If disasters related to droughts, floods, and other extreme weather seem more common globally, it’s because they are: nearly twice as many such disasters occur annually now as 25 years ago. These problems are not going away. Last year, the World Economic Forum declared water crises to be the top global risk to society over the next decade. As we look to safeguard clean drinking water, manage and adapt to more frequent droughts and floods, and balance environmental protection with economic progress, renowned water expert Sandra Postel’s Replenish: The Virtuous Cycle of Water and Prosperity comes at a critical time. We spoke with Sandra about how cities and farms around the world are finding relief from an unexpected source: a healthier water cycle. Have more questions? Share them in the comments below.

You’re a renowned water expert and prolific writer on water issues around the world. What sets Replenish apart from your previous work?

This book is anchored by stories of real people and places that show how we can fix our broken water cycle, which humanity’s future depends upon. Like all of my books, Replenish is grounded in sound science and extensive research. But most of us learn from, remember, and are motivated by stories.  We face very big water challenges—which I describe in detail—and it’s easy to descend into despair. But what I show is that a future of depleted rivers, dried-up wetlands, and toxic dead zones is not inevitable. Yes, the water cycle is broken, but one river, one wetland, one city, one farm at a time, we can begin to fix it.

For centuries we’ve relied on engineering infrastructure like dams and levees to manage freshwater. Why is it important to take a more interdisciplinary approach to water management?   

Freshwater ecosystems, when healthy and functioning well, service the economy in vital ways. A healthy watershed stores and cleanses water, reducing the cost of water treatment. A healthy, flowing river supports habitat for birds and wildlife and offers recreational opportunities critical to local economies. For a couple centuries we’ve been trading nature’s services for engineering services—for example, building levees to control floods rather than letting natural floodplains do that work. But those engineering solutions are no longer working as well as they once did, and their economic costs are rising. Now that we better understand how nature functions, and how valuable its services are, we can blend ecology and engineering, along with the social and economic sciences, to produce more optimal solutions to our growing water problems, including worsening floods and droughts.

An almond farm in California's Central Valley is flooded in the wintertime to replenish groundwater supplies while scientists study the effects on soils, tree health, and water quality. Photo by Joe Proudman/UC Davis.

Except when referring to official titles or organizations, you do not use the phrase “water resources” in Replenish. Was this a conscious choice? What power does language have to change the way we think about our relationship to freshwater? 

For many years now I have made a conscious decision to not use the phrase “water resources.” First and foremost, water is the basis of life. If we refer to rivers and lakes as “water resources” we immediately think of them in a utilitarian way—that they’re there for us to use and take as we see fit, much the way we think of oil or coal. It’s important that we think of a river as a living, flowing part of nature that sustains life. Yes, that river can be a “resource” for the generation of energy and the provision of water supplies, but most fundamentally, it’s a river.

Economic and environmental interests are often positioned in opposition to one another. Why is this a false narrative in terms of water?

A secure supply of water is critical to everything—producing food, manufacturing goods, enjoying the outdoors, and sustaining life. In the Colorado River Basin, economic activity that generates some $26 billion a year depends on water staying in rivers rather than taking it out of them. So the key is finding the balance that, in economic terms, maximizes the value of water. For example, on the Verde River in central Arizona, conservationists have partnered with irrigators to install automated headgates on ditch systems that allow irrigators to take just the water they need, rather than diverting all of the river’s flow. There’s no loss of farm production, the community gets a healthier, flowing river during the summer recreation season, and birds and wildlife get healthier habitat. So the water in the Verde now has more value. One of the key messages of Change the Course, the national water restoration initiative I helped create, and which has restored billions of gallons of water to depleted ecosystems in North America, is that by getting smarter about how we use water, we can have healthy rivers, productive agriculture, and vibrant economies side by side. 

Replenish by Sandra Postel

Replenish explores innovative water projects all over the world. Is there a particular project that stands out to you?

Wow, that’s a tough one.  A number of projects stand out—from China’s “sponge cities,” to Europe’s efforts to give the Danube and other rivers room to flood again, to the innovative irrigation methods being pioneered in Georgia’s Flint River Basin, to the restoration of the Colorado River Delta. But if I had to pick one I think it would be the creation of the Rio Grande Water Fund in New Mexico. This is a collaborative initiative to rehabilitate forested watersheds to build resilience against the impacts of wildfire on downstream drinking water supplies. It connects the whole community to its source of water—the watershed—and brings businesses, water utilities, conservationists, and local citizens together to build greater water security. It is stewardship in action.

News about water in the age of climate change is often despondent, but Replenish is hopeful. What gives you that hope? 

What gives me hope is that we can point to farmers, ranchers, cities, and businesses that are making a difference and showing that we can live more harmoniously with nature and its freshwater ecosystems. The challenge is to learn from these experiences, adapt them to new situations, and scale up these solutions. This is easier said than done; it will take changes in policies and incentives. But it’s doable. 

I should add that I am not terribly hopeful that we will prevent a good share of the rich diversity of life in freshwaters—fish, mussels, amphibians, and other species—from going extinct. The combination of dams, diversions, pollution, and climate change puts more and more species in peril. And this deeply saddens me. But as I show in Replenish, we can absolutely take action to slow the rate of extinction and save more species. Restoring and preserving flows in the Verde, San Pedro, and Gila Rivers in the American Southwest, for example, will help sustain incredibly diverse populations of birds that depend on those riparian habitats.

Casey Wade moves cattle according to his rotational grazing plan on the Dixon Water Foundation's Mimms Ranch outside of Marfa, Texas. Photo © Terrie Wade.

Was there anything you found in the course of researching and writing this book that surprised you?

I grew up in New York, on Long Island, and it surprised me to learn how much of Long Island’s coastal bays and estuaries and inland lakes and ponds are now degraded by toxic algal blooms. When I was a kid, some of these water bodies were premier areas for clams, oysters, and recreation. These algal blooms pose threats to the local fishing economy and the health of people and pets. Research suggests that if nothing is done to reduce the nitrogen pollution causing these toxic algal blooms, much of which comes from inadequate treatment of human sewage, the costs to fishing, tourism, and real estate on Long Island could total some $25 billion over the next thirty years. Algal blooms are spreading in many coastal areas around the world, and these blooms will worsen as waters warm. Technologies and measures exist to reduce the nitrogen and phosphorus pollution causing these algal blooms, but we need to implement them.

What do you hope readers take away from this book? 

I’d like readers to come away knowing that we have the capacity to write a new water story.  Yes, our water challenges are big, and Replenish provides a good overview of their nature and magnitude. But depletion and dead zones do not have to define our future.  We have barely tapped the innovative ways we can do more with less water – and then give some water back to nature.  We live on a finite planet with finite water. As the basis of life, water needs to be shared with all of life. Replenish offers up ideas for how we can all engage in water stewardship. My hope is that it inspires more people, communities, farmers, businesses, and political leaders to act.