U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Datums Page Page 1 of 5
Station ID: 8660098 PUBLICATION DATE: 08/03/2004
Name: LITTLE RIVER NECK
SOUTH CAROLINA
NOAA Chart: 11535 Latitude: 33° 52.2' N
USGS Quad: LITTLE RIVER Longitude: 78° 34.4' W
To reach the tidal bench marks from the overpass of State Road 90 over U.S.
Highway 17 at Little River, proceed SW on State Road 90 for 0.2 km (0.1 mi),
then turn left onto Sea Mountain Highway and proceed SE following the signs for
Cherry Grove for 0.2 km (0.1 mi) to the first intersection after the bridge,
then turn left and proceed east and NE on Little River Neck Road (S-26-236) for
6.3 km (3.9 mi), following the signs for Little River Neck, passing underneath
the overpass of U.S. Highway 17 over the Intracoastal Waterway, to the entrance
gate of Tilghman Point. Check with the caretaker at the first house on the
left. From the front gate proceed east along the dirt road for 2.4 km (1.5 mi),
turn left onto the first dirt road on the left past the summerhouse driveway.
The bench marks are along the dirt road and in the vicinity of a fresh water
pond. The tide gage and staff were on a piling in Little River across the
channel from daymarker #2.
T I D A L B E N C H M A R K S
PRIMARY BENCH MARK STAMPING: IW NO 1 1975
DESIGNATION: 866 0098 TIDAL IW 1
MONUMENTATION: Tidal Station disk VM#: 3664
AGENCY: National Ocean Survey (NOS) PID#: DD1747
SETTING CLASSIFICATION: Copper clad steel rod
The bench mark is a disk located between the fresh water pond and the dirt road
surrounding the pond, 15.85 m (52.0 ft) WSW of a multi-trunk tree on the east
side of the dirt road, 13 m (43 ft) SE of the NE end of the pond, 12.19 m (40.0
ft) SSW of the centerline of the dirt road at the beginning of the curve at the
NE end of the pond, 9 m (30 ft) north of the north face of a 0.46 m (1.5 ft)
diameter leaning pine tree on the NW side of a fire trail, 8.08 m (26.5 ft) west
of the intersection of the dirt road and the fire trail, and 6.16 m (20.2 ft)
SSW of a 0.37 m (1.2 ft) diameter pine tree on the SW side of the dirt road.
The bench mark is set 0.15 m (0.5 ft) below the ground, crimped to the top of a
copper-clad steel rod driven an unspecified depth and encased in a 5-inch PVC
pipe and concrete kickblock.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 2 of 5
Station ID: 8660098 PUBLICATION DATE: 08/03/2004
Name: LITTLE RIVER NECK
SOUTH CAROLINA
NOAA Chart: 11535 Latitude: 33° 52.2' N
USGS Quad: LITTLE RIVER Longitude: 78° 34.4' W
T I D A L B E N C H M A R K S
BENCH MARK STAMPING: IW NO 2 1975
DESIGNATION: 866 0098 TIDAL IW 2
MONUMENTATION: Tidal Station disk VM#: 3665
AGENCY: National Ocean Survey (NOS) PID#: DD1746
SETTING CLASSIFICATION: Copper clad steel rod
The bench mark is a disk located between the fresh water pond and the road
surrounding the pond, 7 m (22 ft) NW of the NW end of the pond, and 3.35 m (11.0
ft) SE of the centerline of the dirt road. The bench mark is set 3 cm (0.1 ft)
below the ground, crimped to the top of a copper-clad steel rod driven to an
unspecified depth to refusal and encased in a PVC pipe and concrete kickblock.
