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Bench Mark Sheet for 8773963, NORTH MATAGORDA 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Superseded Epoch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Small blue map location marker Unpublished bench mark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: 8773963                         PUBLICATION DATE:  04/26/2008
Name:       NORTH MATAGORDA                                   
            TX
NOAA Chart: 11313                           Latitude:   28° 20.0' N (  28.33330)
USGS Quad:  PASS CAVALLO SW                 Longitude:  96° 27.7' W ( -96.46170)


To reach the tidal bench marks from Port O'Connor by boat, proceed SW down the
Intracoastal Waterway for 6.4 km (4.0 mi) to the ferry channel leading to
Matagorda Island and  follow the ferry channel to the landing dock at the
abandoned Matagorda Island Air Force Base. The tide station platform is NE of
the abandoned Matagorda Island Air Force Base landing dock.  The tidal bench
marks are located along the beach in the vicinity of the dock.


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


                 PRIMARY BENCH MARK STAMPING:  90023 A
                         DESIGNATION:          877 3963 A

MONUMENTATION:           Tidal Station disk                    VM#:        12347
AGENCY:                  Conrad Blucher Institute (CBI)        IDB PID#:  DP0713
SETTING CLASSIFICATION:  Stainless steel rod                   OPUS PID#: DP0713
LATITUDE:   28° 19.9' N (  28.33170)          LONGITUDE:  96° 27.5' W ( -96.45830)


The primary bench mark is a disk located on a small, grassy sand mound, 30 m
(100 ft) from the SE corner of the station platform, and 0.3 m (1 ft) from a 
0.06 m x 0.21 m (0.2 ft x 0.7 ft) stake.  The bench mark is set 6 cm (0.2 ft)
below ground level, crimped to the top of a stainless steel rod driven 16.7 m
(55 ft) to refusal, 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  5

                                                                                
Station ID: 8773963                         PUBLICATION DATE:  04/26/2008
Name:       NORTH MATAGORDA                                   
            TX
NOAA Chart: 11313                           Latitude:   28° 20.0' N (  28.33330)
USGS Quad:  PASS CAVALLO SW                 Longitude:  96° 27.7' W ( -96.46170)


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


                         BENCH MARK STAMPING:  90023 B
                         DESIGNATION:          877 3963 B

MONUMENTATION:           Tidal Station disk                    VM#:        12348
AGENCY:                  Conrad Blucher Institute (CBI)        IDB PID:         
SETTING CLASSIFICATION:  Stainless steel rod                   OPUS PID#: BBGJ97
LATITUDE:   28° 19.9' N (  28.33170)          LONGITUDE:  96° 27.5' W ( -96.45830)


The bench mark is a disk located SE of the station platform, and 80 m (262 ft)
SE from bench mark 90023 A.  The bench mark is set at ground level, crimped to
the top of a stainless steel rod driven 16.7 m (55 ft) to refusal, and encased
in a 6-inch PVC pipe and concrete kickblock.



                         BENCH MARK STAMPING:  90023 C
                         DESIGNATION:          877 3963 C

MONUMENTATION:           Tidal Station disk                    VM#:        12349
AGENCY:                  Conrad Blucher Institute (CBI)        IDB PID:         
SETTING CLASSIFICATION:  Stainless steel rod                   OPUS PID:        
LATITUDE:   28° 19.9' N (  28.33170)          LONGITUDE:  96° 27.4' W ( -96.45670)


The bench mark is a disk located on the north side of an asphalt road, and 140 m
(459 ft) SE from bench mark 90023 B, 23.60 m (77.4 ft) east of the east end of a
concrete culvert under an asphalt road, 10.10 m (33.1 ft) north of the
centerline of the asphalt road.  The bench mark is set at ground level, crimped
to the top of a stainless steel rod driven 16.7 m (55 ft) to refusal, 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  3 of  5

