U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Datums Page Page 1 of 6
Station ID: 8779977 PUBLICATION DATE: 01/23/2004
Name: PORT OF BROWNSVILLE
TX
NOAA Chart: 11302 Latitude: 25° 57.1' N ( 25.95170)
USGS Quad: EAST BROWNSVILLE Longitude: 97° 24.1' W ( -97.40170)
To reach the tidal bench marks from the intersection of US Highway 77 and Farm
Road 511 in Brownsville, proceed east on Road 511 South for 14.3 km (8.9 mi) to
the stop sign at Highway 48, then turn left through the gate at the Port of
Brownsville for 0.8 km (0.5 mi), then turn right and continue 0.2 km (0.1 mi) to
the Harbormaster's Office. The bench marks are located in the vicinity of the
office, and Cargo Shed 4. The tide gauge was located along the bulkhead near
Cargo Dock 3.
T I D A L B E N C H M A R K S
PRIMARY BENCH MARK STAMPING: 9977 A 2002
DESIGNATION: 877 9977 A
MONUMENTATION: Bench Mark disk VM#: 16705
AGENCY: Conrad Blucher Institute (CBI) IDB PID#:
SETTING CLASSIFICATION: Wharf deck OPUS PID:
LATITUDE: 25° 57.1' N ( 25.95170) LONGITUDE: 97° 24.2' W ( -97.40330)
The primary bench mark is a disk set in the deck of Cargo Dock 3 south of the
Harbormaster's office, 17.50 m (57.4 ft) east of the NW corner of the concrete
dock, 10.50 m (34.4 ft) SW of the SW corner of a 2 m x 3 m (6 ft x 9 ft) brick
building, and 0.91 m (3.0 ft) SW of the ramp on the north side of the loading
dock.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 2 of 6
Station ID: 8779977 PUBLICATION DATE: 01/23/2004
Name: PORT OF BROWNSVILLE
TX
NOAA Chart: 11302 Latitude: 25° 57.1' N ( 25.95170)
USGS Quad: EAST BROWNSVILLE Longitude: 97° 24.1' W ( -97.40170)
T I D A L B E N C H M A R K S
BENCH MARK STAMPING: 9977 B 2002
DESIGNATION: 877 9977 B
MONUMENTATION: Bench Mark disk VM#: 16706
AGENCY: Conrad Blucher Institute (CBI) IDB PID#:
SETTING CLASSIFICATION: Barge pier curb OPUS PID:
LATITUDE: 25° 57.1' N ( 25.95170) LONGITUDE: 97° 24.3' W ( -97.40500)
The bench mark is a disk set in the concrete curb north of Cargo Dock 3 south of
the Harbormaster's Office, 22.90 m (75.1 ft) north of the base of the ramp on
the north side of Cargo Dock 3, 17.01 m (55.8 ft) east of power pole No. 27248,
15.10 m (49.5 ft) SE of the SE corner of a two door garage brick building south
of the Harbormaster's Office, and 14 m (46 ft) south of power pole No. 27247.
BENCH MARK STAMPING: 9977 C 2002
DESIGNATION: 877 9977 C
MONUMENTATION: Bench Mark disk VM#: 16707
AGENCY: Conrad Blucher Institute (CBI) IDB PID#:
SETTING CLASSIFICATION: Wharf deck OPUS PID:
LATITUDE: 25° 57.2' N ( 25.95330) LONGITUDE: 97° 24.2' W ( -97.40330)
The bench mark is a disk set in the ramp at the rear (east side) of the
Harbormaster's Office, 11.30 m (37.1 ft) west of a three pile bollard, 8.10 m
(26.6 ft) SE of a concrete AC unit pad at the rear of the office, 3.40 m (11.2
ft) east of the east wall of the office, and 0.2 m (0.7 ft) from the SE corner
of the ramp.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 3 of 6
Station ID: 8779977 PUBLICATION DATE: 01/23/2004
Name: PORT OF BROWNSVILLE
TX
NOAA Chart: 11302 Latitude: 25° 57.1' N ( 25.95170)
USGS Quad: EAST BROWNSVILLE Longitude: 97° 24.1' W ( -97.40170)
T I D A L B E N C H M A R K S
BENCH MARK STAMPING: 535 R/L 1948 89+679.68
DESIGNATION: 535 R/L 679.68
MONUMENTATION: Survey disk VM#: 16708
AGENCY: Conrad Blucher Institute (CBI) IDB PID#:
SETTING CLASSIFICATION: Wharf deck OPUS PID:
LATITUDE: 25° 57.2' N ( 25.95330) LONGITUDE: 97° 24.2' W ( -97.40330)
The bench mark is a disk set in the roadway of Cargo Shed 4, 19.20 m (63.0 ft)
north of the bulkhead, 14.11 m (46.3 ft) WSW of the SW corner of Shed 4, and
2.10 m (6.9 ft) south of the north edge of the shed.
