Mean Lower Low Water
The United States' National Oceanic and Atmospheric Administration uses mean lower low water (MLLW), which is the average height of the lowest tide recorded at a tide station each day during the recording period. MLLW is only a mean, so some tidal levels may be negative relative to MLLW.
Read more about this topic: Chart Datum
Famous quotes containing the word water:
“If there’s water in the big rivers, the small rivers will be full.”
—Chinese proverb.