U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Datums Page Page 1 of 5
PUBLICATION DATE: 01/22/1985
Station ID: 8676766 SUPERCEDED DATE: 04/21/2003
Name: DAY MARK #239, MACKAY RIVER
GEORGIA
NOAA Chart: 11506 Latitude: 31° 12.6' N
USGS Quad: DARIEN Longitude: 81° 25.5' W
To reach the tidal bench marks proceed by boat to the east shore of MacKay
River, 0.5 mile (0.8 km) south of the intersection of Troup Creek and Back River
with MacKay River and 0.2 mile (0.3 km) south of Jove Creek. The bench marks
are located in the marshy area adjacent to Day Mark 239. The tide gage and
staff were located on the Day Mark 239 structure.
T I D A L B E N C H M A R K S
PRIMARY BENCH MARK STAMPING: 6766 A 1980
MONUMENTATION: Survey Disk VM#: 4909
AGENCY: PID:
SETTING CLASSIFICATION: Unspecified Rod
The bench mark is located in a marshy area immediately adjacent (east) of Day
Mark 239, 62.0 feet (18.9 m) east of the shoreline, bearing NE of the west tower
of Back River Bridge, north of the west tower of Frederica Bridge and NE of the
tall water tank of the Gulf Creosite Plant. The bench mark is set atop a deep
driven rod protected by a white 4-inch diameter PVC pipe projecting 0.8 foot
(0.2 m) above ground and surrounded by a circular concrete kickblock.
BENCH MARK STAMPING: 6766 B 1980
MONUMENTATION: Survey Disk VM#: 4910
AGENCY: PID:
SETTING CLASSIFICATION: Unspecified Rod
The bench mark is located in the marshy area immediately adjacent (east) of Day
Mark 239, 189.5 feet (57.8 m) east of the shoreline, 127.5 feet (38.9 m) west of
Bench Mark 6766 A 1980, bearing of NNE of the west tower of Back River Bridge,
north of the west tower of Frederica Bridge and ENE of the tall water tank of
the Gulf Creosite Plant. The bench mark is set atop a deep driven rod protected
by a white 4-inch PVC pipe projecting 0.9 foot (0.3 m) above ground, and
surrounded by a circular concrete kickblock.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 2 of 5
PUBLICATION DATE: 01/22/1985
Station ID: 8676766 SUPERCEDED DATE: 04/21/2003
Name: DAY MARK #239, MACKAY RIVER
GEORGIA
NOAA Chart: 11506 Latitude: 31° 12.6' N
USGS Quad: DARIEN Longitude: 81° 25.5' W
T I D A L B E N C H M A R K S
BENCH MARK STAMPING: 6766 C 1980
MONUMENTATION: Survey Disk VM#: 4911
AGENCY: PID:
SETTING CLASSIFICATION: Unspecified Rod
The bench mark is located in the marshy area immediately adjacent (east) of Day
Mark 239, 312.0 feet (95.1 m) east of the shoreline, 123.0 feet (37.5 m) east
of Bench Mark 6766 B 1980, bearing NNE of the west tower of Back River Bridge,
north of the west tower of Frederica Bridge and ENE from the tall water tank of
the Gulf Creosite Plant. The bench mark is set atop a deep driven rod protected
by a white 4-inch PVC pipe projecting 1.0 foot (0.3 m) above ground and
surrounded by a circular concrete kickblock.
