Can We Save Earth's Rivers?

An excerpt from the book Rivers for Life: Managing Water for People and Nature, which explores the unhealthy state of the world’s rivers following decades of industrial damming, diversions and other insults, and describes the tools and techniques that could be used to restore them back to health. The following excerpt, from the book’s last chapter, asks the tough questions: What will it take to change our destructive ways before it is too late?

No generation before ours would have asked the question posed in this title. It has an ominous ring: how can it possibly be up to us to save earth’s rivers? But the degree of our dominion over rivers has put us in exactly this position. Most rivers are no longer controlled by nature, but by us.

Human impacts on the hydrologic environment have increased on the order of nine-fold since 1950. This is an enormous change in a very short period of time. Only a portion of this impact stems directly from withdrawals of water for irrigation, industries, and cites, which have tripled over the last half century. Most of it stems from human manipulation of natural flow patterns through the construction and operation of dams, reservoirs, dikes, and levees. Species that evolved over the millennia within earth’s aquatic ecosystems are now reeling from these human-induced impacts. We have cast them into a race for survival for which they are not evolutionarily prepared. By virtue of our domination, we have become their stewards.

Ecologists now are warning us that stewardship of nature is not an altruistic act, but rather a rational one of self-preservation. The goods and services that aquatic ecosystems provide are too central to human well-being for us to get along for any great length of time without them. They perform functions we depend upon and cannot replicate. Technology has not freed us from this dependence, but has blinded us to it. Whether we realize it or not, our staying power as a species depends upon our ability to coexist with other species.

The deep conundrum we face is how to exercise stewardship of other species when the needs and aspirations of our fellow Homo sapiens are so large, and still growing. Within a generation, some 3 billion people will be living in water-stressed countries. Is there hope for rivers and freshwater species in those places? Between 1950 and today, about 3.5 billion people were added to the planet; 3 billion more will likely be added over the next half century. All people must have access to sufficient water, food, and energy for a healthy and secure life. At the same time, a large global middle class aspires to the high-consumption lifestyles now enjoyed by the richest 1 billion people – including meat-rich diets, luxurious caches of clothes and cars, and sizeable homes with lush green lawns. Even as world population is growing, per capita global water demand is rising, intensifying total human impacts on freshwater ecosystems.

As if this predicament was not difficult enough, global climate change from the buildup of greenhouse gases will greatly complicate our efforts to create a water-secure future. Glaciers and mountain snowpacks, the natural reservoirs that feed many of the world’s rivers, are melting. As temperatures rise, they will melt faster. Glaciers are already retreating, from the Alps to Alaska. But they are retreating fastest in the high-altitude regions of Africa, Asia, and Latin America, where most of the world’s poor people live and where most of the world’s population growth will take place. For a period of time, accelerated glacial melting will produce an increase in river runoff; but then it will be gone. Officials in La Paz, Bolivia, for example, now openly worry about future water shortages because the glaciers that provide the city’s water are retreating so quickly. As Robert Gallaire, a hydrologist with a French scientific institute studying the Bolivian glaciers told the New York Times, “The problem is we are using reserves that are being reduced. So we have to ask, what will happen in fifty years? Fifty years, you know, is tomorrow.”

Against this backdrop of demographic, consumptive, and climatic pressures, rivers and the panoply of life they sustain would seem doomed. However, disastrous loss of freshwater biodiversity is not yet a foregone conclusion. Homo sapiens is among the life-forms that rivers sustain. At some point, the compulsion to save our species will trigger an impulse to save the aquatic ecosystems that life depends upon. The question is, what quality of life will be left when that instinctive impulse kicks us into action? Will the Colorado pike-minnow still ply its ancestral waters? Will the Yangtze River dolphin, which now numbers fewer than 200 individuals, still grace China’s largest river? Will salmon still carry out their legendary migrations within the great rivers of northern Europe, New England, and the Pacific Northwest, or will they move only from fish farms to our dinner tables? Will coastal estuaries receive enough fresh water and nutrients to remain productive enough to feed the growing populations that depend upon them? Will legions of filter-feeding mussels still cleanse the river water running by them? Will enough floodplain habitat remain for the feeding and breeding of fish populations that help sustain millions of subsistence dwellers in developing countries, not to mention tropical biodiversity?

Current trends strongly suggest that the answer to all of these questions will be no. We are moving rapidly toward a freshwater world of greater ecological degradation, species extinction, and loss of natural ecosystem services. This may not be the world we want for ourselves or our descendants, but it is the one that is coming if no course corrections are made.

We now have a narrow window of opportunity in which to redirect the ecological trajectory of the planet’s rivers toward improvement rather than decline. With the scientific tools and innovative policies described in earlier chapters, the time is ripe for mobilizing a global river restoration movement. The good news coming from the restoration efforts now under way around the world is this: when given a chance, river systems often heal. Reconnect a river with its floodplain, and fish and riparian plant communities will rebound. Remove a dam, and species long gone will return upriver. Release a flood pulse from a reservoir, and key habitat improvements will materialize. The science supporting river restoration is now strong enough to warrant greater societal investment in rebalancing human and ecosystem water needs. Moreover, river health can often be improved with minimal social or economic disruption.

