 Recurrence Intervals and Frequencies of Utah Drought Conditions.............................................. 17 Brief Summary of the Identified Droughts ........................................................................................... 19 Drought of 1898- 1905.................................................................................................................... 19 Drought of 1928- 1936.................................................................................................................... 21 Drought of 1946- 1964.................................................................................................................... 22 Drought of 1976- 1979.................................................................................................................... 23 Drought of 1987- 1992.................................................................................................................... 23 Drought of 1999- 2004.................................................................................................................... 24 Wildfires and Drought ............................................................................................................. 26 National Impacts ...................................................................................................................... 27 Drought Snapshots and Additional Impacts.......................................................................................... 27 Drought Snapshots ......................................................................................................................... 27 Additional Impacts and Vulnerability ............................................................................................ 27 Table of Contents 3 DROUGHT FROM A PALEOCLIMATIC PERSPECTIVE AND CURRENT CLIMATE TRENDS .... 33 Proxy Data Types ............................................................................................................................... . 34 PDSI Reconstruction Methodology...................................................................................................... 34 Tree Rings ............................................................................................................................... ............ 35 Tree- Ring Climatic Record- Nationally and the West ................................................................. 35 Tree- Ring Climatic Record- Utah ................................................................................................ 37 Drought Condition Recurrence Intervals and Frequencies- Utah ................................................ 38 Drought Duration and Severity- Utah .......................................................................................... 41 Geologic Proxies ............................................................................................................................... .. 43 Geologic Proxies and Climate- Utah............................................................................................ 43 Geologic Proxies and Climate- Great Plains................................................................................ 43 Future Climate and Trends ................................................................................................................... 45 Climate Driving Forces ( Climate Forcings)................................................................................... 45 Climate Change......................................................................................................................... .... 47 4 MITIGATION STRATEGIES AND DROUGHT FORECASTING......................................................... 55 Defining Mitigation..................................................................................................................... ........ 55 The Economics of Risk Management ............................................................................................ 56 Utah's Mitigation Plan ......................................................................................................................... 56 Utah's Pre- Disaster Mitigation Plan .............................................................................................. 56 Drought Mitigation Strategies .............................................................................................................. 60 Water Redistribution................................................................................................................. .... 60 Conjunctive Management ............................................................................................................. 61 Water System Interconnections ..................................................................................................... 64 Water Development and Inter- Basin Transfers ............................................................................. 65 Water Reuse.......................................................................................................................... ........ 66 Demand Management .................................................................................................................... 68 Public Education and Outreach ............................................................................................... 68 Alternative Landscaping.......................................................................................................... 69 Incentive Pricing...................................................................................................................... 70 Water Metering and Leak Detection Programs.............................................................................. 71 Weather Modification ( Cloud Seeding)......................................................................................... 72 Additional Mitigation Strategies.................................................................................................... 72 Vulnerability Assessments ...................................................................................................... 72 Remove Water- Loving Invasive Species ................................................................................ 73 Watershed Management .......................................................................................................... 73 Drought Forecasting ............................................................................................................................. 73 Use of Proxies........................................................................................................................ ....... 74 Climate Trends......................................................................................................................... ..... 75 The Drought Monitor and Seasonal Drought Outlook................................................................... 75 National Integrated Drought Information System ......................................................................... 75 Funding and Other Assistance for Drought Mitigation........................................................................ 76 Utah State Water Resources Development Funding...................................................................... 76 Federal Mitigation Assistance........................................................................................................ 77 5 DROUGHT RESPONSE....................................................................................................................... .... 81 Utah's Drought Response Plan............................................................................................................. 81 Monitoring..................................................................................................................... ............... 82 viii Table of Contents Assessment..................................................................................................................... ............... 82 Response....................................................................................................................... ................. 82 Drought Response Strategies ................................................................................................................ 83 Demand Management- Water Use Restrictions............................................................................ 83 Drought ( Water Shortage) Contingency Plans......................................................................... 84 Emergency Outdoor Watering Restrictions or Declarations.................................................... 84 Ground Water Use and Temporary Well Permits .......................................................................... 85 Temporary Well Placement ..................................................................................................... 85 Agricultural Management............................................................................................................... 86 Land Management ................................................................................................................... 86 Crop Management.................................................................................................................... 86 Water Management.................................................................................................................. 87 Efficient Irrigation and Agricultural Management Systems .................................................... 87 Water Hauling ............................................................................................................................... 88 Legislation.................................................................................................................... ................. 88 State Assistance..................................................................................................................... ........ 89 Federal Assistance..................................................................................................................... .... 89 6 CONCLUSION AND RECOMMENDATIONS........................................................................................ 93 Mitigation and Response to Drought in Utah ....................................................................................... 93 Recommendations................................................................................................................ ................ 94 1: Develop Drought Management Plan .......................................................................................... 94 2: Water Redistribution and Interconnections................................................................................ 95 3: Agreements on Reservoir Operation .......................................................................................... 95 4: Data Collection..................................................................................................................... ..... 95 Survey ............................................................................................................................... ...... 96 Socioeconomic Impact Data .................................................................................................... 96 Additional Research................................................................................................................. 96 APPENDICIES Appendix Page A- Comparison of Drought Indices .................................................................................................................. 99 B- Assessing Drought Impacts: The Drought Impact Reporter ..................................................................... 103 C- Instrumental PDSI Versus Tree- Ring PDSI.............................................................................................. 107 D- Federal Drought Assistance Programs ...................................................................................................... 109 ix Table of Contents LIST OF FIGURES Figure Page Text 1- 1 Storage and Capacity of 26 Critical Reservoirs in Utah ............................................................................... 1 1- 2 Progression of Drought Conditions and Impacts .......................................................................................... 3 1- 3 SWSI vs. Palmer Indices........................................................................................................................ ...... 7 1- 4 Population Projections and Drought Vulnerability ..................................................................................... 10 2- 1 Instrumental PDSI Record- Drought Delineation ..................................................................................... 15 2- 2 Great Salt Lake Elevations During Drought ............................................................................................... 16 2- 3 Average Annual River Flow and Drought .................................................................................................. 17 2- 4 Utah Statewide Precipitation and Temperature- Peak of Drought Periods ............................................... 18 2- 5 Percent of Utah Experiencing Mild to Severe Drought Conditions Based the PDSI ................................. 20 2- 6 Bear Lake Elevations During Drought........................................................................................................ 24 3- 1 Smoothed Reconstructed PDSI- Tree- Ring Grid Point 086...................................................................... 39 3- 2 Average Duration ( yr) of Drought- Tree- Ring Reconstructed PDSI ........................................................ 42 3- 3 Water Lily Lake and Drought ..................................................................................................................... 44 3- 4 Elk Lake Proxy Indicators of Holocene Period Drought ............................................................................ 