U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Datums Page Page 1 of 6
Station ID: 8774230 PUBLICATION DATE: 10/01/2020
Name: ARANSAS WILDLIFE REFUGE, SAN ANTONIO BAY
TX
NOAA Chart: 11315 Latitude: 28° 13.7' N ( 28.22830)
USGS Quad: MESQUITE BAY Longitude: 96° 47.7' W ( -96.79500)
To reach the station from Main Street in Austwell, travel 0.43 km (0.27 mi) SE
to FM 774, proceed south on FM 774 for 1.16 km (0.72 mi) to FM 2040, turn left
and travel south on FM 2040 for 10.27 km (6.38 mi) to the entrance of the
Aransas Wildlife Refuge. From the check in office follow Park Road 13.11 km
(8.15 mi) to the facility boat ramp. The station is located at the end of the
canal leading to the ICWW. The bench marks are located on both sides of the
canal.
T I D A L B E N C H M A R K S
PRIMARY BENCH MARK STAMPING: 4230 B 2012
DESIGNATION: 877 4230 B
MONUMENTATION: Flange-encased Rod VM#: 20708
AGENCY: Conrad Blucher Institute (CBI) IDB PID#:
SETTING CLASSIFICATION: OPUS PID:
LATITUDE: 28° 13.8' N ( 28.22953) LONGITUDE: 96° 47.8' W ( -96.79711)
The bench mark is a flange encased rod located 95.58 m (313.5 ft) north of 877
4230 A, 88.20 m (289.3 ft) SE of bench mark 877 4230 C, 6.90 m (22.8 ft) NE of
the NE side of the channel. The datum point is the top of a stainless steel rod
driven 18.3m to refusal and encased in a 6 inch PVC pipe with concrete
kickblock.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 2 of 6
Station ID: 8774230 PUBLICATION DATE: 10/01/2020
Name: ARANSAS WILDLIFE REFUGE, SAN ANTONIO BAY
TX
NOAA Chart: 11315 Latitude: 28° 13.7' N ( 28.22830)
USGS Quad: MESQUITE BAY Longitude: 96° 47.7' W ( -96.79500)
T I D A L B E N C H M A R K S
BENCH MARK STAMPING: 4230 A 2012
DESIGNATION: 877 4230 A
MONUMENTATION: Flange-encased Rod VM#: 20707
AGENCY: Conrad Blucher Institute (CBI) IDB PID:
SETTING CLASSIFICATION: OPUS PID:
LATITUDE: 28° 13.7' N ( 28.22867) LONGITUDE: 96° 47.8' W ( -96.79708)
The bench mark is a flange-encased rod located 95.58 m (313.5 ft) south of 877
4230 B, 4.24 m (13.9 ft) SW of the SW side of the channel. The datum point is
the top of a stainless steel rod driven 18.30m (60.0 ft) to refusal and encased
in a 6 inch PVC pipe with concrete kickblock.
BENCH MARK STAMPING: 4230 C 2012
DESIGNATION: 877 4230 C
MONUMENTATION: Flange-encased Rod VM#: 20709
AGENCY: Conrad Blucher Institute (CBI) IDB PID:
SETTING CLASSIFICATION: OPUS PID:
LATITUDE: 28° 13.8' N ( 28.23017) LONGITUDE: 96° 47.9' W ( -96.79764)
The bench mark is a flange encased rod located 93.13 (305.5 ft) SE of 877 4230
D, 88.20 m (289.3 ft) NW of bench mark 877 4230 B, 6.10 m (20.02 ft) NE of the
NE side of the channel. The datum point is the top of a stainless steel rod
driven 18.30m (60.0 ft) to refusal and encased in a 6 inch PVC pipe with
concrete kickblock.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 3 of 6
Station ID: 8774230 PUBLICATION DATE: 10/01/2020
Name: ARANSAS WILDLIFE REFUGE, SAN ANTONIO BAY
TX
NOAA Chart: 11315 Latitude: 28° 13.7' N ( 28.22830)
USGS Quad: MESQUITE BAY Longitude: 96° 47.7' W ( -96.79500)
T I D A L B E N C H M A R K S
BENCH MARK STAMPING: 4230 D 2012
DESIGNATION: 877 4230 D
MONUMENTATION: Flange-encased Rod VM#: 20710
AGENCY: Conrad Blucher Institute (CBI) IDB PID:
SETTING CLASSIFICATION: OPUS PID:
LATITUDE: 28° 13.9' N ( 28.23089) LONGITUDE: 96° 47.9' W ( -96.79814)
The bench mark is a flange encased rod located 93.70 m (307.5 ft) NE of Bench
mark 877 4230 C, 82.02 m (269.1 ft) SE of 877 4230 E, 11.70 m (38.4 ft) NE of
the NE side of the channel. The datum point is the top of stainless steel rod
driven 18.30 m (60.0 ft) to refusal and encased in a 6 inch PVC pipe with
concrete kickblock.
