This book shares essential insights on evaporites and their effects on dams and reservoirs. The intensity of the solution and suffusion process in evaporites (gypsum and salt) is much greater than the solution of carbonates, and evaporites are particularly vulnerable at dam and reservoir sites. Moreover, the presence of evaporites in the vicinity of dams or reservoirs often leads to serious problems: numerous dams in countries around the world (e.g. China, Germany, Iran, Iraq, Peru, Russia, Spain, the Unites States, and Venezuela) have been affected by evaporite dissolution problems. Several of these dams were seriously endangered or ultimately abandoned, even though the best available engineering prevention and remediation practices were applied. Conventional geotechnical methods based on treating the underground (e.g. grout curtains) or surface (e.g. protective blankets) were not successful. This book presents and analyzes revealing case studies in this regard. To improve geotechnical remediation in connection with preventing seepage from reservoirs situated in evaporites, particularly in gypsum, it puts forward a new chemical solution that, after painstaking laboratory testing, was successfully applied in the field.