U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Datums Page Page 1 of 5
Station ID: 8676329 PUBLICATION DATE: 03/09/2004
Name: MACKAY RIVER, ICWW, BUTTERMILK SOUND
GA
NOAA Chart: 11508 Latitude: 31° 17.1' N ( 31.28500)
USGS Quad: BRUNSWICK EAST Longitude: 81° 23.1' W ( -81.38500)
To reach the tidal bench marks, proceed by boat to the marshy area on the east
shore of Mackay River on Little St. Simons Island, 1.6 km (1.0 mi) north of the
intersection with Hampton River and Wilson Creek. The bench marks are situated
between two small hammocks immediately adjacent to Day Mark 221, 32 m (105 ft)
south of northern hammock and 15.24 m (50.0 ft) north of southern hammock. The
tide gage and staff were located on Day Mark 221 on the Intracoastal Waterway.
T I D A L B E N C H M A R K S
PRIMARY BENCH MARK STAMPING: 6329 A 1980
DESIGNATION: 867 6329 A TIDAL
MONUMENTATION: Tidal Station disk VM#: 4904
AGENCY: National Ocean Survey (NOS) IDB PID#:
SETTING CLASSIFICATION: Unspecified deep rod OPUS PID:
LATITUDE: 31° 17.6' N ( 31.29330) LONGITUDE: 81° 23.7' W ( -81.39500)
The primary bench mark is a disk located in a marshy area on the east shore of
Mackay River situated between two small hammocks immediately adjacent to Day
Mark 221, 21 m (69 ft) east of the shoreline. The bench mark is crimped to the
top of a deep rod driven 18.3 m (60 ft) to refusal and encased in a 1.16 m (3.8
ft) piece of white 4-inch PVC pipe which protrudes 0.37 m (1.2 ft) above ground.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 2 of 5
Station ID: 8676329 PUBLICATION DATE: 03/09/2004
Name: MACKAY RIVER, ICWW, BUTTERMILK SOUND
GA
NOAA Chart: 11508 Latitude: 31° 17.1' N ( 31.28500)
USGS Quad: BRUNSWICK EAST Longitude: 81° 23.1' W ( -81.38500)
T I D A L B E N C H M A R K S
BENCH MARK STAMPING: 6329 B 1980
DESIGNATION: 867 6329 B TIDAL
MONUMENTATION: Tidal Station disk VM#: 4905
AGENCY: National Ocean Survey (NOS) IDB PID#:
SETTING CLASSIFICATION: Unspecified deep rod OPUS PID:
LATITUDE: 31° 17.6' N ( 31.29330) LONGITUDE: 81° 23.7' W ( -81.39500)
The bench mark is a disk located in a marshy area on the east shore of Mackay
River situated between two hammocks, immediately adjacent to Day Mark 221, 45 m
(148 ft) east of the shoreline, 24 m (79 ft) NE of bench mark 6329 A 1980, 22.56
m (74.0 ft) south of northern hammock, and 12.50 m (41.0 ft) north of southern
hammock. The bench mark is crimped to the top of a deep rod driven 18.3 m (60
ft) to refusal and encased in a 1.22 m (4.0 ft) piece of white 4-inch PVC pipe
in length which protrudes 0.40 m (1.3 ft) above ground.
