U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Datums Page Page 1 of 4
Station ID: 8760943 PUBLICATION DATE: 04/26/2008
Name: PILOT STATION, SW PASS
LOUISIANA
NOAA Chart: 11361 Latitude: 28° 55.5' N
USGS Quad: BURRWOOD BAYOU WEST Longitude: 89° 25.1' W
To reach the tidal bench marks from Venice, proceed by boat south on the
Mississippi River for 16.1 km (8.7 nm) to the Head of Passes, continue south
down Southwest Pass for 29.3 km (15.8 nm) to the Associated Branch Pilots House.
The bench marks are located on the river side of the Mississippi River along
river bank. The tide gage and the staff are located on the SW corner of a pier
near the water tower.
T I D A L B E N C H M A R K S
PRIMARY BENCH MARK STAMPING: 0943A 1996
DESIGNATION: 876 0943 A
MONUMENTATION: Flange-encased Rod VM#: 16856
AGENCY: National Ocean Service (NOS) PID:
SETTING CLASSIFICATION: Stainless steel rod
The primary bench mark is a flange-encased rod located on the river side of the
Mississippi River levee, 153 m (503 ft) SSW of the intersection of stone riprap
and a wooden pile dike, 9 m (31 ft) NW of stone riprap that protects the bank,
and 5 m (16 ft) NNE of the NE corner of small wooden ramp that is attached to a
walkway from Bar Pilot's House to the river bank. The bench mark is crimped to
the top of a stainless steel rod driven 24.4 m (80 ft) to substantial
resistance, and encased in a 5-inch PVC pipe with access cover.
BENCH MARK STAMPING: 0943B 1996
DESIGNATION: 876 0943 B
MONUMENTATION: Flange-encased Rod VM#: 16858
AGENCY: National Ocean Service (NOS) PID:
SETTING CLASSIFICATION: Stainless steel rod
The bench mark is flange-encased rod located on the river side of the
Mississippi River levee, 113 m (370 ft) NW of ramp and conveyor belt in BP Oil
Company Coke Dock, and 9 m (30 ft) from the base of the levee. The bench mark is
set 0.8 m (2.5 ft) above the ground, crimped to the top of a 1/2-inch stainless
steel rod driven 24.4 m (80 ft) to substantial resistance, and encased in a
4-inch white PVC pipe.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 2 of 4
Station ID: 8760943 PUBLICATION DATE: 04/26/2008
Name: PILOT STATION, SW PASS
LOUISIANA
NOAA Chart: 11361 Latitude: 28° 55.5' N
USGS Quad: BURRWOOD BAYOU WEST Longitude: 89° 25.1' W
T I D A L B E N C H M A R K S
BENCH MARK STAMPING: 0943C 1996
DESIGNATION: 876 0943 C
MONUMENTATION: Flange-encased Rod VM#: 16859
AGENCY: National Ocean Service (NOS) PID:
SETTING CLASSIFICATION: Stainless steel rod
The bench mark is a flange-encased rod located on the river side of the
Mississippi River levee, 228 m (749 ft) NNE along river bank from a small wooden
ramp attached to a walkway that leads to Bar Pilot's House in SW pass, 17 m (55
ft) west of stone riprap that protects the bank, and 15 m (49 ft) NNE of the
intersection of the stone riprap and the wooden pile dike. The bench mark is
set 0.6 m (2 ft) above the ground, crimped to the top of a 1/2-inch stainless
steel rod driven 24.4 m (80 ft) to substantial resistance, and encased in a
5-inch white PVC pipe with access cover.
BENCH MARK STAMPING: 0943E 1996
DESIGNATION: 876 0943 E
MONUMENTATION: Flange-encased Rod VM#: 16861
AGENCY: National Ocean Service (NOS) PID:
SETTING CLASSIFICATION: Stainless steel rod
The bench mark is a flange-encased rod located on the river side of the
Mississippi River levee, 220 m (723 ft) SSW of intersection of stone riprap and
wooden pile dike, 67 m (220 ft) SSW along river bank from small wooden ramp
attached to a walkway that leads to Bar Pilot's House in SW pass, 19 m (61 ft)
west of stone riprap that protects the river bank. The mark is set 0.6 m (2 ft)
above the ground, crimped to the top of a 1/2-inch stainless steel rod driven
24.4 m (80 ft) to substantial resistance, and encased in a 5-inch white PVC
pipe with access cover.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 3 of 4
Station ID: 8760943 PUBLICATION DATE: 04/26/2008
Name: PILOT STATION, SW PASS
LOUISIANA
NOAA Chart: 11361 Latitude: 28° 55.5' N
USGS Quad: BURRWOOD BAYOU WEST Longitude: 89° 25.1' W
T I D A L D A T U M S
Tidal datums at PILOT STATION, SW PASS based on:
LENGTH OF SERIES: 18 MONTHS
TIME PERIOD: September 2002 - February 2004
TIDAL EPOCH: 1983-2001
CONTROL TIDE STATION: 8761724 GRAND ISLE, EAST POINT
Elevations of tidal datums referred to Mean Lower Low Water (MLLW), in METERS:
HIGHEST OBSERVED WATER LEVEL (09/26/2002) = 1.099
MEAN HIGHER HIGH WATER (MHHW) = 0.383
MEAN HIGH WATER (MHW) = 0.378
MEAN SEA LEVEL (MSL) = 0.194
MEAN TIDE LEVEL (MTL) = 0.192
MEAN LOW WATER (MLW) = 0.007
MEAN LOWER LOW WATER (MLLW) = 0.000
LOWEST OBSERVED WATER LEVEL (12/31/1997) = -0.596
National Geodetic Vertical Datum (NGVD 29)
Bench Mark Elevation Information In METERS above:
Stamping or Designation MLLW MHW
0943A 1996 0.553 0.175
0943B 1996 0.668 0.290
0943C 1996 0.665 0.287
0943E 1996 0.489 0.111
Foot Notes:
Benchmarks 0943B 1996 and 0943C 1996 are based on one differential leveling
connection and do not meet the quality control standards of the NOS. Therefore,
caution should be used when deriving elevations for these marks.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 4 of 4
Station ID: 8760943 PUBLICATION DATE: 04/26/2008
Name: PILOT STATION, SW PASS
LOUISIANA
NOAA Chart: 11361 Latitude: 28° 55.5' N
USGS Quad: BURRWOOD BAYOU WEST Longitude: 89° 25.1' W
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 (NAVD 88).
NGVD 29 is a fixed datum adopted as a national standard geodetic reference for
heights but is now considered superseded. NGVD 29 is sometimes referred to as
Sea Level Datum of 1929 or as Mean Sea Level on some early issues of Geological
Survey Topographic Quads. NGVD 29 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 NGVD 29 are available from the National
Geodetic Survey (NGS) data base via the World Wide Web at
National Geodetic Survey.
NAVD 88 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. NAVD 88 replaces NGVD 29 as the national
standard geodetic reference for heights. Bench mark elevations relative to
NAVD 88 are available from NGS through the World Wide Web at
National Geodetic Survey.
NGVD 29 and NAVD 88 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 NAVD 88 elevation is shown on the Elevations of Tidal Datums Table Referred
to MLLW only when two or more of the bench marks listed have NAVD 88 elevations.
The NAVD 88 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, NAVD 88 bench mark elevations computed indirectly from the tidal
datums elevation table may differ slightly from NAVD 88 elevations listed for
each bench mark in the NGS database.