Rivers and Lakes

Sustainable Waters — Helping Rivers to Go with the Flow

For most of us, flowing water means turning on the tap. But outside our homes and offices, the environmental flow of water — its ability to follow natural patterns of rising and receding — is critical to the health of all freshwater ecosystems and the species that depend on them.

To better understand why natural water flows are important, nature.org spoke with Eloise Kendy, director of the Conservancy’s Environmental Flows Program. Kendy and more than 800 other scientists and resource managers recently issued the Brisbane Declaration calling for the global protection and restoration of water flows.
"The whole river ecosystem is like a symphony that's orchestrated with the rising and falling of water levels. When human needs mess with those natural rhythms, the ecosystem begins to unravel."

Eloise Kendy, director of the Conservancy's Environmental Flows Program


What changes occur in nature when water flows are disrupted?

Eloise Kendy:

Plants and animals are adapted to natural variations in water flows. For instance, rising water levels are a "cue" to many fish that it's time to spawn. And in rivers that flood seasonally, many tree species disperse their seeds to take advantage of the ample moisture available on the floodplains along rivers.

The whole river ecosystem is like a symphony that's orchestrated with the rising and falling of water levels. When humans mess with those natural water rhythms, the ecosystem begins to unravel.


How are people affected by changes in water flows?

Eloise Kendy:

Human communities suffer when they lose the fish they depend upon for protein, or when the river becomes less popular for tourism.

Healthy freshwater ecosystems — rivers, lakes, floodplains, wetlands and estuaries — provide essential clean water, food, fiber and energy. And they fulfill other cultural and spiritual needs: aesthetics, recreation and our profound connection to nature. The Brisbane Declaration says it all: "Freshwater ecosystems are essential to human health and well-being."


Is this all about dams — or are there other factors that disrupt the natural flow of rivers?

Eloise Kendy:

It's not just dams. Humans change natural water flows by diverting water out of rivers into canals or pipelines, or by pumping groundwater that would have eventually drained into rivers, lakes and wetlands. And levees designed to protect human settlements from floods can disconnect highly-productive floodplains from their rivers, causing important natural habitats to disappear.

Paving the landscape, cutting down forests — just about anything we do to the land can change water flows in rivers.


How do we identify rivers that need our help — and how do we typically get involved?

Eloise Kendy:

I can't think of a river that doesn't need our help. The seemingly insatiable demands of the growing human population threaten every river on Earth, even the ones that are pristine today. So, our task is twofold — to restore environmental flows and to maintain them.

The Nature Conservancy takes a concrete, scientific approach to the problem. First we ask, "How much water does a river need?" The answer to this question tells us how much flow alteration a river can withstand.

Then we take this knowledge and create partnerships. For example, our Sustainable Rivers Project with the Army Corps of Engineers is helping both organizations learn how to minimize the ecological impacts of dams. We're also working with governments in developing countries such as Honduras and China to pioneer ways of building new dams with less environmental impact than older dams.


What are some of the struggles we're encountering, and how do we overcome those?

Eloise Kendy:

Until recently, legislators and directors of water and energy agencies did not understand the importance of protecting water flows in their rivers. Now, most water managers understand the need to protect and restore these flows, but they can't imagine how to do it on their limited budgets.

That's where The Nature Conservancy steps in. We've developed cost-effective scientific approaches and computer tools for defining flow needs across large regions — like a state, country or large river basin — instead of one river at a time.

We are also forming novel partnerships with energy companies, engineering firms and banks that loan money for water development. By demonstrating how we can meet all human needs — including those that depend upon healthy ecosystems — we can help lead the way to a more sustainable future.


What are some of the tools in the toolbox?

Eloise Kendy:

There are so many that water managers are often stymied by the task of choosing the right one! We're developing guidelines to help scientists and governments decide which tools best suit their circumstances.

When assessing environmental flow needs, we recommend approaches that integrate various science disciplines — hydrology, ecology, geomorphology — along with sociology and economics.

To restore rivers that have been overtapped, we're pioneering and demonstrating strategies such as trading of water rights, water conservation and modifying dam operations. We're developing useful guidance on these strategies, including online training courses, so that other organizations can apply them.


How are your approaches different in, say, China or Africa, than they are in the United States?

Eloise Kendy:

In the U.S. we can work fairly effectively from the top down. If we can get a law enacted, then usually that law will be implemented and enforced. For instance, in many places in the U.S., dam operators have asked us to help them comply with new requirements under the Endangered Species Act.

But in many developing countries, the legal system is extremely weak. So, in order for water management to change on the ground, the people who are affected have to be deeply involved.

The decision making tends to take longer, but the results are strongly upheld by the community. That's a lesson that can benefit similar work here in the U.S.


How do our recommendations stand a chance against the demands of growing populations and economies in places such as China?

Eloise Kendy:

Human communities are not separate from — or in competition with — healthy freshwater ecosystems. The key is to manage our water demands so that we can live within the limits of what nature provides. On the Yangtze River in China, we're working with dam developers to identify ways to generate electricity and provide flood protection while maintaining adequate water flows in the river. By doing this, we'll sustain a fishery that has been feeding millions of Chinese people for many generations.


How do you know when your approach is working?

Eloise Kendy:

We measure how much water continues to flow through the river. But we don't blindly accept the premise that restoring a river's flow will automatically improve its ecological health, so we also watch how the fish, trees and other species respond to changes in water flow.

For example, on the Savannah River in the southeastern U.S., we're working with the Army Corps of Engineers to release small floods of water from dams so sturgeon can move from the ocean upstream to their spawning grounds. Radio transmitters attached to the sturgeon help us track their movements when the floods are released. The sturgeon are telling us what works, and what doesn't.

Eloise Kendy is director of The Nature Conservancy’s Environmental Flows Program. She works closely with governments, water resource managers and NGOs to advance the protection and restoration of environmental flows. Previously, Kendy conducted water-resource assessments and hydrologic modeling and provided public education and policy support for sustainable surface and groundwater management. Kendy holds a Ph.D. in Environmental Engineering from Cornell University, an M.S. in Hydrogeology from the University of Wisconsin, and a B.A. in Geological Sciences from the University of California.


x animal

Sign up for Nature eNews!

Sign Up for Nature e-News

Learn about the places you love. Find out
how you can help.

Thank you for joining our online community!

We’ll be in touch soon with more Nature Conservancy news, updates and exciting stories.

Please leave this field empty

I'm already on the list!

Read our privacy policy.