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National Ocean Service
Datums Page Page 1 of 7
Station ID: 8779749 PUBLICATION DATE: 05/21/2021
Name: SPI BRAZOS SANTIAGO, BRAZOS SANTIAGO PASS
TX
NOAA Chart: 11302 Latitude: 26° 4.0' N ( 26.06739)
USGS Quad: PORT ISABEL Longitude: 97° 9.3' W ( -97.15478)
TO REACH THE STATION FROM THE INTERSECTION OF HWY 100 AND ST PARK RD 100 IN
SOUTH PADRE ISLAND, TURN RIGHT ONTO PK RD 100 AND TRAVEL SOUTH FOR 1.01 KM (0.63
MI) TO THE ENTRANCE OF THE ISLA BLANCE STATE PARK, PROCEED SOUTH ON CHANNEL VIEW
LOOP FOR 0.91 KM (0.56 MI) TO THE BOAT RAMP. THE TIDE STATION IS LOCATED SSE OF
THE PARK, 24.65 M (80.88 FT) SOUTH OF THE NORTH JETTY. THE BENCHMARKS ARE
LOCATED ALONG THE JETTY BASE AND CHANNEL VIEW ROAD.
T I D A L B E N C H M A R K S
PRIMARY BENCH MARK STAMPING: 9749 B 2016
DESIGNATION: 877 9749 B
MONUMENTATION: Flange-encased Rod VM#: 22165
AGENCY: IDB PID:
SETTING CLASSIFICATION: Stainless steel rod OPUS PID#: BBFL15
LATITUDE: 26° 4.2' N ( 26.06953) LONGITUDE: 97° 9.4' W ( -97.15742)
The primary bench mark is located 33 m (108.3 ft) NE of a Jesus statue, 22.90 m
(75.1 ft) south of the centerline of Channelview Road, 22.50 m (73.8 ft) west of
a power pole, 6.00 m (19.6 ft) east of concrete drainage culvert. The datum
point is the top of a stainless steel rod driven 30.5 m (100 ft) to refusal and
set flush to the ground in 6 inch PVC pipe encased with a concrete kickblock.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 2 of 7
Station ID: 8779749 PUBLICATION DATE: 05/21/2021
Name: SPI BRAZOS SANTIAGO, BRAZOS SANTIAGO PASS
TX
NOAA Chart: 11302 Latitude: 26° 4.0' N ( 26.06739)
USGS Quad: PORT ISABEL Longitude: 97° 9.3' W ( -97.15478)
T I D A L B E N C H M A R K S
BENCH MARK STAMPING: 9749 C 2016
DESIGNATION: 877 9749 C
MONUMENTATION: Flange-encased Rod VM#: 22166
AGENCY: IDB PID:
SETTING CLASSIFICATION: Stainless steel rod OPUS PID#: BBGG43
LATITUDE: 26° 4.2' N ( 26.07031) LONGITUDE: 97° 9.6' W ( -97.15961)
The benchmark is located 28.00 m (91.8 ft) west of concrete light pole, 13.90 m
(45.6 ft) NNE of centerline of a bike path, 6.00 m (19.6 ft) NNE of the
centerline of Channelview Road, and 0.30 m (0.9 ft) SW of a wooden fence. The
bench mark is the top of a stainless steel rod driven 21.9 m (72 ft) to refusal
and set flush to the ground in 6 inch PVC pipe encased with a concrete
kickblock.
BENCH MARK STAMPING: 9749 D 2016
DESIGNATION: 877 9749 D
MONUMENTATION: Flange-encased Rod VM#: 22167
AGENCY: IDB PID:
SETTING CLASSIFICATION: Stainless steel rod OPUS PID#: BBGG42
LATITUDE: 26° 4.2' N ( 26.07036) LONGITUDE: 97° 9.6' W ( -97.16064)
The bench mark is located 30.75 m (100.8 ft) west of a concrete light pole,
19.30 m (63.3 ft) NE of the centerline of a bike path, 11.70 m (38.3 ft) NE of a
centerline of Channelview Road, and 0.67 m (2.2 ft) SW of a wooden fence. The
bench mark is the top of a stainless steel rod driven 21.9 m (72 ft) to refusal
and set flush to the ground in 6 inch PVC pipe encased with a concrete
kickblock.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 3 of 7
Station ID: 8779749 PUBLICATION DATE: 05/21/2021
Name: SPI BRAZOS SANTIAGO, BRAZOS SANTIAGO PASS
TX
NOAA Chart: 11302 Latitude: 26° 4.0' N ( 26.06739)
USGS Quad: PORT ISABEL Longitude: 97° 9.3' W ( -97.15478)
T I D A L B E N C H M A R K S
BENCH MARK STAMPING: 9749 A 2016
DESIGNATION: 877 9749 A
MONUMENTATION: Flange-encased Rod VM#: 22169
AGENCY: IDB PID:
SETTING CLASSIFICATION: Stainless steel rod w/o sleeve OPUS PID#: BBGG44
LATITUDE: 26° 4.2' N ( 26.06917) LONGITUDE: 97° 9.4' W ( -97.15664)
To reach the bench mark from the park entrance, travel 1.08 km (0.67 mi) to the
bait stand at the jetty base, then proceed by foot 12.7 m (41.6 ft) east. The
mark is located 13.95 m (45.76 ft) W of a fire hydrant, 12.70 m (41.6 ft) E from
SE corner of jetty bait stand, 8.0 m (26.24 ft) SW of power pole with
transformer. The benchmark is a stainless steel rod driven 34.1 m (112 ft) to
refusal and set flush to the ground in 6 inch PVC pipe encased with a concrete
kickblock.
