U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Datums Page Page 1 of 6
Station ID: 8770931 PUBLICATION DATE: 07/16/2021
Name: SMITH POINT, GALVESTON BAY
TX
NOAA Chart: 11326 Latitude: 29° 32.1' N ( 29.53500)
USGS Quad: SMITH POINT Longitude: 94° 46.9' W ( -94.78170)
To reach from the intersection of Texas Highway 124 and Farm to Market Road 1985
(FM 1985 - Whites Ranch Road) north of High Island, Texas, proceed westerly 14.7
mi (23.7 km) on FM 1985 to Farm to Market Road 562 (FM 562 Smith Point Road),
stay left and continue on FM 562 15.1 mi (24.3 km) to Hawkins Camp Road. turn
right onto Hawkins Camp Road and proceed northwesterly 1.3 mi (2.1 km) to an
intersection, stay right and continue on Old Dutchman Road 0.3 mi (0.5 km) to RV
Park Spoonbill. Proceed north 200 ft (61.0 m) along the west edge of the RV
park to a peninsula between the Trinity River channel and a small boat basin
then proceed west along the peninsula to the east edge of a 90 x 160 ft channel.
The bench marks are located along the southern shore of the channel and within
the park. The tide gauge was located at the western tip of the peninsula.
T I D A L B E N C H M A R K S
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 2 of 6
Station ID: 8770931 PUBLICATION DATE: 07/16/2021
Name: SMITH POINT, GALVESTON BAY
TX
NOAA Chart: 11326 Latitude: 29° 32.1' N ( 29.53500)
USGS Quad: SMITH POINT Longitude: 94° 46.9' W ( -94.78170)
T I D A L B E N C H M A R K S
PRIMARY BENCH MARK STAMPING: 0931 G 2019
DESIGNATION: 877 0931 G
ALIAS: 0907 G 2019
MONUMENTATION: Flange-encased Rod VM#: 23395
AGENCY: National Ocean Service (NOS) IDB PID:
SETTING CLASSIFICATION: Stainless steel rod in sleeve OPUS PID#: BBGR58
LATITUDE: 29° 32.8' N ( 29.54644) LONGITUDE: 94° 47.0' W ( -94.78339)
The primary bench mark is a flange encased rod set in the grass to the west of
an RV park, 42.05 m (138.0 ft) west of a 4x4 metal no wake sign, 16.00 m (52.5
ft) SSE of the corner of a seawall at the channel that leads into a boat basin
from the trinity river channel, 15.20 m (49.9 ft) SW of the last piling of the
seawall along the Trinity River channel, 7.64 m (25.1 ft) east of a channel that
is between a boat basin and the Trinity River channel and 0.45 m (1.5 ft) south
of a carsonite post. The datum point is 3 cm (1 inch) below ground, being the
top of a stainless steel rod driven 18.3 m (60.0 ft) to refusal and encased in a
7.25-inch (18 cm) NOS logo cap and concrete kick block.
BENCH MARK STAMPING: 0907 B 2012
DESIGNATION: 877 0907 B
MONUMENTATION: Tidal Station disk VM#: 23396
AGENCY: Conrad Blucher Institute (CBI) IDB PID:
SETTING CLASSIFICATION: Concrete pad OPUS PID#: BBGR59
LATITUDE: 29° 32.8' N ( 29.54608) LONGITUDE: 94° 46.8' W ( -94.78011)
The bench mark is a disk set in a concrete slab to the east of an RV park, 57.0
m (187.0 ft) north of a light pole, 18.50 m (60.7 ft) NW of a palm tree, 15.92 m
(52.2 ft) NNE of the NE corner of a trailer home, 15.88 m (52.1 ft) SSW of the
SE steel beam for a pavilion and 8.92 m (29.3 ft) SSE of the SW steel beam for a
pavilion.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 3 of 6
Station ID: 8770931 PUBLICATION DATE: 07/16/2021
Name: SMITH POINT, GALVESTON BAY
TX
NOAA Chart: 11326 Latitude: 29° 32.1' N ( 29.53500)
USGS Quad: SMITH POINT Longitude: 94° 46.9' W ( -94.78170)
T I D A L B E N C H M A R K S
BENCH MARK STAMPING: 0931 F 2019
DESIGNATION: 877 0931 F
MONUMENTATION: Flange-encased Rod VM#: 23397
AGENCY: National Ocean Service (NOS) IDB PID:
SETTING CLASSIFICATION: Stainless steel rod in sleeve OPUS PID:
LATITUDE: 29° 32.8' N ( 29.54622) LONGITUDE: 94° 46.9' W ( -94.78231)
The bench mark is a flange encased rod set in the grass to the west of an RV
park, 52.50 m (172.2 ft) WSW of the western end of a seawall at the RV park,
46.13 m (151.3 ft) NNE of a tall pile at the end of a seawall that is near the
SE corner of a boat basin, 31.40 m (103.0 ft) west of the centerline of a Gravel
Road, 6.65 m (21.8 ft) east of the NE corner of a seawall, 5.26 m (17.3 ft) NNE
of northernmost pile of three piles that support the roof of a pavilion and 0.40
m (1.3 ft) south of a carsonite post. The datum point is 3 cm (1 inch) below
the ground, being the top of a stainless steel rod driven 25 m (82.0 ft) to
refusal and encased in a 7.25-in (18 cm) NOS logo cap and concrete kick block.
