Water level

{{Short description|Elevation of the free surface of a stream, lake or reservoir relative to a specified vertical datum}}

{{about|the elevation level of the surface of water|the device of the same name|Water level (device)|the draft of a boat|waterline||Water level (disambiguation)}}

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Water level, also known as gauge height or stage, is the elevation of the free surface of a sea, stream, lake or reservoir relative to a specified vertical datum.ISO 772: 1996. Hydrometric determinations – Vocabulary and symbols.

Over long distances, neglecting external forcings (such as wind), water level tends to conform to an equigeopotential surface.[https://www.merriam-webster.com/dictionary/level Merriam Webster Dictionary Definition of level (Entry 3 of 3): conforming to the curvature of the liquid parts of the earth's surface]