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Datums Page Page 1 of 7
Station ID: 8779748 PUBLICATION DATE: 10/01/2020
Name: SOUTH PADRE ISLAND COAST GUARD STATION
TX
NOAA Chart: 11301 Latitude: 26° 4.4' N ( 26.07310)
USGS Quad: PORT ISABEL Longitude: 97° 10.1' W ( -97.16750)
From Port Isabell proceed across the bridge onto South Padre Island and proceed
south on Padre Blvd. Turn right on Wallace L. Reed road and follow it to the
gate into the USCG facility.
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 7
Station ID: 8779748 PUBLICATION DATE: 10/01/2020
Name: SOUTH PADRE ISLAND COAST GUARD STATION
TX
NOAA Chart: 11301 Latitude: 26° 4.4' N ( 26.07310)
USGS Quad: PORT ISABEL Longitude: 97° 10.1' W ( -97.16750)
T I D A L B E N C H M A R K S
PRIMARY BENCH MARK STAMPING: Unstamped
DESIGNATION: USCG
ALIAS: FLAG POLE
MONUMENTATION: Tidal Station disk VM#: 15615
AGENCY: US Coast and Geodetic Survey
(USC&GS) IDB PID:
SETTING CLASSIFICATION: Concrete monument OPUS PID:
LATITUDE: 26° 4.4' N ( 26.07306) LONGITUDE: 97° 10.0' W ( -97.16614)
The primary bench mark is a disk set in concrete near the flag pole in front of
the USCG building, 7.62 m (25.0 ft) SSE of the centerline of a paved street
(Wallace L. Reed), 5.10 m (16.7 ft) east of a light pole at the intersection of
a sidewalk and the street, 2.44 m (8.0 ft) north of the flagpole, and flush with
the ground.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 3 of 7
Station ID: 8779748 PUBLICATION DATE: 10/01/2020
Name: SOUTH PADRE ISLAND COAST GUARD STATION
TX
NOAA Chart: 11301 Latitude: 26° 4.4' N ( 26.07310)
USGS Quad: PORT ISABEL Longitude: 97° 10.1' W ( -97.16750)
T I D A L B E N C H M A R K S
BENCH MARK STAMPING: N 1142 1959
DESIGNATION: N 1142 1959
MONUMENTATION: Bench Mark disk VM#: 15614
AGENCY: US Coast and Geodetic Survey
(USC&GS) IDB PID#: AB0258
SETTING CLASSIFICATION: Concrete foundation OPUS PID:
LATITUDE: 26° 4.5' N ( 26.07433) LONGITUDE: 97° 9.8' W ( -97.16394)
The benchmark is a disk set in the floor of the porch at the SE corner of the
old Coast Guard building, 12 m (39.3 ft) south of the center of a stairway on
east side of the building, 1 m (0.49 ft) north of the south edge of porch floor,
and 0.3 m (1.0 ft) east of the east wall. The mark is 0.3 m (1.0 ft) above
ground.
BENCH MARK STAMPING: NO 5
DESIGNATION: 877 9748 TIDAL 5
MONUMENTATION: Survey disk VM#: 15616
AGENCY: US Coast and Geodetic Survey
(USC&GS) IDB PID#: AB1238
SETTING CLASSIFICATION: Concrete slab OPUS PID:
LATITUDE: 26° 4.5' N ( 26.07456) LONGITUDE: 97° 9.8' W ( -97.16408)
The bench mark is a disk set in the floor of the porch at the NE corner of the
Old Coast Guard Building, 18.5m (60.7 ft) West and across the street from a fire
hydrant, 9.7m (31.8 ft) North of the center of a stairway on East side of
building, 0.3m (1.0 ft) East of the East wall, and 0.15m (0.49 ft) South of the
North edge of porch floor. The mark is 0.3m (1.0 ft) above ground.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 4 of 7
Station ID: 8779748 PUBLICATION DATE: 10/01/2020
Name: SOUTH PADRE ISLAND COAST GUARD STATION
TX
NOAA Chart: 11301 Latitude: 26° 4.4' N ( 26.07310)
USGS Quad: PORT ISABEL Longitude: 97° 10.1' W ( -97.16750)
T I D A L B E N C H M A R K S
BENCH MARK STAMPING: SPICGS 001
DESIGNATION: 877 9748 001 Tidal
MONUMENTATION: Tidal Station disk VM#: 21966
AGENCY: Conrad Blucher Institute IDB PID:
SETTING CLASSIFICATION: Stainless steel rod w/o sleeve OPUS PID#: BBGG36
LATITUDE: 26° 4.4' N ( 26.07325) LONGITUDE: 97° 10.0' W ( -97.16650)
The bench mark is a brass survey disk set atop a stainless steel rod and located
on the grounds of the South Padre Island Coast Guard Station, in a concrete
slab, 16.77 m (55.02 ft) ENE of the NE corner of the concrete breakwater cap on
the north side of the mooring slips, 7.02 m (23.03 ft) NNW of the NE corner of
the shop bldg., 6.37 m (20.90 ft) west of a water meter, and 0.69 m (2.26 ft) NE
of the NE corner of a concrete slab foundation for an electric transformer. The
rod is driven 18.3m (60.0 ft) into the ground encased in a 4' pvc pipe and
concrete kickblock, and accessed by removing a 4-inch threaded PVC plug.
