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National Ocean Service
Datums Page Page 1 of 6
Station ID: 8779739 PUBLICATION DATE: 12/12/2003
Name: W QUEEN ISABELLA CAUSEWAY, PORT ISABEL
TX
NOAA Chart: 11301 Latitude: 26° 4.3' N ( 26.07170)
USGS Quad: PORT ISABEL Longitude: 97° 11.5' W ( -97.19170)
To reach the tidal bench marks from the west end of the new Queen Isabel
Bridge/Causeway in Port Isabel, proceed 1.0 km (0.6 mi) SE on old State Highway
100 to a drawbridge over Intracoastal Waterway, continue 1.3 km (0.8 mi) over
the bridge and east on old State Highway 100 to the west end of the old Queen
Isabel Causeway bridge (presently a state fishing pier). The bench marks are on
the old bridge and on the bulkhead on the north and south sides of the old
bridge. The tide gage and staff were on the bulkhead about 15 m (50 ft) NW of
the old bridge.
T I D A L B E N C H M A R K S
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 2 of 6
Station ID: 8779739 PUBLICATION DATE: 12/12/2003
Name: W QUEEN ISABELLA CAUSEWAY, PORT ISABEL
TX
NOAA Chart: 11301 Latitude: 26° 4.3' N ( 26.07170)
USGS Quad: PORT ISABEL Longitude: 97° 11.5' W ( -97.19170)
T I D A L B E N C H M A R K S
PRIMARY BENCH MARK STAMPING: L 1142 1959
DESIGNATION: L 1142
MONUMENTATION: Tidal Station disk VM#: 7918
AGENCY: US Coast and Geodetic Survey
(USC&GS) IDB PID#: AB0256
SETTING CLASSIFICATION: Concrete bulkhead OPUS PID:
LATITUDE: 26° 4.3' N ( 26.07170) LONGITUDE: 97° 11.4' W ( -97.19000)
The primary bench mark is a disk set in the top of a concrete bulkhead at the
west end of old Queen Isabel Causeway, 16.73 m (54.9 ft) north of the NE corner
of a bait/ tackle shop and restaurant, 15.24 m (50.0 ft) NW of the centerline of
old State Highway 100, 11.43 m (37.5 ft) west of the NW corner of the old
bridge, 0.61 m (2.0 ft) west of a 0.3 m (1 ft) metal pipe projecting 0.91 m (3.0
ft) above the seawall, and 0.61 m (2.0 ft) below the old bridge.
BENCH MARK STAMPING: NO 10 1973
DESIGNATION: 877 9739 TIDAL 10
MONUMENTATION: Tidal Station disk VM#: 7919
AGENCY: National Ocean Survey (NOS) IDB PID#: AB1232
SETTING CLASSIFICATION: Concrete bulkhead OPUS PID:
LATITUDE: 26° 4.3' N ( 26.07170) LONGITUDE: 97° 11.4' W ( -97.19000)
The bench mark is a disk set in the top of a concrete bulkhead on the north side
at the west end of old Queen Isabel Causeway, 28.62 m (93.9 ft) north of the
centerline of old State Highway 100, 26.64 m (87.4 ft) NNE of the center one of
three light poles, 22.71 m (74.5 ft) east of the west end of the bulkhead, 10.64
m (34.9 ft) west of the north end of a wood fence running NW/SE, and 0.3 m (1
ft) below the highway.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 3 of 6
Station ID: 8779739 PUBLICATION DATE: 12/12/2003
Name: W QUEEN ISABELLA CAUSEWAY, PORT ISABEL
TX
NOAA Chart: 11301 Latitude: 26° 4.3' N ( 26.07170)
USGS Quad: PORT ISABEL Longitude: 97° 11.5' W ( -97.19170)
T I D A L B E N C H M A R K S
BENCH MARK STAMPING: NO 11 1973
DESIGNATION: 877 9739 TIDAL 11
MONUMENTATION: Tidal Station disk VM#: 7920
AGENCY: National Ocean Survey (NOS) IDB PID#: AB1233
SETTING CLASSIFICATION: Concrete bulkhead OPUS PID:
LATITUDE: 26° 4.3' N ( 26.07170) LONGITUDE: 97° 11.4' W ( -97.19000)
The bench mark is a disk set in the top of a concrete bulkhead on the south side
at the west end of old Queen Isabel Causeway, 33.22 m (109.0 ft) NE of bench
mark NO 12 1973, 29.20 m (95.8 ft) SE of the centerline of the highway, 24.32 m
(79.8 ft) east of a power pole with light and transformer, 19.81 m (65.0 ft) SSW
of the SW corner of the old bridge, 13.72 m (45.0 ft) SW of the NE end of the
bulkhead, 0.24 m (0.8 ft) NW of the SE edge of the bulkhead, and 0.3 m (1 ft)
below the highway.
