water level

water level (plural water levels)

1. The level of a body of water, especially when measured above a datum line.
2. The level of the water table below ground.
3. The waterline of a ship.
4. 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. (attributive) Of a route that follows a riverbank or shoreline.
   • 1960 October, P. Ransome-Wallis, “Modern motive power of the German Federal Railway: Part Two”, in Trains Illustrated, page 613:

     The water-level route, the whistle and the loud staccato exhaust of this great engine recalled most vividly memories of the New York Central Hudsons highballing along the Hudson River between Harmon and Albany!