U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Datums Page Page 1 of 5
Station ID: 8664992 PUBLICATION DATE: 03/09/2004
Name: NORTH DEWEE'S ISLAND
SC
NOAA Chart: 11521 Latitude: 32° 51.0' N ( 32.85000)
USGS Quad: CAPERS INLET Longitude: 79° 42.2' W ( -79.70330)
To reach the tidal bench marks proceed by boat to the NE end of Dewees Island in
Capers Inlet. The bench marks are located along a dirt road leading south from
the shoreline of Capers Inlet. The tide gage and staff were located near the NE
corner of the pier at the north end of the dirt road.
T I D A L B E N C H M A R K S
PRIMARY BENCH MARK STAMPING: N.D.I. NO 1 1975
DESIGNATION: 866 4992 TIDAL 1
MONUMENTATION: Tidal Station disk VM#: 4124
AGENCY: National Ocean Survey (NOS) IDB PID#:
SETTING CLASSIFICATION: Copper-clad steel rod OPUS PID:
LATITUDE: 32° 51.0' N ( 32.85000) LONGITUDE: 79° 42.2' W ( -79.70330)
The primary bench mark is a disk located in a small group of cedar trees at the
north end of Dewees Island, 18.75 m (61.5 ft) SSE of the SE corner of a wooden
pier, 6 m (20 ft) east of the centerline of the dirt road, 0.70 m (2.3 ft) NE of
a metal witness post with sign, and 0.64 m (2.1 ft) ESE of a second witness post
with sign. The bench mark is set 3 cm (0.1 ft) below ground level, crimped to
the top of a copper-clad steel rod driven to an unspecified depth, and 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: 8664992 PUBLICATION DATE: 03/09/2004
Name: NORTH DEWEE'S ISLAND
SC
NOAA Chart: 11521 Latitude: 32° 51.0' N ( 32.85000)
USGS Quad: CAPERS INLET Longitude: 79° 42.2' W ( -79.70330)
T I D A L B E N C H M A R K S
BENCH MARK STAMPING: N.D.I. NO 2 1975
DESIGNATION: 866 4992 TIDAL 2
MONUMENTATION: Tidal Station disk VM#: 4125
AGENCY: National Ocean Survey (NOS) IDB PID#:
SETTING CLASSIFICATION: Copper-clad steel rod OPUS PID:
LATITUDE: 32° 51.0' N ( 32.85000) LONGITUDE: 79° 42.2' W ( -79.70330)
The bench mark is a disk located 45.75 m (150.1 ft) south of bench mark N.D.I.
NO 1 1975, 3.78 m (12.4 ft) east of the centerline of the dirt road, and 0.43 m
(1.4 ft) SE of a witness post with sign. The bench mark is crimped to the top
of a copper-clad steel rod driven to an unspecified depth, and encased in a PVC
pipe and concrete kickblock.
BENCH MARK STAMPING: N.D.I. NO 3 1975
DESIGNATION: 866 4992 TIDAL 3
MONUMENTATION: Tidal Station disk VM#: 4126
AGENCY: National Ocean Survey (NOS) IDB PID#:
SETTING CLASSIFICATION: Copper-clad steel rod OPUS PID:
LATITUDE: 32° 51.0' N ( 32.85000) LONGITUDE: 79° 42.2' W ( -79.70330)
The bench mark is a disk located 38.10 m (125.0 ft) south of bench mark N.D.I.