BENCH MARK STAMPING: 4230 E 2012
DESIGNATION: 877 4230 E
MONUMENTATION: Flange-encased Rod VM#: 20711
AGENCY: Conrad Blucher Institute (CBI) IDB PID:
SETTING CLASSIFICATION: OPUS PID#: BBGF02
LATITUDE: 28° 13.9' N ( 28.23144) LONGITUDE: 96° 47.9' W ( -96.79869)
The bench mark is a flange encased rod located 105.7 m (346.9 ft) SE of bench
mark 90028 B, 82.02 m (269.1 ft) NW of 877 4230 D, 15.00 m (50.3 ft) NE of the
SE corner of boat barn. The datum point is the top of a stainless steel rod
driven 18.30 m (60.0 ft) to refusal and encased in a 6 inch PVC pipe with
concrete kickblock.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 4 of 6
Station ID: 8774230 PUBLICATION DATE: 10/01/2020
Name: ARANSAS WILDLIFE REFUGE, SAN ANTONIO BAY
TX
NOAA Chart: 11315 Latitude: 28° 13.7' N ( 28.22830)
USGS Quad: MESQUITE BAY Longitude: 96° 47.7' W ( -96.79500)
T I D A L B E N C H M A R K S
BENCH MARK STAMPING: B 1992
DESIGNATION: 877 90038 B
MONUMENTATION: Survey disk VM#: 20712
AGENCY: CBI IDB PID#: DP0714
SETTING CLASSIFICATION: OPUS PID#: DP0714
LATITUDE: 28° 13.9' N ( 28.23228) LONGITUDE: 96° 48.0' W ( -96.79922)
The bench mark is a survey disk at the end of the channel leading from the
Aransass Wildlife Refuse, 105.9 m (347.4 ft) NW of benchmark 877 4230 E, 43.90m
(144.0 ft) North of the fork in the road leading to the boat ramp, and 4.54m
(14.9 ft) West from the centerline of the service road. The disk is crimped to
the top of a stainless steel rod driven 18.30m (60.0 ft) to refusal.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 5 of 6
Station ID: 8774230 PUBLICATION DATE: 10/01/2020
Name: ARANSAS WILDLIFE REFUGE, SAN ANTONIO BAY
TX
NOAA Chart: 11315 Latitude: 28° 13.7' N ( 28.22830)
USGS Quad: MESQUITE BAY Longitude: 96° 47.7' W ( -96.79500)
T I D A L D A T U M S
Tidal datums at ARANSAS WILDLIFE REFUGE, SAN ANTONIO BAY based on:
LENGTH OF SERIES: 3 YEARS
TIME PERIOD: January 2016 - December 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) = 1.567
MEAN HIGHER HIGH WATER MHHW = 0.101
MEAN HIGH WATER MHW = 0.100
MEAN SEA LEVEL MSL = 0.051
MEAN TIDE LEVEL MTL = 0.050
MEAN LOWER LOW WATER MLLW = 0.000
MEAN LOW WATER MLW = 0.000
North American Vertical Datum NAVD88 = -0.290
LOWEST OBSERVED WATER LEVEL (02/11/2016) = -0.335
North American Vertical Datum (NAVD88)
Bench Mark Elevation Information In METERS above:
Stamping or Designation MLLW MHW
4230 B 2012 1.175 1.075
4230 A 2012 0.239 0.139
4230 C 2012 1.068 0.968
4230 D 2012 0.827 0.727
4230 E 2012 0.927 0.827
B 1992 0.896 0.796
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 6 of 6
Station ID: 8774230 PUBLICATION DATE: 10/01/2020
Name: ARANSAS WILDLIFE REFUGE, SAN ANTONIO BAY
TX
NOAA Chart: 11315 Latitude: 28° 13.7' N ( 28.22830)
USGS Quad: MESQUITE BAY Longitude: 96° 47.7' W ( -96.79500)
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.