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United States Department of Agriculture

Agricultural Research Service

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Image Number K8721-4

Thirty years of data from many U.S. watersheds went into constructing the computer model called SWAT, used to predict the effects of farming practices on water quality. Water samples are still being collected weekly to validate the model. Here, technician Jeff Nichols collects a sample from the Walnut Creek watershed in Ames, Iowa, for analysis.

Photo by Keith Weller.



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Last Modified: 5/23/2006