Nonpoint source nutrient pollution from agriculture entering Iowa’s surface water bodies (Figure 1) is a problem for impaired local watersheds throughout the Corn Belt, and as far away as the Gulf of Mexico. The Mississippi River drains 40 percent of the continental US and carries almost 140 cubic miles of water yearly (Libra 1998). The U.S. Geological Survey estimated an average of 1.65 million tons/year of nitrogen (N) were exported into the Gulf of Mexico from 1987-1996 causing a condition called hypoxia (Libra 1998). Hypoxia, also known as a dead zone, is an area where water has no or very little oxygen necessary for fish and other marine life. Nitrogen accelerates the production of marine phytoplankton whose life cycle consumes oxygen previously available for fish and shrimp (Libra 1998). Estimates in 1996 suggested that Iowa supplied on average almost 25 percent of the nitrate-N to the Gulf of Mexico via the Mississippi River; much of it from agricultural land-use practices (Libra 1998).