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United States Department of Agriculture

Agricultural Research Service

Title: Subsurface Geology: a Key to Understanding Water Quality Problems

item Simpkins, William - IOWA STATE UNIVERSITY
item Parkin, Timothy
item Moorman, Thomas
item Burkart, Michael

Submitted to: Clean Water Clean Environment 21st Century Conference Proceedings
Publication Type: Proceedings
Publication Acceptance Date: January 5, 1995
Publication Date: N/A

Technical Abstract: Detailed hydrogeological characterization of the subsurface environment is a key to understanding the effect of farming practices on groundwater quality. In this study, we characterized the subsurface environment in the Walnut Creek watershed, a 21.6-square-mile agricultural watershed in central Iowa. In the shallow subsurface (< 100 ft), carbon-rich till and loess units (aquitard) of Wisconsinan age have the potential to consume NO3-N in groundwater for the next 91 to 363 years. In the deeper subsurface (> 100 ft), groundwater ages in the aquifer generally predate agricultural activities in the region and NO3-N was not observed in groundwater under reducing conditions. Future contamination of domestic water supplies in the watershed will almost likely result from problems with well construction and distribution systems.

Last Modified: 4/19/2015
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