BENCH MARK STAMPING: NO 12 1973
DESIGNATION: 877 9739 TIDAL 12
MONUMENTATION: Tidal Station disk VM#: 7921
AGENCY: National Ocean Survey (NOS) IDB PID#: AB1234
SETTING CLASSIFICATION: Concrete bulkhead OPUS PID:
LATITUDE: 26° 4.3' N ( 26.07170) LONGITUDE: 97° 11.4' W ( -97.19000)
The bench mark is a disk set in the top of a concrete bulkhead on the south side
at the west end of old Queen Isabel Causeway, 31.64 m (103.8 ft) SE of the
centerline of the highway, 13.72 m (45.0 ft) NE of the SW end of the bulkhead,
10.94 m (35.9 ft) south of a power pole with light and transformer, 0.15 m (0.5
ft) NW of the SE edge of the bulkhead, and 0.3 m (1 ft) below the highway.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 4 of 6
Station ID: 8779739 PUBLICATION DATE: 12/12/2003
Name: W QUEEN ISABELLA CAUSEWAY, PORT ISABEL
TX
NOAA Chart: 11301 Latitude: 26° 4.3' N ( 26.07170)
USGS Quad: PORT ISABEL Longitude: 97° 11.5' W ( -97.19170)
T I D A L B E N C H M A R K S
BENCH MARK STAMPING: 1973
DESIGNATION: 877 9739 1973
MONUMENTATION: Survey disk VM#: 7922
AGENCY: Cameron County IDB PID#:
SETTING CLASSIFICATION: Concrete curb OPUS PID:
LATITUDE: 26° 4.3' N ( 26.07170) LONGITUDE: 97° 11.4' W ( -97.19000)
The bench mark is a disk set in the north curb at the west end of old Queen
Isabel Causeway, 11.70 m (38.4 ft) SE of bench mark L 1142 1959, 4.08 (13.4 ft)
NW of the centerline of the bridge, and 0.85 m (2.8 ft) NE of the SW end of the
bridge.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 5 of 6
Station ID: 8779739 PUBLICATION DATE: 12/12/2003
Name: W QUEEN ISABELLA CAUSEWAY, PORT ISABEL
TX
NOAA Chart: 11301 Latitude: 26° 4.3' N ( 26.07170)
USGS Quad: PORT ISABEL Longitude: 97° 11.5' W ( -97.19170)
T I D A L D A T U M S
Tidal datums at W QUEEN ISABELLA CAUSEWAY, PORT ISABEL based on:
LENGTH OF SERIES: 2 YEARS
TIME PERIOD: January 1974 - December 1975
TIDAL EPOCH: 1983-2001
CONTROL TIDE STATION: 8779770 PORT ISABEL, LAGUNA MADRE
Elevations of tidal datums referred to Mean Lower Low Water (MLLW), in METERS:
HIGHEST OBSERVED WATER LEVEL (09/01/1977) = 1.117
MEAN HIGHER HIGH WATER MHHW = 0.362
MEAN HIGH WATER MHW = 0.349
North American Vertical Datum NAVD88 = 0.225
MEAN SEA LEVEL MSL = 0.195
MEAN TIDE LEVEL MTL = 0.189
MEAN LOW WATER MLW = 0.030
MEAN LOWER LOW WATER MLLW = 0.000
LOWEST OBSERVED WATER LEVEL (02/22/1978) = -0.429
North American Vertical Datum (NAVD88)
Bench Mark Elevation Information In METERS above:
Stamping or Designation MLLW MHW
L 1142 1959 1.648 1.299
NO 10 1973 1.457 1.108
NO 11 1973 1.639 1.290
NO 12 1973 1.245 0.896
1973 2.475 2.126
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 6 of 6
Station ID: 8779739 PUBLICATION DATE: 12/12/2003
Name: W QUEEN ISABELLA CAUSEWAY, PORT ISABEL
TX
NOAA Chart: 11301 Latitude: 26° 4.3' N ( 26.07170)
USGS Quad: PORT ISABEL Longitude: 97° 11.5' W ( -97.19170)
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.