For this movement to gain steam, governments must act swiftly to enact policies that protect river health even as water continues to be appropriated for human needs. Following South Africa’s lead, these policies must call for freshwater reserves that consist of the volume and timing of river flows needed to safeguard ecological health. For their part, water managers must embrace the new philosophy of adaptive management, or learning by doing. Delaying action because of uncertainty is no longer a valid excuse, because through experimentation, monitoring, and periodic resetting of goals, progress can be made even in the face of uncertainty. With species extinctions and other irreversible changes around the corner, it is simply essential to get started.

Ultimately, for these policy and management reforms to have a durable impact, society’s relationship to freshwater ecosystems will need to change in several overarching ways. Water affects so many aspects of our lives that a move to live in better balance with it inevitably will involve some fundamental changes in societal priorities and individual choices. First, human communities must learn to integrate better with nature’s cycles. Homo sapiens, like every other species, is part of nature. But whereas all other life-forms live in synchrony with nature’s variability, we actively negate or defy that variability in order to make water supplies reliable for us. Indeed, this is one of the principal aims of modern water engineering. By doing this, however, we reduce the survival chances of many of our earthly companions whose life cycles are keyed to nature’s cycles. They need floods to create good habitat. They need water in dry spells as desperately as we do. Once-perennial rivers that now routinely run dry because of heavy irrigation withdrawals will not long support the life that evolved within them. Unless human communities begin to adapt to natural cycles and coexist with aquatic communities, those natural communities will disappear and the ecological work they perform will be lost.

What this means from a practical standpoint is that instead of planning to make every year as good as it can be for us, we plan instead to share the hardship of water-deficit years and the surplus of water-abundant years with the natural communities around us. In periods of drought, we expect to adjust our water-use practices not just to stretch out the available supply for human uses, but because other species need water too. Rationing or other curbs on water use become not signals of failed water management but of the desire to coexist with the life around us. Of course, such a policy will result in short-term economic losses in some years; but the benefit will be healthier and more resilient ecosystems contributing valuable goods and services to the economy over the long term.

Second, we will need to reduce human pressures on the aquatic environment by slowing growth in population and consumption, and by boosting water productivity. Populations continue to grow rapidly in some of the most water-stressed regions of the world, including parts of western and south-central Asia, much of Africa, and the southwestern United States. Currently, about 77 million people are being added to the global population each year, the equivalent of adding another Germany.

Reduced population growth rates, both globally and regionally, are critical to meeting human and ecosystem needs for water. At the same time, reducing per capita use of both water and energy, particularly among the top 2 billion or so consumers, would reduce the number and size of dams and reservoirs required, and provide water managers greater flexibility in satisfying environmental flow requirements. Raising water productivity – the output derived per liter of water extracted from the natural environment – is critical to remaining within any sustainability boundary established to protect river health. Higher water productivity in the global food system is particularly important. Nearly 70% of all the water withdrawn from freshwater ecosystems goes to irrigated agriculture, yet drip irrigation – which often doubles yield per liter of water compared with conventional irrigation methods – accounts for only 1% of world irrigated area.

At the individual level, dietary choices make a large difference on per capita human impact on rivers and aquifers. A typical American diet requires about 1,970 cubic meters of water per year to produce, while an equally nutritious vegetarian diet takes only 950 cubic meters. A large-scale shift from animal to vegetable protein could save large quantities of water – indeed, two people could be fed instead of one.

Third, the globalized trend toward the commodification and privatization of water requires a strong reaffirmation that water is a public trust to be preserved for the common good of this generation and those to come. The relatively recent and quickly expanding search for profits from water ownership and management poses a large threat to ecosystem health and species preservation. Those aimed at profiting from water have little incentive to conserve it or to protect its ecological functions. With no “world ecosystem organization” to match the powers of the World Trade Organization, this protective action may need to come in the form of an international freshwater convention, comparable in scope to existing UN conventions on climate change and biodiversity. A principal aim of such a convention would be for signatories to agree to establish water allocations specifically to sustain ecosystem health – and to give these allocations priority over nonessential human uses of water.

Lastly, an ethic of stewardship toward fresh water and its dependent species requires that we err on the side of allocating too much water to ecosystems rather than too little. Each habitat and species in the natural world is a life-support component, performing tasks we may not be aware of or know the value of. For our own self-preservation, it makes sense to conserve all the components unless we can say with certainty that a particular piece can be eliminated without causing serious harm. With so many components already gone or at risk, there is a premium now on preserving those that remain. Most deeply, an ethic of stewardship is about respecting the beauty and mystery of a natural world we did not create and cannot fully understand, but over which we have acquired dominance. It is about adding a healthy dose of humility as an antidote to our past hubris. And it is about applying the best of our science, policy, and technology not to further manipulate nature but to better adapt ourselves to its time-tested, life-sustaining cycles.


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*Reproduced with permission of Island Press (Washington, D.C. and Covelo, California). Copyright 2003.