45 3- 5 Moon Lake Salinity- Regime Shift ........................................................................................................... 46 3- 6 PDO, AMO Phases and Drought ................................................................................................................ 48 3- 7 Reconstructed Surface Temperature ........................................................................................................... 49 4- 1 Disaster Management Cycle ....................................................................................................................... 56 4- 2 Agricultural and Urban Land Use............................................................................................................... 62 4- 3 Conjunctive Management ........................................................................................................................... 64 4- 4 Breakdown of Public System Water Use Including Secondary Water ( 2005) ........................................... 69 4- 5 The Drought Monitor........................................................................................................................ ......... 76 4- 6 Seasonal Drought Outlook........................................................................................................................ . 77 5- 1 Drought Plans by State.......................................................................................................................... ..... 82 5- 2 Organization of Drought Assessment and Response .................................................................................. 83 5- 3 Water Use: Percentage of Ground Water and Surface Water for Public Supply and Irrigation ................. 86 6- 1 Reservoir Operating Curve with Drought Indicators.................................................................................. 96 Appendices A- 1 PDSI vs. PHDI for Climatic Region 1 ( 1925- 2005) ................................................................................... 99 A- 2 Drought Indices and Identified Drought .................................................................................................. 101 A- 3 Surface Water Supply Index and Identified Drought ............................................................................... 102 B- 1 Drought Impact Reporter Map.................................................................................................................. 104 B- 2 Comparison of Reported Impact and Drought Monitor Maps- Spatial Extent........................................ 104 C- 1 Climatic Regions and Tree- Ring Grid Points........................................................................................... 107 C- 2 Instrumental PDSI Record vs. Tree- Ring Reconstructed PDSI Record ( 1895- 2003) .............................. 108 x Table of Contents LIST OF TABLES Table Page Text 1- 1 Palmer Drought Indices Classifications ........................................................................................................ 5 1- 2 Categories of Drought Impacts...................................................................................................................... 9 2- 1 Recurrence of Mild to Severe Drought Conditions Based on the PDSI...................................................... 19 2- 2 Longest Drought on Record by Climatic Region Based on the PDSI......................................................... 21 2- 3 Most Intense Droughts on Record by Climatic Region ( Lowest PDSI Average of Drought Duration) ..... 21 2- 4 5- Year Average Flow ( 1999- 2003) Rankings of River Basins ................................................................... 25 2- 5 Statewide Annual Temperature Rankings- Warmest................................................................................. 25 2- 6 Fire Management Assistance Declarations ................................................................................................. 26 3- 1 Driest Years from AD 1226- 2001 Reconstructed from Uinta Basin Study ................................................ 38 3- 2 Recurrence and Frequency of Mild to Severe Drought Conditions PDSI vs. Tree- Ring Reconstructed PDSI........................................................................................................................... ....................................... 40 3- 3 Statewide Mild to Severe Drought Conditions Recurrence and Frequency PDSI vs. Tree- Ring ............... 40 3- 4 Paleo- Drought Duration- Tree- Ring Reconstructed PDSI ........................................................................ 41 3- 5 Drought Duration- Instrumental PDSI....................................................................................................... 41 4- 1 State Drought Mitigation Goals, Objectives and Example Projects............................................................ 58 4- 2 Drought Mitigation Programs and Measures of Cities within the Listed County ....................................... 59 4- 3 Agricultural Water Use by Basin ................................................................................................................ 61 4- 4 Acceptable Uses for Treated Effluent ......................................................................................................... 67 4- 5 Drought Mitigation Strategies ..................................................................................................................... 72 5- 1 State Assistance Programs ( Response)........................................................................................................ 90 6- 1 Drought Mitigation and Response Actions ................................................................................................. 94 Appendices A- 1 PDSI and PHDI R- Squared Values .......................................................................................................... 100 A- 2 SWSI versus Palmer Indices' R- Squared Values ..................................................................................... 100 D- 1 Federal Assistance Programs- Mitigation................................................................................................ 111 D- 2 Federal Assistance Programs- Monitoring.............................................................................................. 117 D- 3 Federal Assistance Programs- Response................................................................................................. 119 BOXES Box Page 2- 1 Utah Climate Divisions ............................................................................................................................... 14 2- 2 Drought Conditions: Intervals and Frequencies .......................................................................................... 19 2- 3 Drought Snapshots ............................................................................................................................... ...... 28 xi Table of Contents 3- 1 Climate Proxy Requirements for Application to Drought Planning ........................................................... 34 3- 2 The Study of Tree Rings ............................................................................................................................. 35 3- 3 North American Drought Atlas................................................................................................................... 36 3- 4 Dry Period or Event ............................................................................................................................... .... 37 3- 5 Definitions ............................................................................................................................... .................. 47 4- 1 Flood Mitigation and Preparedness- An Illustrative Example .................................................................. 57 4- 2 California's Water Redistribution Program ................................................................................................ 63 4- 3 Limitations of Demand Management.......................................................................................................... 68 4- 4 Definitions and Acronyms .......................................................................................................................... 74 xii EXECUTIVE SUMMARY Drought in Utah is a common occurrence and has given rise to various issues, from environmental to societal stresses. This natural phenomenon brings with it impacts that may take years to fully develop and similarly years to recover from. Water in Utah is a limited resource and drought only amplifies this truism. Water development projects and wise man-agement practices are an integral part of Utah's bur-geoning growth and appeal. As the population con-tinues to grow, so too does the demand for water. This growth can potentially increase the state's vul-nerability to drought and result in economically up-setting consequences. In many cases, current man-agement of drought is based upon a response-oriented methodology, which can be a rather costly and sometimes ineffective approach. Management of drought, in general, needs to change from a re-sponse- oriented methodology to one of mitigation. Drought in Utah: Learning from the Past- Preparing for the Future emphasizes the need to plan and implement mitigation strategies- actions taken to ensure a reliable water supply before a drought occurs- in order to satisfy future water de-mand during periods of drought. Some water sup-pliers, such as Salt Lake City, have already taken measures to diversify their water supplies and thus mitigate for drought. This document reinforces such actions. Drought can never fully be mitigated and an element of " coping" or " living with drought" will always exist, however, the effects of drought- related impacts can be limited through mitigation. This document also highlights droughts of the past 111 years ( the time since weather conditions have been monitored- instrumental record) and compares these droughts with droughts of the not- so- distant past and ancient droughts ( pre- instrumental record- paleoclimatic record) in order to expand current un-derstanding of drought's natural variability and po-tential future impacts. It suggests possible mitiga-tion strategies that could be employed and stresses the importance of proactively managing drought us-ing a " risk" management ( mitigation) based method-ology rather than traditional " crisis" management ( response) practices. This document is intended to be a reference to local water planners, managers and decision- makers as they strive to meet water chal-lenges during drought. It will also be of help to those in the general public who are interested in making greater contributions to water- related deci-sions being made by local, state and federal govern-ment officials regarding drought. The following paragraphs summarize the main points of each chap-ter. CHAPTER 1 INTRODUCTION: DROUGHT, INDICES AND IMPACTS The purpose of this report is to: 􀂾 Present the significance of historical drought events, drought- related impacts and soci-ety's vulnerabilities to drought. 􀂾 Warn of the likelihood of longer- term and more severe drought based upon recon-structed climate records and climate change. 􀂾 Discuss mitigation strategies that could be implemented well in advance of drought. 􀂾 Make recommendations for action to help manage and mitigate drought. xiii Executive Summary 􀂾 Encourage discussion among the water community regarding drought management. Drought is a dynamic phenomenon and challeng-ing to define; no one definition adequately explains it. Several definitions ( meteorological, agricultural, hydrological and socioeconomic) have been devel-oped and when put together, give a better description of drought. Monitoring drought is equally as chal-lenging. Several drought indices have also been de-veloped in an attempt to measure drought severity through comparison of climatological variables to the normal or long- term average ( see Box I). In order to gain a better understanding of drought, its impacts need to be understood. Impacts can be categorized broadly as economic, social and envi-ronmental. However, impacts generally are not con-fined to a single category. Drought impacts can be far reaching and result in economic, social and envi-ronmental consequences all at once. In general, Utah's potential vulnerability to drought and its im-pacts may increase as the population and demand for water continue to grow. Some water suppliers' vul-nerability to drought has been greatly reduced due to continual planning efforts and actions taken. Box I- Drought Indices Drought Indices: 􀂾 Palmer Drought Severity Index ( PDSI): based upon meteorological conditions such as temperature and precipitation and weather and climate trends. 􀂾 Palmer Hydrological Drought Index ( PHDI): also based upon meteorological conditions, however it lacks the " trends" component of the PDSI and therefore becomes a hydrologi-cal index. 􀂾 Surface Water Supply Index ( SWSI): based upon meteorological and hydrological condi-tions, and takes into account snowpack and stored water supplies. 