U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Datums Page Page 1 of 6
Station ID: 8773701 PUBLICATION DATE: 04/27/2020
Name: PORT O'CONNOR, MATAGORDA BAY
TX
NOAA Chart: 11319 Latitude: 28° 26.8' N ( 28.44586)
USGS Quad: PORT O'CONNOR Longitude: 96° 23.7' W ( -96.39556)
To reach the tidal bench marks from Adams Street in Port OConnor proceed west on
Adams Street to Park Avenue, then north on Park Avenue to the Port OConnor park
on the east side of Park Avenue. The bench marks are in the park and along Park
Avenue. The tide gauge is located on a 6'x6' wooden 4 pile structure just
offshore of Port O'Connor on the north side of the jetty position is 28 26'
45.1" N by 96 23' 44.1" W
T I D A L B E N C H M A R K S
PRIMARY BENCH MARK STAMPING: 3701 K 1998
DESIGNATION: 877 3701 K
MONUMENTATION: Tidal Station disk VM#: 17530
AGENCY: Conrad Blucher Institute (CBI) IDB PID:
SETTING CLASSIFICATION: Stainless steel rod OPUS PID#: BBDN99
LATITUDE: 28° 26.7' N ( 28.44503) LONGITUDE: 96° 24.2' W ( -96.40269)
The primary bench mark is a brass disk marked with an orange fiberglass witness
post, located on the NW corner of the intersection of Commerce Street and
Washington, 10.2 m (33.5 ft) from the centerline of Washington Street, 7.5 m
(24.6 ft) NNW from the centerline of Commerce Street, and 0.7 m (2.3 ft) north
from the street sign marking Commerce Street and Washington Street. The bench
mark is set 0.1 m (0.3 ft) below the surface of the ground, crimped to a
stainless steel rod driven 13.7 m (44.9 ft), and encased in a 6-inch PVC pipe
and concrete kickblock.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 2 of 6
Station ID: 8773701 PUBLICATION DATE: 04/27/2020
Name: PORT O'CONNOR, MATAGORDA BAY
TX
NOAA Chart: 11319 Latitude: 28° 26.8' N ( 28.44586)
USGS Quad: PORT O'CONNOR Longitude: 96° 23.7' W ( -96.39556)
T I D A L B E N C H M A R K S
BENCH MARK STAMPING: 3701 H 1998
DESIGNATION: 877 3701 H
MONUMENTATION: Tidal Station disk VM#: 17526
AGENCY: Conrad Blucher Institute (CBI) IDB PID:
SETTING CLASSIFICATION: Granite rock OPUS PID:
LATITUDE: 28° 26.7' N ( 28.44553) LONGITUDE: 96° 23.8' W ( -96.39650)
The bench mark is a brass survey disk set into a hole drilled into the top of a
large granite block which is a part of the Port O'Connor jetties, 546.99 m
(1794.6 ft) ENE of the west edge of the westernmost granite block in the north
jetty on the fourth block south from the north side of the jetty, 0.30 m (0.98
ft) north of the south edge of the block, 0.21 m (0.69 ft) west of the east edge
of the block, and flush with the top of the block.
BENCH MARK STAMPING: 3701 I 1998
DESIGNATION: 877 3701 I
MONUMENTATION: Tidal Station disk VM#: 17527
AGENCY: Conrad Blucher Institute (CBI) IDB PID:
SETTING CLASSIFICATION: Granite rock OPUS PID:
LATITUDE: 28° 26.7' N ( 28.44528) LONGITUDE: 96° 23.9' W ( -96.39872)
The bench mark is a disk set into a hole drilled into the top of a large granite
block which is a part of the Port O'Connor jetties, 329.00 m (1079.4 ft) ENE of
the west edge of the westernmost granite block in the north jetty on the second
block south from the north side of the jetty, 0.56 m (1.84 ft) south of the
north edge of the block, 0.38 m (1.25 ft) east of the west edge of the block,
and flush with the top of the block.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 3 of 6
Station ID: 8773701 PUBLICATION DATE: 04/27/2020
Name: PORT O'CONNOR, MATAGORDA BAY
TX
NOAA Chart: 11319 Latitude: 28° 26.8' N ( 28.44586)
USGS Quad: PORT O'CONNOR Longitude: 96° 23.7' W ( -96.39556)
T I D A L B E N C H M A R K S
BENCH MARK STAMPING: 3701 J 1998
DESIGNATION: 877 3701 J
MONUMENTATION: Tidal Station disk VM#: 17528
AGENCY: Conrad Blucher Institute (CBI) IDB PID:
SETTING CLASSIFICATION: Granite rock OPUS PID:
LATITUDE: 28° 26.7' N ( 28.44500) LONGITUDE: 96° 24.1' W ( -96.40094)
The bench mark is a brass survey disk set into a hole drilled into the top of a
large granite block which is part of the Port O'Connor jetties, 109 m (357.6 ft)
ENE of the west edge of the westernmost granite block in the north jetty on the
second block south from the north side of the jetty, 0.91 m (2.99 ft) south of
the north edge of the block, 0.68 m (2.23 ft) east of the west edge of the block
and flush with the top of the block.
