The tidal information and orthometric elevations of a specific survey control mark can be viewed graphically. This mark can be associated with several tidal stations. Displayed will be the differences between the published National Geodetic Survey's ( NGS ) NAVD88 and NGVD29 and Center for Operational and Oceanographic Products and Services' ( CO-OPS ) Mean Lower Low Water (MLLW) datums. Also displayed are the Mean Higher High Water(MHHW), Mean High Water(MHW), Mean Tide Level(MTL), MLLW, and Mean Low Water(MLW) datums. All values are displayed in feet.


Insert an NGS control mark identifier, PID.


A valid PID is of the form, HU0108

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If you do not know which NGS PIDs are available for your area then specify a latitude and longitude in decimal degrees. ex. Lat - N38.9 Lon - W074.95


A list of PIDs within a 25 mile radius, and their latitudes and longitudes in degrees, minutes, and seconds, sorted by latitude will be displayed. Select a PID from this list to get the graphical display


Insert a Latitude and Longitude of the form, Hdd.ddd and Hddd.ddd, respectively. H is N or S for the latitude and W for the longitude. d is degrees with as many digits to the right of the decimal point as needed


A valid position is of the form, N38.9 W074.95

Latitude:
Longitude:

For assistance contact The NGS Information Center