􀂾 Standardized Precipitation Index ( SPI): based upon precipitation. CHAPTER 2 HISTORICAL DROUGHT EVENTS FROM THE INSTRUMENTAL RECORD Utah scientists began to measure and record weather conditions using instruments in the late 1800s. This instrumental record spans a 111- year period ( 1895- present) and is used in the calculation of drought indices. The Palmer Drought Severity Index ( PDSI), which relies on the data from the in-strumental record, was used in this report to identify significant drought periods in Utah. It was chosen due to its relatively long record in comparison to other drought indices' records ( since climate meas-urements have been recorded) and direct compara-bility with reconstructed PDSI records ( paleocli-matic or proxy records as discussed in Chapter 3). Utah is divided into seven climatically similar re-gions. PDSI records exist for each of the seven divi-sions. Using severity and duration of dry conditions as a guide, the Utah Division of Water Resources identified six drought events in Utah within the in-strumental PDSI record. Severity and drought-related impacts varied from region to region and several droughts consisted of consecutive years of mild ( PDSI < - 1) to severe ( PDSI < - 3) statewide drought conditions. See Box II for the identified drought events and some related impacts. CHAPTER 3 DROUGHT FROM A PALEOCLIMATIC PERSPECTIVE AND CURRENT CLIMATE TRENDS Although the instrumental PDSI record yields valuable information on drought, it is limited. This record may be over a century in length, however, drought contained within this time interval does not provide a complete picture of drought variability. Drought occurred years and millennia before the start of monitoring and recording climatic/ weather conditions. To gain a broader knowledge and clearer picture regarding drought, analysis of records of longer duration is needed. In order to accomplish this, natural environmental or " proxy" records of xiv Executive Summary Box II- Drought Snapshots 􀂾 1896- 1905: Large cattle operations folded, leaving small operations to fight over what was left of adequate grazing lands. The drought forced settlers to uproot their families as lands were drying up and water rights were inadequate. 􀂾 1924- 1936: The " Dust Bowl Years" affected approximately 75% of Utah. Agriculture pro-ductivity was decreased to almost half of prior years production and the number of farms significantly decreased. 􀂾 1946- 1964: Multiple areas within Utah were declared disaster areas. Statewide, impacts could have been worse but were lessened due to steps taken to enhance the water sup-ply. 􀂾 1974- 1979: Conditions in seven of Utah's counties prompted the governor to request Federal Disaster Declarations for these counties. By the end of 1977 the state and its citizens lost $ 41 million ($ 132 million in 2005 dollars) due to the drought impacts. 􀂾 1986- 1992: Drought blanketed the entire state of Utah for multiple consecutive years. Nationally, 1988 was the most costly drought ever, and until Hurricane Katrina, was the most costly natural catastrophe in U. S. history. 􀂾 1999- 2004: The drought produced some of the hottest years and one of the driest years ( 2002) on record. Statewide reservoir capacity plunged below 50% and farmers and ranchers struggled to make ends meet. climate variability, such as tree- rings, fossil pollen, sediments and ice cores are used. Tree rings are commonly used to assess past cli-mate. Patterns and densities of these annual growth rings strongly correlate with regional climatic condi-tions ( wide and narrow growth rings equate to wet and dry conditions respectively). From these growth rings, scientists have been able to reconstruct a long-term PDSI record. This record dates back over two thousand years. Analysis of this record indicates that many droughts, before the advent of the instru-mental record, were more severe, more frequent and impacted larger areas. On average, drought con-tained in the reconstructed PDSI record ( roughly 1,900 years before the instrumental record) was ap-proximately 10.9 years in length compared to the average drought duration of 6.8 years during the last 111 years ( instrumental record). Geologic records, analysis of lake and eolian ( wind- borne) sediments, reinforce this conclusion. Research indicates that prolonged dry periods have occurred in greater fre-quency than has been experienced within the last century. These results coupled with the evidence of climate change, suggest that drought within the past century is not a complete subset of drought variability and that drought similar to episodes of the past ( more severe and longer duration) will likely happen again. CHAPTER 4 MITIGATION STRATEGIES AND DROUGHT FORECASTING The possibility of decade- long or longer drought occurring in Utah's future is real. Utah has devel-oped a Pre- Disaster Mitigation Plan that addresses drought ( to a degree) and other natural hazards. However, more drought specific planning and action is warranted. Water managers and purveyors can, and do, take several feasible actions to address fu-ture droughts. Mitigation or action taken well in advance of any disaster or drought event is a meth-odology of drought management that should be un-derstood and implemented ( see Figure I- Disaster Management Cycle, page xvii). Several existing mitigation strategies can lessen the severity of some future drought- related impacts. Addressing Utah's vulnerabilities to drought- through mitigation and diversification- is essential to providing a reliable water supply during prolonged periods of drought ( decade or longer). Mitigation strategies discussed in this report are listed in Box III. xv Executive Summary Box III- Mitigation Strategies 􀂾 Water Redistribution: transfer of agricultural water ( or other water) via a water banking system (" brokering" system) from " willing sellers" to " willing buyers" during times of drought. Large volumes of agricultural water could possibly be available for M& I uses ( agriculture to M& I transfers) during prolonged periods of drought or drought of any length. 􀂾 Conjunctive Management: conjunctive use of surface and ground water supplies. Store water when it is available in surface facilities and/ or sub- surface aquifers ( aquifer storage and recovery [ ASR]), for use when needed, such as during drought. Potential ASR pro-ject sites have been identified by the Utah Division of Water Resources and generally 􀂾 Water System Interconnections: extensive water networks exist throughout Utah, how-ever many of these are not well- integrated or integrated at all. Increased integration of conveyance networks and implementation of advanced monitoring and control systems can increase efficacy in meeting regional water demands during drought of any length ( M& I to M& I transfers). Extensive planning, cooperation, coordination and establishment of agreements between all involved parties would be needed. 􀂾 Water Development: efficient use of dams, reservoirs and other water systems as well as construction of necessary additional projects currently plays a significant role in satis-fying water demands of the projected population growth and in maintaining a reliable wa-ter supply during prolonged drought. 􀂾 Water Reuse: use of treated wastewater effluent ( may require new facilities, convey-ance, permits, and water rights) for nonpotable uses. Use of this relatively constant and quantifiable source can temporarily lower and/ or reduce consumption of potable water used for irrigation and industrial purposes. 􀂾 Demand Management: more aggressive demand management practices, beyond cur-rent water conservation policy, can be implemented to mitigate drought, such as reducing lawn/ turf size, eliminating parking strips and requiring water- wise landscapes. o Public Education and Outreach: use of programs to instill a " water wise" ethic in both children and adults as well as promote possible water use regulatory changes. o Alternative Landscaping: by encouraging or requiring more efficient landscapes ( water wise and more drought tolerant), outdoor water use can be significantly decreased with minimal influence upon everyday life. Aggressive demand man-agement programs such as this could delay the need for additional water devel-opment projects. o Incentive Pricing: effective year- round pricing can help mitigate drought by low-ering water use rates. 􀂾 Water Metering and Leak Detection Programs: billions of gallons of water are lost each day nationwide due to leaks, overflows, pipe bursts and inaccurate or no metering. These system and operational inefficiencies are abundant nationally and throughout Utah. Water suppliers should regularly conduct system water- audits to ensure that the water system is properly metered and in working order. 􀂾 Weather Modification: the state of Utah views cloud seeding as a cost- effective strategy to supplement the water supply. Additional weather modification projects or improve-ments to projects already in place should be pursued to help to further mitigate future drought impacts and further research is encouraged. 􀂾 Forecasting ( Early Warning System): although scientists are currently unable to predict future drought, advancements are being made and cooperation at all levels within the state with scientists and drought- forecasting programs is highly encouraged. xvi : ent: cost much less than surface storage. : : : : : : : Redistribution Managem Interconnections Development Management Landscaping Pricing Programs System) Executive Summary These strategies are not a panacea to all future water manage-ment challenges, how-ever, when multiple strategies are imple-mented and managed as one system, with drought components embedded within each strategy, they can serve as long- term mitigation actions or " solutions." Without drought com-ponents embedded within these strategies, they may serve only as short- term drought mitigation solutions. FIGURE I Although current drought forecasting technologies are lim-ited, predicting drought is becoming more and more of a possibility as scientists come to a clearer understanding of the driving forces that underlie most climatic events. The ability to forecast weather events greatly in-creases the effectiveness of both mitigation and pre-paredness activities. Several federal programs are dedicated to drought monitoring, research and pre-diction; and new programs are being developed that will enhance forecasting abilities. One such pro-gram is the National Integrated Drought Information System ( NIDIS). The NIDIS Act, which allows the formation of NIDIS within the National Oceanic and Atmospheric Administration, was passed in Decem-ber 2006. CHAPTER 5 DROUGHT RESPONSE Though movement towards drought mitigation is needed, response will always be a part of drought management. Response to drought can take place concurrently with the impacts or after they occur, when needs may be more apparent. Federal relief has traditionally been the foundation of drought re-sponse. Utah has used such relief during drought, but has done so as an option of last resort. Following its drought response plan, Utah has adequately re-sponded to recent droughts and has employed sev-eral drought response strategies ( see Box IV). CHAPTER 6 CONCLUSION AND RECOMMENDATIONS During drought, an already scarce resource be-comes even scarcer. Proper management of Utah's finite water supply is the essential aspect of ensuring a reliable supply and environmental integrity during drought. As the population and subsequent water demand continue to grow, so too does society's po-tential vulnerability to drought. By using sound mitigation and response strate-gies, it may be possible to satisfy future water de- Disaster Management Cycle Risk Management Crisis Management Protection Recovery Mitigation Preparedness Disaster Recovery Response Source: Adapted from the National Drought Mitigation Center's " Disaster Management Cy-cle" figure, University of Lincoln- Nebraska. xvii Executive Summary Box IV- Response Strategies 􀂾 Demand Management- Water Use Restrictions: many water suppliers have devel-oped conservation plans that contain drought management elements. These aspects of water management during drought should ideally be included in separate contingency plans. In order to curtail water use during drought and other emergencies, cities, conser-vancy districts and purveyors may adopt more aggressive water management strategies as set forth in these plans, as is the case with some, such as Salt Lake City's Water Shortage Contingency Plan. These management strategies may include water use re-strictions and ordinances, limiting water use to certain times of the day and certain days of the week. However these strategies must be monitored for effectiveness. See dis-cussion in Chapter 5 on pages 83- 85. 􀂾 Ground Water Use and Temporary Well Permits: during drought, ground water with-drawals tend to increase as surface water supplies decrease. The Utah state engineer can approve the installation and use of temporary wells in response to water deficiencies. Some temporary wells could possibly be placed near current reservoirs to take advan-tage of water infiltrated from the reservoir and the nearby conveyance systems. Water rights are a large component in this response strategy. 􀂾 Agricultural Management: the agricultural sector is generally impacted first and most severely by drought. Management of agricultural resources is therefore paramount dur-ing drought and includes land management, crop management and water management. Systems and management strategies have been developed to aid farmers with manage-ment decisions and minimize losses during drought. 􀂾 Water Hauling: when the water supply has been greatly reduced or rendered unusable due to drought, water can be and has been hauled in for public use. Although uncom-mon, this has recently been done in rural areas affected by drought. Quick and efficient response by local authorities can significantly reduce drought- related impacts. 􀂾 Legislation: on occasion drought has prompted responses form the Utah Legislature in the form of laws, acts and other actions. mands without increasing society's vulnerability to drought- even if future droughts are more severe than historic droughts of the 20th Century. Leaders in the water supply industry, legislators and other community leaders are encouraged to implement the strategies and methods put forth in this publication and adopt a methodology of mitigation rather than one primarily of response to drought. The Utah Division of Water Resources has made recommendations to assist with managing drought and implementing mitigation strategies ( see Box V). xviii Executive Summary Box V- Recommendations 1) Develop Drought Management Plan: in order to maximize efficiency, cost effective-ness, supply diversification, maintain environmental integrity and ensure a reliable water supply during periods of drought, water suppliers should develop drought mitigation and water shortage contingency components. Mitigation components should detail vulner-ability assessments and layout a plan of action to address identified vulnerabilities through the implementation of mitigation strategies. Water shortage contingency com-ponents should outline more aggressive response actions that address management of water shortages and can be applied to drought, such as Salt Lake City's Water Shortage Contingency Plan. 2) Water Redistribution and Interconnections: develop a mechanism to facilitate tempo-rary redistribution of agricultural water ( or other water) to supplement the public supply during drought. Additional infrastructure may be needed. 