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Bench Mark Sheet for 8773767, Matagorda Bay Entrance Channel, TX TX

Superseded Epoch

Large map location marker Station Location
Small red map location marker Published bench mark
Small blue map location marker Unpublished bench mark

Bench mark positions only appear on the map if their coordinates in the CO-OPS database are at the precision of degrees/minutes/seconds/and tenths of seconds. If the coordinates are less precise, the mark will not appear.

Printable version

                          U.S. DEPARTMENT OF COMMERCE
                National Oceanic and Atmospheric Administration
                            National Ocean Service
Datums Page                                                        Page  1 of  5

                                                                                
Station ID: 8773767                         PUBLICATION DATE:  12/12/2018
Name:       MATAGORDA BAY ENTRANCE CHANNEL, MATAGORD          
            TX
NOAA Chart: 11319                           Latitude:   28° 25.6' N (  28.42690)
USGS Quad:  DECROS POINT                    Longitude:  96° 19.8' W ( -96.33010)


To reach the tidal bench marks from the boat launch facilities at the end of
Byers Drive in Port O'Connor TX, proceed by boat east down the canal out of Port
O'Connor 9.7 km (5.0 miles) and then proceed SE in the Matagorda Ship Channel
for 4.2 km (2.6 miles).  The bench marks are located on the shore to the SW and
parallel along a dirt road heading NW on Matagorda Island.  The tide gauge is
located on a single pile instrumentation platform just west of the shipping
channel in the pass.


                         T I D A L   B E N C H   M A R K S


                 PRIMARY BENCH MARK STAMPING:  3767 A 2016
                         DESIGNATION:          877 3767 A

MONUMENTATION:           Metal Rod                             VM#:        21980
AGENCY:                  National Ocean Service (NOS)          IDB PID:         
SETTING CLASSIFICATION:  Flange encased rod                    OPUS PID:        
LATITUDE:   28° 25.6' N (  28.42669)          LONGITUDE:  96° 19.8' W ( -96.33083)


The bench mark is located 70.50 m (231.3 ft) NE of bench mark 877 3767 B, 4.51 m
(14.8 ft) east of the centerline of a gravel road running north to south along
the island, and 0.91 m (3.0 ft) SW of a witness post.  The datum point is set is
set flush with the ground, being the top of a stainless steel rod driven 7.3 m
(24 ft) to refusal, in a sleeve depth of 0.9 m (3 ft) and encased in a 5-inch
NOS logo cap.

                          U.S. DEPARTMENT OF COMMERCE
                National Oceanic and Atmospheric Administration
                            National Ocean Service
                                                                   Page  2 of  5

                                                                                
Station ID: 8773767                         PUBLICATION DATE:  12/12/2018
Name:       MATAGORDA BAY ENTRANCE CHANNEL, MATAGORD          
            TX
NOAA Chart: 11319                           Latitude:   28° 25.6' N (  28.42690)
USGS Quad:  DECROS POINT                    Longitude:  96° 19.8' W ( -96.33010)


                         T I D A L   B E N C H   M A R K S


                         BENCH MARK STAMPING:  3767 B 2016
                         DESIGNATION:          877 3767 B

MONUMENTATION:           Metal Rod                             VM#:        21981
AGENCY:                  National Ocean Service (NOS)          IDB PID:         
SETTING CLASSIFICATION:  Flange encased rod                    OPUS PID#: BBFG26
LATITUDE:   28° 25.6' N (  28.42667)          LONGITUDE:  96° 19.9' W ( -96.33156)


The bench mark is located 81.50 m (267.4 ft) south of bench mark 877 3767 C,
4.40 m (14.4 ft) NE of the centerline of the gravel road running north to south
along the island, and 3.40 m (11.2 ft) south of a witness post. The datum point
is set is set flush with the ground, being the top of a stainless steel rod
driven 19.5 m (64 ft) to refusal, in a sleeve depth of 0.9 m (3 ft) and encased
in a 5-inch NOS logo cap.



                         BENCH MARK STAMPING:  3767 C 2016
                         DESIGNATION:          877 3767 C

MONUMENTATION:           Metal Rod                             VM#:        21982
AGENCY:                  National Ocean Service (NOS)          IDB PID:         
SETTING CLASSIFICATION:  Flange encased rod                    OPUS PID:        
LATITUDE:   28° 25.6' N (  28.42722)          LONGITUDE:  96° 19.9' W ( -96.33206)


The bench mark is located 78 m (255.9 ft) south of bench mark 877 3767 E, 5.50 m
(18.0 ft) east of the centerline of the gravel road running north to south on
the island, and 0.70 m (2.3 ft) SW of a witness post. The datum point is set is
set flush with the ground, being the top of a stainless steel rod driven 17.4 m
(57 ft) to refusal, in a sleeve depth of 0.9 m (3 ft) and encased in a 5-inch
NOS logo cap.

