U.S. DEPARTMENT OF COMMERCE
                National Oceanic and Atmospheric Administration
                            National Ocean Service
Datums Page                                                        Page  1 of  5

                                                                                
Station ID: 8665111                         PUBLICATION DATE:  07/21/2003
Name:       SOUTH DEWEES ISLAND, DEWEES INLET                 
            SC
NOAA Chart: 11521                           Latitude:   32° 50.0' N (  32.83330)
USGS Quad:  CAPERS INLET                    Longitude:  79° 43.6' W ( -79.72670)


To reach the tidal bench marks proceed by boat to the SW side of Dewees Island. 
The bench marks are located along a dirt road leading NE from the creek.  The
tide gage and staff were located on a T-shaped pier on the SW side of Dewees
Island, just north of Old House Creek in the channel between Dewees Island and
Big Hill Marsh.


                         T I D A L   B E N C H   M A R K S


                 PRIMARY BENCH MARK STAMPING:  S.D.I. NO 2 1975
                         DESIGNATION:          866 5101 S.D.I. TIDAL 2

MONUMENTATION:           Tidal Station disk                    VM#:         4138
AGENCY:                  National Ocean Survey (NOS)           IDB PID#:        
SETTING CLASSIFICATION:  Copper-clad steel rod                 OPUS PID:        
LATITUDE:   32° 50.1' N (  32.83555)          LONGITUDE:  79° 43.7' W ( -79.72759)


The primary bench mark is a disk located along the dirt road, 5 m (16 ft) NW of
the centerline of the road, and 0.43 m (1.4 ft) SE of a metal witness post with
sign.  The bench mark is set 6 cm (0.2 ft) above 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: 8665111                         PUBLICATION DATE:  07/21/2003
Name:       SOUTH DEWEES ISLAND, DEWEES INLET                 
            SC
NOAA Chart: 11521                           Latitude:   32° 50.0' N (  32.83330)
USGS Quad:  CAPERS INLET                    Longitude:  79° 43.6' W ( -79.72670)


                         T I D A L   B E N C H   M A R K S


                         BENCH MARK STAMPING:  S.D.I. NO 4 1975
                         DESIGNATION:          866 5101 S.D.I. TIDAL 4

MONUMENTATION:           Tidal Station disk                    VM#:         4139
AGENCY:                  National Ocean Survey (NOS)           IDB PID#:        
SETTING CLASSIFICATION:  Copper pipe                           OPUS PID:        
LATITUDE:   12° 50.0' N (  12.83330)          LONGITUDE:  79° 43.6' W ( -79.72670)


The bench mark is a disk located 18.59 m (61.0 ft) SW of the dirt road leading
to the beach, 11.58 m (38.0 ft) SE of the centerline of the dirt road leading to
the center of the island, 2.68 m (8.8 ft) east of a 0.3 m (1 ft) diameter cedar
tree, and 0.58 m (1.9 ft) NE of a metal witness post with sign.  The bench mark
is set at ground level, brazed to the top of a copper pipe and surrounded by
soilcrete.



                         BENCH MARK STAMPING:  S.D.I. NO 5 1975
                         DESIGNATION:          866 5101 S.D.I. TIDAL 5

MONUMENTATION:           Tidal Station disk                    VM#:         4140
AGENCY:                  National Ocean Survey (NOS)           IDB PID#:        
SETTING CLASSIFICATION:  Copper pipe                           OPUS PID:        
LATITUDE:   12° 50.0' N (  12.83330)          LONGITUDE:  79° 43.6' W ( -79.72670)


The bench mark is a disk located 26.97 m (88.5 ft) north of bench mark S.D.I. NO
4 1975, 9.45 m (31.0 ft) NW of the centerline of the dirt road leading to the
center of the island, 1.40 m (4.6 ft) SE of an oak tree, and 0.61 m (2.0 ft) NE
of a metal witness post with sign.  The bench mark is set 0.15 m (0.5 ft) above
ground level, brazed to the top of a copper pipe and surrounded by soilcrete.

