U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Datums Page Page 1 of 6
Station ID: 8659084 PUBLICATION DATE: 08/14/2003
Name: SOUTHPORT
NC
NOAA Chart: 11537 Latitude: 33° 54.9' N ( 33.91500)
USGS Quad: SOUTHPORT Longitude: 78° 1.1' W ( -78.01830)
To reach the tidal bench marks from the Southport Post Office on Dry Street
proceed south to East Moore Street, turn west on East Moore Street for 1 block
to Davis Street, and then turn south on Davis Street for 1 block to the
Southport Fishing Pier. The bench marks are located on the Fort Johnson
Reservation grounds, and along Howe, East Nash, and East Moore Streets. The tide
gage and staff were located about 100 m (328 ft) south of the inshore end of the
pier.
T I D A L B E N C H M A R K S
PRIMARY BENCH MARK STAMPING: GAR 2 21.48 1939 1962
MONUMENTATION: Triangulation Station disk VM#: 3636
AGENCY: US Army Corps of Engineers (USE) IDB PID#: DD0054
SETTING CLASSIFICATION: Concrete block OPUS PID:
LATITUDE: 33° 55.1' N ( 33.91830) LONGITUDE: 78° 1.0' W ( -78.01670)
The primary bench mark is a disk set flush in a 0.73 m x 0.91 m (2.4 ft x 3.0
ft) concrete block at the Fort Johnston Reservation, 38.25 m (125.5 ft) SE of
the SW corner of a brick house, 30.94 m (101.5 ft) SW of the SW corner of a
white wood house, 30.48 m (100.0 ft) ENE of a large boulder with a tablet by the
North Carolina Society of Colonial Dames, 24.38 m (80.0 ft) WSW of a large
boulder with a tablet by the National Society of United States Daughters of
1812, 23.77 m (78.0 ft) NNW of the centerline of East Bay Street, 17.80 m (58.4
ft) SE of a 0.61 m (2.0 ft) diameter oak tree, and 5.94 m (19.5 ft) south of a
guy wired 0.10 m (0.3 ft) diameter tree.
BENCH MARK STAMPING: NO 1A 1974
MONUMENTATION: Tidal Station disk VM#: 3627
AGENCY: National Ocean Survey (NOS) IDB PID#:
SETTING CLASSIFICATION: Concrete foundation OPUS PID:
LATITUDE: 33° 54.9' N ( 33.91500) LONGITUDE: 78° 1.1' W ( -78.01830)
The bench mark is a disk set in a concrete foundation located at the shore end
of Southport Municipal Pier, 31.4 m (103 ft) SE of the storm warning tower at
the Fort Johnston Reservation, 6.40 m (21 ft) south on the extended centerline
of E. Bay Street, and 0.15 m (0.5 ft) east of the west edge of the pier.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 2 of 6
Station ID: 8659084 PUBLICATION DATE: 08/14/2003
Name: SOUTHPORT
NC
NOAA Chart: 11537 Latitude: 33° 54.9' N ( 33.91500)
USGS Quad: SOUTHPORT Longitude: 78° 1.1' W ( -78.01830)
T I D A L B E N C H M A R K S
BENCH MARK STAMPING: NO 1 B 1974
MONUMENTATION: Tidal Station disk VM#: 3628
AGENCY: National Ocean Survey (NOS) IDB PID#: DD0990
SETTING CLASSIFICATION: Concrete sidewalk OPUS PID:
LATITUDE: 33° 55.2' N ( 33.92000) LONGITUDE: 78° 1.2' W ( -78.02000)
The bench mark is a disk set flush in a concrete sidewalk at the NE corner of
Howe Street and E. Nash Street, 14.63 m (48.0 ft) north of the centerline of E.
Nash Street, 2.44 m (8.0 ft) north of the north curb of E. Nash Street, and 0.30
m (1.0 ft) east of the east curb of Howe Street.
BENCH MARK STAMPING: NO 2 1974
MONUMENTATION: Tidal Station disk VM#: 3629
AGENCY: National Ocean Survey (NOS) IDB PID#: DD0991
SETTING CLASSIFICATION: Concrete flagpole foundation OPUS PID:
LATITUDE: 33° 55.0' N ( 33.91670) LONGITUDE: 78° 1.0' W ( -78.01670)
The bench mark is a disk set in the NW corner of a flagpole base in front of the
Community Center Building (Building 223) at the Fort Johnston Reservation, 21.64
m (71.0 ft) east of a large boulder with a tablet by the National Society of
United States Daughters of 1812, 19.90 m (65.3 ft) SE of the SE corner of
Building 223, 13.56 m (44.5 ft) south of the front door of Building 223, and 0.3
m (1 ft) above ground.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 3 of 6
Station ID: 8659084 PUBLICATION DATE: 08/14/2003
Name: SOUTHPORT
NC
NOAA Chart: 11537 Latitude: 33° 54.9' N ( 33.91500)
USGS Quad: SOUTHPORT Longitude: 78° 1.1' W ( -78.01830)
T I D A L B E N C H M A R K S
BENCH MARK STAMPING: X 28 1932
MONUMENTATION: Bench Mark disk VM#: 3630
AGENCY: US Coast and Geodetic Survey
(USC&GS) IDB PID#: DD0052
SETTING CLASSIFICATION: Building OPUS PID:
LATITUDE: 33° 55.1' N ( 33.91830) LONGITUDE: 78° 1.1' W ( -78.01830)
The bench mark is a disk set vertically in the SE wall of the City Hall building
located in the SW quadrant of the intersection of Moore Street and S. Davis
Street, 4.57 m (15.0 ft) east of the main entrance, 0.30 m (1.0 ft) west of the
east corner of the building, recessed in the stucco wall 1.90 cm (0.06 ft), and
1.52 m (5.0 ft) above ground.