BENCH MARK STAMPING: 3701 L 1998
DESIGNATION: 877 3701 L
MONUMENTATION: Tidal Station disk VM#: 17531
AGENCY: Conrad Blucher Institute (CBI) IDB PID:
SETTING CLASSIFICATION: Stainless steel rod OPUS PID:
LATITUDE: 28° 26.8' N ( 28.44625) LONGITUDE: 96° 24.2' W ( -96.40342)
The bench mark is a brass survey disk marked with an orange fiberglass witness
post and located on the NW corner of the intersection of Maple and Washington,
17.10 m (56.1 ft) ENE from the SE corner post of the residence located at 312
Maple, 17.10 m (56.1 ft) WSW from the centerline of Washington, 9.60 m (31.5 ft)
NNW from the centerline of Maple, and 0.49 m (1.6 ft) WSW from the street sign
marking Maple and Washington. The bench mark is crimped to a stainless steel rod
driven 15.2 m (49.9 ft), and encased in a 6-inch PVC pipe and concrete
kickblock.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 4 of 6
Station ID: 8773701 PUBLICATION DATE: 04/27/2020
Name: PORT O'CONNOR, MATAGORDA BAY
TX
NOAA Chart: 11319 Latitude: 28° 26.8' N ( 28.44586)
USGS Quad: PORT O'CONNOR Longitude: 96° 23.7' W ( -96.39556)
T I D A L B E N C H M A R K S
BENCH MARK STAMPING: 3701 M 1998
DESIGNATION: 877 3701 M
MONUMENTATION: Tidal Station disk VM#: 17533
AGENCY: Conrad Blucher Institute (CBI) IDB PID:
SETTING CLASSIFICATION: Stainless steel rod OPUS PID#: BBGF01
LATITUDE: 28° 26.9' N ( 28.44808) LONGITUDE: 96° 24.2' W ( -96.40408)
The bench mark is a brass survey disk marked with an orange figerglass witness
post and located in Port O Connor, TX on the SE corner of the intersection of
Main Street and Washington Street, 14.69 m (48.2 ft) ENE from the centerline of
Main Street, 14.30 m (46.9 ft) SSE from the centerline of Main Street, 5.21 m
(17.1 ft) WNW from the NW corner of the residence located on the SE corner of
the intersection, and 2.41 m (7.9 ft) NNW from the centerline of the concrete
sidewalk on the south side of Main Street. The bench mark is set 15 cm (0.49 ft)
below the surface of the ground, crimped to a stainless steel rod driven 13.7 m
(44.9 ft) into the ground, and encased in a 6-inch PVC pipe and concrete
kickblock.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 5 of 6
Station ID: 8773701 PUBLICATION DATE: 04/27/2020
Name: PORT O'CONNOR, MATAGORDA BAY
TX
NOAA Chart: 11319 Latitude: 28° 26.8' N ( 28.44586)
USGS Quad: PORT O'CONNOR Longitude: 96° 23.7' W ( -96.39556)
T I D A L D A T U M S
Tidal datums at PORT O'CONNOR, MATAGORDA BAY based on:
LENGTH OF SERIES: 3 YEARS
TIME PERIOD: 6/15-5/16, 10/16-9/18
TIDAL EPOCH: 2002-2006
CONTROL TIDE STATION: 8775792 PACKERY CHANNEL
Elevations of tidal datums referred to Mean Lower Low Water (MLLW), in METERS:
HIGHEST OBSERVED WATER LEVEL (08/26/2017) = 1.071
MEAN HIGHER HIGH WATER MHHW = 0.219
MEAN HIGH WATER MHW = 0.215
MEAN SEA LEVEL MSL = 0.122
MEAN TIDE LEVEL MTL = 0.110
MEAN LOW WATER MLW = 0.006
MEAN LOWER LOW WATER MLLW = 0.000
North American Vertical Datum NAVD88 = -0.117
LOWEST OBSERVED WATER LEVEL (01/20/2019) = -0.491
North American Vertical Datum (NAVD88)
Bench Mark Elevation Information In METERS above:
Stamping or Designation MLLW MHW
3701 K 1998 1.024 0.809
3701 H 1998 0.864 0.649
3701 I 1998 0.940 0.725
3701 J 1998 0.925 0.710
3701 L 1998 1.203 0.988
3701 M 1998 1.428 1.213
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 6 of 6
Station ID: 8773701 PUBLICATION DATE: 04/27/2020
Name: PORT O'CONNOR, MATAGORDA BAY
TX
NOAA Chart: 11319 Latitude: 28° 26.8' N ( 28.44586)
USGS Quad: PORT O'CONNOR Longitude: 96° 23.7' W ( -96.39556)
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.