3) Agreements on Reservoir Operations: water users who rely on water supplies from a major reservoir in Utah should craft, a reservoir operation agreement to dictate reservoir operation during drought. In situations where broad segments of the population will be affected by such agreements, a reservoir operation curve ( or appropriate indicator) should be developed, posted and regularly updated to help the public understand when and why various operating criteria and water restrictions are triggered. 4) Data Collection: governing bodies, counties and cities ( or appropriate institution) should collect beneficial information that will assist decision makers and the legislative body re-garding drought. Survey municipal water utilities, suppliers and conservancy districts throughout and at the terminus of droughts and provide results upon request. Monitor economic sectors ( socioeconomic impact data) during and after drought in order to more fully understand and quantify drought impacts. Encourage additional research within state agencies, universities and other institutions regarding climate change and precipi-tation in Utah. Also support of federal research programs already in place is highly en-couraged. xix 1 INTRODUCTION: DROUGHT, INDICES AND IMPACTS Utah's most recent drought affected parts or all of the state during 1999- 2004. At its peak ( 2002 and 2003), many agricultural water users and municipal water suppliers in Utah encountered difficulties meeting their needs. These difficulties include the following: 􀂾 Farmers suffered millions of dollars in losses due to low crop yields and outright crop failure. 􀂾 Some ranchers went bankrupt as they were forced to sell off entire herds of cattle and other livestock at a loss. 􀂾 Thousands of fish died in East Canyon Creek and water quality standards were compromised when the stream dried up. 􀂾 Salt Lake City diverted drinking water into ditches to satisfy century- old exchange agreements with irrigators. 􀂾 The Utah State Engineer cut- off several Bear River irrigators ( by water right prior-ity) due to low flows. 􀂾 City officials in Monticello restricted out-door watering to once a week to preserve dwindling storage capacity in Lloyds Lake. 􀂾 Government officials facilitated the hauling of water to residents of Navajo Mountain FIGURE 1- 1 as springs went dry. As severe as the problems were, they could have been much more widespread had the drought continued a few more years. During each successive year, reservoir levels dropped ( see Figure 1- 1), ground water levels declined, and the environ-ment became drier and more susceptible to devastating wildfires. When above normal precipitation finally returned to most areas of Utah in 2005, water suppli-ers breathed a collective sigh of relief- many had avoided what could have Storage and Capacity of 26 Critical Reservoirs in Utah 0 1 2 3 4 1998 1999 2000 2001 2002 2003 2004 2005 Million Acre- Feet Stored Water ( June 1) Unused Capacity Source: Utah Division of Water Resources analysis, 2006. Note: Does not include Lake Powell, Flaming Gorge, Strawberry, Jordanelle and other smaller reservoirs. 1 1 - Introduction: Drought, Indices and Impacts been an extremely adverse situation. Although most Utahns remember various aspects of the drought, attention has been diverted from this natural climatological hazard to other issues of more immediate concern. It is hoped that this report will again focus some attention on drought and assist decision makers and water managers with mitigating drought and preparing for it well in advance, particu-larly during wet years. PURPOSE OF THIS REPORT The purpose of this document is multifaceted. It: 1) Present the significance of drought's influ-ence on society from a historical perspective and how projected growth can potentially make Utah more vulnerable to its impacts. 2) Warns about the likelihood of more severe and longer- term droughts in the future based on reconstructed climate and proxy records as well as climate change. 3) Explores various strategies to mitigate, pre-pare for and respond to future drought events. 4) Makes recommendations for future action. 5) Encourages discussion among decision makers and water managers regarding drought management. A main objective of the report is to highlight those things that have successfully limited drought- related impacts on society in the past, motivate policy-makers and water managers to continue to imple-ment appropriate measures and move toward a more mitigation- centered water management strategy. This report compiles a vast array of research and presents new information all into one place- thereby providing a comprehensive view of drought in Utah and what can be done to mitigate and better prepare for future events. Simply put, this document is a word of warning about drought and a strategy for mitigation and preparedness. WHAT IS DROUGHT? Drought is unique among natural hazards. Unlike a flood, earthquake, hurricane or tornado, drought is not an easily recognized event. While most natural hazards are sudden and result in immediate impacts, droughts " sneak up on us quietly disguised as lovely, sunny weather" 1 and can last a long time. As a re-sult, it is difficult to know exactly when a drought begins and equally challenging to pinpoint when it ends. Drought is a normal, recurrent feature of climate that occurs everywhere to some degree. It is mani-fested in different ways depending upon the region and the impact it has on human activities. In the most general sense, drought can be defined as " a deficiency of precipitation [ or effective moisture] over an extended period of time, resulting in a water shortage for some activity, group, or environmental sector." 2 Thus, drought is much more than simply a climatic phenomenon- and can only be fully de-scribed in light of its broader impacts on society and the environment. Over the years, drought experts have developed several different ways to define and measure drought. The following four drought categories3 have evolved: 􀂾 Meteorological drought 􀂾 Agricultural drought 􀂾 Hydrologic drought 􀂾 Socioeconomic drought Although these categories have some unique char-acteristics, it may make more sense to think of these as " phases" of the same drought ( as depicted in Fig-ure 1- 2), rather than different types of droughts. Meteorological Drought Meteorological drought is determined by measur-ing climatological conditions, particularly precipita-tion. It is usually defined by the degree of dryness compared to a " normal" or long- term average. 4 Defining drought in meteorological terms is the easiest way to gauge drought conditions. If recent precipitation is less than normal, then it follows that meteorological drought conditions exist. The more precipitation amounts are less than normal and the longer this persists, the more severe the drought. While this approach provides a relatively " early warning" of drought conditions, it can also produce false alarms. For instance, a dry period may end before a watershed is seriously affected and water users experience a water supply deficit. Also, after 2 Introduction: Drought, Indices and Impacts - 1 prolonged drought conditions, a period of above av-erage precipitation may signal an end to the mete-orological drought, when in reality the watershed is a long way from recovering, and water supply defi-cits persist for some time. As long as winter precipi-tation is adequate, several areas in Utah can endure a meteorological drought during the spring, summer and fall months by capturing available runoff in res-ervoirs and releasing it as needed during the year. However, in addition to winter precipitation, some areas rely on spring precipitation as a water supply source. For example Alta receives roughly 34 and 31% of total precipitation in the winter and spring, respectively. A common measure of meteorological drought across the country is the Palmer Drought Severity Index ( PDSI). The PDSI, although not a true meas-ure of meteorological drought in the strictest sense, adequately de-scribes it. The PDSI and other drought indices will be discussed later in this chapter. Agricultural Drought Drought typically im-pacts agriculture first and most severely. Dry farms, which rely on soil mois-ture at the beginning of the growing season and precipitation throughout the growing season, are quickly impacted by ab-normally hot or dry condi-tions. While irrigated farms are not immediately impacted by dry condi-tions- because they rely on streamflows, reservoir storage and ground water to supplement precipita-tion- they too suffer when drought conditions persist long enough to impact hydrologic condi-tions. Typically, in the West, agriculture uses most of the available water supply within a region ( 81% in Utah). In Utah, only the Salt Lake Valley is an exception to this. Consequently, any water short-age translates directly to economic losses in the agri-cultural sector. High temperatures associated with drought and decreased water supplies make it diffi-cult to keep up with watering requirements and crop yield subsequently may decrease in amount and/ or quality. Energy costs ( such as pumping) may also increase and result in negative economic implica-tions. Hydrologic Drought Hydrologic drought is determined by the overall water supply ( or hydrologic) conditions of a water-shed- snowpack, soil moisture, streamflows and reservoir storage. The severity of hydrologic FIGURE 1- 2 Progression of Drought Conditions and Impacts Drought Conditions & Impacts Time ( duration) Precipitation deficiency ( amount, intensity, timing) High temp., high winds, low relative humidity, greater sunshine, less cloud cover Socioeconomic Hydrological Agricultural Meteorological Drought Drought Drought Drought Reduced infiltration, runoff, deep percolation, and ground water recharge Increased evaporation and transpiration Soil water deficiency Plant water stress, reduced biomass and yield Reduced streamflow, inflow to reservoirs, lakes and ponds; declining water table; reduced wetlands and wildlife habitat Economic impacts Social impacts Environmental impacts Disruption of the supply of economic goods, long- term environmental damage and social stress ( may be apparent in all drought " phases" to some degree) Source: Adapted from a graphic by the National Drought Mitigation Center found on their web page, " What is Drought? Understanding and Defining Drought." Re-trieved from: http:// drought. unl. edu/ whatis/ concept. htm, August 2006. 3 1 - Introduction: Drought, Indices and Impacts drought is determined by the deviation from normal or long- term average values. While this analysis is more involved and time consuming than the mete-orological approach, it provides a more detailed pic-ture. In Utah and other mountainous regions, where water users are largely dependent upon winter snowpack and reservoir storage for their water sup-ply, this approach is quite useful. In the Intermountain West, several indices are used that adequately describe hydrologic drought: the Palmer Hydrologic Drought Index ( PHDI), long-term Standardized Precipitation Index ( SPI) and the Surface Water Supply Index ( SWSI). These indices will be discussed in more detail later in this chapter. Socioeconomic Drought If dry conditions persist long enough and severely impact reservoir storage and ground water levels, drought enters its most disruptive phase: socioeco-nomic drought. " Socioeconomic definitions of drought associate the supply and demand of some economic good with elements of meteorological, hydrological, and agricultural drought." 5 Socioeco-nomic drought reaches well beyond the agricultural community and affects community drinking water supplies and consequently many social and eco-nomic enterprises. At this stage, long- term damage to vegetation, wildlife habitat and other natural envi-ronments is also likely to occur. A weakness of the socioeconomic drought defini-tion, as well as with the other types of drought, is that no standardized methodology or index exists that truly measures its severity and impacts. Al-though attempts have been made in the past to measure total economic costs of drought- which is the most logical way to reflect the severity of socio-economic drought- these efforts have been inade-quate and, thus, not very useful. A consistent meth-odology for socioeconomic drought impact analysis is needed and warrants further research and devel-opment. Sequence of Drought in Utah The typical drought sequence ( as depicted previ-ously in Figure 1- 2) begins with meteorological drought and progresses to agricultural drought. If abnormally dry conditions last long enough, hydro-logical drought begins and ultimately progresses to socioeconomic drought. While this sequence de-scribes the various " phases" of drought in a logical way that is broadly applicable, in reality the se-quence of events is not always so simple and may vary from region to region. In Utah, for instance, agricultural drought only precedes hydrological drought for dry- crop farmers who do not irrigate. Farmers who irrigate and ranchers who water live-stock using streamflow or reservoir storage do not experience agricultural drought ( to the same degree as dry- crop farmers) until these parameters are af-fected and hydrologic drought begins. Even then, farmers who have access to or rely solely on ground water may never truly experience agricultural drought, because even prolonged drought may not completely deplete ground water supplies. How-ever, prolonged drought may make it economically infeasible for farmers to pump ground water if levels After several years of drought, water levels in Echo Reservoir dropped precipitously, exposing vast mudflats in the fall of 1990. 