U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Datums Page Page 1 of 5
Station ID: 9751494 PUBLICATION DATE: 11/08/2011
Name: DOG ISLAND, ST THOMAS
VI
NOAA Chart: 25647 Latitude: 18° 17.8' N ( 18.29714)
USGS Quad: EASTERN ST. THOMAS Longitude: 64° 49.1' W ( -64.81775)
To reach the bench marks by boat from the Ferry Terminal in Redhook, St. Thomas
proceed 2.0 km (1.2 mi) ENE from the harbor, then 2.3 km (1.4 mi) SSE to the
west side of Greater St. James Island, then 1.8 km (1.1 mi) south to the north
point of Dog Island, ESE of Little St. James Island. The tide gauge orifices
are on the west side of the north point of the island and the benchmarks are
along the same rock point and the west end of the beach on the north side of the
island.
T I D A L B E N C H M A R K S
PRIMARY BENCH MARK STAMPING: 1494 C 2011
DESIGNATION: 975 1494 C
MONUMENTATION: Tidal Station disk VM#: 20017
AGENCY: National Ocean Service (NOS) IDB PID#:
SETTING CLASSIFICATION: Bedrock OPUS PID#: BBCK22
LATITUDE: 18° 17.8' N ( 18.29692) LONGITUDE: 64° 49.1' W ( -64.81754)
The primary bench mark is a disk set in bedrock just north of the north extent
of vegetation on the island, 24.48 m (80.3 ft) WNW from the high rock point on
the north side of the island at the west end of the Long Beach, 18.88 m (61.9
ft) SE from bench mark 975 1494 B, and 8.79 m (28.8 ft) east from the high rock
point on the west side of the island that is south of a rock cut 10.00 m (32.8
ft) wide that crosses the north tip of the island from east to west.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 2 of 5
Station ID: 9751494 PUBLICATION DATE: 11/08/2011
Name: DOG ISLAND, ST THOMAS
VI
NOAA Chart: 25647 Latitude: 18° 17.8' N ( 18.29714)
USGS Quad: EASTERN ST. THOMAS Longitude: 64° 49.1' W ( -64.81775)
T I D A L B E N C H M A R K S
BENCH MARK STAMPING: 1494 B 2011
DESIGNATION: 975 1494 B
MONUMENTATION: Tidal Station disk VM#: 20018
AGENCY: National Ocean Service (NOS) IDB PID#:
SETTING CLASSIFICATION: Bedrock OPUS PID:
LATITUDE: 18° 17.8' N ( 18.29708) LONGITUDE: 64° 49.1' W ( -64.81767)
The bench mark is a disk set in bedrock near the north end of the island and
north of the 10.00 m (32.8 ft) wide rock cut that crosses the island west to
east, 23.81 m (78.1 ft) SSE of bench mark 975 1494 A, 18.88 m (61.9 ft) NW of
bench mark 975 1494 C, 2.07 m (6.8 ft) north of the high point of the rock
outcrop, 0.43 m (1.4 ft) west of the side of the rock outcrop, and 1.68 m (5.5
ft) above the rock cut.
BENCH MARK STAMPING: 1494 A 2011
DESIGNATION: 975 1494 A
MONUMENTATION: Tidal Station disk VM#: 20019
AGENCY: National Ocean Service (NOS) IDB PID#:
SETTING CLASSIFICATION: Bedrock OPUS PID:
LATITUDE: 18° 17.8' N ( 18.29728) LONGITUDE: 64° 49.1' W ( -64.81775)
The bench mark is a disk set flush in a bedrock point at the north end of the
island, 23.81 m (78.1 ft) NNW of bench mark 975 1494 B, 12.02 m (39.4 ft) south
of the north end of the rock point, 2.50 m (8.2 ft) west of the shallow tidal
lagoon east of the rock point, and 0.64 m (2.1 ft) north of a 1.5 m (5.0 ft)
deep crack in the rock outcrop.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 3 of 5
Station ID: 9751494 PUBLICATION DATE: 11/08/2011
Name: DOG ISLAND, ST THOMAS
VI
NOAA Chart: 25647 Latitude: 18° 17.8' N ( 18.29714)
USGS Quad: EASTERN ST. THOMAS Longitude: 64° 49.1' W ( -64.81775)
T I D A L B E N C H M A R K S
BENCH MARK STAMPING: 1494 D 2011
DESIGNATION: 975 1494 D
MONUMENTATION: Tidal Station disk VM#: 20020
AGENCY: National Ocean Service (NOS) IDB PID#:
SETTING CLASSIFICATION: Bedrock OPUS PID:
LATITUDE: 18° 17.8' N ( 18.29678) LONGITUDE: 64° 49.0' W ( -64.81736)
The bench mark is a disk set in bedrock above the west end of the beach on the
north side of the island, 39.61 m (130.0 ft) WNW of bench mark 975 1494 E, 12.34
m (40.5 ft) SW from the high rock point on the north side of the island at the
west end of the long beach, and 3.68 m (12.1 ft) west from the beach 3.00m (9.8
ft) below.
