Mean Low Water Springs (MLWS)

Mean Low Water Springs (MLWS) is the average height of the low waters at spring tides over a tidal epoch, the lows reached near new and full moon when the tidal range is greatest. It lies below Mean Low Water and close to, though usually above, Lowest Astronomical Tide. On older Admiralty charts MLWS was the sounding datum before the move to LAT, so legacy charted depths reference it. MLWS still appears in tide tables as a level definition and approximates the shallow-water depth available at ordinary spring low water.