NO 2 1975, 3.75 m (12.3 ft) east of the centerline of the dirt road, 0.98 m (3.2
ft) north of a steel witness post with sign, and 0.76 m (2.5 ft) ESE of a second
witness post with sign. The bench mark is crimped to the top of a copper-clad
steel rod driven to an unspecified depth, and encased in a PVC pipe and concrete
kickblock.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 3 of 5
Station ID: 8664992 PUBLICATION DATE: 03/09/2004
Name: NORTH DEWEE'S ISLAND
SC
NOAA Chart: 11521 Latitude: 32° 51.0' N ( 32.85000)
USGS Quad: CAPERS INLET Longitude: 79° 42.2' W ( -79.70330)
T I D A L B E N C H M A R K S
BENCH MARK STAMPING: N.D.I. NO 4 1975
DESIGNATION: 866 4992 TIDAL 4
MONUMENTATION: Tidal Station disk VM#: 4127
AGENCY: National Ocean Survey (NOS) IDB PID#:
SETTING CLASSIFICATION: Braized to a copper pipe OPUS PID:
LATITUDE: 32° 51.0' N ( 32.85000) LONGITUDE: 79° 42.2' W ( -79.70330)
The bench mark is a disk located 23 m (76 ft) SSE of bench mark N.D.I. NO 3
1975, 5.24 m (17.2 ft) east of the centerline of the dirt road, and 0.79 m (2.6
ft) east of a witness post with sign. The bench mark is set 15 cm (0.5 ft)
above ground level, brazed to the top of a copper pipe surrounded by a 0.37 m
(1.2 ft) diameter concrete kickblock.
BENCH MARK STAMPING: N.D.I. NO 5 1975
DESIGNATION: 866 4992 TIDAL 5
MONUMENTATION: Tidal Station disk VM#: 4128
AGENCY: National Ocean Survey (NOS) IDB PID#:
SETTING CLASSIFICATION: Braized to a copper pipe OPUS PID#: BBDS79
LATITUDE: 32° 51.0' N ( 32.85000) LONGITUDE: 79° 42.2' W ( -79.70330)
The bench mark is a disk located 46.15 m (151.4 ft) south of bench mark N.D.I.
NO 4 1975, 3.60 m (11.8 ft) east of the centerline of the dirt road, 0.55 m (1.8
ft) north of a steel witness post with sign, and 0.40 m (1.3 ft) west of a
second witness post with sign. The bench mark is set 10 cm (0.3 ft) above
ground level, brazed to the top of a copper pipe surrounded by a 0.34 m (1.1 ft)
diameter concrete kickblock.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 4 of 5
Station ID: 8664992 PUBLICATION DATE: 03/09/2004
Name: NORTH DEWEE'S ISLAND
SC
NOAA Chart: 11521 Latitude: 32° 51.0' N ( 32.85000)
USGS Quad: CAPERS INLET Longitude: 79° 42.2' W ( -79.70330)
T I D A L D A T U M S
Tidal datums at NORTH DEWEE'S ISLAND based on:
LENGTH OF SERIES: 3 MONTHS
TIME PERIOD: October 1975 - December 1975
TIDAL EPOCH: 1983-2001
CONTROL TIDE STATION: 8664941 SOUTH CAPERS ISLAND, CAPERS CREEK
Elevations of tidal datums referred to Mean Lower Low Water (MLLW), in METERS:
MEAN HIGHER HIGH WATER MHHW = 1.610
MEAN HIGH WATER MHW = 1.506
MEAN SEA LEVEL MSL = 0.797
MEAN TIDE LEVEL MTL = 0.781
MEAN LOW WATER MLW = 0.056
MEAN LOWER LOW WATER MLLW = 0.000
North American Vertical Datum (NAVD88)
Bench Mark Elevation Information In METERS above:
Stamping or Designation MLLW MHW
N.D.I. NO 1 1975 2.639 1.133
N.D.I. NO 2 1975 2.322 0.816
N.D.I. NO 3 1975 2.387 0.881
N.D.I. NO 4 1975 3.023 1.517
N.D.I. NO 5 1975 2.570 1.064
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 5 of 5
Station ID: 8664992 PUBLICATION DATE: 03/09/2004
Name: NORTH DEWEE'S ISLAND
SC
NOAA Chart: 11521 Latitude: 32° 51.0' N ( 32.85000)
USGS Quad: CAPERS INLET Longitude: 79° 42.2' W ( -79.70330)
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.