U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Datums Page Page 1 of 5
Station ID: 8667309 PUBLICATION DATE: 04/01/2004
Name: FENWICK ISLAND, SOUTH EDISTO RIVER
SC
NOAA Chart: 11517 Latitude: 32° 33.6' N ( 32.56000)
USGS Quad: BENNETTS POINT Longitude: 80° 25.1' W ( -80.41830)
To reach the tidal bench marks from Jacksonboro, travel 12.9 km (8.0 mi) SW on
U.S. Highway 17, crossing Ashepoo River, to the intersection of State Road
S-15-26, then turn left and proceed 25.1 km (15.6 mi) south on State Road
S-15-26 to the end of the pavement, turn right onto a dirt road and proceed 0.3
km (0.2 mi) to the boat ramp at Bennett's Point. By boat, travel 0.5 km (0.4
nm) to Ashepoo River, proceed downstream 5.6 km (4.0 nm) on Ashepoo River to
Fenwick Cut, thrn proceed north through the cut and continue 2.9 km (2.1 nm)
north on South Edisto River to the gage site. The bench marks can be reached
without a boat by following the tracks along fields on Fenwick Island from
Mosquito Creek to the gage site, but it is advised to attempt the trip during
the dry seasons. The bench marks are located along a dirt road near the west
shore of the river. The tide gage and staff were located on a platform
constructed 30 m (100 ft) from the east edge of the high marsh, off the west
shore of the river.
T I D A L B E N C H M A R K S
PRIMARY BENCH MARK STAMPING: 7309 B 1979
DESIGNATION: 866 7309 B TIDAL
MONUMENTATION: Tidal Station disk VM#: 6752
AGENCY: National Ocean Survey (NOS) IDB PID#:
SETTING CLASSIFICATION: Stainless steel rod OPUS PID:
LATITUDE: 32° 33.6' N ( 32.56000) LONGITUDE: 80° 25.1' W ( -80.41830)
The primary bench mark is a disk located near the road where it makes a sharp
turn to the north, 73.15 m (240.0 ft) SSE of bench mark 7309 C 1979, 17.19 m
(56.4 ft) SE of the centerline of the road, 9.69 m (31.8 ft) WNW of the edge of
the marsh, 4.21 m (13.8 ft) WSW of a 0.3 m (1.0 ft) diameter palmetto tree, and
1.43 m (4.7 ft) SSW of a witness post. The bench mark is crimped to the top of
a stainless steel rod driven 11.0 m (36 ft) to refusal, encased in a PVC pipe
and concrete kickblock.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 2 of 5
Station ID: 8667309 PUBLICATION DATE: 04/01/2004
Name: FENWICK ISLAND, SOUTH EDISTO RIVER
SC
NOAA Chart: 11517 Latitude: 32° 33.6' N ( 32.56000)
USGS Quad: BENNETTS POINT Longitude: 80° 25.1' W ( -80.41830)
T I D A L B E N C H M A R K S
BENCH MARK STAMPING: 7309 A 1979
DESIGNATION: 866 7309 A TIDAL
MONUMENTATION: Tidal Station disk VM#: 6751
AGENCY: National Ocean Survey (NOS) IDB PID#:
SETTING CLASSIFICATION: Stainless steel rod OPUS PID:
LATITUDE: 32° 33.6' N ( 32.56000) LONGITUDE: 80° 25.1' W ( -80.41830)
The bench mark is a disk located SW of a wire fence, midway between the platform
and the road, 78 m (255 ft) ESE of bench mark 7309 B 1979, 72 m (235 ft) WNW of
a 0.91 m (3.0 ft) bluff at the river edge, 1.37 m (4.5 ft) SW of the 18th fence
post from the river edge, and 0.18 m (0.6 ft) WSW of a witness post. The bench
mark is set 6 cm (0.2 ft) above ground level, crimped to the top of a stainless
steel rod driven 14.6 m (48 ft) to refusal.
