U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Datums Page Page 1 of 6
Station ID: 8666659 PUBLICATION DATE: 03/09/2004
Name: COMBAHEE RIVER AT US HWY. 17
SC
NOAA Chart: 11519 Latitude: 32° 39.1' N ( 32.65170)
USGS Quad: GREEN POND Longitude: 80° 41.0' W ( -80.68330)
To reach the tidal bench marks from the junction of U.S. Highway 17 and State
Highway 303 in Green Pond, proceed SW on U.S. Highway 17 for 9.8 km (6.1 mi) to
the highway bridge over the Combahee River. The bench marks are in the vicinity
of the boat landing and picnic area just SW of the bridge. The tide gage and
staff were on the SE corner of the bridge.
T I D A L B E N C H M A R K S
PRIMARY BENCH MARK STAMPING: C.R.B. NO 5 1976
DESIGNATION: 866 6659 TIDAL CRB 5
MONUMENTATION: Tidal Station disk VM#: 10999
AGENCY: National Ocean Survey (NOS) IDB PID#: CK2256
SETTING CLASSIFICATION: Copper clad steel rod OPUS PID:
LATITUDE: 32° 39.2' N ( 32.65330) LONGITUDE: 80° 41.1' W ( -80.68500)
The primary bench mark is a disk located in the NE corner of the picnic area to
the SW of the bridge, 69 m (225 ft) NNW of the centerline of the highway, 42 m
(139 ft) NNW of a power pole and yard light, 36 m (118 ft) ENE of bench mark
C.R.B. NO 6 1976, 8.84 m (29.0 ft) north of a double trunk oak tree, 7.44 m
(24.4 ft) north of a 12-inch cyprus tree, 7.32 m (24.0 ft) north of a 20-inch
diameter sweet gum, 5 m (15 ft) WSW of the SW bank of the river, and 1.55 m (5.1
ft) SW of a witness post. The bench mark is set 2.41 m (7.9 ft) below the
highway, crimped to the top of a copper-clad steel rod driven 14.6 m (48 ft) to
refusal, encased in a 4-inch PVC pipe and concrete kickblock. NOTE: Mark not
found in 1998 by US Power Squadron.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 2 of 6
Station ID: 8666659 PUBLICATION DATE: 03/09/2004
Name: COMBAHEE RIVER AT US HWY. 17
SC
NOAA Chart: 11519 Latitude: 32° 39.1' N ( 32.65170)
USGS Quad: GREEN POND Longitude: 80° 41.0' W ( -80.68330)
T I D A L B E N C H M A R K S
BENCH MARK STAMPING: NO 3 1934
DESIGNATION: 866 6659 TIDAL 3
MONUMENTATION: Tidal Station disk VM#: 10997
AGENCY: US Coast & Geodetic Survey
(USC&GS) IDB PID#: CK1468
SETTING CLASSIFICATION: Pier OPUS PID:
LATITUDE: 32° 39.1' N ( 32.65170) LONGITUDE: 80° 41.0' W ( -80.68330)
The bench mark is a disk set in the north side of the west concrete pier of the
swinging span of the highway bridge, 19 m (62 ft) NE of the SW end of the
bridge, 5.58 m (18.3 ft) SE of the centerline of the bridge, and 1.20 m (3.9 ft)
below US Highway 17.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 3 of 6
Station ID: 8666659 PUBLICATION DATE: 03/09/2004
Name: COMBAHEE RIVER AT US HWY. 17
SC
NOAA Chart: 11519 Latitude: 32° 39.1' N ( 32.65170)
USGS Quad: GREEN POND Longitude: 80° 41.0' W ( -80.68330)
T I D A L B E N C H M A R K S
BENCH MARK STAMPING: V 106 1962
DESIGNATION: V 106
MONUMENTATION: Bench Mark disk VM#: 10998
AGENCY: US Coast & Geodetic Survey
(USC&GS) IDB PID#: CK1467
SETTING CLASSIFICATION: Concrete abutment OPUS PID:
LATITUDE: 32° 39.2' N ( 32.65330) LONGITUDE: 80° 40.9' W ( -80.68170)
The bench mark is a disk set in the NW concrete abutment at the NE end of the
bridge, 5.33 m (17.5 ft) NW of the centerline of the paved road - Highway 17,
3.66 m (12.0 ft) SSE of the center of the concrete drain, 0.27 m (0.9 ft) NNW of
the edge of the abutment, and 0.3 m (1 ft) above the highway.
