Water storage refers to holding water in a contained area for a period of time. Water storage can be natural or artificial. Natural water storage occurs in all parts of the hydrologic cycle in which water is stored in the atmosphere, on the surface of the Earth, and below ground. Artificial water storage is done for a variety of reasons and is done on small and large scales. Water storage locations are commonly referred to as reservoirs. Surface water storages include natural and artificial reservoirs, lakes, ponds and lagoons, also the bodies of water held behind weirs and dams.