BENCH MARK STAMPING: 7309 C 1979
DESIGNATION: 866 7309 C TIDAL
MONUMENTATION: Tidal Station disk VM#: 6753
AGENCY: National Ocean Survey (NOS) IDB PID#:
SETTING CLASSIFICATION: Concrete monument OPUS PID:
LATITUDE: 32° 33.6' N ( 32.56000) LONGITUDE: 80° 25.1' W ( -80.41830)
The bench mark is a disk set flush in a concrete monument located on the west
side of the road beside a line of palmetto trees, 55.17 m (181.0 ft) south of
bench mark 7309 D 1979, 6.49 m (21.3 ft) west of the centerline of the dirt
road, and 4.75 m (15.6 ft) NE of the edge of a corn field. NOTE: Mark found to
be slightly scraped by R. E. Marriner, in 1979.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 3 of 5
Station ID: 8667309 PUBLICATION DATE: 04/01/2004
Name: FENWICK ISLAND, SOUTH EDISTO RIVER
SC
NOAA Chart: 11517 Latitude: 32° 33.6' N ( 32.56000)
USGS Quad: BENNETTS POINT Longitude: 80° 25.1' W ( -80.41830)
T I D A L B E N C H M A R K S
BENCH MARK STAMPING: 7309 D 1979
DESIGNATION: 866 7309 D TIDAL
MONUMENTATION: Tidal Station disk VM#: 6754
AGENCY: National Ocean Survey (NOS) IDB PID#:
SETTING CLASSIFICATION: Concrete monument OPUS PID:
LATITUDE: 32° 33.6' N ( 32.56000) LONGITUDE: 80° 25.1' W ( -80.41830)
The bench mark is a disk set flush in a concrete monument located on the east
side of the road near a large live oak tree, 62 m (203 ft) SE of bench mark 7309
E 1979, 11.19 m (36.7 ft) south of a 0.3 m (1.0 ft) diameter palmetto tree, 6.19
m (20.3 ft) SW of a 1.28 m (4.2 ft) diameter live oak tree, and 5.43 m (17.8 ft)
NE of the centerline of the road.
BENCH MARK STAMPING: 7309 E 1979
DESIGNATION: 866 7309 E TIDAL
MONUMENTATION: Tidal Station disk VM#: 6755
AGENCY: National Ocean Survey (NOS) IDB PID#:
SETTING CLASSIFICATION: Stainless steel rod OPUS PID:
LATITUDE: 32° 33.6' N ( 32.56000) LONGITUDE: 80° 25.1' W ( -80.41830)
The bench mark is a disk located on the east side of the road, north of the 1.28
m (4.2 ft) diameter live oak tree, 32 m (105 ft) west of the edge of the marsh,
15.51 m (50.9 ft) north of a 0.46 m (1.5 ft) diameter pine tree, 4.21 m (13.8
ft) ENE of the centerline of the road, 0.98 m (3.2 ft) south of a 0.46 m (1.5
ft) diameter pine tree with a witness sign, and 0.94 m (3.1 ft) WNW of a 0.34 m
(1.1 ft) diameter pine tree. The bench mark is crimped to the top of a
stainless steel rod driven 14.6 m (48 ft) to refusal, encased in a PVC pipe and
concrete kickblock.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 4 of 5
Station ID: 8667309 PUBLICATION DATE: 04/01/2004
Name: FENWICK ISLAND, SOUTH EDISTO RIVER
SC
NOAA Chart: 11517 Latitude: 32° 33.6' N ( 32.56000)
USGS Quad: BENNETTS POINT Longitude: 80° 25.1' W ( -80.41830)
T I D A L D A T U M S
Tidal datums at FENWICK ISLAND, SOUTH EDISTO RIVER based on:
LENGTH OF SERIES: 3 MONTHS
TIME PERIOD: June 1979 - August 1979
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 = 2.060
MEAN HIGH WATER MHW = 1.955
MEAN SEA LEVEL MSL = 1.097
MEAN TIDE LEVEL MTL = 1.011
MEAN LOW WATER MLW = 0.067
MEAN LOWER LOW WATER MLLW = 0.000
North American Vertical Datum (NAVD88)
Bench Mark Elevation Information In METERS above:
Stamping or Designation MLLW MHW
7309 B 1979 2.503 0.548
7309 A 1979 2.111 0.156
7309 C 1979 3.815 1.860
7309 D 1979 3.019 1.064
7309 E 1979 3.542 1.587
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 5 of 5
Station ID: 8667309 PUBLICATION DATE: 04/01/2004
Name: FENWICK ISLAND, SOUTH EDISTO RIVER
SC
NOAA Chart: 11517 Latitude: 32° 33.6' N ( 32.56000)
USGS Quad: BENNETTS POINT Longitude: 80° 25.1' W ( -80.41830)
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.