26122 Water Resources and Environment The World Bank Technical Note C.2 Public Disclosure Authorized Environment Department The World Bank 1818 H Street, N.W. Washington, D.C. 20433, U.S.A. www.worldbank.org For information on these publications contact the ESSD Advisory Service at [email protected] or call 202.522.3773 Public Disclosure Authorized Environmental Flows: Case Studies Public Disclosure Authorized Public Disclosure Authorized Series Editors Richard Davis Rafik Hirji WATER RESOURCES AND ENVIRONMENT TECHNICAL NOTE C.2 Environmental Flows: Case Studies SERIES EDITORS RICHARD DAVIS, RAFIK HIRJI The World Bank Washington, D.C. Water Resources and Environment Technical Notes A. Environmental Issues and Lessons Note A.1 Environmental Aspects of Water Resources Management Note A.2 Water Resources Management Policy Implementation: Early Lessons B. Institutional and Regulatory Issues Note B.1 Strategic Environmental Assessment: A Watershed Approach Note B.2 Water Resources Management: Regulatory Dimensions Note B.3 Regulations for Private Sector Utilities C. Environmental Flow Assessment Note C.1 Environmental Flows: Concepts and Methods Note C.2 Environmental Flows: Case Studies Note C.3 Environmental Flows: Flood Flows Note C.4 Environmental Flows: Social Issues D. Water Quality Management Note D.1 Water Quality: Assessment and Protection Note D.2 Water Quality: Wastewater Treatment Note D.3 Water Quality: Nonpoint-Source Pollution E. Irrigation and Drainage Note E.1 Irrigation and Drainage: Development Note E.2 Irrigation and Drainage: Rehabilitation F. Water Conservation and Demand Management Note F.1 Water Conservation: Urban Utilities Note F.2 Water Conservation: Irrigation Note F.3 Wastewater Reuse G. Waterbody Management Note G.1 Groundwater Management Note G.2 Lake Management Note G.3 Wetlands Management Note G.4 Management of Aquatic Plants H. Selected topics Note H.1 Interbasin Transfers Note H.2 Desalination Note H.3 Climate Variability and Climate Change Copyright © 2003 The International Bank for Reconstruction and Development/THE WORLD BANK 1818 H Street, N.W., Washington, D.C. 20433, U.S.A. All rights reserved. Manufactured in the United States of America First printing March 2003 2 CONTENTS Foreword 5 Acknowledgments 7 Introduction 9 River Ecosystems and Environmental Flows 10 Rivers respond to both natural disturbances and man- made disturbances. In general, the more the flows are changed for a specific river, the more the river‘s ecol- ogy will change. The Lesotho Highlands Water Project 12 One of the world’s largest water resource develop- ments, the Lesotho Highlands Water Project will even- Authors tually comprise seven major dams on the headwaters Jacqueline King, Catherine Brown of the Senqu River system. Social and ecological con- cerns about the first dam built led to an environmen- Technical Adviser tal flow assessment for existing and planned parts of Stephen Lintner the development. Editor The Skagit River Hydroelectric Project 17 Robert Livernash An application to renew the operating license for hy- dropower dams on the Skagit River in the northwest- Production Staff ern United States created an opportunity to incorporate Cover Design: Cathe Fadel environmental flows into the license. Design and Production: The Word Express, Inc. The Murray-Darling Cap on Abstractions 20 Rivers of the Murray-Darling Basin in southeastern Aus- Notes tralia are seriously degraded as a result of over-ab- Unless otherwise stated, straction and increasing nutrient and salinity levels. A all dollars = U.S. dollars. “cap” on abstractions will limit further degradation until All tons are metric tons. flow assessments can be completed and environmen- tal flows implemented. The boundaries, colors, denominations, and any other information shown on any Widening Application of the Concept of maps do not imply, Environmental Flows 24 on the part of the World Bank Group, Environmental flow assessments also can be applied any judgment on the legal to wetlands, lakes, deltas, and inland seas. status of any territory, or any endorsement or acceptance of such boundaries. Conclusion 27 Water resources developments that alter the pattern Cover photo by of water movement in aquatic ecosystems need to J. Turpie be assessed for possible ecosystem effects. Waterbirds, Berg River floodplain, South Africa Further Information 28 3 WATER RESOURCES AND ENVIRONMENT • TECHNICAL NOTE C.2 Boxes 1. The main components of a river ecosystem 10 2. Phases of the Lesotho Highlands Water Project 12 3. Benefits and direct monetary costs of Phase 1 of the LHWP 13 4. Specialists involved in the Lesotho Flow Assessment 15 5. Predicted implications of four possible flow scenarios from Phase 1 and 2 dams in Lesotho 16 6. Costs of enhancement measures in the Settlement Agreement. 