U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Datums Page Page 1 of 5
Station ID: 8667676 PUBLICATION DATE: 03/09/2004
Name: EDISTO MARINA, BIG BAY CREEK
SC
NOAA Chart: 11522 Latitude: 32° 29.6' N ( 32.49330)
USGS Quad: EDISTO BEACH Longitude: 80° 20.4' W ( -80.34000)
To reach the tidal bench marks from U.S. Highway 17 in the village of Osborn,
proceed south on State Highway 174 for 40 km (25 mi) through the village of
Edisto Beach, and then NW along the Edisto River to the end of State Highway
174. The bench marks are along the highway (Dock Site Road) beside the Oristo
Golf Course. The tide gage and staff were located on the west side of a small
pier at the Edisto Marina.
T I D A L B E N C H M A R K S
PRIMARY BENCH MARK STAMPING: EM NO 1 1975
DESIGNATION: 866 7676 TIDAL EM 1
MONUMENTATION: Tidal Station disk VM#: 4375
AGENCY: National Ocean Survey (NOS) IDB PID#: CK1830
SETTING CLASSIFICATION: Copper clad steel rod OPUS PID:
LATITUDE: 32° 29.6' N ( 32.49330) LONGITUDE: 80° 20.4' W ( -80.34000)
The primary bench mark is a disk located in the parking lot of the Edisto
Marina, 45.17 m (148.2 ft) west of the NW corner of a one story concrete block
building housing the Edisto Marina Office and Store, 30.66 m (100.6 ft) SW of
the marina dock, 21.88 m (71.8 ft) WSW of the center of two gas tanks, 20.82 m
(68.3 ft) SW of utility pole #248315, 19.51 m (64.0 ft) west of the west tank of
two fuel tanks, 4 m (13 ft) east of the marsh bank and in a direct line with a
row of cedar trees running north to south, and 1.40 m (4.6 ft) west of the SW
corner of a concrete slab at the south end of a dry dock ramp. The bench mark
is set at ground level, crimped to the top of a steel rod driven 12.2 m (40 ft)
to refusal, and encased in a PVC pipe and concrete kickblock. NOTE: Mark not
found in 1995 by US Power Squadron.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 2 of 5
Station ID: 8667676 PUBLICATION DATE: 03/09/2004
Name: EDISTO MARINA, BIG BAY CREEK
SC
NOAA Chart: 11522 Latitude: 32° 29.6' N ( 32.49330)
USGS Quad: EDISTO BEACH Longitude: 80° 20.4' W ( -80.34000)
T I D A L B E N C H M A R K S
BENCH MARK STAMPING: 2 1934
DESIGNATION: 866 7676 TIDAL 2
MONUMENTATION: Tidal Station disk VM#: 4374
AGENCY: National Ocean Survey (NOS) IDB PID#: CK1826
SETTING CLASSIFICATION: Concrete monument OPUS PID:
LATITUDE: 32° 29.6' N ( 32.49330) LONGITUDE: 80° 20.3' W ( -80.33830)
The bench mark is a disk set in a concrete monument located near the end of the
second dirt driveway, 47 m (153 ft) north of the centerline of the paved road
paralleling the Oristo Golf course, 58 m (190 ft) north of the centerline of
Dock Site Road, 9.39 m (30.8 ft) SE of utility pole #112602, 2.07 m (6.8 ft) NE
of the NE corner of an old tin shed, and 6 cm (0.2 ft) above ground level.
