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.