An edition of: WaterAtlas.orgPresented By: Seminole County, USF Water Institute

Water-Related News

SJRWMD Adopting New Definition of Sea Level

SJRWMD is in the process of changing the reference point that represents zero feet when defining sea level elevations. This new measurement could affect anyone who uses SJRWMD data. Sea level (or zero feet) is measured by a defined reference point known as vertical datum. In 1991 the North American Vertical Datum of 1988 (NAVD 88) was established by Canada, the United States and Mexico, and replaces the National Geodetic Vertical Datum of 1929 (NGVD 29). It holds fixed a single point as the reference point from which all other elevations are measured.

Because the NAVD 88 datum is a more accurate reflection of the height of the earth's surface, the values or numbers that refer to the height of water will change.

Local governments will need to use these new values to communicate with SJRWMD and other users of elevation data. Flood maps have been, or soon will be, converted to NAVD 88 elevations...