BENCH MARK STAMPING: 6329 C 1980
DESIGNATION: 867 6329 C TIDAL
MONUMENTATION: Tidal Station disk VM#: 4906
AGENCY: National Ocean Survey (NOS) IDB PID#:
SETTING CLASSIFICATION: Unspecified deep rod OPUS PID:
LATITUDE: 31° 17.6' N ( 31.29330) LONGITUDE: 81° 23.7' W ( -81.39500)
The bench mark is a disk located in a marshy area on the east shore of Mackay
River situated between two small hammocks immediately adjacent to Day Mark 221,
77 m (252 ft) east of the shoreline, 31.70 m (104.0 ft) NE of bench mark 6329 B
1980, 15.24 m (50.0 ft) north of southern hammock and 15.24 m (50.0 ft) south of
northern hammock. The bench mark is crimped to the top of a deep rod driven
18.3 m (60 ft) to refusal and encased in a 1.13 m (3.7 ft) piece of white 4-inch
PVC pipe which protrudes 0.40 m (1.3 ft) above ground.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 3 of 5
Station ID: 8676329 PUBLICATION DATE: 03/09/2004
Name: MACKAY RIVER, ICWW, BUTTERMILK SOUND
GA
NOAA Chart: 11508 Latitude: 31° 17.1' N ( 31.28500)
USGS Quad: BRUNSWICK EAST Longitude: 81° 23.1' W ( -81.38500)
T I D A L B E N C H M A R K S
BENCH MARK STAMPING: 6329 D 1980
DESIGNATION: 867 6329 D TIDAL
MONUMENTATION: Tidal Station disk VM#: 4907
AGENCY: National Ocean Survey (NOS) IDB PID#:
SETTING CLASSIFICATION: Unspecified deep rod OPUS PID:
LATITUDE: 31° 17.6' N ( 31.29330) LONGITUDE: 81° 23.7' W ( -81.39500)
The bench mark is a disk located in a marshy area on the east shore of Mackay
River situated between two small hammocks immediately adjacent to Day Mark 221,
101.80 m (334.0 ft) east of the shoreline, 33.53 m (110.0 ft) south of northern
hammock and 21.34 m (70.0 ft) north of southern hammock. The bench mark is set
atop a deep rod driven to refusal at 18.3 m (60 ft) and encased in a 1.16 m (3.8
ft) piece of 4-inch white PVC pipe which protrudes 0.37 m (1.2 ft) above ground.
BENCH MARK STAMPING: 6329 E 1980
DESIGNATION: 867 6329 E TIDAL
MONUMENTATION: Tidal Station disk VM#: 4908
AGENCY: National Ocean Survey (NOS) IDB PID#:
SETTING CLASSIFICATION: Unspecified deep rod OPUS PID:
LATITUDE: 31° 17.6' N ( 31.29330) LONGITUDE: 81° 23.7' W ( -81.39500)
The bench mark is a disk located in a marshy area on the east shore of Mackay
River situated between two small hammocks immediately adjacent to Day Mark 221,
142.65 m (468.0 ft) east of the shoreline, 39.62 m (130.0 ft) south of northern
hammock and 21.34 m (70.0 ft) north of southern hammock. The bench mark is
crimped to the top of a deep rod driven 18.3 m (60 ft) to refusal and encased in
a 1.07 m (3.5 ft) piece of white 4-inch PVC pipe which protrudes 0.46 m (1.5 ft)
above ground.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 4 of 5
Station ID: 8676329 PUBLICATION DATE: 03/09/2004
Name: MACKAY RIVER, ICWW, BUTTERMILK SOUND
GA
NOAA Chart: 11508 Latitude: 31° 17.1' N ( 31.28500)
USGS Quad: BRUNSWICK EAST Longitude: 81° 23.1' W ( -81.38500)
T I D A L D A T U M S
Tidal datums at MACKAY RIVER, ICWW, BUTTERMILK SOUND based on:
LENGTH OF SERIES: 1 MONTH
TIME PERIOD: May 1980 - May 1980
TIDAL EPOCH: 1983-2001
CONTROL TIDE STATION: 8670870 FORT PULASKI, SAVANNAH RIVER
Elevations of tidal datums referred to Mean Lower Low Water (MLLW), in METERS:
MEAN HIGHER HIGH WATER MHHW = 2.264
MEAN HIGH WATER MHW = 2.167
MEAN SEA LEVEL MSL = 1.199
MEAN TIDE LEVEL MTL = 1.120
MEAN LOW WATER MLW = 0.073
MEAN LOWER LOW WATER MLLW = 0.000
North American Vertical Datum (NAVD88)
Bench Mark Elevation Information In METERS above:
Stamping or Designation MLLW MHW
6329 A 1980 2.655 0.488
6329 B 1980 2.746 0.579
6329 C 1980 2.750 0.583
6329 D 1980 2.675 0.508
6329 E 1980 2.648 0.481
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 5 of 5
Station ID: 8676329 PUBLICATION DATE: 03/09/2004
Name: MACKAY RIVER, ICWW, BUTTERMILK SOUND
GA
NOAA Chart: 11508 Latitude: 31° 17.1' N ( 31.28500)
USGS Quad: BRUNSWICK EAST Longitude: 81° 23.1' W ( -81.38500)
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 NGS's Integrated Data Base (IDB PID)
provides geodetic datum based on traditionally leveled and bluebooked ties to
the National Spatial Reference System(NSRS) https://www.ngs.noaa.gov/datasheets/.
The NGS Online Positioning User Service (OPUS PID) provides geodetic datum based
on GPS position & tie it to the NSRS https://www.ngs.noaa.gov/OPUS/.
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.