4 Introduction: Drought, Indices and Impacts - 1 decline far enough. Another nuance to the sequence of drought is the beginning of socioeconomic drought. Sequentially, socioeconomic drought typically does not manifest itself fully until the duration of the drought becomes very long. However, socioeconomic drought techni-cally begins as soon as any economic loss is experi-enced and can last the entire duration of a drought and beyond. An example of this could be lack of early snowfall ( an indicator of meteorological drought), which prevents ski areas from opening and causes immediate economic loss ( socioeconomic drought). While it is often helpful to define drought according to the discussed criteria or phases, drought is almost always a much more complex phenome-non. DROUGHT INDICES6 Over the years, scientists have developed various numerical indices to measure drought. Several of these indices use climatological and hydrological parameters such as precipitation, temperature, streamflow, and lake and reservoir levels, to derive a relationship between instrumental measurements and drought. These indices commonly produce a single digit number that falls within a set range and indi-cates the severity ( which is dependant upon duration and intensity) of the drought or wet period. Water managers and policy makers use these indices to help them make important drought management de-cisions. Many of these indices measure the deviation or variation in weather conditions from the observed historical norm. The indices most commonly used in Utah are described in the following sections. Palmer Drought Severity Index7 The Palmer Drought Severity Index ( PDSI), also known as the Palmer Drought Index ( PDI), was de-veloped in 1965 by W. C. Palmer to measure de-creases in moisture based upon supply- and- demand for relatively homogenous regions. The goal of this index is to measure moisture conditions that are standardized to allow comparisons across space and time. The PDSI is used as a meteorological drought index that acts in response to abnormally dry or wet weather conditions. PDSI values generally range from - 4.0 to + 4.0, which represent extremely dry to extremely wet conditions, respectively ( see Table 1- 1). These values are calculated based on precipita-tion, temperature and available water content in the soil. It does not take into account streamflow, lake and reservoir levels, or other hydrological parame-ters that require a long recovery time ( time needed to overcome deficit and return to " normal" conditions). The PDSI also attempts to measure the duration of a drought or wet spell. Long- term drought is cumu-lative8 and therefore the index relies upon current weather conditions and patterns as well as the cumu-lative conditions of previous months ( long- term trends) to estimate the intensity of the drought. Although the PDSI was developed for the Great Plains areas of the United States, it is perhaps the most commonly used index across the United States. Monthly values for the PDSI ( some dating back to the beginning of the instrumental record in 1895) are available for all climatic regions within the United States. Palmer Hydrologic Drought Index9 " In near- real time, Palmer's index [ the PDSI] is no longer a meteorological index but becomes a hy-drological index referred to as the Palmer Hydro-logical Drought Index ( PHDI) because it is based on moisture inflow ( precipitation), outflow, and storage, and does not take into account the long- term TABLE 1- 1 Palmer Drought Indices Classifications Value Description 4.0 or more Extremely wet 3.0 to 4.0 Very wet 2.0 to 3.0 Moderately wet 1.0 to 2.0 Slightly wet 0.5 to 1.0 Incipient wet spell - 0.5 to 0.5 Near normal - 0.5 to - 1.0 Incipient dry spell - 1.0 to - 2.0 Mild drought - 2.0 to - 3.0 Moderate drought - 3.0 to - 4.0 Severe drought - 4.0 or less Extreme drought 5 1 - Introduction: Drought, Indices and Impacts trend." 10 The PHDI is an adaptation of the PDSI that indicates hydrological drought and does not in-corporate weather and climates trends; it is not " backward- looking" like its PDSI counterpart. Be-cause of this, it generally responds more slowly to weather/ hydrologic conditions than the PDSI. As with the PDSI, PHDI numerical values are generated monthly by the National Climatic Data Center ( NCDC) 11 and are available nationally. The Palmer Indices: 12 􀂾 Provide information on weather anomalies and related hydrologic conditions for a re-gion. 􀂾 Allow scientists to compare recent condi-tions to those measured by various instru-ments for more than 100 years. 􀂾 Provide valuable comparable spatial and temporal data on historical droughts. Both of the Palmer Indices have several draw-backs; most notably- for application in Utah- the indices do not recognize the difference between snow and rain. All precipitation is treated as rain in the indices' calculations. Therefore in regions where snowfall is present, potential inaccuracies in the tim-ing of the PDSI and PHDI values can be created. Snowmelt and rainfall runoff is also not adequately considered and modeled, which generally leads to an underestimation of total runoff. 13 These indices also do not take into account large topographical differ-ences that are present in the Intermountain West. Surface Water Supply Index14 Although the Palmer Indices are widely used across the United States, there are limitations to their application in mountainous regions, which have large topographic ( elevation) variations and are largely dependant upon winter snowpack and surface reservoir storage. Shafer and Dezman developed the Surface Water Supply Index ( SWSI) in 1982, to complement the Palmer Indices and address such limitations. The SWSI is designed to monitor streamflow and surface water storage conditions, which are dependent upon mountain snowpack. Al-though the SWSI was originally developed to de-scribe conditions in Colorado, with minor modifica-tions it is also a useful tool to describe drought con-ditions across other Intermountain states due to their topographical and water supply similarities. The SWSI integrates hydrological and meteoro-logical elements to generate a numerical index simi-lar to the Palmer Indices' values and ranges. The SWSI is centered on zero, which indicates normal conditions, and generally extends between - 4.2 and + 4.2, representing dry and wet conditions respec-tively. SWSI values are calculated by using snow-pack, precipitation and reservoir storage during win-ter months and streamflow, precipitation and reser-voir storage during the summer months. Utah officials use the SWSI as part of the state's Drought Response Plan. According to the plan, the SWSI is used to help officials monitor, assess and report drought conditions during early stages and throughout a drought. For more detail regarding Utah's Drought Response Plan, see Chapter 5- Drought Response. Despite the advantages of the SWSI for use in Utah, some characteristics limit its application: 1) the SWSI calculation is unique to each basin or re-gion and it is therefore difficult to compare across basins or broader regions; and 2) the SWSI index is dependent upon frequency distributions for selected stream gages and reservoir storage facilities and thus must be recalculated when gages are discontinued, changed, new storage reservoirs are constructed, and after extreme events. As a result, it is difficult to maintain a long- term SWSI time series and only about half of the Utah basins have a series that goes back further than 1980. Comparison of Drought Indices Figure 1- 3 compares the PDSI, PHDI and SWSI. The figure plots annual average PDSI and PHDI values for the South Central ( climatic region 4), and North Mountains areas ( climatic region 5) alongside annual values of the SWSI for the Upper Sevier, Provo and Weber River drainages ( see inset map and Box 2- 1 for division of climatic regions in Utah). The three indices are similar, with the SWSI varying the most from the two Palmer Indices. This is ex-pected since the SWSI relies heavily upon stream-flow and surface storage measurements from local streams and reservoirs and generally produces a lag or lead regarding the commencement of a drought when compared to the Palmer Indices as seen in 6 Introduction: Drought, Indices and Impacts - 1 Figure 1- 3. Analysis of these indices also reiterates the fact that while one stage or type of drought, such as hydrological drought ( SWSI), can still be under way, another may have terminated, such as meteoro-logical drought ( PDSI). This can be seen most nota-bly in the Provo River Basin during the 1950s drought. Also, hydrological drought conditions may not appear to be as severe as meteorological drought conditions ( or visa versa), as can be seen in the fig-ure during the 1970s drought. In addition, and not surprisingly so due to the no-table similarities between the two indices, the annual PDSI and PHDI values for each climatic region in Utah are strongly correlated, with r- values ranging from 0.97- 0.98. The closer the r- values are to 1, the stronger the correlation or the more similar com-pared values are. The monthly values are also strongly correlated with r- values ranging from 0.90- 0.93, depending upon climatic region. On the other hand, the Palmer Indices and SWSI are moderately correlated. This is due to the differences in the pa-rameters, calculations of the indices, natural hydro-logic factors, and the result of various operational and management factors, which affects streamflows and reservoir levels. Such operational factors may FIGURE 1- 3 SWSI vs. Palmer Indices Climatic Region 5 ( Northern Mountains) SWSI Provo River Basin PDSI Region 5 PHDI Region 5 SWSI Weber River Basin PDSI Region 4 PHDI Region 4 SWSI Upper Sevier River Basin - 6 - 4 - 2 0 2 4 6 8 - 6 - 4 - 2 0 2 4 6 8 - 6 - 4 - 2 0 2 4 6 8 1953 1956 1959 1962 1965 1968 1971 1974 1977 1980 1983 1986 1989 1992 1995 1998 2001 2004 Drought Index Annual Average Year Climatic Region 4 ( South Central) Provo River Basin and Palmer Indices Weber River Basin and Palmer Indices Upper Sevier River Basin and Palmer Indices Source: SWSI data was obtained from the Natural Resources Conservation Service's webpage: www. ut. nrcs. usda. gov/ snow/ watersupply/ swsi. html. PDSI and PHDI data was obtained from the National Climate Data Center's webpage: http:// www. ncdc. noaa. gov/ oa/ climate/ onlineprod/ drought/ xmgr. html. Utah Division of Water Resources analysis, 2006. Note: See Box 2- 1 for Utah climate divisions/ regions. 7 1 - Introduction: Drought, Indices and Impacts include retaining water in a reservoir longer or re-leasing water earlier to compensate for expected runoff conditions and water demands. Additional analysis of drought with regard to the SWSI and comparisons and discussion of these drought indices are in Appendix A- Comparison of Drought Indi-ces. It can be seen in Figure A- 3 ( of Appendix A) that the SWSI records are quite variable in length. Subsequently it is difficult to obtain spatial informa-tion pertaining to early century droughts using the SWSI record. While water managers and drought experts gener-ally agree that the SWSI is one of the most accurate and meaningful indices to gage the severity of drought in Utah, its limited data set and inability to make spatial comparisons limit its usefulness in ana-lyzing historical drought, which is one of the main purposes of this report. Therefore, in this report, the PDSI is used to define and identify drought events within the instrumental and paleoclimatic records ( see Chapter 2- Historical Drought Events from the Instrumental Record and Chapter 3- Drought from a Paleoclimatic Perspective and Current Climate Trends). Standardized Precipitation Index15 Another index that is relatively new, developed in 1993 by T. B Mckee, N. J. Doesken and J. Kliest from Colorado State University, is the Standardized Precipitation Index ( SPI). This index is based upon precipitation and was originated from the under-standing that precipitation deficits impact groundwa-ter, soil moisture, reservoir storage, streamflow and snowpack differently. " The SPI was designed to quantify the precipitation deficit for multiple time scales. These time scales reflect the impact of drought on the availability of the different water re-sources." 16 For example, soil moisture is greatly influenced by short- scale precipitation anomalies whereas changes in groundwater levels, streamflow and reservoir storage are influenced by longer- term precipitation anomalies or events. The SPI therefore can be calculated for various time scales. The pur-pose of this index is to assign a numerical value re-lating to precipitation that can be compared across climatic divisions and varying topographies. The SPI is basically a probability index. It is based upon the probability of measuring a given amount of precipitation. These probabilities are standardized such that an index value of zero indi-cates the median precipitation amount over the pe-riod of record. Positive values indicate precipitation that is greater than median ( normal to wet condi-tions), and negative values indicate precipitation less than median ( normal to dry conditions). Drought events are identified by the SPI when values are con-tinuously negative and reach an intensity equal to or less than - 1.0. The SPI is used extensively in Colorado and by the National Drought Mitigation Center, and merits further investigation for its application and integra-tion in drought- related monitoring and response ac-tivities in Utah. Diversifying Utah's drought moni-toring portfolio, by utilizing several indices at once, can enhance Utah's ability to manage drought effec-tively. DROUGHT IMPACTS Since the impacts of drought are an integral part of defining and understanding drought, a more de-tailed discussion of these impacts is necessary. Drought impacts vary widely across space, time and economic sectors. While drought can manifest itself in similar ways in various locations- dead lawns in urban areas versus dead crops in a rural setting- the impacts to these areas are vastly different. While dead lawns are unlikely to disrupt many economic activities within a city, dead crops can devastate in-dividual and/ or family farms in rural areas. These impacts cannot just be " measured by the crops ru-ined and cattle sold, but at the cash registers and banks in local towns with effects creeping into the larger economy…" 17 While droughts most directly impact agriculture, intense droughts or droughts of significant duration can produce crosscutting im-pacts, from farmland to life in suburbia. Impacts can be extremely complex, span several sectors within a region and reach far beyond the area actually experi-encing the drought. Drought impacts can either be direct or indirect. 