Agriculture generates byproducts that may contribute to the contamination of the United States' water supply. Any effective regulations to ban or restrict agricultural chemical or land use practices in order to improve water quality will affect the farm economy. Some farmers will benefit; some will not. Most agricultural pollutants reach surface waterways in runoff; some leach through soil into ground water. Because surface water systems and ground water systems are interrelated, farm management practices need to focus on water quality in both systems. Modifying farm management practices may raise production costs in some areas. Farmers can reduce runoff losses by reducing input use, implementing soil conservation practices, and changing land use. Also at issue is who should pay for improving water quality: farmers, governments, consumers, or those who benefit from improved water quality. (Author/KC)