BENCH MARK STAMPING: 535 R/L 1948 89+652
DESIGNATION: 535 R/L 89+652
MONUMENTATION: Survey disk VM#: 16709
AGENCY: Conrad Blucher Institute (CBI) IDB PID#:
SETTING CLASSIFICATION: Wharf deck OPUS PID:
LATITUDE: 25° 57.2' N ( 25.95330) LONGITUDE: 97° 24.3' W ( -97.40500)
The bench mark is a disk set in the pavement, 11.0 m (36.1 ft) NW of a 1.4 m
cast iron cleat, 5.70 m (18.7 ft) WSW of the SW corner of Cargo Shed 4, and 2.10
m (6.9 ft) south of the south edge of the shed.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 4 of 6
Station ID: 8779977 PUBLICATION DATE: 01/23/2004
Name: PORT OF BROWNSVILLE
TX
NOAA Chart: 11302 Latitude: 25° 57.1' N ( 25.95170)
USGS Quad: EAST BROWNSVILLE Longitude: 97° 24.1' W ( -97.40170)
T I D A L B E N C H M A R K S
BENCH MARK STAMPING:
DESIGNATION: 877 9977 USE
MONUMENTATION: Survey disk VM#: 16710
AGENCY: Conrad Blucher Institute (CBI) IDB PID#:
SETTING CLASSIFICATION: Wharf deck OPUS PID:
LATITUDE: 25° 57.2' N ( 25.95330) LONGITUDE: 97° 24.3' W ( -97.40500)
The bench mark is a disk set in the pavement south of Cargo Shed 4, 10.40 m
(34.1 ft) ESE of the SW corner of the shed, 10.21 m (33.5 ft) NW of a potable
water manhole cover, and 9.30 m (30.5 ft) north of the bulkhead.
BENCH MARK STAMPING: 535 R/L 1948 89+500
DESIGNATION: 535 R/L 89+500
MONUMENTATION: Survey disk VM#: 16711
AGENCY: Conrad Blucher Institute (CBI) IDB PID#:
SETTING CLASSIFICATION: Barge pier OPUS PID:
LATITUDE: 25° 57.2' N ( 25.95330) LONGITUDE: 97° 24.2' W ( -97.40330)
The bench mark is a disk set in the pavement south of Cargo Shed 4, 12.00 m
(39.4 ft) NW of a potable water manhole cover, 9.20 m (30.2 ft) north of the
bulkhead, and 1.31 m (4.3 ft) south of Cargo Shed 4.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 5 of 6
Station ID: 8779977 PUBLICATION DATE: 01/23/2004
Name: PORT OF BROWNSVILLE
TX
NOAA Chart: 11302 Latitude: 25° 57.1' N ( 25.95170)
USGS Quad: EAST BROWNSVILLE Longitude: 97° 24.1' W ( -97.40170)
T I D A L D A T U M S
Tidal datums at PORT OF BROWNSVILLE based on:
LENGTH OF SERIES: 6 MONTHS
TIME PERIOD: July 2002 - December 2002
TIDAL EPOCH: 1983-2001
CONTROL TIDE STATION: 8779770 PORT ISABEL, LAGUNA MADRE
Elevations of tidal datums referred to Mean Lower Low Water (MLLW), in METERS:
HIGHEST OBSERVED WATER LEVEL (09/26/2002) = 1.069
MEAN HIGHER HIGH WATER MHHW = 0.458
MEAN HIGH WATER MHW = 0.437
MEAN SEA LEVEL MSL = 0.271
MEAN TIDE LEVEL MTL = 0.252
MEAN LOW WATER MLW = 0.067
MEAN LOWER LOW WATER MLLW = 0.000
LOWEST OBSERVED WATER LEVEL (12/21/2002) = -0.383
North American Vertical Datum (NAVD88)
Bench Mark Elevation Information In METERS above:
Stamping or Designation MLLW MHW
9977 A 2002 4.688 4.251
9977 B 2002 3.565 3.128
9977 C 2002 5.074 4.637
535 R/L 1948 89+679.68 4.543 4.106
535 R/L 1948 89+652 4.541 4.104
877 9977 USE 4.549 4.112
535 R/L 1948 89+500 4.562 4.125
Foot Notes:
Bench Mark 535 R/L 1948 89+679.68 is based on one differential leveling
connection and does not meet the quality control standards of the NOS.
Therefore, caution should be used when deriving an elevation for this mark.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 6 of 6
Station ID: 8779977 PUBLICATION DATE: 01/23/2004
Name: PORT OF BROWNSVILLE
TX
NOAA Chart: 11302 Latitude: 25° 57.1' N ( 25.95170)
USGS Quad: EAST BROWNSVILLE Longitude: 97° 24.1' W ( -97.40170)
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.