18 For example, a farmer's harvest may be reduced due to drought, which is a direct impact; the subsequent loss of income to the farmer, increased prices for food, and unemployment are indirect impacts. Fur-thermore, drought impacts generally fall into three categories: economic, social and environmental as 8 Introduction: Drought, Indices and Impacts - 1 shown in Table 1- 2.19 Although these categories are used in this document to simplify the discussion, they may not be entirely distinct and separate from one another. Many impacts have economic, envi-ronmental, and social aspects, such as drought-induced or drought- enhanced wildfires, thus necessi-tating consideration of all feasible impacts during planning, mitigation and response actions. Economic impacts occur more prevalently in sec-tors that rely heavily upon surface or subsurface wa-ter supplies. The economies of agriculture, forestry, fisheries and other related sectors, can be severely impacted by drought due to lower productivity, dis-ease, insect infestations and wind erosion. 20 Such impacts commonly cause a ripple- effect. For in-stance, when farmers lose income, businesses that provide financial support or other services to farmers will also suffer. This can lead to " unemployment, increased credit risk for financial institutions, capital shortfalls, and loss of tax revenue for local, state, and federal government." 21 Agricultural- based or water- intensive commodity prices may increase as producers try to offset reductions in supply. Hydro-power production may be significantly reduced ( roughly 60 hydroelectric plants in Utah) and tour-ism and recreation can be negatively affected, im-pacting local, state and even national economies. Social impacts of drought include public health, safety and quality of life. 22 Drought can also induce physical and emotional stress and has been the im-petus for population migration to less impacted ar-eas, which has occurred in isolated areas in Utah ( for instance, many moved from the Abraham area east of Delta during the drought of the 1890s). Such migrations can place increased pressure on the physical and social infrastructure of the area to which people migrate. It also leaves the rural drought- impacted area ( from which people have mi-grated) lacking valuable human resources23 needed for further economic recovery and development. Environmental impacts include damage to wild-life habitat, plants, water quality, forests and much more. These impacts can linger for years with dev-astating effects. Public awareness of the environ-ment, its resiliency and fragility, is steadily growing and demands public officials to direct greater atten-tion and resources to these effects. 24 A long recov-ery time from these as well as other impacts may be required. Not all drought impacts are negative. Generally agriculture, for example, is hit hardest by drought; however, agricultural producers in unaffected areas may benefit from higher prices for agricultural prod-ucts and thereby decreasing economic impacts on a larger- or national- scale. A critical part of under-standing drought is to understand such impacts. Un-fortunately, many drought- related impacts are never quantified and therefore not fully understood. It is important to remember that drought impacts are the result of natural events combined with the vulner-ability of society to water deficiencies. 25 In order to reduce the effects of drought, we must lessen our vulnerability to it. There is a need for additional monitoring of economic, social and environmental parameters during drought years and a more con-certed effort to quantify impacts. For further discus-sion of assessing drought impacts Refer to Appendix B- Assessing Drought Impacts: The Drought Im-pact Reporter. Drought is a natural process that is easily forgot-ten as it comes and goes at an almost imperceptible pace. Drought and its impacts need to be remem-bered in order to facilitate preparations and mitiga-tory actions, which require time and money. See Chapter 4- Mitigation Strategies and Drought Fore-casting and Chapter 5- Drought Response, for fur-ther discussion on drought mitigation and response. TABLE 1- 2 Categories of Drought Impacts Economic Social Environmental Agriculture and Livestock Nutrition Wetland Transportation Reduced Quality of Life Animal and Plant Industry Health and Stress Water Quality Energy Public Safety Wind Erosion Timber Produc-tion Increased Conflicts Infestation, In-sect Tourism and Recreation Cultural Val-ues and Sites Wildfires Source: Adapted from Cody Knutson, Mike Hayes, and Tom Phillips, " How To Reduce Drought Risk," ( 1998). Produced by the Preparedness and Mitigation Working Group of the Western Drought Coordination Council. 9 1 - Introduction: Drought, Indices and Impacts FIGURE 1- 4 Population Projections and Drought Vulnerability 4 2 0 1850 1900 1950 2000 2050 Population ( millions) Historic Drought Events* 1 3 5 Potential Vulnerability to Drought * Drought periods contained in the instrumental record as defined and discussed in Chapter 2. Source: Population data obtained from the Utah Governor's Office of Planning and Budget, 2005. Utah Division of Water Resources analysis, 2006. DROUGHT VULNERABILITY Throughout Utah's history, water users have been vulnerable to drought and suffered from its impacts. Over the years, water planners and managers have successfully reduced this vulnerability by construct-ing surface reservoirs, drilling wells and developing other available water sources. This extensive water development has allowed Utah's population to grow significantly and enabled the economy to prosper. In some cases, water development may create " new" vulnerabilities, such as high water use rates. How-ever, through effective management strategies and public awareness, these " new" vulnerabilities can largely be avoided. While Utah's population and economy are expected to continue their rapid growth, Utah's developable water supplies are lim-ited. In some areas of the state, such water supplies have essentially been fully developed. As the population increases, so too does societies' potential vulnerability to drought impacts ( see Fig-ure 1- 4). In order to decrease this susceptibility, wa-ter managers will need to implement innovative wa-ter management strategies to ensure that Utah's fu-ture water supplies are efficiently used and as reli-able as possible during periods of drought 10 Introduction: Drought, Indices and Impacts - 1 NOTES 1 McKee, Thomas B., Nolan J. Doesken and John Kleist, A History of Drought in Colorado: Lessons Learned and What Lies Ahead, ( Fort Collins: Colorado Climate Center, 2000), 5. 2 National Drought Mitigation Center, " What is Drought?" Retrieved from the National Drought Mitigation Center's Internet web page: http:// drought. unl. edu/ whatis/ what. htm, August 2006. 3 For an excellent discussion of these drought categories, see: National Drought Mitigation Center, " What is Drought? Understanding and Defining Drought." Available on the center's Internet web page: http:// drought. unl. edu/ whatis/ concept. htm. 4 Ibid. 5 Ibid. 6 Dr. Michael J. Hayes, " What is Drought?: Drought Indices." Retrieved from the National Drought Mitigation Cen-ter's Internet web page: http:// drought. unl. edu/ whatis/ indices. htm# pdsi, June 2006. The following has been adapted from the NDMC discussion on drought indices. 7 Ibid. The following has been adapted from the NDMC discussion on the Palmer Indices. 8 National Climatic Data Center, " Climate of 2006 - August U. S. Palmer Drought Indices." Retrieved from the NOAA Satellite and Information Service's Internet web page: http:// lwf. ncdc. noaa. gov/ oa/ climate/ research/ prelim/ drought/ palmer. html, June 2006. 9 Dr. Michael J. Hayes, June 2006. The following has been adapted from the NDMC discussion on the Palmer indi-ces. 10 Dr. Michael J. Hayes, " What is Drought?: Drought Indices." Retrieved from the National Drought Mitigation Center's Internet web page: http:// drought. unl. edu/ whatis/ indices. htm# pdsi, February 2007. 11 Division of Oil, Gas and Mining, " Precipitation Affects Water Availability." Retrieved from the State of Utah, Department of Natural Resources' Internet web page: http:// www. ogm. utah. gov/ coal/ water/ WEATHER. HTM, June 2006. 12 Dr. Michael J, Hayes, June 2006. 13 Ibid. 14 Ibid. The following has been adapted from the NDMC discussion on the SWSI. 15 Ibid. The following has been adapted from the NDMC discussion on the SPI. 16 Ibid. 17 Nebraska's Senator Nelson, " The Drought, A Nebraskan's View." Retrieved from the Internet web page: http:// www. senate. gov/~ bennelson/ news/ details. cfm? id= 239387&&, July 2006. 18 " Impact of Drought." Retrieved from the NDMC ' s Internet web page: www. drought. unl. edu/ risk/ impacts. htm, June 2006. 11 1 - Introduction: Drought, Indices and Impacts 19 Cody Knutson, Mike Hayes, and Tom Phillips, " How To Reduce Drought Risk," ( 1998). Produced by the Prepar-edness and Mitigation Working Group of the Western Drought Coordination Council. 20 " Impacts of Drought." June 2006. 21 Ibid. 22 Ibid. 23 Ibid. 24 Ibid. 25 Donald A. Wilhite, " Improving Management in the West: The Role of Mitigation and Preparedness," ( Lincoln: National Drought Mitigation Center, 1997), 6. 12 2 HISTORICAL DROUGHT EVENTS FROM THE INSTRUMENTAL RECORD To better understand how to manage Utah's water resources during drought and thereby decrease vul-nerability to it, it is prudent for water managers to take a look at and put in perspective historical drought events that have occurred in Utah. Droughts are common in Utah and the state's natural level of aridity, and limited water supply, compound the ef-fects of drought. Scientists measure drought condi-tions by using various indices ( as described in Chap-ter 1- Introduction: Drought, Indices and Impacts). These indices, some of which go back as far as 1895, make up the instrumental record of historical drought. From this century- long record, several sig-nificant drought events are easily recognized at a national scale as well as within each of Utah's seven climatic regions ( see Box 2- 1). This chapter chroni-cles the severity, areal extent and some of the im-pacts of each of these droughts in Utah as well as nationally. UTAH DROUGHTSWITHIN THE INSTRUMENTAL PDSI RECORD In the late 1800s, scientists began to measure and record weather conditions resulting in an instrumen-tal record, which is widely available today. Gener-ally, the Surface Water Supply Index ( SWSI) is used as a drought indicator ( which triggers the implemen-tation of a certain drought response actions) in Utah. However, due to the lack of long- term SWSI data and in order to allow a direct comparison of droughts recorded in the instrumental record with droughts of the not- so- distant past and ancient droughts recorded in " proxy records," the Palmer Drought Severity Index ( PDSI) instrumental record is used in this report to identify significant drought periods. In Utah this record spans a 111- year period ( from 1895- present) and contains several monitored weather parameters. This record provides us with " a picture of the short- term behavior and spatial pat-terns of drought, helping scientists learn more about the character of droughts." 1 Data reliability of the instrumental record de-creases farther back in time due to fewer weather monitoring stations and less dependable technolo-gies. By analyzing the PDSI data graphically, dis-tinct drought periods are easily recognized. These droughts vary in duration, intensity and impacts to the state. For the purpose of exploring and understanding historical drought contained in the instrumental PDSI record in this document, drought events were defined and identified using the following criteria: 􀂾 A drought was considered to have started with two consecutive years of annual aver-age PDSI values less than or equal to - 1.0. 􀂾 The drought was terminated with two con-secutive years of near or above normal con-ditions ( annual average PDSI above - 0.5). Refer to Table 1- 1 for Palmer Drought Index clas-sifications. Following these basic guidelines, the Utah Division of Water Resources analyzed the PDSI instrumental record. The term " drought" from this point on, with re-gard to the instrumental and tree- ring records, refers to drought as defined by these criteria unless other-wise indicated. 13 2 - Historical Drought Events From the Instrumental Record 14 Box 2- 1- Utah Climate Divisions 0 10 20 40 60 80 Miles Enterprise Current Creek Junction Little Sahara Dunes LEGEND Price Promontory Hiawatha Ferron Capitol Reef Nat'l Park Zion 􀈱 Nat 􀈇 l 􀈱 Park Big Water WESTERN 1 NORTH CENTRAL 3 NORTHERN MOUNTAINS 5 UINTA BASIN 6 SOUTHEAST SOUTH 7 CENTRAL 4 DIXIE 2 Selected Locations Counties Climatic Regions Waterbodies Logan Brigham City Ogden Farmington Salt Lake City Lehi Provo Spanish Fork Nephi Delta Neola Vernal Hanksville Escalante Milford Cedar City Kanab N Utah has been divided into the seven climatic regions as shown. These regions or divi-sions are areas within the state that are relatively homogenous in terms of their climate. The divisions allow for a more detailed representation of climate variability within the state. Identification of Utah Droughts Since the commencement of weather measure-ments, Utah has experienced several noteworthy droughts. Analysis of PDSI data collected in the state's seven climate divisions reveals six significant droughts ( see Figure 2- 1), during 1898- 1905, 1928- 1936, 1946- 1964, 1976- 1979, 1987- 1992 and 1999- 2004. The state maps in Figure 2- 1 represent the cumulative areal extent and intensity of each drought. The graphs also indicate drought intensity as well as drought duration in each of the seven cli-mate divisions. Historical Drought Events From the Instrumental Record - 2 FIGURE 2- 1 Instrumental PDSI Record- Drought Delineation Source: Utah Division of Water Resources analysis, 2006. 