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Published by the American Society of Agricultural and Biological Engineers, St. Joseph, Michigan

Citation:  Pp. 323-331 in Total Maximum Daily Load (TMDL) Environmental Regulations–II Proceedings of the 8-12 November 2003 Conference (Albuquerque, New Mexico USA), Publication Date 8 November 2003.  .(doi:10.13031/2013.15578)
Authors:   Philip W. Gassman, Ali Saleh, Edward Osei, Joju Abraham, and John Rodecap
Keywords:   modeling, watershed, water quality, nutrients, scenarios, environmental, economic

The Maquoketa River drains 1,879 square miles of predominantly agricultural land in northeastern Iowa and is one of 13 tributaries of the Mississippi River that have been identified as contributing some of the highest levels of suspended sediments, nitrogen, and phosphorus to the Mississippi stream system. Initiatives focused on improving water quality have been implemented in several Maquoketa subwatersheds including the Mineral Creek Watershed (MCW), which covers over 12,000 ha in the west central portion of the Maquoketa River Watershed. A key component of the MCW water quality initiative was the application of an environmental and economic modeling system for over 20 different scenarios that include implementation of contouring, terracing, notill, and other practices on part or all of the MCW cropped acreage. Reductions in sediment, total N losses, and total P losses for 15 scenarios reported here were predicted to range from essentially zero to 52%, 0.3 to 26%, and 5 to 63%, respectively, relative to the baseline conditions. Aggregate impacts on producer net returns predicted across the entire watershed for the 15 scenarios as compared to the baseline ranged from an increase of $14/acre to a decline of $19/acre.

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