Sponsored by the Atmospheric Water Management Standards Committee of the Standards Development Council of the Environmental and Water Resources Institute of ASCE Guidelines for Cloud Seeding to Augment Precipitation, Third Edition, supplies the practical details for implementing a cloud seeding project to enhance precipitation efficiency. This technology for atmospheric water management provides a cost-effective means for supplementing available water supplies and reducing damage caused by meteorological events. Cloud seeding offers determinable benefits, such as increased agricultural output and hydroelectric power production, salinity reduction, and strengthened ski industries, while also improving water supplies for fish and wildlife, recreation, municipalities, and industry. This revised and updated Manual of Practice incorporates pertinent background on the science and practice of weather modification through the use of cloud seeding that has developed over the past 10 years. It also presents additional methods of evaluation for such programs or projects. Topics include: social, environmental, and economic aspects; legal aspects associated with weather modification operations; the scientific basis for precipitation enhancement; cloud seeding modes and instrumentation and the updated state of the technology; and steps in the implementation of a cloud seeding program. MOP 81 is an essential guide to cloud seeding for professionals involved in water resources management and weather modification, as well as government regulators and those in industry who may benefit from the enhanced precipitation.