Mean Water Level (MWL) : A datum. The mean surface elevation as determined by averaging the heights of the water at equal intervals of time, usually hourly. Mean water level is used in areas of little or no range in tide
National Oceanic and Atmospheric Administration NOAA, Tide and Current Glossary, National Ocean Service, CO-OPS, Products and Services N/OPS3, Silver Spring, MD, USA 1999. http://co-ops.nos.noaa.gov/publications/glossary2. pdf, (ND/ Tide and Current - Amer) {830}