15 2 - Historical Drought Events From the Instrumental Record These droughts can also be identified ( or verified) using hydrologic data. For instance, these droughts are expressed by fluctuating lake elevations of the Great Salt Lake ( see Figure 2- 2). Pre- 1875 lake ele-vation data is termed " inferred data" as it was de-termined from historical accounts. Post- 1875 data is gauged or measured data. The Great Salt Lake re-ceives mountain runoff, which is extremely sensitive to precipitation changes and therefore lake levels can be used as a record of regional drought ( representing climatic regions 3 and 5). As shown in Figure 2- 2, declines in lake elevation coincide quite nicely with droughts identified using the PDSI and defined drought criteria. Figure 2- 3 displays hydrographs of the Virgin River and Ashley Creek, representing climatic re-gions 2 and 5 respectively. The drought durations identified in these climatic regions ( refer to Figure 2- 1) by using the PDSI record and defined drought criteria are reinforced by these hydrographs. The horizontal green lines represent the historic average or average annual flow for the entire period of re-cord. The areas shaded red indicate below average flow and correspond rather well with the PDSI iden-tified droughts. As would be expected, the vast ma-jority of low flow and extreme low flow events take place during these droughts. PDSI Parameters- Temperature and Precipitation As discussed in Chapter 1, the PDSI is largely based upon temperature and precipitation. Figure 2- 4 presents statewide precipitation and temperature maps of single years- with the lowest annual aver-age PDSI values- within each drought period and the statewide " normal" precipitation and temperature over 1971- 2000. Spatial similarities between pre-cipitation and temperature distribution ( Figure 2- 4) and areal extent and severity of each drought ( Figure 2- 1) can be seen. Precipitation decreased signifi-cantly statewide during the years shown- the peak of each drought- as large areas of the state received only 0- 5 inches of rainfall. FIGURE 2- 2 Great Salt Lake Elevations During Drought * 1999- 2003 * 1987- 1992 * 1976- 1979 * 1900- 1905 * 1930- 1935 4190 4195 4200 4205 4210 4215 1845 1855 1865 1875 1885 1895 1905 1915 1925 1935 1945 1955 1965 1975 1985 1995 2005 Lake Elevation ( ft) * 1953- 1963 Inferred Data Gauged Data Note: * The duration of each drought period correlates with the cumulative drought durations on Figure 2- 1 for climate regions 3 and 5 for each drought. These regions are the main regional areas that contribute to the Great Salt Lake. Source: Utah Division of Water Resources analysis, 2006. 16 Historical Drought Events From the Instrumental Record - 2 FIGURE 2- 3 Variability of precipitation and temperature be-tween each drought event is also expressed in this figure. There are several ways to conduct an analysis of drought, which can be done at several scales. It would be prudent to look at drought using multiple indices and indicators at various spatial scales, such as at the watershed or river basin levels. However, the use of climatic regions satisfies the scope of this chapter, which is to give a general overview of re-gional and local historical drought variability. Recurrence Intervals and Frequencies of Utah Drought Conditions Statewide and regional recurrence intervals and frequencies of mild to severe annual drought condi-tions ( see Box 2- 2 for definition) are shown in Table 2- 1. Recurrence intervals were calculated by divid-ing the total number of years on record by the num-ber of years where a PDSI value was equal to or less than - 1.0, - 2.0 and - 3.0 for mild, moderate and se-vere drought conditions respectively. Frequencies were calculated as the number of years where mild to severe drought conditions occurred divided by the total number of years on record. Average Annual River Flow and Drought Average Annual Flow ( cfs) Water Year Ashley Creek near Vernal 0 50 100 150 1910 1915 1920 1925 1930 1935 1940 1945 1950 1955 1960 1965 1970 1975 1980 1985 1990 1995 2000 2005 Virgin River at Virgin 0 100 200 300 400 500 Modeled Data Note: Virgin River- PDSI drought durations correlate with climatic region 2 ( Figure 2- 1). Ashley Creek- PDSI drought durations correlate with climatic region 5 ( Figure 2- 1). Green line indicates annual average flow over the entire record. 17 2 - Historical Drought Events From the Instrumental Record FIGURE 2- 4 Utah Statewide Precipitation and Temperature- Peak of Drought Periods Precipitation In Inches 0 - 5 5 - 10 10 - 15 15 - 20 20 - 25 25 - 30 30 - 40 40 - 50 50 - 70 Normal ( 1971 to 2000) 1977 1990 2002 1902 1934 1956 Normal ( 1971 to 2000) 1977 1990 2002 Avg. Max 80 - 90 75 - 80 70 - 75 65 - 70 60 - 65 55 - 60 45 - 55 40 - 45 0 - 40 Temperature 1902 1934 1956 Precipitation Temperature Note: Single years with lowest annual average PDSI value during each drought compared to the average annual precipitation over 1971- 2000. Source: Utah Division of Water Resources analysis, 2006. 18 Historical Drought Events From the Instrumental Record - 2 Box 2- 2- Drought Conditions: Intervals and Frequencies Criteria used to calculate recurrence intervals and frequencies of drought conditions differ from the definition of drought used previously ( see drought criteria on page 13) in that all years ( single non- consecutive years included) with a PDSI < - 1.0 were included ( resulting in recurrence intervals and frequencies of annual drought conditions, not necessarily d-roughts per the drought criteria). Therefore drought conditions may refer to a single year. On average, Utah has experienced moderate to se-vere statewide drought conditions once every 15.7 to 36.7 years ( see Table 2- 1) respectively. In reality, years of statewide drought conditions generally oc-cur in groupings of consecutive years ( i. e. not equally distributed every " x" number of years) as can be seen in Figure 2- 5. Regional recurrence in-tervals for moderate to severe drought conditions range from 3.7 to 5.2 and 6.9 to 13.8 years, respec-tively. This means, for example, that regional mod-erate drought conditions are present one out of every 3.7 to 5.2 years on average ( for any given climatic region). The Western area ( climatic region 1) has most frequently experienced mild to severe drought condi-tions in comparison with the other regions, whereas the Northern Mountains ( climatic region 5) has one of the lowest frequency of annual drought condi-tions. BRIEF SUMMARY OF THE IDENTIFIED DROUGHTS The following sections provide a brief summary of the six Utah droughts identified within the in-strumental PDSI record. Although details of some early droughts are not well documented, these sum-maries provide a snapshot of how drought has influ-enced Utah and its citizens over the past century. A few details regarding regional and national impacts of these droughts are also provided, which adds valuable perspective. Drought of 1898- 1905 In 1898, mild drought conditions developed in the Dixie and Southeast climatic regions. These condi-tions intensified the next year and spread to other regions, eventually involving the entire state from 1900- 1903, and persisted two more years in the South Central, North Central, Northern Mountains and Uinta Basin climatic regions. TABLE 2- 1 Recurrence of Mild to Severe Drought Conditions Based on the PDSI PDSI < - 1 PDSI < - 2 PDSI < - 3 Climatic Region Recurrence Interval ( yr) Frequency (%) Recurrence Interval ( yr) Frequency (%) Recurrence Interval ( yr) Frequency (%) 1 2.6 38.2 3.7 27.3 6.9 14.6 2 2.7 37.3 5.0 20.0 13.8 7.3 3 3.1 31.8 4.4 22.7 8.5 11.8 4 3.1 32.7 5.2 19.1 9.2 10.9 5 3.3 30.0 5.2 19.1 8.5 11.8 6 2.9 34.6 4.6 21.8 11.0 9.1 7 2.9 34.6 5.0 20.0 9.2 10.9 Statewide* 10 10 15.7 6.4 36.7 2.7 Note: * Statewide refers to instances where all seven of the climatic regions experience drought conditions simul-taneously. Source: Utah Division of Water Resources analysis, 2007. 19 2 - Historical Drought Events From the Instrumental Record This was the longest drought contained in the in-strumental record experienced in the Southeast ( cli-matic region 7), persisting for a 7- year span ( see Ta-ble 2- 2). During this drought, region 7 also experi-enced the worst multi- year drought PDSI average of any region at - 3.91 fol-lowed by the South Cen-tral and Uinta Basin ( cli-matic regions 4 and 6) with average drought PDSI values of - 3.27 and - 3.17 respectively ( see Table 2- 3). FIGURE 2- 5 Percent of Utah Experiencing Mild to Severe Drought Conditions Many Utah farmers suffered greatly during this drought and were in dire need of assistance. The Relief Society of the Church of Jesus Christ of Latter- day Saints donated nearly 35,000 bushels of wheat in an effort to assist drought- stricken farmers. 2 Ranchers were not faring well either. Due to over-grazing and drought-related conditions, the majority of " speculative cattle operations folded by the end of the dec-ade…" 3 and in 1900, it was reported in the Davis County Clipper ( local newspaper) that the honey crop was only one- fifth of previous years due to the drought and resulting lack of flower blossoms. 4 Many Utahns were forced to find relief from drought- stricken areas and as a result, moved to " greener pastures." The Abraham area, east of Delta, lost many of its settlers due to this drought and inadequate water rights. 5 Many of these settlers did not return, leaving the area without crucial human resources. Based on the PDSI Percentage of State 0 20 40 60 80 100 1895 1905 1915 1925 1935 1945 1955 1965 1975 1985 1995 2005 0 20 40 60 80 100 0 20 40 60 80 100 PDSI < - 1 Mild Drought PDSI < - 2 Moderate Drought PDSI < - 3 Severe Drought Year 1928- 1336 1946- 1964 1976- 1979 1987- 1992 1999- 2004 1898- 1905 Note: Percentages were calculated using the seven climatic regions and their corre-sponding areal percentage of the state. Source: Utah Division of Water Resources analysis, 2006. 20 Historical Drought Events From the Instrumental Record - 2 TABLE 2- 2 Drought of 1928- 1936 The drought of the late- 1920s to mid- 1930s, known as the " Dust Bowl Years," holds a significant place in our nation and state's his-tory. Although this drought may have been shorter than other droughts in Utah ( see Figure 2- 1), it boasts the lowest multi- year PDSI average ( compared to the other five droughts) contained in the instru-mental record of - 5.08. This oc-curred over a 5- year period in the Northern Mountains, climatic re-gion 5 ( see Table 2- 3) from which the majority of the state's popula-tion received its water supply. The drought's areal extent covered ap-proximately 50% of the state for three consecutive years, and at its peak in 1934, moderate drought conditions were manifested in 98% of the state ( see Figure 2- 5) with The drought impacted other southwestern states as devastating impacts. well. The Salt Lake Tribune reported in 1899, that in New Mexico, " on account of unprecedented drought and the recent order of the Interior depart-ment in excluding ranchmen from forest reserva-tions, sheepmen are in a bad plight and sheep are dying by the thousands." 6 In 1934, Utah's annual streamflow was only 50% of its mean annual discharge. This lack of water was reflected in crop production. Merely 59% of the 1921- 1930 average crop yield was produced. 7 The U. S. Department of Agriculture's Statistical Report-ing Service recorded that corn yield had dropped to Longest Drought on Record by Climatic Region Based on the PDSI Climatic Region Years Duration ( yr) Minimum Annual PDSI Value Average An-nual PDSI Value for Drought Du-ration 1 1950- 1961 12 - 3.92 - 3.48 2 1946- 1964 19 - 3.88 - 1.39 3 1953- 1963 11 - 4.34 - 1.96 4 1950- 1964 15 - 4.02 - 1.60 5* 1900- 1905 6 - 4.02 - 2.77 6 1953- 1964 12 - 3.50 - 1.62 7* 1898- 1904 7 - 5.00 - 3.91 Statewide 1900- 1903 4 - 4.29 - 3.57 Note: Drought durations were calculated based on the established drought criteria. * Two droughts were of equal duration; the most severe ( lowest average PDSI) is shown. Source: Utah Division of Water Resources analysis, 2006. See Figure 2- 1 for visual representation. TABLE 2- 3 Most Intense Droughts on Record by Climatic Region ( Lowest PDSI Average of Drought Duration) Climatic Region Years Duration ( yr) Minimum Annual PDSI Value Average Annual PDSI Value for Drought Duration 1 1999- 2004 6 - 4.98 - 3.48 2 1999- 2004 6 - 5.02 - 2.72 3 1900- 1905 6 - 4.70 - 3.10 4 1899- 1905 7 - 4.81 - 3.27 5 1931- 1935 5 - 7.76 - 5.08 6 1899- 1905 7 - 4.99 - 3.17 7 1898- 1904 7 - 5.00 - 3.91 Statewide 1989- 1990 2 - 3.98 - 3.58 Source: Utah Division of Water Resources analysis, 2006. See Figure 2- 1 for visual representation. 21 2 - Historical Drought Events From the Instrumental Record 17 bushels per acre in 1934 from 32 bushels per acre in 1929. Also, winter wheat production decreased from 22 bushels per acre in 1930 to 14 bushels per acre in 1934. A farmer in the Uintah Basin recorded that at the peak of the drought " our grain burned completely and there was no harvest." 8 After the end of the drought in 1936, farm numbers decreased by approximately 3,000 ( 10%) over a three- year pe-riod. Total cattle ( including calves and bulls) de-creased by 73,000 head from 1934 to 1935, a 15% reduction. 9 In addition to agricultural impacts, water storage supplies rapidly diminished; Utah Lake contained only 1/ 3 of its total volume. During the summer of 1934, many communities established outdoor water use restrictions with lawn watering permitted only twice a week. 10 To help alleviate the impacts of the drought, in 1934 Utah appealed to the federal gov-ernment and within thirty- six hours President Roo-sevelt approved a grant for $ 600,000 and another for $ 400,000 shortly thereafter. That is the equivalent of approximately $ 14.6 million in 2005 dollars- dollar amounts, where indicated throughout this chapter, were converted to 2005 dollars using the consumer price index to give a rough estimate of costs. With this funding, several drought response actions were taken: 276 wells were installed, miles of pipeline were laid, and miles of irrigation ditches were lined. 