U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Datums Page Page 1 of 5
Station ID: 8665599 PUBLICATION DATE: 12/12/2003
Name: RHODES DOCK, STONO RIVER
SC
NOAA Chart: 11522 Latitude: 32° 46.1' N ( 32.76830)
USGS Quad: JOHNS ISLAND Longitude: 80° 4.2' W ( -80.07000)
To reach the tidal bench marks from the intersection of U.S. Highway 17 and
Johns Island Road, proceed south on Johns Island Road for 2.7 km (1.7 mi) to
River Road, turn right onto River Road and go east for 3.5 km (2.2 mi) to a road
on the left leading to the Rhodes residence at the intersection of Stono River
and Penny's Creek. The bench marks are south of Rhodes' dock on the Ellis
property on Penny's Creek. The tide gauge and staff were at the NW corner of
Rhodes' dock.
T I D A L B E N C H M A R K S
PRIMARY BENCH MARK STAMPING: NO 1 1974
DESIGNATION: 866 5599 TIDAL 1
MONUMENTATION: Tidal Station disk VM#: 4205
AGENCY: National Ocean Survey (NOS) IDB PID#:
SETTING CLASSIFICATION: Concrete monument OPUS PID:
LATITUDE: 32° 46.1' N ( 32.76830) LONGITUDE: 80° 4.2' W ( -80.07000)
The primary bench mark is a disk set in the top of a concrete monument, 12.2 m
(40 ft) NE of Penny's Creek, 8 m (26 ft) east of the east corner of the Kershaw
residence, and 4 m (12 ft) east of the last utility pole between the Ellis and
Kershaw residences.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 2 of 5
Station ID: 8665599 PUBLICATION DATE: 12/12/2003
Name: RHODES DOCK, STONO RIVER
SC
NOAA Chart: 11522 Latitude: 32° 46.1' N ( 32.76830)
USGS Quad: JOHNS ISLAND Longitude: 80° 4.2' W ( -80.07000)
T I D A L B E N C H M A R K S
BENCH MARK STAMPING: NO 2 1974
DESIGNATION: 866 5599 TIDAL 2
MONUMENTATION: Tidal Station disk VM#: 4206
AGENCY: National Ocean Survey (NOS) IDB PID#:
SETTING CLASSIFICATION: Concrete monument OPUS PID:
LATITUDE: 32° 46.1' N ( 32.76830) LONGITUDE: 80° 4.2' W ( -80.07000)
The bench mark is a disk set in the top of a concrete monument, 10 m (32 ft)
east of bench mark N0 1 1974, and 5 m (15 ft) from the end of the walkway to
Ellis' dock.
BENCH MARK STAMPING: NO 3 1974
DESIGNATION: 866 5599 TIDAL 3
MONUMENTATION: Tidal Station disk VM#: 4207
AGENCY: National Ocean Survey (NOS) IDB PID#:
SETTING CLASSIFICATION: Concrete monument OPUS PID:
LATITUDE: 32° 46.1' N ( 32.76830) LONGITUDE: 80° 4.2' W ( -80.07000)
The bench mark is a disk set in the top of a concrete monument located on the
first high point on the south side of Penny's Creek, 14 m (45 ft) south of bench
mark NO 2 1974, and 1 m (4 ft) west of the west creek bank..
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 3 of 5
Station ID: 8665599 PUBLICATION DATE: 12/12/2003
Name: RHODES DOCK, STONO RIVER
SC
NOAA Chart: 11522 Latitude: 32° 46.1' N ( 32.76830)
USGS Quad: JOHNS ISLAND Longitude: 80° 4.2' W ( -80.07000)
T I D A L B E N C H M A R K S
BENCH MARK STAMPING: NO 4 1974
DESIGNATION: 866 5599 TIDAL 4
MONUMENTATION: Tidal Station disk VM#: 4208
AGENCY: National Ocean Survey (NOS) IDB PID#:
SETTING CLASSIFICATION: Concrete monument OPUS PID:
LATITUDE: 32° 46.1' N ( 32.76830) LONGITUDE: 80° 4.2' W ( -80.07000)
The bench mark is a disk set in the top of a concrete monument, 5 m (18 ft)
south of bench mark NO 3 1974, and 2 m (5 ft) north of a small drain to Penny's
Creek.
BENCH MARK STAMPING: NO 5 1974
DESIGNATION: 866 5599 TIDAL 5
MONUMENTATION: Tidal Station disk VM#: 4209
AGENCY: National Ocean Survey (NOS) IDB PID#:
SETTING CLASSIFICATION: Concrete monument OPUS PID:
LATITUDE: 32° 46.1' N ( 32.76830) LONGITUDE: 80° 4.2' W ( -80.07000)
The bench mark is a disk set in the top of a concrete monument, 9.91 m (32.5 ft)
west of bench mark NO 4 1974, and 5 m (18 ft) north of a cluster of four lines
of oak trees.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 4 of 5
Station ID: 8665599 PUBLICATION DATE: 12/12/2003
Name: RHODES DOCK, STONO RIVER
SC
NOAA Chart: 11522 Latitude: 32° 46.1' N ( 32.76830)
USGS Quad: JOHNS ISLAND Longitude: 80° 4.2' W ( -80.07000)
T I D A L D A T U M S
Tidal datums at RHODES DOCK, STONO RIVER based on:
LENGTH OF SERIES: 2 MONTHS
TIME PERIOD: May 1974 - June 1974
TIDAL EPOCH: 1983-2001
CONTROL TIDE STATION: 8665641 WELCHES WHARF, STONO RIVER
Elevations of tidal datums referred to Mean Lower Low Water (MLLW), in METERS:
MEAN HIGHER HIGH WATER MHHW = 1.795
MEAN HIGH WATER MHW = 1.697
MEAN SEA LEVEL MSL = 1.021
MEAN TIDE LEVEL MTL = 0.887
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
NO 1 1974 3.048 1.351
NO 2 1974 2.918 1.221
NO 3 1974 3.149 1.452
NO 4 1974 3.188 1.491
NO 5 1974 3.009 1.312
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 5 of 5
Station ID: 8665599 PUBLICATION DATE: 12/12/2003
Name: RHODES DOCK, STONO RIVER
SC
NOAA Chart: 11522 Latitude: 32° 46.1' N ( 32.76830)
USGS Quad: JOHNS ISLAND Longitude: 80° 4.2' W ( -80.07000)
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.