BENCH MARK STAMPING: C.R.B. NO 6 1976
DESIGNATION: 866 6659 TIDAL CRB 6
MONUMENTATION: Tidal Station disk VM#: 11000
AGENCY: National Ocean Survey (NOS) IDB PID#: CK2255
SETTING CLASSIFICATION: Copper clad steel rod OPUS PID:
LATITUDE: 32° 39.2' N ( 32.65330) LONGITUDE: 80° 41.1' W ( -80.68500)
The bench mark is a disk located near the NW corner of the picnic area at the SW
end of the bridge, 61 m (199 ft) NNW of the centerline of the highway, 35.66 m
(117.0 ft) SW of bench mark C.R.B. NO 5 1976, 10.06 m (33.0 ft) SE of a 0.76 m
(2.5 ft) diameter pine tree, 1.25 m (4.1 ft) east of a metal witness post with
sign, and 0.91 m (3.0 ft) WSW of a second witness post and sign. The bench mark
is set 2.41 m (7.9 ft) below the highway, crimped to the top of a copper-clad
steel rod driven 14.6 m (48 ft) to refusal, encased in a 4-inch PVC pipe and
concrete kickblock.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 4 of 6
Station ID: 8666659 PUBLICATION DATE: 03/09/2004
Name: COMBAHEE RIVER AT US HWY. 17
SC
NOAA Chart: 11519 Latitude: 32° 39.1' N ( 32.65170)
USGS Quad: GREEN POND Longitude: 80° 41.0' W ( -80.68330)
T I D A L B E N C H M A R K S
BENCH MARK STAMPING: 6659 A 1982
DESIGNATION: 866 6659 A TIDAL
MONUMENTATION: Tidal Station disk VM#: 11001
AGENCY: National Ocean Survey (NOS) IDB PID#: CK2987
SETTING CLASSIFICATION: Stainless steel rod OPUS PID:
LATITUDE: 32° 39.1' N ( 32.65170) LONGITUDE: 80° 41.0' W ( -80.68330)
The bench mark is a disk located just SW of the road leading to the boat
landing, 48 m (158 ft) south of bench mark C.R.B. NO 6 1976, 19.66 m (64.5 ft)
SW of the centerline of the road leading to the boat landing, 12.92 m (42.4 ft)
NW of the centerline of the highway, 8.08 m (26.5 ft) north of a speed limit
sign, 7.56 m (24.8 ft) east of a triple trunk poplar tree. The bench mark is 9
cm (0.3 ft) below grade, crimped to the top of a copper-clad steel rod driven
7.9 m (26 ft) to refusal, encased in a 5-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: 8666659 PUBLICATION DATE: 03/09/2004
Name: COMBAHEE RIVER AT US HWY. 17
SC
NOAA Chart: 11519 Latitude: 32° 39.1' N ( 32.65170)
USGS Quad: GREEN POND Longitude: 80° 41.0' W ( -80.68330)
T I D A L D A T U M S
Tidal datums at COMBAHEE RIVER AT US HWY. 17 based on:
LENGTH OF SERIES: 11 MONTHS
TIME PERIOD: February 1976 - December 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 = 1.626
MEAN HIGH WATER MHW = 1.548
MEAN SEA LEVEL MSL = 0.947
MEAN TIDE LEVEL MTL = 0.812
North American Vertical Datum NAVD88 = 0.758
MEAN LOW WATER MLW = 0.076
MEAN LOWER LOW WATER MLLW = 0.000
North American Vertical Datum (NAVD88)
Bench Mark Elevation Information In METERS above:
Stamping or Designation MLLW MHW
C.R.B. NO 5 1976 3.174 1.626
NO 3 1934 3.612 2.064
V 106 1962 4.305 2.757
C.R.B. NO 6 1976 3.291 1.743
6659 A 1982 3.160 1.612
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 6 of 6
Station ID: 8666659 PUBLICATION DATE: 03/09/2004
Name: COMBAHEE RIVER AT US HWY. 17
SC
NOAA Chart: 11519 Latitude: 32° 39.1' N ( 32.65170)
USGS Quad: GREEN POND Longitude: 80° 41.0' W ( -80.68330)
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.