BENCH MARK STAMPING: 6766 D 1980
MONUMENTATION: Survey Disk VM#: 4912
AGENCY: PID:
SETTING CLASSIFICATION: Unspecified Rod
The bench mark is located in the marshy area immediately adjacent (east) of Day
Mark 239, 421.0 feet (128.3 m) east of the shoreline, 108.5 feet (33.1 m) west
of Bench Mark 6766 C 1980, bearing NNE of the west tower of Back River Bridge,
north of the west tower of Frederica Bridge and NE of the tall water tank of the
Gulf Creosite Plant. The bench mark is set atop a deep driven rod protected by
a white 4-inch PVC pipe projecting 1.3 feet (0.4 m) above ground, and surrounded
by a circular concrete kickblock.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 3 of 5
PUBLICATION DATE: 01/22/1985
Station ID: 8676766 SUPERCEDED DATE: 04/21/2003
Name: DAY MARK #239, MACKAY RIVER
GEORGIA
NOAA Chart: 11506 Latitude: 31° 12.6' N
USGS Quad: DARIEN Longitude: 81° 25.5' W
T I D A L B E N C H M A R K S
BENCH MARK STAMPING: 6766 E 1980
MONUMENTATION: Survey Disk VM#: 4913
AGENCY: PID:
SETTING CLASSIFICATION: Unspecified Rod
The bench mark is located in the marshy area immediately adjacent (east) of Day
Mark 239, 540.5 feet (164.7 m) east of the shoreline, 119.5 feet (36.4 m) east
of Bench Mark 6766 D 1980, bearing north of the west tower of Frederica River
Bridge, NE of the west tower of the Bank River Bridge and NE of the tall water
tank of the Gulf Creosite Plant. The bench mark is set atop a deep driven rod
protected by white 4-inch PVC pipe projecting 1.0 foot (0.3 m) above ground and
surrounded by a circular concrete kickblock.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 4 of 5
PUBLICATION DATE: 01/22/1985
Station ID: 8676766 SUPERCEDED DATE: 04/21/2003
Name: DAY MARK #239, MACKAY RIVER
GEORGIA
NOAA Chart: 11506 Latitude: 31° 12.6' N
USGS Quad: DARIEN Longitude: 81° 25.5' W
T I D A L D A T U M S
Tidal datums at DAY MARK #239, MACKAY RIVER based on:
LENGTH OF SERIES: 62 HW & 62 LW
TIME PERIOD: MAY 17-JUNE 17, 1980
TIDAL EPOCH: 1960-1978
CONTROL TIDE STATION: 8670870 FT. PULASKI
Elevations of tidal datums referred to Mean Lower Low Water (MLLW), in FEET:
HIGHEST OBSERVED WATER LEVEL (06/12/1980) = 9.64
MEAN HIGHER HIGH WATER (MHHW) = 7.64
MEAN HIGH WATER (MHW) = 7.31
MEAN TIDE LEVEL (MTL) = 3.78
MEAN LOW WATER (MLW) = 0.24
MEAN LOWER LOW WATER (MLLW) = 0.00
LOWEST OBSERVED WATER LEVEL (06/08/1980) = -1.43
National Geodetic Vertical Datum (NGVD 29)
Bench Mark Elevation Information In FEET above:
Stamping or Designation MLLW MHW
6766 A 1980 7.78 0.47
6766 B 1980 7.72 0.41
6766 C 1980 8.47 1.16
6766 D 1980 8.16 0.85
6766 E 1980 8.35 1.04
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 5 of 5
PUBLICATION DATE: 01/22/1985
Station ID: 8676766 SUPERCEDED DATE: 04/21/2003
Name: DAY MARK #239, MACKAY RIVER
GEORGIA
NOAA Chart: 11506 Latitude: 31° 12.6' N
USGS Quad: DARIEN Longitude: 81° 25.5' 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 (NAVD 88).
NGVD 29 is a fixed datum adopted as a national standard geodetic reference for
heights but is now considered superseded. NGVD 29 is sometimes referred to as
Sea Level Datum of 1929 or as Mean Sea Level on some early issues of Geological
Survey Topographic Quads. NGVD 29 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 NGVD 29 are available from the National
Geodetic Survey (NGS) data base via the World Wide Web at
National Geodetic Survey.
NAVD 88 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. NAVD 88 replaces NGVD 29 as the national
standard geodetic reference for heights. Bench mark elevations relative to
NAVD 88 are available from NGS through the World Wide Web at
National Geodetic Survey.
NGVD 29 and NAVD 88 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 NAVD 88 elevation is shown on the Elevations of Tidal Datums Table Referred
to MLLW only when two or more of the bench marks listed have NAVD 88 elevations.
The NAVD 88 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, NAVD 88 bench mark elevations computed indirectly from the tidal
datums elevation table may differ slightly from NAVD 88 elevations listed for
each bench mark in the NGS database.