Book excerpt: Nonpoint-source pollution (NPSP) poses a special challenge to society's ability to manage its collective environmental good - especially surface and groundwater quality. Since there is no `point', such as an outfall pipe, from which the pollution is being discharged and can be measured, pollution can reach the ambient environment without being monitored. Since management of air and water polution requires the definition and enforcement of limits on discharges or the imposition of fees on those discharges, inability to measure limits our ability to manage this environmental problem. This book presents a state-of-the-art review and discussion of economists' efforts to resolve this major problem and attempts to provide a way of working around it. The book sets forth the theoretical issues, modeling, and the actual programs set up to confront this issue.