BENCH MARK STAMPING: 1494 E 2011
DESIGNATION: 975 1494 E
MONUMENTATION: Tidal Station disk VM#: 20021
AGENCY: National Ocean Service (NOS) IDB PID#:
SETTING CLASSIFICATION: Bedrock OPUS PID:
LATITUDE: 18° 17.8' N ( 18.29667) LONGITUDE: 64° 49.0' W ( -64.81700)
The bench mark is a disk set flush in coral bedrock near the west end of the
beach on the north side of the island, 39.61 m (130.0 ft) ESE of tidal bench
mark 975 1494 D, 34.63 m (113.6 ft) SE from the rock outcrop at the north end of
the beach, 9.45 m (129.4 ft) NE from the vegetation line at the top of the stone
and sand beach, and 1.24 m (4.1 ft) SW from the approximate MHW line.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 4 of 5
Station ID: 9751494 PUBLICATION DATE: 11/08/2011
Name: DOG ISLAND, ST THOMAS
VI
NOAA Chart: 25647 Latitude: 18° 17.8' N ( 18.29714)
USGS Quad: EASTERN ST. THOMAS Longitude: 64° 49.1' W ( -64.81775)
T I D A L D A T U M S
Tidal datums at DOG ISLAND, ST THOMAS based on:
LENGTH OF SERIES: 3 MONTHS
TIME PERIOD: May 2011 - July 2011
TIDAL EPOCH: 1983-2001
CONTROL TIDE STATION: 9751639 CHARLOTTE AMALIE, ST. THOMAS
Elevations of tidal datums referred to Mean Lower Low Water (MLLW), in METERS:
MEAN HIGHER HIGH WATER MHHW = 0.245
MEAN HIGH WATER MHW = 0.219
MEAN TIDE LEVEL MTL = 0.123
MEAN SEA LEVEL MSL = 0.114
MEAN LOW WATER MLW = 0.027
MEAN LOWER LOW WATER MLLW = 0.000
Bench Mark Elevation Information In METERS above:
Stamping or Designation MLLW MHW
1494 C 2011 4.063 3.844
1494 B 2011 2.278 2.059
1494 A 2011 1.978 1.759
1494 D 2011 4.709 4.490
1494 E 2011 0.543 0.324
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 5 of 5
Station ID: 9751494 PUBLICATION DATE: 11/08/2011
Name: DOG ISLAND, ST THOMAS
VI
NOAA Chart: 25647 Latitude: 18° 17.8' N ( 18.29714)
USGS Quad: EASTERN ST. THOMAS Longitude: 64° 49.1' W ( -64.81775)
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 any other fixed island datum.
This tide station location has a defined island datum (VIVD09). Island datums
are specific fixed geodetic datums whose elevation relationship to local MSL
and other tidal datums may not be consistent from one location to another.
Virgin Islands Vertical Datum of 2009 (VIVD09) is a fixed datum derived from
a simultaneous, least squares, minimum constraint adjustment of leveling
observations. Local mean sea level relative to the 1983-2001 National Tidal
Datum Epoch observed at tide stations 9751401 located at Lime Tree Bay,
St. Croix, 9751381 located at Lameshur Bay, St. John, and 9751639 located at
Charlotte Amalie, St Thomas was held fixed as the single initial constraint.
VIVD09 replaces all previous height system as the national standard geodetic
reference for heights in the Virgin Islands. Bench mark elevations relative
to VIVD09 are available from NGS through the World Wide Web at
National Geodetic Survey.
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 VIVD09 elevation is shown on the Elevations of Tidal Datums Table Referred
to MLLW only when two or more of the bench marks listed have VIVD09 elevations.
The VIVD09 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, VIVD09 bench mark elevations computed indirectly from the tidal
datums elevation table may differ slightly from VIVD09 elevations listed for
each bench mark in the NGS database.