U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Datums Page Page 1 of 5
Station ID: 8674975 PUBLICATION DATE: 08/13/2012
Name: DAYMARK #156, HEAD OF MUD RIVER
GA
NOAA Chart: 11510 Latitude: 31° 29.2' N ( 31.48670)
USGS Quad: DOBOY SOUND Longitude: 81° 19.2' W ( -81.32000)
To reach the tidal bench marks from the intersection of I-95 and highway 99
proceed east on HWY 99 for 8.0 km (5 mi). To the city of Crescent turn NE onto
Susan Baker Drive to the public boat ramp on the Sapelo River. From the boat
ramp proceed SE by boat through the unnamed creek 3.0 km (1.9 mi). To the
intersection with the Crescent River, proceed SE along the Crescent River for
3.7 km (2.3 mi). To the intersection with the ICWW. The station is on Daymark
156 at the intersection. The bench marks are on the land adjacent to the WNW of
Daymark 156.
T I D A L B E N C H M A R K S
PRIMARY BENCH MARK STAMPING: 4975 B 1980
DESIGNATION: 867 4975 B 1980
MONUMENTATION: Survey disk VM#: 4880
AGENCY: National Ocean Survey (NOS) IDB PID#:
SETTING CLASSIFICATION: Unspecified deep rod OPUS PID#: BBCR38
LATITUDE: 31° 29.4' N ( 31.49044) LONGITUDE: 81° 19.5' W ( -81.32483)
The bench mark is a disk located on the land adjacent to the WNW of the Daymark
156 at the intersection of the Crescent River and the ICWW, 61.2m (200.8 ft) W
of NOAA/NOS tide station 867 4975, 22.6 m (74.1 ft) N of the highwater mark of
the southernmost tip of the island, 19.5 m (64.0 ft) SE of bench mark 867 4975
C, 19.0 m (62.3 ft) NW of bench mark 867 4975 A, 3.0 m (9.8 ft) southeast of a
cedar tree. The bench mark is set 0.3 m (1.0 ft) above ground, crimped to a
stainless steel rod driven to refusal and encased in a 4 inch PVC pipe.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 2 of 5
Station ID: 8674975 PUBLICATION DATE: 08/13/2012
Name: DAYMARK #156, HEAD OF MUD RIVER
GA
NOAA Chart: 11510 Latitude: 31° 29.2' N ( 31.48670)
USGS Quad: DOBOY SOUND Longitude: 81° 19.2' W ( -81.32000)
T I D A L B E N C H M A R K S
BENCH MARK STAMPING: 4975 C 1980
DESIGNATION: 867 4975 C 1980
MONUMENTATION: Survey disk VM#: 4881
AGENCY: National Ocean Survey (NOS) IDB PID#:
SETTING CLASSIFICATION: Unspecified deep rod OPUS PID:
LATITUDE: 31° 29.4' N ( 31.49058) LONGITUDE: 81° 19.5' W ( -81.32489)
The bench mark is a disk located on the land adjacent to the WNW of the Daymark
156 at the intersection of the Crescent River and the ICWW, 81.3m (266.7 ft) NW
of NOAA/NOS tide station 867 4975, 20.8 m (68.2 ft) SE of bench mark 867 4975 D,
19.5 m (64.0 ft) NE of bench mark 867 4976 B, 13.4m (44.0 ft) W of the
highwater mark on the eastern most side of the island, 3.0 m (9.8 ft) S of the
southern edge of the woods. The bench mark is set 0.3 m (1.0 ft) above ground,
crimped to a stainless steel rod driven to refusal and encased in a 4 inch PVC
pipe.