BENCH MARK STAMPING: EM NO 2 1975
DESIGNATION: 866 7676 TIDAL EM 2
MONUMENTATION: Tidal Station disk VM#: 4376
AGENCY: National Ocean Survey (NOS) IDB PID#: CK1829
SETTING CLASSIFICATION: Copper clad steel rod OPUS PID:
LATITUDE: 32° 29.6' N ( 32.49330) LONGITUDE: 80° 20.4' W ( -80.34000)
The bench mark is a disk located 91 m (300 ft) SE of bench mark EM No 1 1975,
32.74 m (107.4 ft) ESE of utility pole #45427, 13.56 m (44.5 ft) north of the
centerline of Dock Site Road, 5.46 m (17.9 ft) west of the centerline of the
eastern dirt driveway into Edisto Marina, and 2.53 m (8.3 ft) SW of utility pole
#111963. The bench mark is set 6 cm (0.2 ft) below ground level, crimped to the
top of a steel rod driven 12.2 m (40 ft) to refusal, and encased in a PVC pipe
and concrete kickblock. NOTE: Mark not found in 1995 by US Power Squadron.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 3 of 5
Station ID: 8667676 PUBLICATION DATE: 03/09/2004
Name: EDISTO MARINA, BIG BAY CREEK
SC
NOAA Chart: 11522 Latitude: 32° 29.6' N ( 32.49330)
USGS Quad: EDISTO BEACH Longitude: 80° 20.4' W ( -80.34000)
T I D A L B E N C H M A R K S
BENCH MARK STAMPING: EM NO 3 1975
DESIGNATION: 866 7676 TIDAL EM 3
MONUMENTATION: Tidal Station disk VM#: 4377
AGENCY: National Ocean Survey (NOS) IDB PID#: CK1828
SETTING CLASSIFICATION: Copper clad steel rod OPUS PID:
LATITUDE: 32° 29.6' N ( 32.49330) LONGITUDE: 80° 20.3' W ( -80.33830)
The bench mark is a disk located near the entrance to Oristo Golf Course, 114 m
(375 ft) south of bench mark EM No 2 1975, 61 m (200 ft) north of the NE corner
post of the gate house, 8.02 m (26.3 ft) east of Dock Site Road, and 4.11 m
(13.5 ft) NW of a large cedar tree. The bench mark is set at ground level,
crimped to the top of a steel rod driven 12.2 m (40 ft) to refusal, and encased
in a PVC pipe and concrete kickblock. NOTE: Mark not found in 1995 by US Power
Squadron.
BENCH MARK STAMPING: EM NO 4 1975
DESIGNATION: 866 7676 TIDAL EM 4
MONUMENTATION: Tidal Station disk VM#: 4378
AGENCY: National Ocean Survey (NOS) IDB PID#: CK1827
SETTING CLASSIFICATION: Copper clad steel rod OPUS PID:
LATITUDE: 32° 29.6' N ( 32.49330) LONGITUDE: 80° 20.3' W ( -80.33830)
The bench mark is a disk located 85 m (280 ft) east of bench mark EM No 3 1975,
11.43 m (37.5 ft) west of the centerline of Flowers Road, 9.20 m (30.2 ft) north
of the centerline of Dock Site Road, 3.63 m (11.9 ft) WNW of a power pole
#275741 with two guy anchors, and 3.74 m (11.4 ft) NE of the north corner of an
underground telephone cable junction box. The bench mark is set at ground
level, crimped to the top of a steel rod driven 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 4 of 5
Station ID: 8667676 PUBLICATION DATE: 03/09/2004
Name: EDISTO MARINA, BIG BAY CREEK
SC
NOAA Chart: 11522 Latitude: 32° 29.6' N ( 32.49330)
USGS Quad: EDISTO BEACH Longitude: 80° 20.4' W ( -80.34000)
T I D A L D A T U M S
Tidal datums at EDISTO MARINA, BIG BAY CREEK based on:
LENGTH OF SERIES: 5 MONTHS
TIME PERIOD: May 1976 - September 1976
TIDAL EPOCH: 1983-2001
CONTROL TIDE STATION: 8667679 CARTER'S DOCK, BIG BAY CREEK
Elevations of tidal datums referred to Mean Lower Low Water (MLLW), in METERS:
MEAN HIGHER HIGH WATER MHHW = 1.987
MEAN HIGH WATER MHW = 1.876
North American Vertical Datum NAVD88 = 1.107
MEAN SEA LEVEL MSL = 1.009
MEAN TIDE LEVEL MTL = 0.968
MEAN LOW WATER MLW = 0.060
MEAN LOWER LOW WATER MLLW = 0.000
North American Vertical Datum (NAVD88)
Bench Mark Elevation Information In METERS above:
Stamping or Designation MLLW MHW
EM NO 1 1975 2.528 0.652
2 1934 2.559 0.683
EM NO 2 1975 2.710 0.834
EM NO 3 1975 2.587 0.711
EM NO 4 1975 2.490 0.614
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 5 of 5
Station ID: 8667676 PUBLICATION DATE: 03/09/2004
Name: EDISTO MARINA, BIG BAY CREEK
SC
NOAA Chart: 11522 Latitude: 32° 29.6' N ( 32.49330)
USGS Quad: EDISTO BEACH Longitude: 80° 20.4' W ( -80.34000)
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.