                          U.S. DEPARTMENT OF COMMERCE
                National Oceanic and Atmospheric Administration
                            National Ocean Service
                                                                   Page  3 of  5

                                                                                
Station ID: 8773767                         PUBLICATION DATE:  12/12/2018
Name:       MATAGORDA BAY ENTRANCE CHANNEL, MATAGORD          
            TX
NOAA Chart: 11319                           Latitude:   28° 25.6' N (  28.42690)
USGS Quad:  DECROS POINT                    Longitude:  96° 19.8' W ( -96.33010)


                         T I D A L   B E N C H   M A R K S


                         BENCH MARK STAMPING:  3767 D 2016
                         DESIGNATION:          877 3767 D

MONUMENTATION:           Metal Rod                             VM#:        21983
AGENCY:                  National Ocean Service (NOS)          IDB PID:         
SETTING CLASSIFICATION:  Flange encased rod                    OPUS PID:        
LATITUDE:   28° 25.7' N (  28.42836)          LONGITUDE:  96° 20.0' W ( -96.33311)


The bench mark is 80 m (262.5 ft) NW of bench mark 877 3767 E, 75.20 m (246.7
ft) SW of the western edge of a rock jetty at the shoreline, 5.80 m (19.0 ft) NE
of the centerline of the gravel road running north to south on the island, and 3
m (9.8 ft) SW of a witness post. The datum point is set is set flush with the
ground, being the top of a stainless steel rod driven 19.2 m (63 ft) to refusal,
in a sleeve depth of 0.9 m (3 ft) and encased in a 5-inch NOS logo cap.



                         BENCH MARK STAMPING:  3767 E 2016
                         DESIGNATION:          877 3767 E

MONUMENTATION:           Metal Rod                             VM#:        21984
AGENCY:                  National Ocean Service (NOS)          IDB PID:         
SETTING CLASSIFICATION:  Flange encased rod                    OPUS PID:        
LATITUDE:   28° 25.7' N (  28.42778)          LONGITUDE:  96° 20.0' W ( -96.33264)


The bench mark is located 78.0 m (255.9 ft) south of bench mark 877 3767 C, 5.50
m (18.0 ft) NE of the centerline of the gravel road running north to south on
the island, and 3.30 m (10.8 ft) SW of a witness post. The datum point is set is
set flush with the ground, being the top of a stainless steel rod driven 17.7 m
(58 ft) to refusal, in a sleeve depth of 0.9 m (3 ft) and encased in a 5-inch
NOS logo cap.

                          U.S. DEPARTMENT OF COMMERCE
                National Oceanic and Atmospheric Administration
                            National Ocean Service
                                                                   Page  4 of  5

                                                                                
Station ID: 8773767                         PUBLICATION DATE:  12/12/2018
Name:       MATAGORDA BAY ENTRANCE CHANNEL, MATAGORD          
            TX
NOAA Chart: 11319                           Latitude:   28° 25.6' N (  28.42690)
USGS Quad:  DECROS POINT                    Longitude:  96° 19.8' W ( -96.33010)


                            T I D A L   D A T U M S 


Tidal datums at MATAGORDA BAY ENTRANCE CHANNEL, MATAGORD based on:

     LENGTH OF SERIES:      1 YEAR
     TIME PERIOD:           July 2016 - June 2017
     TIDAL EPOCH:           1983-2001
     CONTROL TIDE STATION:  8775870 BOB HALL PIER, CORPUS CHRISTI


Elevations of tidal datums referred to Mean Lower Low Water (MLLW), in METERS:

     HIGHEST OBSERVED WATER LEVEL (10/08/2017)         =  1.030
     MEAN HIGHER HIGH WATER                     MHHW   =  0.375
     MEAN HIGH WATER                            MHW    =  0.365
     MEAN SEA LEVEL                             MSL    =  0.224
     MEAN TIDE LEVEL                            MTL    =  0.199
     MEAN LOW WATER                             MLW    =  0.034
     MEAN LOWER LOW WATER                       MLLW   =  0.000
     LOWEST  OBSERVED WATER LEVEL (01/12/2018)         = -0.418

North American Vertical Datum (NAVD88)

Bench Mark Elevation Information                In METERS above:

     Stamping or Designation                    MLLW        MHW

     3767 A 2016                                 2.262    1.897
     3767 B 2016                                 2.066    1.701
     3767 C 2016                                 2.196    1.831
     3767 D 2016                                 2.108    1.743
     3767 E 2016                                 2.136    1.771


                          U.S. DEPARTMENT OF COMMERCE
                National Oceanic and Atmospheric Administration
                            National Ocean Service
                                                                   Page  5 of  5

                                                                                
Station ID: 8773767                         PUBLICATION DATE:  12/12/2018
Name:       MATAGORDA BAY ENTRANCE CHANNEL, MATAGORD          
            TX
NOAA Chart: 11319                           Latitude:   28° 25.6' N (  28.42690)
USGS Quad:  DECROS POINT                    Longitude:  96° 19.8' W ( -96.33010)


                             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.

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Products available at 8773767 Matagorda Bay Entrance Channel, TX, TX

Revised: 08/08/2018
NOAA / National Ocean Service
Web site owner: Center for Operational Oceanographic Products and Services