Issues in Ecology Number 10 Winter 2003 Sustaining Healthy Freshwater Ecosystems by Jill S.Baron,N.LeRoy Poff,Paul L.Angermeier,Clifford N.Dahm,Peter H.Gleick,Nelson G.Hairston,Jr..Robert B. Jackson,Carol A.Johnston,Brian D.Richter,Alan D.Steinmar INTRODUCTION that focuses primarily on maintaining the lowest acceptable water quality and minimal flows,and protecting single species Fresh water is vital to human life and economic well- rather than aquatic communities.A fundamental change in being,and societies draw heavily on rivers,lakes,wetlands, water management policies is needed,one that embraces a and underground aquifers to supply water for drinking. much broader view of the dynamic nature of freshwater irrigating crops,and running ndustrlal processes.Ihe benenit resources and the short-and long-term benefits they provide of these extractive uses of fresh water have traditionally Our current educational practices are as inadequat f water that remains as management policies to the cha es Hydrologis engineer managers, e who design and ma 96 th eco wa d rarely d00 ut the o taught (Figur seque sider the c tical role of ter ir tra society or to d the human and industrial wastes habitat for institutions that manage wate plants and animals and production of fish omists dev Der and politician and other foods and marketable aoods seldom project far enough into the futur These human benefits are what ecologists Figure 1-Freshwater ecosystems pro to fully account for the potential call ecolonical services defined as "the vide economically valuable commodities ecological costs of short-term plans.Few conditions and processes through which and services to humans (drinking water. Americans are aware of the infrastructure natural ecosystems,and the species that rrigation.transportation.recreation etc.).as well as habitat for plants and that brings them pure tap water or make them up,sustain and fulfill human r wastes away and fewer stil life."Over the lona term.healthy freshwater animals. carries their understand the ecological tradeoffs tha ecosvstems are likely to retain the adaptive are made to allow these conveniences capacity to sustain production of these ecological services in the Although the requirements of healthy freshwate face of future environmental disruptions such as climate change ecosystems are often at odds with human activity.this conflic Ecological services are costly and often impossible need not be inevitable The challenge is to determine how to replace when aquatic ecosystems are degraded Yet today. society can extract the water resources it needs whil aquatic ecosystems are being severely altered or destroyed protec ting the important natural complexity and adaptiv at a greaterrate than at any other time in h nan history capacity or tre hwater ecosystems en scientifi and far faster han they are b ing restored.Debates involving nding ma possible to outline here sustainab wate resour e qua y. esnwat osysten timing the ru ate hat ust b onside mong the c tin ecosyste will b erent polic ty. Ame natura pu e informatio ab anageme society d States are able tom po appro thi sed the overall of different rnment entities have y in what wa condition nized that can be discharged into water or how water is used a water movement thro uthe biosphere is highly redistributed.and the goals of one are often at cros altered by human activities purposes with those of others.U.S.laws and water is intensively used by humans concerning water are implem ented in a manaoe ement context poor water quality is pervasive2 Issues in Ecology Number 10 Winter 2003 Sustaining Healthy Freshwater Ecosystems by Jill S. Baron, N. LeRoy Poff, Paul L. Angermeier, Clifford N. Dahm, Peter H. Gleick, Nelson G. Hairston, Jr., Robert B. Jackson, Carol A. Johnston, Brian D. Richter, Alan D. Steinman INTRODUCTION Fresh water is vital to human life and economic well￾being, and societies draw heavily on rivers, lakes, wetlands, and underground aquifers to supply water for drinking, irrigating crops, and running industrial processes. The benefits of these extractive uses of fresh water have traditionally overshadowed the equally vital benefits of water that remains in stream to sustain healthy aquatic ecosystems. There is growing recognition that functionally intact and biologically complex freshwater ecosystems provide many economically valuable commodities and services to society (Figure 1). The services supplied by freshwater ecosystems include flood control, transportation, recreation, purification of human and industrial wastes, habitat for plants and animals, and production of fish and other foods and marketable goods. These human benefits are what ecologists call ecological services, defined as “the conditions and processes through which natural ecosystems, and the species that make them up, sustain and fulfill human life.” Over the long term, healthy freshwater ecosystems are likely to retain the adaptive capacity to sustain production of these ecological services in the face of future environmental disruptions such as climate change. Ecological services are costly and often impossible to replace when aquatic ecosystems are degraded. Yet today, aquatic ecosystems are being severely altered or destroyed at a greater rate than at any other time in human history, and far faster than they are being restored. Debates involving sustainable allocation of water resources should recognize that maintenance of freshwater ecosystem integrity is a legitimate goal that must be considered among the competing demands for fresh water. Coherent policies are required that more equitably allocate water resources between natural ecosystem functioning and society’s extractive needs. Current water management policies in the United States are clearly unable to meet this goal. Literally dozens of different government entities have a say in what wastes can be discharged into water or how water is used and redistributed, and the goals of one agency are often at cross￾purposes with those of others. U. S. laws and regulations concerning water are implemented in a management context that focuses primarily on maintaining the lowest acceptable water quality and minimal flows, and protecting single species rather than aquatic communities. A fundamental change in water management policies is needed, one that embraces a much broader view of the dynamic nature of freshwater resources and the short- and long-term benefits they provide. Our current educational practices are as inadequate as management policies to the challenge of sustainable water resource management. Hydrologists, engineers, and water managers, the people who design and manage the nation’s water resource systems, are rarely taught about the ecological consequences of management policies. Likewise, ecologists are rarely trained to consider the critical role of water in human society or to understand the institutions that manage water. Economists, developers, and politicians seldom project far enough into the future to fully account for the potential ecological costs of short-term plans. Few Americans are aware of the infrastructure that brings them pure tap water or carries their wastes away, and fewer still understand the ecological tradeoffs that are made to allow these conveniences. Although the requirements of healthy freshwater ecosystems are often at odds with human activity, this conflict need not be inevitable. The challenge is to determine how society can extract the water resources it needs while protecting the important natural complexity and adaptive capacity of freshwater ecosystems. Current scientific understanding makes it possible to outline here in general terms the requirements for adequate quantity, quality, and timing of water flow to sustain the functioning of freshwater ecosystems. A critical next step will be communication of these requirements to a broader community. The American public, when given information about management alternatives, supports ecologically based management approaches, particularly toward fresh water. Several previous studies that have addressed the overall condition of freshwater resources have recognized that • water movement through the biosphere is highly altered by human activities; • water is intensively used by humans; • poor water quality is pervasive; Figure 1—Freshwater ecosystems pro￾vide economically valuable commodities and services to humans (drinking water, irrigation, transportation, recreation, etc.), as well as habitat for plants and animals