11 This drought impacted the na-tion and affected an entire gen-eration. Approximately 65% of the country was affected by the drought in 1934.12 Residents of the Great Plains were over-whelmed by agricultural and economic losses. 13 As a result, agriculture was abandoned in some areas of the country and large numbers of people relo-cated to California, impairing the economic substructure that supported agriculture in the Great Plains. 14 " By 1940, 2.5 million people had moved out of the Plains states; of those, 200,000 moved to California." 15 The environmental impacts were undoubtedly severe and aggravated by poor agricultural practices as farmers struggled to turn a profit. Barren and over-grazed agricultural land perpetuated immense dust storms throughout the mid- West. It was estimated that the federal government provided financial assis-tance upwards of approximately $ 14.1 billion ( in 2005 dollars). 16 Additional unmeasured individual economic losses, costs in the form of social distress, and much more certainly raise the toll of the Dust Bowl not only nationally but within Utah as well. Drought of 1946- 1964 In many aspects, the drought that spanned the en-tire 1950s in most of Utah's climatic regions rivals the Dust Bowl. In the majority of Utah's climatic regions, this drought surpasses the Dust Bowl in du-ration. In the Western and Southeast ( climatic re-gions 1 and 7) the Dust Bowl is exceeded in inten-sity as well. This period was the longest drought contained in the instrumental record for all regions of the state ( with exception of the Northern Moun-tains and Southeast), averaging 13.8 years. Drought conditions existed statewide during 1954 and 1960 ( see Figure 2- 5). During this drought, a significant portion of Utah was declared a disaster area17 with impacts more Dust storm in Stratford, Texas in April of 1935. This was a common sight as the landscape was ravaged by drought and wind erosion. Photo: cred-ited to NOAA George E. Marsh Album. Source: http:// www. photolib. noaa. gov/ historic/ c& gs/ theb1365. htm 22 Historical Drought Events From the Instrumental Record - 2 severe than the 1930s drought in some local areas. However, impacts overall ( statewide) appear to have been reduced due to action taken and lessons learned from previous drought. Mitigation measures ( al-though not called that at the time) including con-struction of reservoirs and other water supply pro-jects such as ground water development were pur-sued and completed. In addition, advancements were made in agricultural practices and land man-agement, and a much stronger economy was in place. Even with such improvements, however, ag-riculture could not endure the drought unscathed. There was a significant reduction in crop yield statewide. Winter wheat harvest decreased from 22 bushels per acre to a low of 13 bushels per acre in 1952. During the 1950 and 1951 water years ( Oct.- Sept.), southern Utah received approximately 57% of the precipitation average of 1921- 194518 ( an av-erage that includes the 1928- 1936 drought); how-ever, due to mitigation projects, the impacts were subdued. Without the mitigatory measures taken to develop water resources and stabilize the water sup-ply prior to this drought, its impacts would have been far more severe. During the early 1950s, just under half19 of the contiguous United States was affected by drought. Low rainfall and excessively high temperatures characterized this event. 20 Millions of cattle died across the Southwest and southern Plains, causing ranchers to relocate their livelihood to other regions of the country. 21 Crop yields in some areas dropped as much as 50%. 22 Due to this and other losses, the federal government estimated that it spent $ 3.95 bil-lion ( in 2005 dollars), in relief efforts during this drought. 23 Drought of 1976- 1979 The period from August 1975 through most of 1977 was one of the driest periods on record. In 1976 the statewide average precipitation was only 7.71 inches24 and mild drought conditions affected 92% of the state and moderate drought conditions were experienced statewide in 1977 ( Figure 2- 5). In an attempt to curtail wasteful water use, ap-proximately 36% of the surveyed municipal ( or pub-lic) water suppliers increased water rates during 1977.25 Seven of Utah's counties were hit especially hard, with 40 to 100%, of the crops lost. In 1977, Governor Matheson requested Federal Disaster Dec-larations for these counties. 26 The state and its citi-zens lost millions of dollars from decreased agricul-ture productivity and reduced recreation activity. From 1976 to 1977, decreased field crop production resulted in a loss of $ 13 million ($ 38.9 million in 2005 dollars) in potential revenue. 27 Winter snowpack was also limited and, as a result, the ski industry greatly suffered, losing millions of dollars. The Utah Ski Association was forced to look into obtaining federal loans for Utah's ski re-lated businesses due to impacts of this drought. By the end of 1977, it was estimated that the state and its citizens lost a total of $ 41 million28 ($ 132 million in 2005 dollars) due to drought- related impacts. The environment felt the effects of the drought as well. Reservoir levels dropped significantly, resulting in increased water temperatures, subsequent large die-off of fish and other environmental impacts. Lack of winter precipitation resulted in harsh drought conditions in the West, and at the peak of the drought, affected approximately 35% of the country. 29 The Western Governors' Policy Office estimated federal drought response to this short- lived drought cost roughly $ 7.62 billion ( in 2005 dol-lars). 30 A separate estimate indicated that federal assistance was upwards of $ 10.8 billion ( in 2005 dollars) for agriculture alone. 31 The disparity be-tween these two estimates illustrates the need for better drought impact assessments of all economic sectors. Drought of 1987- 1992 In 1987, drought conditions manifested them-selves in the western and northern regions of the state. These conditions intensified the following year and spread to other regions of the state, eventu-ally affecting the entire state. In 1989 and 1990 moderate and severe drought conditions, respec-tively, were statewide ( see Figure 2- 5). The drought persisted two more years in all climatic regions ex-cept for the Dixie and Southeast regions. The North Central region ( climatic region 3) recorded the low-est PDSI average for the duration of this drought at - 2.89 ( relative to PDSI averages for the duration of the drought in other regions). Statewide, stream-flows were well below average, however, in 1990 the Colorado River and Wasatch Front Basins were 23 2 - Historical Drought Events From the Instrumental Record in relatively well condition up to this point with 72 and 77 percent of their respective reservoir capaci-ties. 32 The 1987 water year for the Salt Lake area was sub- par, with total precipitation of only 9.94 inches compared to the average 15.31 inches. Water storage in Bear Lake was well below average as well; indicated by an extremely low water elevation by the end of the drought. Only dur-ing the Dust Bowl and most recent drought ( 1999- 2004) have Bear Lake elevations been lower ( see Figure 2- 6). Springs and wells in northern Utah dried up and flows in streams and rivers were well below normal, 33 not boding well for wildlife and agricultural activities. It was reported that in certain units throughout the state, up to 80% of the deer population was lost during the winter of 1992 due to the lack of suitable forage in the preceding months. This lack of forage and suitable rangeland was also a problem for cattle and sheep during the drought. In 1988, much of the summer range was diminished due to the drought, most notably in the northern re-gions of the state, resulting in low cattle and sheep prices as ranchers were forced to thin out their herds. 34 Efforts were made to alleviate impacts to the ag-riculture sector. Temporary water sales, totaling 10,000 acre- feet, were made from Soldier Creek Reservoir to the Central Utah Project for irrigation purposes. 35 Other areas of the state enacted water use ordinances and restrictions, as was the case in the City of Price. 36 The drought affected approximately 36% of the country. 37 The northern and eastern Great Plains, which have greater agricultural productivity and a denser population ( relative to the Southwest) were hit hardest by the drought. 38 It was estimated that $ 6.59 billion ( in 2005 dollars) in relief for the agri-culture sector was appropriated by the federal gov-ernment. 39 Total cost of the drought from both di-rect and indirect impacts range from an estimated $ 39 billion40 to a staggering $ 61.6 billion ($ 66.9 billion in 2005 dollars). 41 Along with this monetary cost, societal impacts were abundant with approxi-mately 7,500 deaths attributable to the heat wave that accompanied the drought. The drought year of 1988 is the most costly drought- related event on re-cord. Prior to Hurricane Katrina it was the single most costly natural catastrophe in U. S. history. Drought of 1999- 2004 FIGURE 2- 6 Bear Lake Elevations During Drought 5900 5905 5910 5915 5920 5925 1920 1925 1930 1935 1940 1945 1950 1955 1960 1965 1970 1975 1980 1985 1990 1995 2000 2005 Lake Elevation ( ft) Note: Annual maximum and minimum elevations are shown. Color shading indicates droughts per the PDSI instrumental record. The width of the shading correlates to the drought durations for climatic region 5 ( Figure 2- 1), in which Bear Lake is located. Similar to the 20th Century, the 21st Century was ushered in with drought. The year 2002 was one of the hottest and driest on record, ranking 18th and 7th respectively ( as of 2005). Although this drought faded away in Utah during 2005, it lingered on in some areas of the U. S. It is comparable to other ma-jor droughts in duration and magnitude. 42 In the Dixie and Western regions ( climatic regions 1 and 2) the drought lasted 6 years and yielded the lowest average PDSI values ( for the duration of the drought) relative to past droughts in the instrumental record for these regions ( see Table 2- 3). Drought 24 Historical Drought Events From the Instrumental Record - 2 conditions reached a statewide areal extent for two consecutive years, 2002- 2003, with moderate condi-tions in 2003 ( Figure 2- 5). Although it is compara-ble to past droughts of the 20th Century in several respects, 43 due to the notable increase in population and subsequent increased demand for water, the im-pacts in some areas of the state were more severe than previous droughts. 44 This drought would have had much greater impacts had it not been for the many water development ( mitigation) projects that were in operation. The drought first began in the Dixie and Western regions in 1999 and by 2000, except for the South Central climatic region, drought conditions were apparent throughout the state. It is reported to be the worst drought experienced in parts of the Upper Colorado River Basin ( the eastern half of the state) in the last 80 years. 45 The water deficit of the Colo-rado River ( near Cisco, Utah) incurred due to the drought was almost equal to two years of average stream flow. 46 The National Weather Service ( NWS) analyzed flows of six Utah river basins ( river headwater gauge volumes) and ranked the driest or lowest 5- year average flows over 1999- 2003 ( see Table 2- 4). 47 During this 5- year span, the Bear River Basin experienced the lowest 5- year average flow in its period of record ( 1948- 2003) and flows of four other basins experienced averages that fell within the top five lowest, 5- year averages of their respective records. Statewide temperature rankings for individual years during this drought are presented in Table 2- 5. From 1999- 2004, statewide annual average tempera-tures were consistently above normal, which com-pounded drought conditions throughout the state. In addition, in 2002 statewide precipitation plummeted below normal conditions, lowering surface runoff. Several stream flows in the state were well below their average flow. Small reservoirs profoundly felt the effects as well. Where water once was 30 feet deep there was only a puddle as a 390 acre- foot res-ervoir near Enterprise, Utah dried up. 48 Several years of below- normal precipitation lowered levels of numerous large reservoirs as well, resulting in the capacity of critical reservoirs falling below 50% in 2004 ( see Figure 1- 1 of Chapter 1). Such conditions required three towns, Park Valley, Ponderosa Ranch and Oak City to haul in water49 in order to supple-ment the public water supply. Dry- crop farmers were hit exceptionally hard by the drought. One farmer of southern Utah, east of Monticello said that their 5,000- acre farm usually yields 20 to 25 bushels per acre of wheat but in 2002 they averaged only 6 bushels per acre and their corn did not produce a harvestable crop. Governor Leavitt declared a statewide agricultural disaster, which was promptly followed by additional disaster declarations due to grasshopper and Mormon cricket infestations. 50 TABLE 2- 4 5- Year Average Flow ( 1999- 2003) Rankings of River Basins River Basin Rank Bear River Drainage* 1 Logan River Drainage 13 Provo River Drainage 3 Sevier River Drainage 5 Virgin River Drainage 4 Weber River Drainage 4 * Example: Bear River had the lowest 5- year average flow- from 1999- 2003- in its record, compared to other five- year averages. Source: Adapted from a presentation given by Brian McInerney, NWS entitled " Comparison of Utah's Current Drought to Past Years," 2003. TABLE 2- 5 Statewide Annual Temperature Rankings- Warmest Year ( Jan- Dec) Years in Record Rank Description 1999 105 6 Much above normal 2000 106 2 Much above normal 2001 107 4 Much above normal 2002 108 16 Above normal 2003 109 3 Much above normal 2004 110 24 Above normal Source: Compiled data from Annual Climate Review re-ports