U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Datums Page Page 1 of 4
PUBLICATION DATE: 10/01/1985
Station ID: 8720135 SUPERCEDED DATE: 04/21/2003
Name: NASSAU RIVER ENTRANCE, NASSAU RIVER
FLORIDA
NOAA Chart: 11488 Latitude: 30° 31.1' N
USGS Quad: AMELIA CITY Longitude: 81° 27.2' W
To reach the tidal bench marks from the intersection of the Mayport Ferry and
Florida Highway A1A, proceed north on Highway A1A for 9.3 miles (15.0 km) to the
Swing Span Highway Bridge over the Nassau River. The bench marks are located
near the south end of the bridge. The tide gage and staff were located 120 feet
(37 m) SE of the center of the Swing Span at the extreme NE corner of the SE
section of the wooden fence.
T I D A L B E N C H M A R K S
PRIMARY BENCH MARK STAMPING: M 326 1970
MONUMENTATION: Survey Disk VM#: 5033
AGENCY: PID#: BC0198
SETTING CLASSIFICATION: Bridge Abutment
The bench mark is set on top of the SW end of the NW concrete walkway of the
large highway bridge over Nassau Sound, directly over the SW bridge abutment,
13.0 feet (4.0 m) NW of the centerline of the highway, and 1.0 foot (0.30 m) NE
of the SW end of the walkway.
BENCH MARK STAMPING: 0135 B 1978
MONUMENTATION: Survey Disk VM#: 5034
AGENCY: PID#: BC1369
SETTING CLASSIFICATION: Concrete Slab
The bench mark is 96 feet (29 m) SW of the power pole with meter attachment, 88
feet (27 m) NW of the centerline of State Highway A1A, 7 feet (2 m) SW of power
pole BB 72, 7 feet (2 m) SE of a witness post, and 0.43 feet (0.1 m) NW of an
8-inch cedar tree.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 2 of 4
PUBLICATION DATE: 10/01/1985
Station ID: 8720135 SUPERCEDED DATE: 04/21/2003
Name: NASSAU RIVER ENTRANCE, NASSAU RIVER
FLORIDA
NOAA Chart: 11488 Latitude: 30° 31.1' N
USGS Quad: AMELIA CITY Longitude: 81° 27.2' W
T I D A L B E N C H M A R K S
BENCH MARK STAMPING: NO 3 1953
MONUMENTATION: Survey Disk VM#: 5035
AGENCY: PID#: BC0199
SETTING CLASSIFICATION: Bridge Abutment
The bench mark is on the east end of the north concrete abutment of the highway
bridge over Sawpit Creek, 15.5 feet (4.7 m) east of the centerline of the
highway.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 3 of 4
PUBLICATION DATE: 10/01/1985
Station ID: 8720135 SUPERCEDED DATE: 04/21/2003
Name: NASSAU RIVER ENTRANCE, NASSAU RIVER
FLORIDA
NOAA Chart: 11488 Latitude: 30° 31.1' N
USGS Quad: AMELIA CITY Longitude: 81° 27.2' W
T I D A L D A T U M S
Tidal datums at NASSAU RIVER ENTRANCE, NASSAU RIVER based on:
LENGTH OF SERIES: 3 MONTHS
TIME PERIOD: JUN, SEP-OCT 1978
TIDAL EPOCH: 1960-1978
CONTROL TIDE STATION: 8720098 NASSAUVILLE
Elevations of tidal datums referred to Mean Lower Low Water (MLLW), in FEET:
HIGHEST OBSERVED WATER LEVEL (11/03/1978) = 7.83
MEAN HIGHER HIGH WATER MHHW = 5.68
MEAN HIGH WATER MHW = 5.34
MEAN TIDE LEVEL MTL = 2.77
MEAN LOW WATER MLW = 0.20
MEAN LOWER LOW WATER MLLW = 0.00
LOWEST OBSERVED WATER LEVEL (04/02/1978) = -2.05
North American Vertical Datum (NAVD88)
Bench Mark Elevation Information In FEET above:
Stamping or Designation MLLW MHW
M 326 1970 17.15 11.81
0135 B 1978 11.61 6.27
NO 3 1953 21.49 16.15
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 4 of 4
PUBLICATION DATE: 10/01/1985
Station ID: 8720135 SUPERCEDED DATE: 04/21/2003
Name: NASSAU RIVER ENTRANCE, NASSAU RIVER
FLORIDA
NOAA Chart: 11488 Latitude: 30° 31.1' N
USGS Quad: AMELIA CITY Longitude: 81° 27.2' W
D E F I N I T I O N S
Mean Sea Level (MSL) is a tidal datum determined over a 19-year National Tidal
Datum Epoch. It pertains to local mean sea level and should not be confused
with the fixed datums of North American Vertical Datum of 1988 (NAVD88).
NAVD88 is a fixed datum derived from a simultaneous, least squares, minimum
constraint adjustment of Canadian/Mexican/United States leveling observations.
Local mean sea level observed at Father Point/Rimouski, Canada was held fixed as
the single initial constraint. NAVD88 replaces NGVD29 as the national
standard geodetic reference for heights. Bench mark elevations relative to
NAVD88 are available from NGS through the World Wide Web at
National Geodetic Survey.
NGVD29 is a fixed datum adopted as a national standard geodetic reference for
heights but is now considered superseded. NGVD29 is sometimes referred to as
Sea Level Datum of 1929 or as Mean Sea Level on some early issues of Geological
Survey Topographic Quads. NGVD29 was originally derived from a general
adjustment of the first-order leveling networks of the U.S. and Canada after
holding mean sea level observed at 26 long term tide stations as fixed.
Numerous local and wide-spread adjustments have been made since establishment in
1929. Bench mark elevations relative to NGVD29 are available from the National
Geodetic Survey (NGS) data base via the World Wide Web at
National Geodetic Survey.
NAVD88 and NGVD29 are fixed geodetic datums whose elevation relationships to
local MSL and other tidal datums may not be consistent from one location to
another.
The Vertical Mark Number (VM#) and PID# shown on the bench mark sheet are unique
identifiers for bench marks in the tidal and geodetic databases, respectively.
Each bench mark in either database has a single, unique VM# and/or PID# assigned.
Where both VM# and PID# are indicated, both tidal and geodetic elevations are
available for the bench mark listed.
The NAVD88 elevation is shown on the Elevations of Tidal Datums Table Referred
to MLLW only when two or more of the bench marks listed have NAVD88 elevations.
The NAVD88 elevation relationship shown in the table is derived from an average
of several bench mark elevations relative to tide station datum. As a result of
this averaging, NAVD88 bench mark elevations computed indirectly from the tidal
datums elevation table may differ slightly from NAVD88 elevations listed for
each bench mark in the NGS database.