Submitted to: Agricultural Nonpoint Source Pollution: Watershed Management and Hydrology
Publication Type: Book / Chapter
Publication Acceptance Date: June 1, 2000
Publication Date: N/A
Interpretive Summary: Nonpoint source pollution of groundwater and surface water from irrigated agriculture is a concern in many areas of the western United States and elsewhere. Pesticides, nutrients, salts, and sediments cause water quality impairment in rivers and streams while nitrate causes groundwater pollution. In irrigated agriculture, irrigation water is a primary transporter of potential pollutants from agricultural fields to streams and groundwater. Reducing pollution requires improved management of both chemical and fertilizer application practices, and irrigation practices. This book chapter describes the basic processes involved in irrigation related nonpoint source pollution, reviews past work and summarizes several case studies where irrigation-induced pollution was successfully reduced. Reductions in pollution will result in better quality water supplies and healthier ecosystems.
Irrigated agriculture can result in increased pollutants in streams and groundwaters. Deep percolation from irrigated fields can transport nitrate, and occasionally pesticides, to groundwater. Irrigation can also result in increasing drainage of poor quality groundwater to streams. Although some potential pollutants, including salts and trace elements such as selenium, occur naturally in the arid lands geology, addition of irrigation water can result in transporting and concentrating these substances in receiving streams and lakes. On sloping lands, irrigation can result in surface erosion of soils. These sediments may degrade the quality of rivers and lakes, and may carry phosphorus and other potential pollutants. This book chapter describes the basic processes involved in irrigation related pollution and management practices that have reduced pollution. Several case studies describe projects where irrigation- induced pollution was successfully reduced.