Iowa's economy is dependent upon Agriculture.  There is no denying that agricultural practices contribute to the degradation of Iowa's water quality.  However, their have been many voluntary conscientious efforts to reduce this problem over the years.  Many land stewards are working with state and federal agencies to design and implement water friendly agricultural practices.  For instance, periodic testing of nutrient levels in the soils will allow the farm operators to more accurately place chemicals where needed instead of putting on excess.  Another practice that is currently being used is building riparian buffer zones around waterways.  These natural buffers will help prevent direct nutrient runoff into an open waterway.  These are just a few of the ways the agricultural community has been working toward cleaner water.  For more information about sustainable agricultural practices contact your local Natural Resources Conservation Service,  Iowa State University Extension Office...etc.