BENCH MARK STAMPING: SPICGS 002
DESIGNATION: 877 9748 002 Tidal
MONUMENTATION: Tidal Station disk VM#: 21967
AGENCY: Conrad Blucher Institute IDB PID:
SETTING CLASSIFICATION: Stainless steel rod w/o sleeve OPUS PID:
LATITUDE: 26° 4.4' N ( 26.07353) LONGITUDE: 97° 10.0' W ( -97.16592)
The bench mark is a brass survey disk set atop a stainless steel rod marked with
an orange fiberglass witness post, located on the grounds of the South Padre
Island Coast Guard station 20.80 m (68.24 ft) NW of the first concrete light
pole east of the parking lot on the north side of the paved entrance road, 18.13
m (59.48 ft) WSW of a wooden power pole, 3.72 m (12.20 ft) NE of a wooden power
pole number t 6018, and 1.13 m (3.71 ft) north of the northern corner of the
hazardous waste building. The rod is driven 15.2m (49.9 ft) into the ground
encased in a 4' pvc pipe and concrete kickblock.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 5 of 7
Station ID: 8779748 PUBLICATION DATE: 10/01/2020
Name: SOUTH PADRE ISLAND COAST GUARD STATION
TX
NOAA Chart: 11301 Latitude: 26° 4.4' N ( 26.07310)
USGS Quad: PORT ISABEL Longitude: 97° 10.1' W ( -97.16750)
T I D A L B E N C H M A R K S
BENCH MARK STAMPING: SPICGS 003
DESIGNATION: 877 9748 003 Tidal
MONUMENTATION: Tidal Station disk VM#: 21968
AGENCY: Conrad Blucher Institute IDB PID#: DP0738
SETTING CLASSIFICATION: Stainless steel rod w/o sleeve OPUS PID#: DP0738
LATITUDE: 26° 4.4' N ( 26.07392) LONGITUDE: 97° 9.9' W ( -97.16494)
The bench mark is a brass survey disk set atop a stainless steel rod, located on
the grounds of the South Padre Island Coast Guard station, 29.89 m (98.06 ft)
ENE of the second post east of the west end of a chainlink fence on the north
side and parallel to the paved entrance road, 25.89 m (84.94 ft) ENE of a wooden
power pole, 21.57 m (70.77 ft) NW of the gate post in the chainlink fence on
the south side of the paved entrance road, 8.78 m (28.81 ft) south of the NE
corner of the chainlink fence, and 5.30 m (17.39 ft) north of the NE corner of
the concrete foundation slab for the electrical power box for the gate in the
chainlink fence. The rod is driven 15.2m (49.9 ft) into the ground encased in a
4' pvc pipe and concrete kickblock.
BENCH MARK STAMPING: SPICGS 004
DESIGNATION: 877 9748 004 Tidal
MONUMENTATION: Tidal Station disk VM#: 21970
AGENCY: Conrad Blucher Institute IDB PID:
SETTING CLASSIFICATION: Concrete bulkhead OPUS PID#: BBGG35
LATITUDE: 26° 4.4' N ( 26.07275) LONGITUDE: 97° 10.0' W ( -97.16644)
The benchmark is a brass disk located on a concrete bulkhead leading to the tide
gauge, 25.5 m (83.6 ft) WSW of the WSW corner of the USCG main office, 18 m (59
ft) south of the SSE corner of the USCG boat shop building, and 2 m (6.5 ft) WSW
of a flag pole located near the ESE corner of the USCG boat basin.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 6 of 7
Station ID: 8779748 PUBLICATION DATE: 10/01/2020
Name: SOUTH PADRE ISLAND COAST GUARD STATION
TX
NOAA Chart: 11301 Latitude: 26° 4.4' N ( 26.07310)
USGS Quad: PORT ISABEL Longitude: 97° 10.1' W ( -97.16750)
T I D A L D A T U M S
Tidal datums at SOUTH PADRE ISLAND COAST GUARD STATION based on:
LENGTH OF SERIES: 4 YEARS
TIME PERIOD: October 2015 - September 2019
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 (10/07/2017) = 1.082
MEAN HIGHER HIGH WATER MHHW = 0.417
MEAN HIGH WATER MHW = 0.400
North American Vertical Datum NAVD88 = 0.283
MEAN SEA LEVEL MSL = 0.247
MEAN TIDE LEVEL MTL = 0.222
MEAN LOW WATER MLW = 0.043
MEAN LOWER LOW WATER MLLW = 0.000
LOWEST OBSERVED WATER LEVEL (12/22/2018) = -0.295
North American Vertical Datum (NAVD88)
Bench Mark Elevation Information In METERS above:
Stamping or Designation MLLW MHW
Unstamped 1.505 1.105
N 1142 1959 1.366 0.966
NO 5 1.360 0.960
SPICGS 001 1.420 1.020
SPICGS 002 0.851 0.451
SPICGS 003 1.035 0.635
SPICGS 004 1.860 1.460
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 7 of 7
Station ID: 8779748 PUBLICATION DATE: 10/01/2020
Name: SOUTH PADRE ISLAND COAST GUARD STATION
TX
NOAA Chart: 11301 Latitude: 26° 4.4' N ( 26.07310)
USGS Quad: PORT ISABEL Longitude: 97° 10.1' W ( -97.16750)
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.