U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Datums Page Page 1 of 5
Station ID: 8773146 PUBLICATION DATE: 01/07/2020
Name: MATAGORDA CITY
TX
NOAA Chart: 11319 Latitude: 28° 42.6' N ( 28.71006)
USGS Quad: MATAGORDA Longitude: 95° 54.8' W ( -95.91400)
Need boat to access station on ICWW. Head northeast on ICWW out of Matagorda
Harbor (189 County Rd 213, Matagorda, TX 77457) for approximately 2 miles, and
the station will be on the northwest bank. The benchmarks are located along the
south side of CR 213, between the shoulder of the road and the drainage ditch.
The station is a four pile wooden structure. For chartering a boat, contact
Captain Charlie Paradoski at 713-725-2401.
T I D A L B E N C H M A R K S
PRIMARY BENCH MARK STAMPING: 3146 B 2012
DESIGNATION: 877 3146 B
MONUMENTATION: Flange-encased Rod VM#: 20597
AGENCY: Conrad Blucher Institute (CBI) IDB PID#: DP0706
SETTING CLASSIFICATION: Stainless steel rod OPUS PID#: DP0706
LATITUDE: 28° 42.6' N ( 28.71056) LONGITUDE: 95° 54.9' W ( -95.91517)
The bench mark is a stainless steel deep rod mark located 64.62 m (212.0 ft)
east of historical marker, 26.71 m (87.6 ft) SW of a power pole, 9.60 m (31.5
ft) west of the fence line on the east side, and 5.64 m (18.5 ft) south of the
centerline of the street. The datum point is the top of a stainless steel rod
driven until refusal to a depth of 12.4 m and encased in a 6 inch (15 cm) PVC
pipe with a concrete kickblock.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 2 of 5
Station ID: 8773146 PUBLICATION DATE: 01/07/2020
Name: MATAGORDA CITY
TX
NOAA Chart: 11319 Latitude: 28° 42.6' N ( 28.71006)
USGS Quad: MATAGORDA Longitude: 95° 54.8' W ( -95.91400)
T I D A L B E N C H M A R K S
BENCH MARK STAMPING: 3146 A 2012
DESIGNATION: 877 3146 A
MONUMENTATION: Bench Mark disk VM#: 20596
AGENCY: Conrad Blucher Institute (CBI) IDB PID:
SETTING CLASSIFICATION: OPUS PID#: BBGD67
LATITUDE: 28° 42.6' N ( 28.71083) LONGITUDE: 95° 54.9' W ( -95.91422)
The bench mark is a brass survey disk set in the bridge at Matagorda City, TX.
The bench mark is located 3.35 m (11.0 ft) east of the centerline of the bridge,
1.52 m (5.0 ft) south of the north end of the concrete bridge, and 0.30 m (1.0
ft) west of the east edge of the bridge. The bench mark is set flush in the
bridge.
BENCH MARK STAMPING: 3146 C 2012
DESIGNATION: 877 3146 C
MONUMENTATION: Flange-encased Rod VM#: 20598
AGENCY: Conrad Blucher Institute (CBI) IDB PID:
SETTING CLASSIFICATION: OPUS PID:
LATITUDE: 28° 42.6' N ( 28.71028) LONGITUDE: 95° 55.0' W ( -95.91611)
The bench mark is a stainless steel deep rod mark located 31.10 m (102.0 ft)
east from the Battle Island historical marker, 26.60 m (87.3 ft) from power
pole, and 9.75 m (32.0 ft) to a private fence line bearing 335 degrees west of
an H brace in the fence line. The datum point is the top of a stainless steel
rod driven until refusal encased in a 6 inch (15 cm) PVC pipe with a concrete
kick block.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 3 of 5
Station ID: 8773146 PUBLICATION DATE: 01/07/2020
Name: MATAGORDA CITY
TX
NOAA Chart: 11319 Latitude: 28° 42.6' N ( 28.71006)
USGS Quad: MATAGORDA Longitude: 95° 54.8' W ( -95.91400)
T I D A L B E N C H M A R K S
BENCH MARK STAMPING: 3146 D 2012
DESIGNATION: 877 3146 D
MONUMENTATION: Flange-encased Rod VM#: 20599
AGENCY: Conrad Blucher Institute (CBI) IDB PID:
SETTING CLASSIFICATION: OPUS PID:
LATITUDE: 28° 42.6' N ( 28.70997) LONGITUDE: 95° 55.0' W ( -95.91706)
The bench mark is a stainless steel deep rod located 30.90 m (101.4 ft) bearing
212 degrees from the power pole, 8.80 m (28.9 ft) from the fence line, and 6.10
m (20.0 ft) SSE from the centerline of the road. The datum point is a stainless
steel rod driven until refusal and encased in a 6 inch (15 cm) PVC pipe with a
concrete kick block.
BENCH MARK STAMPING: 3146 E 2012
DESIGNATION: 877 3146 E
MONUMENTATION: Flange-encased Rod VM#: 20600
AGENCY: Conrad Blucher Institute (CBI) IDB PID:
SETTING CLASSIFICATION: OPUS PID:
LATITUDE: 28° 42.6' N ( 28.70969) LONGITUDE: 95° 55.1' W ( -95.91797)
The bench mark is a stainless steel rod located 91.74 m (301.0 ft) south of 3146
D 2012, 32.0 m (105.0 ft) from a power pole, 7.8 m (25.6 ft) to a private fence
and 6.40m (21.0 ft) SSE of hte centerline of the road. The datum point is the
top of a stainless steel rod driven until refusal encased in a 6 inch (15 cm)
PVC pipe with a concrete kick block.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 4 of 5
Station ID: 8773146 PUBLICATION DATE: 01/07/2020
Name: MATAGORDA CITY
TX
NOAA Chart: 11319 Latitude: 28° 42.6' N ( 28.71006)
USGS Quad: MATAGORDA Longitude: 95° 54.8' W ( -95.91400)
T I D A L D A T U M S
Tidal datums at MATAGORDA CITY based on:
LENGTH OF SERIES: 2 YEARS
TIME PERIOD: October 2016 - September 2018
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) = 1.047
MEAN HIGHER HIGH WATER MHHW = 0.124
MEAN HIGH WATER MHW = 0.121
MEAN SEA LEVEL MSL = 0.075
MEAN TIDE LEVEL MTL = 0.062
MEAN LOW WATER MLW = 0.003
MEAN LOWER LOW WATER MLLW = 0.000
North American Vertical Datum NAVD88 = -0.146
LOWEST OBSERVED WATER LEVEL (01/13/2018) = -0.361
North American Vertical Datum (NAVD88)
Bench Mark Elevation Information In METERS above:
Stamping or Designation MLLW MHW
3146 B 2012 0.574 0.453
3146 A 2012 1.515 1.394
3146 C 2012 0.606 0.485
3146 D 2012 0.575 0.454
3146 E 2012 0.597 0.476
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 5 of 5
Station ID: 8773146 PUBLICATION DATE: 01/07/2020
Name: MATAGORDA CITY
TX
NOAA Chart: 11319 Latitude: 28° 42.6' N ( 28.71006)
USGS Quad: MATAGORDA Longitude: 95° 54.8' W ( -95.91400)
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.