BENCH MARK STAMPING: 4975 D 1980
DESIGNATION: 867 4975 D 1980
MONUMENTATION: Survey disk VM#: 4882
AGENCY: National Ocean Survey (NOS) IDB PID#:
SETTING CLASSIFICATION: Unspecified deep rod OPUS PID:
LATITUDE: 31° 29.4' N ( 31.49075) LONGITUDE: 81° 19.5' W ( -81.32500)
The bench mark is a disk located on the land adjacent to the WNW of the Daymark
156 at the intersection of the Crescent River and the ICWW, 100.4 m (329.4 ft)
NW of NOAA/NOS tide station 867 4975, 25.7 m (84.3 ft) ESE of bench mark 867
4975 E, 20.8 m (68.2 ft) NW of bench mark 867 4975 C, 17.3 m (56.8 ft) W of the
highwater mark of the eastern most side of the island, 3.0 m (9.8 ft) S of the
southern edge of the woods. The bench mark is set 0.3 m (1.0 ft) above ground,
crimped to a stainless steel rod driven to refusal and encased in a 4 inch PVC
pipe.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 3 of 5
Station ID: 8674975 PUBLICATION DATE: 08/13/2012
Name: DAYMARK #156, HEAD OF MUD RIVER
GA
NOAA Chart: 11510 Latitude: 31° 29.2' N ( 31.48670)
USGS Quad: DOBOY SOUND Longitude: 81° 19.2' W ( -81.32000)
T I D A L B E N C H M A R K S
BENCH MARK STAMPING: 4975 E 1980
DESIGNATION: 867 4975 E 1980
MONUMENTATION: Survey disk VM#: 4883
AGENCY: National Ocean Survey (NOS) IDB PID#:
SETTING CLASSIFICATION: Unspecified deep rod OPUS PID:
LATITUDE: 31° 29.4' N ( 31.49081) LONGITUDE: 81° 19.5' W ( -81.32528)
The bench mark is a disk located on the land adjacent to the WNW of the day mark
156 at the intersection of the crescent river and the ICWW, 122.3 m (401.2 ft)
NW of NOAA/NOS tide station 867 4975, 35.6 m (116.8 ft) WNW of bench mark 867
4975 C, 25.7 m (84.3 ft)WNW of bench mark 867 4975 d, 23.8 m (78.1 ft) W of the
highwater mark of the eastern most side of the island, 3.0 m (9.8 ft) S of the
southern edge of the woods. The bench mark is set 0.3 m (1.0 ft) above ground,
crimped to a stainless steel rod driven to refusal and encased in a 4 inch PVC
pipe.
BENCH MARK STAMPING: 4975 A 2012
DESIGNATION: 867 4975 A 2012
MONUMENTATION: Survey disk VM#: 20480
AGENCY: IDB PID#:
SETTING CLASSIFICATION: Unspecified deep rod OPUS PID:
LATITUDE: 31° 29.4' N ( 31.49025) LONGITUDE: 81° 19.5' W ( -81.32481)
The bench mark is a flanged-encased rod located on the land adjacent to the WNW
of the Daymark 156 at the intersection of the Crescent River and the ICWW, 52.79
m (173.2 ft) W of NOAA/NOS tide station 867 4975, 19.0 m (62.3 ft) SE of bench
mark 867 4975 B, 11.2 m (36.7 ft) south of the southern edge of the woods, 3.7 m
(12.1 ft) north of the high-water mark on the southernmost tip of the island.
The datum point is set 15.0 cm (6 inches) above the ground, being the top of a
stainless steel rod driven 12.0 m (39.4 ft) to refusal and encased in a NOS
5-inch logo cap.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 4 of 5
Station ID: 8674975 PUBLICATION DATE: 08/13/2012
Name: DAYMARK #156, HEAD OF MUD RIVER
GA
NOAA Chart: 11510 Latitude: 31° 29.2' N ( 31.48670)
USGS Quad: DOBOY SOUND Longitude: 81° 19.2' W ( -81.32000)
T I D A L D A T U M S
Tidal datums at DAYMARK #156, HEAD OF MUD RIVER based on:
LENGTH OF SERIES: 3 MONTHS
TIME PERIOD: February 2012 - April 2012
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 = 2.471
MEAN HIGH WATER MHW = 2.354
MEAN SEA LEVEL MSL = 1.281
MEAN TIDE LEVEL MTL = 1.211
MEAN LOW WATER MLW = 0.068
MEAN LOWER LOW WATER MLLW = 0.000
North American Vertical Datum (NAVD88)
Bench Mark Elevation Information In METERS above:
Stamping or Designation MLLW MHW
4975 B 1980 3.261 0.907
4975 C 1980 3.257 0.903
4975 D 1980 3.484 1.130
4975 E 1980 3.340 0.986
4975 A 2012 2.879 0.525
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 5 of 5
Station ID: 8674975 PUBLICATION DATE: 08/13/2012
Name: DAYMARK #156, HEAD OF MUD RIVER
GA
NOAA Chart: 11510 Latitude: 31° 29.2' N ( 31.48670)
USGS Quad: DOBOY SOUND Longitude: 81° 19.2' W ( -81.32000)
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.