This webinar will discuss use of geomembranes in embankment, concrete, masonry, and roller compacted concrete (RCC) dams as part of a geosynthetic barrier system. Presently, geomembranes are the main barrier component in 300 large dams around the world. The geomembrane is generally used with other geosynthetics, such as, geonets for drainage and geotextiles for mechanical protection and drainage, thereby forming a geosynthetic barrier system. In the webinar, the uses of geosynthetic barrier systems in construction of new dams and rehabilitation of existing dams will be discussed. In particular, the performance of plasticized polyvinyl chloride (PVC-P) geomembranes used in rehabilitation of concrete and masonry dams in Europe will be discussed. Lifetime prediction of PVC-P geomembranes will be presented based on test results from a 30-year study on PVC-P geomembranes installed on the upstream face of dams at high elevations in the Alps. Finally, an overview of recent geomembrane applications in dams and reservoirs for artificial snow systems will be addressed.