WMS:NGVD System

NGVD 29 (The National Geodetic Vertical Datum of 1929) is a vertical geodetic datum formerly called "Sea Level Datum of 1929" or "mean sea level". The datum was found by averaging the sea level over a period of many years at 26 tide stations along the coasts of the US and Canada. Because it is an average, it does not represent the local mean sea level at any particular place. Conversion to NAVD 88 is done by interpolating between data points between the two data.