                                                                                
Station ID: 8773963                         PUBLICATION DATE:  04/26/2008
Name:       NORTH MATAGORDA                                   
            TX
NOAA Chart: 11313                           Latitude:   28° 20.0' N (  28.33330)
USGS Quad:  PASS CAVALLO SW                 Longitude:  96° 27.7' W ( -96.46170)


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


                         BENCH MARK STAMPING:  90023 D
                         DESIGNATION:          877 3963 D

MONUMENTATION:           Tidal Station disk                    VM#:        12350
AGENCY:                  Conrad Blucher Institute (CBI)        IDB PID:         
SETTING CLASSIFICATION:  Stainless steel rod                   OPUS PID:        
LATITUDE:   28° 20.0' N (  28.33330)          LONGITUDE:  96° 27.7' W ( -96.46170)


The bench mark is a disk  located on the north side of the asphalt road near a
road intersection, and 160 m (525 ft) NE 71  from bench mark 90023 C.  The bench
mark is crimped to top of a stainless steel rod driven 16.7 m (55 ft) to
refusal, and encased in a 6-inch PVC pipe and concrete kickblock.



                         BENCH MARK STAMPING:  90023 E
                         DESIGNATION:          877 3963 E

MONUMENTATION:           Tidal Station disk                    VM#:        12351
AGENCY:                  Conrad Blucher Institute (CBI)        IDB PID:         
SETTING CLASSIFICATION:  Stainless steel rod                   OPUS PID:        
LATITUDE:   28° 20.0' N (  28.33330)          LONGITUDE:  96° 27.7' W ( -96.46170)


The bench mark is a disk located on the east side of an asphalt road
intersection, and 3.40 m (11.2 ft) south of the centerline of the road. The
bench mark is set at ground level, crimped to the top of a 1/2-inch stainless
steel rod driven 16.7 m (55 ft) to refusal, 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  5

                                                                                
Station ID: 8773963                         PUBLICATION DATE:  04/26/2008
Name:       NORTH MATAGORDA                                   
            TX
NOAA Chart: 11313                           Latitude:   28° 20.0' N (  28.33330)
USGS Quad:  PASS CAVALLO SW                 Longitude:  96° 27.7' W ( -96.46170)


                            T I D A L   D A T U M S 


Tidal datums at NORTH MATAGORDA based on:

     LENGTH OF SERIES:      1 YEAR
     TIME PERIOD:           March 1993 - February 1994
     TIDAL EPOCH:           1983-2001
     CONTROL TIDE STATION:  8774770 ROCKPORT, ARANSAS BAY


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

     HIGHEST OBSERVED WATER LEVEL (06/20/1993)         =  0.534
     MEAN HIGHER HIGH WATER                     MHHW   =  0.131
     MEAN HIGH WATER                            MHW    =  0.130
     MEAN SEA LEVEL                             MSL    =  0.072
     MEAN TIDE LEVEL                            MTL    =  0.066
     MEAN LOW WATER                             MLW    =  0.002
     MEAN LOWER LOW WATER                       MLLW   =  0.000
     LOWEST  OBSERVED WATER LEVEL (01/05/1994)         = -0.542

North American Vertical Datum (NAVD88)

Bench Mark Elevation Information                In METERS above:

     Stamping or Designation                    MLLW        MHW

     90023 A                                     0.309    0.179
     90023 B                                     0.329    0.199
     90023 C                                     0.785    0.655
     90023 D                                     1.053    0.923
     90023 E                                     1.198    1.068


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

                                                                                
Station ID: 8773963                         PUBLICATION DATE:  04/26/2008
Name:       NORTH MATAGORDA                                   
            TX
NOAA Chart: 11313                           Latitude:   28° 20.0' N (  28.33330)
USGS Quad:  PASS CAVALLO SW                 Longitude:  96° 27.7' W ( -96.46170)


                             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 8773963 NORTH MATAGORDA, TX

Revised: 08/08/2018
NOAA / National Ocean Service
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