Portion of a stream, canal, aquifer*, lake or homogeneous coastal zone. This is a basic breakdown of aquatic environments to become the assessment unit of the Water Framework Directive 2000/60/EC. A surface water body is a discrete and significant element of surface water such as a lake, a reservoir, a stream, river or canal, part of a stream, river or canal, a transitional water or a stretch of littoral water. For waterways, delineation of water bodies is primarily based on the size of the stream and the concept of hydro-ecoregion. Water bodies are grouped into homogeneous types that are the basis for the definition of the concept of good status. A groundwater body is a distinct volume of groundwater within an aquifer or aquifers. We also speak, out of the Water Framework Directive, of ocean water body to designate a volume of marine water with specific characteristics of temperature and salinity.