BENCH MARK STAMPING: 9084 A 1977
MONUMENTATION: Tidal Station disk VM#: 3632
AGENCY: National Ocean Survey (NOS) IDB PID#:
SETTING CLASSIFICATION: Concrete sidewalk OPUS PID:
LATITUDE: 33° 54.9' N ( 33.91500) LONGITUDE: 78° 1.1' W ( -78.01830)
The bench mark is a disk set in a concrete sidewalk at 115 East Moore Street,
20.39 m (66.9 ft) north of the centerline of East Moore Street, 6.34 m (20.8 ft)
west of the SE corner of the building.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 4 of 6
Station ID: 8659084 PUBLICATION DATE: 08/14/2003
Name: SOUTHPORT
NC
NOAA Chart: 11537 Latitude: 33° 54.9' N ( 33.91500)
USGS Quad: SOUTHPORT Longitude: 78° 1.1' W ( -78.01830)
T I D A L B E N C H M A R K S
BENCH MARK STAMPING: 9084 B 1979
MONUMENTATION: Tidal Station disk VM#: 3633
AGENCY: National Ocean Survey (NOS) IDB PID#:
SETTING CLASSIFICATION: Galvanized steel rod OPUS PID:
LATITUDE: 33° 54.9' N ( 33.91500) LONGITUDE: 78° 1.1' W ( -78.01830)
The bench mark is a disk located on the north side of East Nash Street at the
Rescue Building, 21.34 m (70.0 ft) north of the centerline of East Nash Street,
8.78 m (28.8 ft) NW of a phone box, and 0.49 m (1.6 ft) SE of the SE corner of
the Rescue Building. The bench mark is set 6 cm (0.2 ft) below ground level,
crimped to a galvanized steel rod driven 11.9 m (39 ft) to refusal, and encased
in a 4-inch PVC pipe and concrete kickblock.
BENCH MARK STAMPING: 9084 C 1979
MONUMENTATION: Tidal Station disk VM#: 3634
AGENCY: National Ocean Survey (NOS) IDB PID#:
SETTING CLASSIFICATION: Galvanized steel rod OPUS PID:
LATITUDE: 33° 54.9' N ( 33.91500) LONGITUDE: 78° 1.1' W ( -78.01830)
The bench mark is a disk located at the intersection of N. Howe and E. West
Streets, 15.54 m (51.0 ft) south of the centerline of E. West Street, 15.36 m
(50.4 ft) east of the centerline of N. Howe Street, and 5.94 m (19.5 ft) SE of a
fire hydrant located at the SE corner of the intersection of N. Howe Street and
E. West Street. The bench mark is set 15 cm (0.5 ft) below ground level, crimped
to a galvanized steel rod driven 14.6 m (48 ft) to refusal, and encased in a
4-inch PVC pipe and concrete kickblock.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 5 of 6
Station ID: 8659084 PUBLICATION DATE: 08/14/2003
Name: SOUTHPORT
NC
NOAA Chart: 11537 Latitude: 33° 54.9' N ( 33.91500)
USGS Quad: SOUTHPORT Longitude: 78° 1.1' W ( -78.01830)
D A T U M S
Datums at SOUTHPORT based on:
LENGTH OF SERIES: 10 Years
TIME PERIOD: January 1978 - December 1987
TIDAL EPOCH: 1983-2001
CONTROL TIDE STATION: 8665530 CHARLESTON, COOPER RIVER ENTRANCE
Elevations of datums referred to Mean Lower Low Water (MLLW), in METERS:
HIGHEST OBSERVED WATER LEVEL (12/02/1986) = 2.096
MEAN HIGHER HIGH WATER MHHW = 1.442
MEAN HIGH WATER MHW = 1.340
North American Vertical Datum NAVD88 = 0.847
MEAN SEA LEVEL MSL = 0.706
MEAN TIDE LEVEL MTL = 0.694
MEAN LOW WATER MLW = 0.047
MEAN LOWER LOW WATER MLLW = 0.000
LOWEST OBSERVED WATER LEVEL (03/18/1980) = -0.620
North American Vertical Datum (NAVD88)
Bench Mark Elevation Information In METERS above:
Stamping or Designation MLLW MHW
GAR 2 21.48 1939 1962 6.362 5.022
NO 1A 1974 4.800 3.460
NO 1 B 1974 6.716 5.376
NO 2 1974 6.504 5.164
X 28 1932 8.445 7.105
9084 A 1977 5.780 4.440
9084 B 1979 6.530 5.190
9084 C 1979 7.058 5.718
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 6 of 6
Station ID: 8659084 PUBLICATION DATE: 08/14/2003
Name: SOUTHPORT
NC
NOAA Chart: 11537 Latitude: 33° 54.9' N ( 33.91500)
USGS Quad: SOUTHPORT Longitude: 78° 1.1' W ( -78.01830)
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.