What is the difference between mean low water and mean lower low water?
Sarah Silva
Updated on April 27, 2026
Furthermore, what does mean low water mean?
Mean Lower Low Water (MLLW) is simply the lowest of the two low tides per day (or the one low tide) averaged over a 19-year period. This 19-year period is called the National Tidal Datum Epoch, which currently runs from 1983 through 2001.
Also Know, what is lower high water? Definition: The average of the lower high water height of each tidal day observed over a National Tidal Datum Epoch.
Considering this, what is the mean low water mark?
Mean Low Water (MLW): The average of all the low water heights observed over a 19-year period.
What does mean high water mean?
Mean High Water (MHW) is a Tidal Datum representing the average of all the daily tidal high water heights observed over a period of several years. In the United States this period spans 19 years and is referred to as the National Tidal Datum Epoch.
Related Question Answers
What datum means?
known or assumedWhat does MSL mean in water level?
mean sea levelWhat does NAVD 88 mean?
North American Vertical Datum of 1988What datum is MSL?
Mean Sea LevelWhat are flood tides?
(flŭd′tīd′) 1. The incoming or rising tide, occurring between the time when the tide is lowest and the time when the following tide is highest.What is low water datum?
By definition, Low Water Datum (LWD), or chart datum, is “the lake-wide surface so low that the water level will seldom fall below it”.What does MSL mean?
Mean Sea LevelWhat is chart datum level?
Definition of Chart datum (CD):The level to which both tidal levels and water depths are reduced. On most Admiralty charts, this level is that of the predicted lowest astronomical tide (LAT).. This is the common definition for Chart datum (CD), other definitions can be discussed in the article.
What is mean water level?
Definition: The average of all hourly water levels over the available period of record.What does MLW mean?
MLW| Acronym | Definition |
|---|---|
| MLW | Mean Low Water |
| MLW | My Loving Wife |
| MLW | Maximum Landing Weight (aviation) |
| MLW | Montreal Locomotive Works (Canadian division of ALCO) |