water level

Short definition from Wiktionary

Noun

1. 1
   The level of a body of water, especially when measured above a datum line.
2. 2
   The level of the water table below ground.
3. 3
   The waterline of a ship.
4. 4
   (Relating to) an instrument to show the level by means of the surface of water in a trough, or in upright tubes connected by a pipe.
5. 5
   Of a route that follows a riverbank or shoreline.

Adjective

1. 1
   Of or pertaining to a water level.