19 7. Examples of flow regulation protective measures for chinook salmon in the new license for operating the SRP 19 8. The Terror Lake Hydropower Project 20 9. The Central Valley Project, California, U.S.A.Box The Central Valley Project, California, U.S.A. 24 Figures 1. Environmental flow assessments in the decisionmaking process 11 2. The Lesotho Highlands Water Project 12 3. DRIFT Modules 15 4. The Murray-Darling Basin in Southeast Australia 21 5. Growth in water use in Murray-Darling Basin 22 4 ENVIRONMENTAL FLOWS: CASE STUDIES FOREWORD The environmentally sustainable development and priority in Bank lending. Many lessons have been management of water resources is a critical and learned, and these have contributed to changing complex issue for both rich and poor countries. It attitudes and practices in World Bank operations. is technically challenging and often entails difficult trade-offs among social, economic, and political con- Water resources management is also a critical de- siderations. Typically, the environment is treated velopment issue because of its many links to pov- as a marginal issue when it is actually key to sus- erty reduction, including health, agricultural tainable water management. productivity, industrial and energy development, and sustainable growth in downstream communi- According to the World Bank’s recently approved ties. But strategies to reduce poverty should not lead Water Resources Sector Strategy, “the environment to further degradation of water resources␣ or eco- is a special ‘water-using sector’ in that most envi- logical services. Finding a balance between these ronmental concerns are a central part of overall objectives is an important aspect of the Bank’s in- water resources management, and not just a part terest in sustainable development. The 2001 Envi- of a distinct water-using sector” (World Bank 2003: ronment Strategy underscores the linkages among 28). Being integral to overall water resources man- water resources management, environmental agement, the environment is “voiceless” when other sustainability, and poverty, and shows how the 2003 water using sectors have distinct voices. As a con- Water Resources Sector Strategy’s call for using sequence, representatives of these other water us- water as a vehicle for increasing growth and re- ing sectors need to be fully aware of the importance ducing poverty can be carried out in a socially and of environmental aspects of water resources man- environmentally responsible manner. agement for the development of their sectoral in- terests. Over the past few decades, many nations have been subjected to the ravages of either droughts or floods. For us in the World Bank, water resources man- Unsustainable land and water use practices have agement—including the development of surface and contributed to the degradation of the water resources groundwater resources for urban, rural, agriculture, base and are undermining the primary investments energy, mining, and industrial uses, as well as the in water supply, energy and irrigation infrastruc- protection of surface and groundwater sources, pol- ture, often also contributing to loss of biodiversity. lution control, watershed management, control of In response, new policy and institutional reforms water weeds, and restoration of degraded ecosys- are being developed to ensure responsible and sus- tems such as lakes and wetlands—is an important tainable practices are put in place, and new predic- element of our lending, supporting one of the es- tive and forecasting techniques are being developed sential building blocks for sustaining livelihoods and that can help to reduce the impacts and manage for social and economic development in general. the consequences of such events. The Environment Prior to 1993, environmental considerations of such and Water Resources Sector Strategies make it clear investments were addressed reactively and prima- that water must be treated as a resource that spans rily through the Bank’s safeguard policies. The 1993 multiple uses in a river basin, particularly to main- Water Resources Management Policy Paper broad- tain sufficient flows of sufficient quality at the ap- ened the development focus to include the protec- propriate times to offset upstream abstraction and tion and management of water resources in an pollution and sustain the downstream social, eco- environmentally sustainable, socially acceptable, logical, and hydrological functions of watersheds and economically efficient manner as an emerging and wetlands. 5 WATER RESOURCES AND ENVIRONMENT • TECHNICAL NOTE C.2 With the support of the Government of the Nether- The Notes are in eight categories: environmental lands, the Environment Department has