BENCH MARK STAMPING: C1 1934
DESIGNATION: 877 9749 USGS C1
MONUMENTATION: Survey disk VM#: 22180
AGENCY: U.S. Geodetic Survey (USGS) IDB PID:
SETTING CLASSIFICATION: Granite rock jetty OPUS PID:
LATITUDE: 26° 4.1' N ( 26.06864) LONGITUDE: 97° 9.4' W ( -97.15650)
The bench mark is a disk set atop of a granite jetty boulder located 61.58 m
(202 ft) west of USCG 826, 33.10 m (108.5 ft) SW of a lighted wooden pole, and
21.20 m (69.5 ft) west of a wooden telephone pole.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 4 of 7
Station ID: 8779749 PUBLICATION DATE: 05/21/2021
Name: SPI BRAZOS SANTIAGO, BRAZOS SANTIAGO PASS
TX
NOAA Chart: 11302 Latitude: 26° 4.0' N ( 26.06739)
USGS Quad: PORT ISABEL Longitude: 97° 9.3' W ( -97.15478)
T I D A L B E N C H M A R K S
BENCH MARK STAMPING: 1 1939
DESIGNATION: USCGS NO 1
ALIAS: 877 9749 TIDAL 1
MONUMENTATION: Survey disk VM#: 22181
AGENCY: U.S. Geodetic Survey (USGS) IDB PID:
SETTING CLASSIFICATION: Granite rock jetty OPUS PID#: BBGH51
LATITUDE: 26° 4.1' N ( 26.06833) LONGITUDE: 97° 9.4' W ( -97.15592)
The bench mark is a disk set atop of a granite jetty boulder located 47.02 m
(154.2 ft) west of a concrete retaining wall, 40.38 m (132.48 ft) east of a
wooden telephone pole, and 26.06 m (85.49 ft) SE of a metal no parking sign with
a metal post.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 5 of 7
Station ID: 8779749 PUBLICATION DATE: 05/21/2021
Name: SPI BRAZOS SANTIAGO, BRAZOS SANTIAGO PASS
TX
NOAA Chart: 11302 Latitude: 26° 4.0' N ( 26.06739)
USGS Quad: PORT ISABEL Longitude: 97° 9.3' W ( -97.15478)
T I D A L B E N C H M A R K S
BENCH MARK STAMPING:
DESIGNATION: 8779749 USACE 1
ALIAS: USACE 1
MONUMENTATION: Survey disk VM#: 22184
AGENCY: U.S. Corp of Engineers (USACE) IDB PID:
SETTING CLASSIFICATION: Granite rock jetty OPUS PID:
LATITUDE: 26° 4.1' N ( 26.06767) LONGITUDE: 97° 9.3' W ( -97.15464)
The benchmark is a disk set atop of a granite jetty boulder 101.8 m (334 ft)
ESE of a large concrete retaining wall, 28.00 m (91.8 ft) NE of the tide
station, and 4.25 m (13.9 ft) north of the jetty edge.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 6 of 7
Station ID: 8779749 PUBLICATION DATE: 05/21/2021
Name: SPI BRAZOS SANTIAGO, BRAZOS SANTIAGO PASS
TX
NOAA Chart: 11302 Latitude: 26° 4.0' N ( 26.06739)
USGS Quad: PORT ISABEL Longitude: 97° 9.3' W ( -97.15478)
T I D A L D A T U M S
Tidal datums at SPI BRAZOS SANTIAGO, BRAZOS SANTIAGO PASS based on:
LENGTH OF SERIES: 4 YEARS
TIME PERIOD: January 2017 - December 2020
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 (09/22/2020) = 1.205
MEAN HIGHER HIGH WATER MHHW = 0.449
MEAN HIGH WATER MHW = 0.429
North American Vertical Datum NAVD88 = 0.375
MEAN SEA LEVEL MSL = 0.266
MEAN TIDE LEVEL MTL = 0.240
MEAN LOW WATER MLW = 0.051
MEAN LOWER LOW WATER MLLW = 0.000
LOWEST OBSERVED WATER LEVEL (12/22/2018) = -0.291
North American Vertical Datum (NAVD88)
Bench Mark Elevation Information In METERS above:
Stamping or Designation MLLW MHW
9749 B 2016 2.612 2.183
9749 C 2016 2.518 2.089
9749 D 2016 1.885 1.456
9749 A 2016 2.854 2.425
C1 1934 1.759 1.330
1 1939 1.665 1.236
8779749 USACE 1 1.668 1.239
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 7 of 7
Station ID: 8779749 PUBLICATION DATE: 05/21/2021
Name: SPI BRAZOS SANTIAGO, BRAZOS SANTIAGO PASS
TX
NOAA Chart: 11302 Latitude: 26° 4.0' N ( 26.06739)
USGS Quad: PORT ISABEL Longitude: 97° 9.3' W ( -97.15478)
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.