                          U.S. DEPARTMENT OF COMMERCE
                National Oceanic and Atmospheric Administration
                            National Ocean Service
                                                                   Page  3 of  5

                                                                                
Station ID: 8665111                         PUBLICATION DATE:  07/21/2003
Name:       SOUTH DEWEES ISLAND, DEWEES INLET                 
            SC
NOAA Chart: 11521                           Latitude:   32° 50.0' N (  32.83330)
USGS Quad:  CAPERS INLET                    Longitude:  79° 43.6' W ( -79.72670)


                         T I D A L   B E N C H   M A R K S


                         BENCH MARK STAMPING:  5111 F 1982
                         DESIGNATION:          866 5101 F TIDAL

MONUMENTATION:           Tidal Station disk                    VM#:         4141
AGENCY:                  National Ocean Survey (NOS)           IDB PID#:        
SETTING CLASSIFICATION:  Stainless steel rod                   OPUS PID:        
LATITUDE:   12° 50.0' N (  12.83330)          LONGITUDE:  79° 43.6' W ( -79.72670)


The bench mark is a disk set in the front lawn of the caretaker's house, 123 m
(403 ft) NE of bench mark S.D.I. NO 2 1975, 12.44 m (40.8 ft) SE of utility pole
#141362, 1.89 m (6.2 ft) NE of a 0.46 m (1.5 ft) diameter palmetto tree, and
1.37 m (4.5 ft) south of a metal witness post with sign.  The bench mark is set
6 cm (0.2 ft) below ground level, crimped to the top of a stainless steel rod
driven 9.8 m (32 ft) to refusal, and encased in a 5-inch PVC pipe and concrete
kickblock.



                         BENCH MARK STAMPING:  S.D.I. NO 1 1975
                         DESIGNATION:          866 5101 S.D.I. TIDAL 1

MONUMENTATION:           Tidal Station disk                    VM#:        17128
AGENCY:                  National Ocean Survey (NOS)           IDB PID#:        
SETTING CLASSIFICATION:  Copper-clad steel rod                 OPUS PID:        
LATITUDE:   12° 50.0' N (  12.83330)          LONGITUDE:  79° 43.6' W ( -79.72670)


The bench mark is a disk located near the pier, 2 m (8 ft) SE of the center of
the turnaround in the dirt causeway road, 1.62 m (5.3 ft) NE of the end of the
dock, and 0.58 m (1.9 ft) NW of a metal witness post. The bench mark is set 6 cm
(0.2 ft) below ground level, crimped to the top of a unspecified rod and driven
to an unspecified depth.

                          U.S. DEPARTMENT OF COMMERCE
                National Oceanic and Atmospheric Administration
                            National Ocean Service
                                                                   Page  4 of  5

                                                                                
Station ID: 8665111                         PUBLICATION DATE:  07/21/2003
Name:       SOUTH DEWEES ISLAND, DEWEES INLET                 
            SC
NOAA Chart: 11521                           Latitude:   32° 50.0' N (  32.83330)
USGS Quad:  CAPERS INLET                    Longitude:  79° 43.6' W ( -79.72670)


                            T I D A L   D A T U M S 


Tidal datums at SOUTH DEWEES ISLAND, DEWEES INLET based on:

     LENGTH OF SERIES:      1 YEAR
     TIME PERIOD:           January 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:

     HIGHEST OBSERVED WATER LEVEL (11/21/1976)         =  2.185
     MEAN HIGHER HIGH WATER                     MHHW   =  1.671
     MEAN HIGH WATER                            MHW    =  1.555
     MEAN SEA LEVEL                             MSL    =  0.823
     MEAN TIDE LEVEL                            MTL    =  0.803
     MEAN LOW WATER                             MLW    =  0.052
     MEAN LOWER LOW WATER                       MLLW   =  0.000
     LOWEST  OBSERVED WATER LEVEL (02/07/1976)         = -0.625

North American Vertical Datum (NAVD88)

Bench Mark Elevation Information                In METERS above:

     Stamping or Designation                    MLLW        MHW

     S.D.I. NO 2 1975                            2.199    0.644
     S.D.I. NO 4 1975                            2.787    1.232
     S.D.I. NO 5 1975                            2.998    1.443
     5111 F 1982                                 2.752    1.197
     S.D.I. NO 1 1975                            2.412    0.857


Foot Notes:

Bench marks 5111 F 1982 and S.D.I. NO 1 1975 are based on one differential
leveling connection and do not meet the quality control standards of the NOS. 
Therefore, caution should be used when deriving elevations for these marks.

                          U.S. DEPARTMENT OF COMMERCE
                National Oceanic and Atmospheric Administration
                            National Ocean Service
                                                                   Page  5 of  5

                                                                                
Station ID: 8665111                         PUBLICATION DATE:  07/21/2003
Name:       SOUTH DEWEES ISLAND, DEWEES INLET                 
            SC
NOAA Chart: 11521                           Latitude:   32° 50.0' N (  32.83330)
USGS Quad:  CAPERS INLET                    Longitude:  79° 43.6' W ( -79.72670)


                             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.