BENCH MARK STAMPING: 0907 C 2012
DESIGNATION: 877 0907 C
MONUMENTATION: Flange-encased Rod VM#: 23398
AGENCY: Conrad Blucher Institute (CBI) IDB PID#: DO9989
SETTING CLASSIFICATION: Stainless steel rod OPUS PID#: DO9989
LATITUDE: 29° 32.7' N ( 29.54547) LONGITUDE: 94° 46.7' W ( -94.77911)
The bench mark is a rod set in the grass to the east of an RV park, 108.0 m
(354.3 ft) SE of the SW steel beam for a pavilion, 100 m (328.1 ft) ENE of a
power pole with a single transformer, 91.47 m (300.1 ft) east of a light pole,
52.42 m (172.0 ft) SSE of a palm tree and 0.40 m (1.3 ft) NW of a carsonite
post. The datum point is 10 cm (4 inches) below ground, being the top of a
stainless steel rod driven 28 m (91.9 ft) to refusal encased in an aluminum
cover and concrete kick block.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 4 of 6
Station ID: 8770931 PUBLICATION DATE: 07/16/2021
Name: SMITH POINT, GALVESTON BAY
TX
NOAA Chart: 11326 Latitude: 29° 32.1' N ( 29.53500)
USGS Quad: SMITH POINT Longitude: 94° 46.9' W ( -94.78170)
T I D A L B E N C H M A R K S
BENCH MARK STAMPING: 0931 H 2019
DESIGNATION: 877 0931 H
MONUMENTATION: Flange-encased Rod VM#: 23399
AGENCY: National Ocean Service (NOS) IDB PID:
SETTING CLASSIFICATION: Stainless steel rod in sleeve OPUS PID:
LATITUDE: 29° 32.7' N ( 29.54547) LONGITUDE: 94° 46.9' W ( -94.78219)
The bench mark is a flange encased rod set in the grass to the south of an RV
park, 48.7 m (159.8 ft) SW of a utility box at a pad in the RV park, 44.70 m
(146.7 ft) SE of a tall piling for a seawall at the SE corner a boat basin,
34.15 m (112.0 ft) SSW of a 'Y' in the road, 22.23 m (72.9 ft) east of a power
pole, 12.00 m (39.4 ft) ENE of the centerline of a road, 6.62 m (21.7 ft) SSW of
a palm tree to the east of a gravel road and 0.32 m (1.0 ft) south of a
carsonite post. The datum point is 4 cm (2 inches) below the ground, being the
stop of a stainless steel rod driven 23.8 m (78.1 ft) to refusal and encased in
a 7.25-inch (18 cm) NOS logo cap with concrete kick block.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 5 of 6
Station ID: 8770931 PUBLICATION DATE: 07/16/2021
Name: SMITH POINT, GALVESTON BAY
TX
NOAA Chart: 11326 Latitude: 29° 32.1' N ( 29.53500)
USGS Quad: SMITH POINT Longitude: 94° 46.9' W ( -94.78170)
T I D A L D A T U M S
Tidal datums at SMITH POINT, GALVESTON BAY based on:
LENGTH OF SERIES: 6 MONTHS
TIME PERIOD: December 2019 - May 2020
TIDAL EPOCH: 1983-2001
CONTROL TIDE STATION: 8771013 EAGLE POINT, GALVESTON BAY
Elevations of tidal datums referred to Mean Lower Low Water (MLLW), in METERS:
MEAN HIGHER HIGH WATER MHHW = 0.388
MEAN HIGH WATER MHW = 0.367
MEAN SEA LEVEL MSL = 0.211
MEAN TIDE LEVEL MTL = 0.199
North American Vertical Datum NAVD88 = 0.038
MEAN LOW WATER MLW = 0.031
MEAN LOWER LOW WATER MLLW = 0.000
North American Vertical Datum (NAVD88)
Bench Mark Elevation Information In METERS above:
Stamping or Designation MLLW MHW
0931 G 2019 1.207 0.840
0907 B 2012 1.555 1.188
0931 F 2019 1.269 0.902
0907 C 2012 1.519 1.152
0931 H 2019 0.995 0.628
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 6 of 6
Station ID: 8770931 PUBLICATION DATE: 07/16/2021
Name: SMITH POINT, GALVESTON BAY
TX
NOAA Chart: 11326 Latitude: 29° 32.1' N ( 29.53500)
USGS Quad: SMITH POINT Longitude: 94° 46.9' W ( -94.78170)
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.