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National Ocean Service
Datums Page Page 1 of 5
Station ID: 8776604 PUBLICATION DATE: 10/25/2018
Name: BAFFIN BAY
TX
NOAA Chart: 11308 Latitude: 27° 17.8' N ( 27.29700)
USGS Quad: POINT OF ROCKS, TX Longitude: 97° 24.3' W ( -97.40517)
To reach the station from the intersection of HWY 361 and Park Road 22 on Padre
Island in Corpus Christi, TX, proceed SE on Park Road 22 for 17.6 km (10.98 mi)
to the access road to Bird Island Basin in the Padre Island National Seashore,
turn right and continue west on the access road 2.0 km (1.25 mi) to the public
boat ramp. Proceed by boat west for 1.3 km (0.80 mi) out of the Bird Island
Basin to its intersection with the ICWW. Proceed south for 21.8 km (13.55 mi)
along the ICWW. The bench marks are located on the island around the main
fishing cabin. The station is 120 m (393 ft) west of the Spoil Island, 75 m (246
ft) east of the ICWW.
T I D A L B E N C H M A R K S
PRIMARY BENCH MARK STAMPING: 90068 A 1998
DESIGNATION: 877 6604 A
MONUMENTATION: Bench Mark disk VM#: 17523
AGENCY: Conrad Blucher Institute (CBI) IDB PID:
SETTING CLASSIFICATION: Stainless steel rod OPUS PID#: BBFG90
LATITUDE: 27° 17.8' N ( 27.29608) LONGITUDE: 97° 24.3' W ( -97.40428)
The primary bench mark is a disk located on an island on the east side of the
GIWW (Gulf Intracoastal Water Way) at Baffin Bay, 25.53 m (83.76 ft) NNE (15
magnetic) from the NE corner of cabin P1416, 13.32 m (43.70 ft) east (95
magnetic) from the center of the east end of a wooden pier where it meets a
concrete sidewalk, 11.85 m (38.88 ft) SW (228 magnetic) from the SW corner of
cabin P1418. The bench mark is flush with the surface of the ground and is
crimped to the top of a stainless steel rod and encased in a 6" PVC pipe and
with concrete kickblock
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 2 of 5
Station ID: 8776604 PUBLICATION DATE: 10/25/2018
Name: BAFFIN BAY
TX
NOAA Chart: 11308 Latitude: 27° 17.8' N ( 27.29700)
USGS Quad: POINT OF ROCKS, TX Longitude: 97° 24.3' W ( -97.40517)
T I D A L B E N C H M A R K S
BENCH MARK STAMPING: 90068 B 1998
DESIGNATION: 877 6604 B
MONUMENTATION: Bench Mark disk VM#: 17524
AGENCY: Conrad Blucher Institute (CBI) IDB PID:
SETTING CLASSIFICATION: Stainless steel rod OPUS PID:
LATITUDE: 27° 17.8' N ( 27.29589) LONGITUDE: 97° 24.2' W ( -97.40397)
BENCH MARK STAMPING: 90068 C 1998
DESIGNATION: 877 6604 C
MONUMENTATION: Bench Mark disk VM#: 17525
AGENCY: Conrad Blucher Institute (CBI) IDB PID:
SETTING CLASSIFICATION: Stainless steel rod OPUS PID:
LATITUDE: 27° 17.7' N ( 27.29569) LONGITUDE: 97° 24.3' W ( -97.40436)
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 3 of 5
Station ID: 8776604 PUBLICATION DATE: 10/25/2018
Name: BAFFIN BAY
TX
NOAA Chart: 11308 Latitude: 27° 17.8' N ( 27.29700)
USGS Quad: POINT OF ROCKS, TX Longitude: 97° 24.3' W ( -97.40517)
T I D A L B E N C H M A R K S
BENCH MARK STAMPING: 90068 D 1998
DESIGNATION: 877 6604 D
MONUMENTATION: Bench Mark disk VM#: 17529
AGENCY: Conrad Blucher Institute (CBI) IDB PID#: DP0728
SETTING CLASSIFICATION: Stainless steel rod OPUS PID:
LATITUDE: 27° 17.7' N ( 27.29547) LONGITUDE: 97° 24.2' W ( -97.40406)
The bench mark is a disk and located on an island on the east side of the GIWW
(Gulf Intracoastal Water Way) at Baffin Bay, 37.66 m (123.56 ft) ESE from bench
mark 877 6604 C, 14.44 m (47.38 ft) SSE from the SE corner of cabin P1409, 13.68
m (44.88 ft) SE from the SE corner of a generator enclosure, and 5.77 m NE from
the NE corner of an outhouse. The benchmark is flush with the surface of the
ground and is crimped to a stainless steel rod driven 22.1m into the ground and
encased in a 6" PVC pipe with with concrete kickblock.
BENCH MARK STAMPING: 90068 E 1998
DESIGNATION: 877 6604 E
MONUMENTATION: Bench Mark disk VM#: 17532
AGENCY: Conrad Blucher Institute (CBI) IDB PID:
SETTING CLASSIFICATION: Stainless steel rod OPUS PID:
LATITUDE: 27° 17.7' N ( 27.29581) LONGITUDE: 97° 24.2' W ( -97.40358)
The bench mark is a disk and located on an island on the east side of the GIWW
(Gulf Intracoastal Water Way) at Baffin Bay, 59.29 m (194.52 ft) NE from the NE
corner of cabin p1409, and approximately 8 m (26.2 ft) NNW from a mesquite bush.
The bench mark is flush with the surface of the ground and is crimped to a
stainless steel rod and encased in a 6" PVC pipe with with concrete kickblock.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 4 of 5
Station ID: 8776604 PUBLICATION DATE: 10/25/2018
Name: BAFFIN BAY
TX
NOAA Chart: 11308 Latitude: 27° 17.8' N ( 27.29700)
USGS Quad: POINT OF ROCKS, TX Longitude: 97° 24.3' W ( -97.40517)
T I D A L D A T U M S
Tidal datums at BAFFIN BAY based on:
LENGTH OF SERIES: 3 Years
TIME PERIOD: 10/12-09/13, 03/14-02/15 and 06/16-05/17
TIDAL EPOCH: 2002-2006
CONTROL TIDE STATION: 8774770 ROCKPORT, ARANSAS BAY
Elevations of tidal datums referred to Mean Sea Level (MSL), in METERS:
MEAN SEA LEVEL MSL = 0.000
North American Vertical Datum NAVD88 = -0.148
North American Vertical Datum (NAVD88)
Bench Mark Elevation Information In METERS above:
Stamping or Designation MSL
90068 A 1998 0.848
90068 B 1998 1.790
90068 C 1998 1.214
90068 D 1998 1.547
90068 E 1998 2.184
Foot Notes:
This station has been determined to be Non-tidal for tidal datum purposes. There
is either no measureable periodic rise and fall of the tide at this location, or
it may be present but inconsistent, or the periodic tide is present and
consistent, however the Mean Range of Tide (MN) is negligible, that is below the
established tidal/non-tidal threshold of 0.03m (0.10ft). Only the datum of local
Mean Sea Level (MSL) is published at these stations. For Nautical Charting Datum
applications, a non-tidal Low Water Datum (LWD)is established as 0.50ft (0.15m)
below MSL.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 5 of 5
Station ID: 8776604 PUBLICATION DATE: 10/25/2018
Name: BAFFIN BAY
TX
NOAA Chart: 11308 Latitude: 27° 17.8' N ( 27.29700)
USGS Quad: POINT OF ROCKS, TX Longitude: 97° 24.3' W ( -97.40517)
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.