U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Datums Page Page 1 of 5
Station ID: 8776687 PUBLICATION DATE: 04/13/2005
Name: YARBROUGH PASS
TX
NOAA Chart: 11304 Latitude: 27° 10.0' N ( 27.16670)
USGS Quad: YARBROUGH PASS Longitude: 97° 26.0' W ( -97.43330)
To reach the tidal bench marks from John F. Kennedy Causeway/Bridge, proceed
south by boat down the Gulf Intracoastal Waterway (GIWW) for approximately 48 km
(30 mi) to a spoil island on the east side of the channel. The bench marks are
on the spoil island. The tide guage is on a platform just north of USCG Buoy
#57.
T I D A L B E N C H M A R K S
PRIMARY BENCH MARK STAMPING: 6687 A 1990
DESIGNATION: 877 6687 A
MONUMENTATION: Tidal Station disk VM#: 12216
AGENCY: National Ocean Service (NOS) IDB PID#:
SETTING CLASSIFICATION: Stainless steel rod OPUS PID:
LATITUDE: ' °deg (0) LONGITUDE: ' °deg (0)
The primary bench mark is a disk marked with an orange fiberglass witness post
located on the spoil island east of the gauge and just south of Yarborough Pass
cut, 229 m (750 ft) SE of the tide gauge platform, and 30 m (100 ft) east of the
waters edge. The bench mark is set level with the ground, crimped to the top of
a stainless steel rod driven 15.5 m (51 ft) to refusal, and encased in a 6-inch
PVC pipe.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 2 of 5
Station ID: 8776687 PUBLICATION DATE: 04/13/2005
Name: YARBROUGH PASS
TX
NOAA Chart: 11304 Latitude: 27° 10.0' N ( 27.16670)
USGS Quad: YARBROUGH PASS Longitude: 97° 26.0' W ( -97.43330)
T I D A L B E N C H M A R K S
BENCH MARK STAMPING: 6687 B 1990
DESIGNATION: 877 6687 B
MONUMENTATION: Tidal Station disk VM#: 12217
AGENCY: National Ocean Service (NOS) IDB PID#:
SETTING CLASSIFICATION: Stainless steel rod OPUS PID:
LATITUDE: ' °deg (0) LONGITUDE: ' °deg (0)
The bench mark is a disk marked by an orange fiberglass witness post located on
the spoil island just south of Yarborough Pass cut, and 115.9 m (380.4 ft) SSW
of bench mark 6687 A 1990. The bench mark is set level with the ground, crimped
to the top of a stainless steel rod driven 13.4 m (44 ft) to substantial
resistance, and encased in a 6-inch PVC pipe.
BENCH MARK STAMPING: 6687 C 1990
DESIGNATION: 877 6687 C
MONUMENTATION: Tidal Station disk VM#: 12218
AGENCY: National Ocean Service (NOS) IDB PID#:
SETTING CLASSIFICATION: Stainless steel rod OPUS PID:
LATITUDE: ' °deg (0) LONGITUDE: ' °deg (0)
The bench mark is a disk marked by an orange fiberglass witness post located on
the spoil island just south of Yarborough Pass cut, and 76.41 m (250.6 ft) SS E
of bench mark 6687 B 1990. The bench mark is set level with the ground, crimped
to the top of a stainless steel rod driven 12.2 m (40 ft) to substantial
resistance, and encased in a 6-inch PVC pipe.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 3 of 5
Station ID: 8776687 PUBLICATION DATE: 04/13/2005
Name: YARBROUGH PASS
TX
NOAA Chart: 11304 Latitude: 27° 10.0' N ( 27.16670)
USGS Quad: YARBROUGH PASS Longitude: 97° 26.0' W ( -97.43330)
T I D A L B E N C H M A R K S
BENCH MARK STAMPING: 6687 D 1990
DESIGNATION: 877 6687 D
MONUMENTATION: Tidal Station disk VM#: 12219
AGENCY: National Ocean Service (NOS) IDB PID#:
SETTING CLASSIFICATION: Stainless steel rod OPUS PID:
LATITUDE: ' °deg (0) LONGITUDE: ' °deg (0)
The bench mark is a disk marked by an orange fiberglass witness post located on
the spoil island just south of Yarborough Pass cut, and 112.99 m (370.7 ft) SSW
of bench mark 6687 C 1990. The bench mark is set level with the ground, crimped
to the top of a stainless steel rod driven 12.2 m (40 ft) to substantial
resistance, and encased in a 6-inch PVC pipe.
BENCH MARK STAMPING: 6687 E 1990
DESIGNATION: 877 6687 E
MONUMENTATION: Tidal Station disk VM#: 12220
AGENCY: National Ocean Service (NOS) IDB PID#:
SETTING CLASSIFICATION: Stainless steel rod OPUS PID:
LATITUDE: ' °deg (0) LONGITUDE: ' °deg (0)
The bench mark is a disk marked by an orange fiberglass witness post located on
the spoil island just south of Yarborough Pass cut, and 76.57 m (251.2 ft) WSW
of bench mark 6687 D 1990. The bench mark is set level with the ground, crimped
to the top of a stainless steel rod driven 13.4 m (44 ft) to substantial
resistance, and encased in a 6-inch PVC pipe.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 4 of 5
Station ID: 8776687 PUBLICATION DATE: 04/13/2005
Name: YARBROUGH PASS
TX
NOAA Chart: 11304 Latitude: 27° 10.0' N ( 27.16670)
USGS Quad: YARBROUGH PASS Longitude: 97° 26.0' W ( -97.43330)
T I D A L D A T U M S
Tidal datums at YARBROUGH PASS based on:
LENGTH OF SERIES: 3 YEARS
TIME PERIOD: January 1991 - December 1993
TIDAL EPOCH: 1983-2001
CONTROL TIDE STATION: 8778490 PORT MANSFIELD
Elevations of tidal datums referred to Mean Sea Level (MSL), in METERS:
HIGHEST OBSERVED WATER LEVEL (10/31/1991) = 0.487
MEAN SEA LEVEL MSL = 0.000
LOWEST OBSERVED WATER LEVEL (09/13/1993) = -0.379
North American Vertical Datum (NAVD88)
Bench Mark Elevation Information In METERS above:
Stamping or Designation MSL
6687 A 1990 1.122
6687 B 1990 0.968
6687 C 1990 0.775
6687 D 1990 0.851
6687 E 1990 1.162
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 5 of 5
Station ID: 8776687 PUBLICATION DATE: 04/13/2005
Name: YARBROUGH PASS
TX
NOAA Chart: 11304 Latitude: 27° 10.0' N ( 27.16670)
USGS Quad: YARBROUGH PASS Longitude: 97° 26.0' W ( -97.43330)
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.