Lessons learned about the performance of USDA agricultural nonpoint source pollution programs

Abstract

Agricultural production often emits pollutants that affect the quality of the nation's water resources and impose costs on water users. The extent and magnitude of agricultural pollution is difficult to assess because of its nonpoint nature. However, agriculture is believed to be the leading source of impairment in the nation's rivers and lakes, and a major source of impairment to estuaries (U.S. Environmental Protection Agency 1995). Producing food and fiber involves many activities and practices that can affect the quality of water resources under and near the field. For example, tilling the soil and leaving it without plant cover for extended periods of time results in accelerated soil erosion. Some of this erosion eventually reaches water as sediment. The use of chemical inputs increases the probability that some of these materials will be carried in runoff or in percolating water into water resources. Irrigation can move salt and other dissolved minerals to surface water. Livestock operations produce large amounts of waste which, if not properly utilized, can threaten human health as well as contribute to excess nutrient problems in streams, rivers, and lakes. Over the past several decades the USDA has had a number of programs for …