This new single source reference covers all the latest techniques and methods of managing large watershed areas, with an emphasis on controlling non-point source pollution, especially from agricultural run-off, one of the most intransigent problems now faced by environmental engineers and hydrologists. Leading experts thoroughly cover such topics as nitrate and phosphate pollution, pesticide run-off, erosion and sedimentation, water-table management, and watershed monitoring with an eye towards the integrated management of water quality and water resources over a defined area or region.