Get to Know a Watershed Near You

By Alexandra Soderlund

It’s clear that climate change is an issue society will face in the coming century, but we don’t always know what the effects of climate change will be. It’s easier to plan ahead and prepare if we know what types of changes may be possible.

Recently, a group of EPA scientists and collaborators did just this, using models—not the models you see on fashion runways, but computer modeling tools—to learn how different future climate change scenarios could affect our water.

EPA researchers used a cool model with a cool name—SWAT (or the Soil and Water Assessment Tool) as one tool in their recently released draft 20 Watersheds Report. The model can be used to predict the impact of land management practice on water and sediments in watersheds, and they used it to gain a better understanding of the sensitivity of streamflow and water quality to the impacts of climate change.

Map from the "20 Watersheds Report." Copies of the draft are available in the "Download" section at:

A watershed is an area of land where all the water that drains off of it or from under it goes into the same place. To develop the 20 Watersheds Report, EPA looked at things like streamflow, nutrient (phosphorous and nitrogen), and sediment loading and, using computer models, projected how these attributes might be affected by different future climate change scenarios.

There are a couple of things that make this report really exciting. First, the scope of the report is much bigger than a lot of what’s currently out there. The 20 watersheds in the title refer to watersheds all over the U.S. in each of EPA’s ten geographic regions. So it’s quite possible you live near one of these watersheds. Second, the report presents important methodological protocols for such work. Using the same models and measures to look at a broad range of areas is very useful. It helps to set a standard for comparison.  Without standards, things can be confusing (take this from an Australian who has been living with the Imperial measurement system for a while).

The draft watersheds report, when final, and the tools and methods it generates, are going to be really useful as a jumping off point for further and more focused research.

About the Author:  When not interning at the EPA, Alexandra Soderlund studies at the University of New South Wales (NSW) in Sydney, Australia. She is majoring in media/technology and genetics, and is also the online coordinator for the NSW branch of the Australian Youth Climate Coalition.