BENCH MARK STAMPING: IW NO 3 1975
DESIGNATION: 866 0098 TIDAL IW 3
MONUMENTATION: Tidal Station disk VM#: 3666
AGENCY: National Ocean Survey (NOS) PID#: DD1744
SETTING CLASSIFICATION: Concrete monument
The bench mark is a disk set in the top of a concrete monument south of the
fresh water pond, 152 m (498 ft) south of bench mark IW NO 4 1975, 35.60 m
(116.8 ft) WSW of the northernmost unnumbered pole (first of five poles north to
south), 21 m (70 ft) NW of a 0.55 m (1.8 ft) diameter pecan tree, 16.61 m (54.5
ft) SE of a 0.46 m (1.5 ft) diameter pecan tree, and 16 m (54 ft) SW of a 0.70 m
(2.3 ft) diameter pecan tree across the road.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 3 of 5
Station ID: 8660098 PUBLICATION DATE: 08/03/2004
Name: LITTLE RIVER NECK
SOUTH CAROLINA
NOAA Chart: 11535 Latitude: 33° 52.2' N
USGS Quad: LITTLE RIVER Longitude: 78° 34.4' W
T I D A L B E N C H M A R K S
BENCH MARK STAMPING: IW NO 4 1975
DESIGNATION: 866 0098 TIDAL IW 4
MONUMENTATION: Tidal Station disk VM#: 3667
AGENCY: National Ocean Survey (NOS) PID#: DD1745
SETTING CLASSIFICATION: Copper clad steel rod
The bench mark is a disk located at the intersection of the dirt road and the
road surrounding the pond, 320 m (1050 ft) SW of bench mark IW NO 2 1975, 13 m
(42 ft) NE of the centerline of the dirt road, 13 m (42 ft) NW of the centerline
of the pond road, and 4 m (13 ft) east of a 0.3 m (1 ft) diameter pecan tree.
The bench mark is set 9 cm (0.3 ft) below the ground, crimped to the top of a
copper-clad steel rod driven to an unspecified depth to refusal, and encased in
a PVC pipe and concrete kickblock.
BENCH MARK STAMPING: IW NO 5 1975
DESIGNATION: 866 0098 TIDAL IW 5
MONUMENTATION: Tidal Station disk VM#: 3668
AGENCY: National Ocean Survey (NOS) PID#: DD1748
SETTING CLASSIFICATION: Concrete monument
The bench mark is a disk set in the top of a concrete monument in a small
clearing on the west side of the road, 0.2 km (0.1 mi) SSE of bench mark IW NO 1
1975, 1622 m (530 ft) SE of the pond, 5 m (17 ft) west of the centerline of the
dirt road, 1.01 m (3.3 ft) SW of a wooden witness post, and level with the
ground.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 4 of 5
Station ID: 8660098 PUBLICATION DATE: 08/03/2004
Name: LITTLE RIVER NECK
SOUTH CAROLINA
NOAA Chart: 11535 Latitude: 33° 52.2' N
USGS Quad: LITTLE RIVER Longitude: 78° 34.4' W
T I D A L D A T U M S
Tidal datums at LITTLE RIVER NECK based on:
LENGTH OF SERIES: 9 MONTHS
TIME PERIOD: May 1975 - January 1976
TIDAL EPOCH: 1983-2001
CONTROL TIDE STATION: 8665530 CHARLESTON, COOPER RIVER ENTRANCE
Elevations of tidal datums referred to Mean Lower Low Water (MLLW), in METERS:
MEAN HIGHER HIGH WATER (MHHW) = 1.577
MEAN HIGH WATER (MHW) = 1.460
NORTH AMERICAN VERTICAL DATUM-1988 (NAVD) = 0.863
MEAN SEA LEVEL (MSL) = 0.760
MEAN TIDE LEVEL (MTL) = 0.754
MEAN LOW WATER (MLW) = 0.049
MEAN LOWER LOW WATER (MLLW) = 0.000
National Geodetic Vertical Datum (NGVD 29)
Bench Mark Elevation Information In METERS above:
Stamping or Designation MLLW MHW
IW NO 1 1975 4.260 2.800
IW NO 2 1975 4.959 3.499
IW NO 3 1975 8.153 6.693
IW NO 4 1975 8.031 6.571
IW NO 5 1975 6.485 5.025
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 5 of 5
Station ID: 8660098 PUBLICATION DATE: 08/03/2004
Name: LITTLE RIVER NECK
SOUTH CAROLINA
NOAA Chart: 11535 Latitude: 33° 52.2' N
USGS Quad: LITTLE RIVER Longitude: 78° 34.4' 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.