U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Datums Page Page 1 of 4
Station ID: 8771341 PUBLICATION DATE: 04/29/2020
Name: GALVESTON BAY ENTRANCE, NORTH JETTY
TX
NOAA Chart: 11324 Latitude: 29° 21.4' N ( 29.35730)
USGS Quad: GALVESTON Longitude: 94° 43.5' W ( -94.72480)
To reach the tide gage from Galveston Island launch vessel at Galveston Marina
via boat, proceed WNW in the Galveston Channel to the Houston Ship Channel, then
to Starboard (right). The tide gage is located 0.8 km (0.4 nm) south of the
ferry landing at Port Bolivar, 48.3 km (26.1 nm) SE of the North Jetty.
T I D A L B E N C H M A R K S
PRIMARY BENCH MARK STAMPING: 1341 J 2006
DESIGNATION: 877 1341 J
MONUMENTATION: Metal Rod VM#: 18805
AGENCY: Texas Coastal Ocean Observation NetworkIDB PID#: DO9995
SETTING CLASSIFICATION: Stainless steel rod in sleeve OPUS PID#: DO9995
LATITUDE: 29° 22.2' N ( 29.37069) LONGITUDE: 94° 45.2' W ( -94.75356)
The primary bench mark is a disk located on the west corner of the intersection
of 15th Street and Front Avenue, located 3.7 m (12.00 ft) SE of a telephone
cable box, 15 cm (6 in) SE of a fiberglass witness post. The bench mark is set
flush with the ground, crimped to a stainless steel rod driven 19.5 m (64 ft) to
refusal, in a sleeve extending to an unspecified depth.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 2 of 4
Station ID: 8771341 PUBLICATION DATE: 04/29/2020
Name: GALVESTON BAY ENTRANCE, NORTH JETTY
TX
NOAA Chart: 11324 Latitude: 29° 21.4' N ( 29.35730)
USGS Quad: GALVESTON Longitude: 94° 43.5' W ( -94.72480)
T I D A L B E N C H M A R K S
BENCH MARK STAMPING: 1341 G 2006
DESIGNATION: 877 1341 G
MONUMENTATION: Bench Mark disk VM#: 18803
AGENCY: Texas Coastal Ocean Observation NetworkIDB PID:
SETTING CLASSIFICATION: Stainless stee rod in sleeve OPUS PID#: BBGC99
LATITUDE: 29° 22.3' N ( 29.37111) LONGITUDE: 94° 45.1' W ( -94.75111)
The bench mark is a disk located on the south corner of the intersection of 17th
Street and Galveston Avenue, 32 m (105.0 ft) from power pole 2-56 and phone box
410 on the north corner of the intersection, 13.2 m (43.3 ft) from the center of
the intersection and 9 m (29.5 ft) from the center of Galveston Avenue. The
bench mark is set flush with the ground, crimped to a stainless steel rod driven
21 m (69 ft) to refusal, in a sleeve extending to an unspecified depth.
BENCH MARK STAMPING: 1341 H 2006
DESIGNATION: 877 1341 H
MONUMENTATION: Bench Mark disk VM#: 18804
AGENCY: Conrad Blucher Institute IDB PID:
SETTING CLASSIFICATION: Stainless steel rod in sleeve OPUS PID:
LATITUDE: 29° 22.2' N ( 29.37056) LONGITUDE: 94° 45.1' W ( -94.75167)
The bench mark is a disk located on the east corner of the intersection of 16th
Street and Galveston Avenue, 14 m (45.9 ft) from the center of 16th Sreet and
11.40 m (37.4 ft) from the center of Galveston Avenue. The bench mark is
attached to the top of a steel rod driven 19.5 m (64 ft) into the ground. The
bench mark is set flush with the ground, crimped to a stainless steel rod driven
19.5 m (64 ft) to refusal, in a sleeve extending to an unspecified depth .
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 3 of 4
Station ID: 8771341 PUBLICATION DATE: 04/29/2020
Name: GALVESTON BAY ENTRANCE, NORTH JETTY
TX
NOAA Chart: 11324 Latitude: 29° 21.4' N ( 29.35730)
USGS Quad: GALVESTON Longitude: 94° 43.5' W ( -94.72480)
T I D A L D A T U M S
Tidal datums at GALVESTON BAY ENTRANCE, NORTH JETTY based on:
LENGTH OF SERIES: 7 YEARS
TIME PERIOD: 5/11-4/13, 4/14-3/19
TIDAL EPOCH: 1983-2001
CONTROL TIDE STATION: 8771450 GALVESTON PIER 21, GALVESTON CHANNEL
Elevations of tidal datums referred to Mean Lower Low Water (MLLW), in METERS:
HIGHEST OBSERVED WATER LEVEL (07/15/2003) = 1.759
MEAN HIGHER HIGH WATER MHHW = 0.509
MEAN HIGH WATER MHW = 0.474
MEAN SEA LEVEL MSL = 0.297
MEAN TIDE LEVEL MTL = 0.296
North American Vertical Datum NAVD88 = 0.171
MEAN LOW WATER MLW = 0.118
MEAN LOWER LOW WATER MLLW = 0.000
LOWEST OBSERVED WATER LEVEL (12/23/2007) = -0.835
North American Vertical Datum (NAVD88)
Bench Mark Elevation Information In METERS above:
Stamping or Designation MLLW MHW
1341 J 2006 1.239 0.765
1341 G 2006 1.266 0.792
1341 H 2006 1.330 0.856
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 4 of 4
Station ID: 8771341 PUBLICATION DATE: 04/29/2020
Name: GALVESTON BAY ENTRANCE, NORTH JETTY
TX
NOAA Chart: 11324 Latitude: 29° 21.4' N ( 29.35730)
USGS Quad: GALVESTON Longitude: 94° 43.5' W ( -94.72480)
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.