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High Water Conditions

What does this mean?
  • When observed or forecast water levels at NOS tide stations are high enough to cause potential flooding. Check the National Weather Service for any coastal flood advisories.

Stations currently in high water condition

Low Water Conditions

What does this mean?
  • Tidal stations - when a station is 1.5 feet below Mean Lower Low Water (MLLW) for at least 18 minutes continually.
  • Great Lakes stations - when the average of the previous 12 hours of observations were found to be below the elevation of Low Water Datum (LWD).
  • Use caution when transiting these areas as depth soundings may be less than those found on the NOAA nautical charts.

Stations currently in low water condition

Revised: 08/08/2018
NOAA / National Ocean Service
Web site owner: Center for Operational Oceanographic Products and Services