Sandra Postel Talks About the Key to Restoring Our Watershed

How could you explain what an intact watershed looks like?

So a watershed is really the gathering place for the river - all the land, all the forests all the wetlands that exist across the landscape sort of feed into the river. So how we manage the land directly impacts the quality and the health of the river. And so the quality of the water as Luna Leopold says, in some sense the health of our waters are the clearest measure of how we live on the land.

So how exactly do those components come together to create clean healthy water?

I think of a watershed as kind of a nature’s water factory. The components really work together to create reliable clean water. And all those parts work together just like a water treatment plant except that it’s run on free solar energy and it’s all done by nature and so that system is a beautiful system that unfortunately we’ve intervened with in how we’ve managed the land.

Here in North America how do we impact watersheds?

We’re a population of 300 million people now and so we’ve expanded out into the watersheds to live in rural towns and big cities and as a consequence we’ve converted the landscape to a more human landscape and removed a lot of the pieces of the ecosystem that do this important work.

And so those pieces gradually get whittled away and as a consequence the quality and reliability of the water supply begins to diminish.

What do you mean when you say “more rivers will be rivers again”?

We had 5,000 large dams around the world in 1950. We have 50,000 large dams around the world today. So we’ve been building on average two large dams a day, every day for half a century and this is a major hydrologic change in a very short period of time.

If you think about what a dam does it does a lot of really good things for us. It generates hydropower and it controls floods and supplies irrigation water and drinking water, provides recreational opportunities but if you think from an ecological perspective what the dam does it’s disconnecting the river from all these different parts of its watershed.

So the dam creates a disconnection of the river with its channel, because it changes the flow. It creates a disconnection of the river from its floodplain because the river doesn’t flood. And it creates a disconnection downstream if the river no longer reaches the sea, because the water is parceled out along the way. And each of those disconnections has an ecological impact.

And so when I talk about rivers flowing like rivers again my hope is that we’ll begin to apply some ecological intelligence to how we manage rivers and dams. And go back and say yes these dams are doing good things but can we give the river something back. Can we give the river back the flows it needs to be healthy.

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Sandra Postel directs the independent Global Water Policy Project, based in New Mexico, and lectures, writes and consults on global water issues. She is the National Geographic Society's first Freshwater Fellow, and serves as lead water expert for the Society's Freshwater Initiative. Postel is also a fellow of the Post Carbon Institute.