U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Datums Page Page 1 of 5
Station ID: 8760412 PUBLICATION DATE: 06/23/2003
Name: NORTH PASS
LA
NOAA Chart: 11361 Latitude: 29° 12.3' N ( 29.20500)
USGS Quad: PASS A LOUTRE EAST Longitude: 89° 2.2' W ( -89.03670)
To reach the tidal bench marks from the intersection of U.S. Highway 90 and
State Road 23 in Gretna, proceed south on State Road 23 for 121 km (75 mi) to
Venice, then through Venice for 1.3 km (0.8 mi) to Elhzys Marine where public
launch facilities are available. Proceed by boat south on the Mississippi River
for 15.8 km (8.5 nm) to Pass-A-Loutre, then east on Pass-A-Loutre and North Pass
for 23 km (12 nm) to the Chevron Oil Company facility on the north shore of
North Pass. The bench marks are located inside a dike surrounding seven fuel
tanks. The tide station was located on the west end of the oil company pier
beside the workers living quarters.
T I D A L B E N C H M A R K S
PRIMARY BENCH MARK STAMPING: 0412 B 1980
DESIGNATION: 876 0412 B
MONUMENTATION: Tidal Station disk VM#: 6215
AGENCY: National Ocean Survey (NOS) IDB PID#:
SETTING CLASSIFICATION: Stainless steel rod OPUS PID:
LATITUDE: 29° 12.3' N ( 29.20500) LONGITUDE: 89° 2.2' W ( -89.03670)
The primary bench mark is a disk set near feul tank #1, 71 m (234 ft) NE of
bench mark 0412 A 1980, 51 m (167 ft) SE of the centerline of the boardwalk
bisecting the dike, 14 m (47 ft) NW of the south shoreline of the dike, and 6 m
(19 ft) SE of the SE face of fuel tank #1. The bench mark is set 0.27 m (0.9
ft) above ground level, crimped to the top of a stainless steel rod driven 15.2
m (50 ft) to refusal, and encased in a 4-inch PVC pipe.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 2 of 5
Station ID: 8760412 PUBLICATION DATE: 06/23/2003
Name: NORTH PASS
LA
NOAA Chart: 11361 Latitude: 29° 12.3' N ( 29.20500)
USGS Quad: PASS A LOUTRE EAST Longitude: 89° 2.2' W ( -89.03670)
T I D A L B E N C H M A R K S
BENCH MARK STAMPING: 0412 A 1980
DESIGNATION: 876 0412 A
MONUMENTATION: Tidal Station disk VM#: 6214
AGENCY: National Ocean Survey (NOS) IDB PID#:
SETTING CLASSIFICATION: Stainless steel rod OPUS PID:
LATITUDE: 29° 12.3' N ( 29.20500) LONGITUDE: 89° 2.2' W ( -89.03670)
The bench mark is a disk located near the SW corner of the dike, 42 m (137 ft)
SE of the centerline of a boardwalk bisecting the dike, 23 m (77 ft) south of
the south face of fuel tank #7, 14 m (46 ft) north of the shoreline of the SW
corner of the dike, and 12 m (38 ft) NE of the west shoreline of the dike. The
bench mark is set 0.27 m (0.9 ft) above ground level, crimped to the top of a
stainless steel rod driven 15.2 m (50 ft) to refusal, and encased in a 4-inch
PVC pipe.
BENCH MARK STAMPING: 0412 C 1980
DESIGNATION: 876 0412 C
MONUMENTATION: Tidal Station disk VM#: 6216
AGENCY: National Ocean Survey (NOS) IDB PID#:
SETTING CLASSIFICATION: Stainless steel rod OPUS PID:
LATITUDE: 29° 12.3' N ( 29.20500) LONGITUDE: 89° 2.2' W ( -89.03670)
The bench mark is a disk set near feul tank #2, 75 m (246 ft) NE of bench mark
0412 B 1980, 49 m (160 ft) SE of the centerline of the boardwalk bisecting the
dike, 30 m (100 ft) west of the shoreline of the NE corner of the dike, and 5 m
(16 ft) south of the south face of fuel tank #2. The bench mark is set 0.24 m
(0.8 ft) above ground level, crimped to the top of a stainless steel rod driven
15.2 m (50 ft) to refusal, and encased in a 4-inch PVC pipe.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 3 of 5
Station ID: 8760412 PUBLICATION DATE: 06/23/2003
Name: NORTH PASS
LA
NOAA Chart: 11361 Latitude: 29° 12.3' N ( 29.20500)
USGS Quad: PASS A LOUTRE EAST Longitude: 89° 2.2' W ( -89.03670)
T I D A L B E N C H M A R K S
BENCH MARK STAMPING: 0412 D 1980
DESIGNATION: 876 0412 D
MONUMENTATION: Tidal Station disk VM#: 6217
AGENCY: National Ocean Survey (NOS) IDB PID#:
SETTING CLASSIFICATION: Stainless steel rod OPUS PID:
LATITUDE: 29° 12.3' N ( 29.20500) LONGITUDE: 89° 2.2' W ( -89.03670)
The bench mark is a disk located on the north side of the boardwalk bisecting
the dike, 73 m (241 ft) NW of bench mark 0412 C 1980, 27 m (87 ft) NNW of the
centerline of the boardwalk, 26 m (85 ft) NE of the NE face of fuel tank #4, 26
m (84 ft) SE of the north shoreline of the dike, and 4 m (13 ft) south of the
south face of fuel tank #3. The bench mark is set 0.24 m (0.8 ft) above ground
level, crimped to the top of a stainless steel rod driven 15.2 m (50 ft) to
refusal, and encased in a 4-inch PVC pipe.
BENCH MARK STAMPING: 0412 E 1980
DESIGNATION: 876 0412 E
MONUMENTATION: Tidal Station disk VM#: 6218
AGENCY: National Ocean Survey (NOS) IDB PID#:
SETTING CLASSIFICATION: Stainless steel rod OPUS PID:
LATITUDE: 29° 12.3' N ( 29.20500) LONGITUDE: 89° 2.2' W ( -89.03670)
The bench mark is a disk located on the north side of the boardwalk bisecting
the dike, 64 m (210 ft) west of bench mark 0412 D 1980, 30 m (100 ft) SE of the
north shoreline of the dike, 23 m (76 ft) NW of the centerline of the boardwalk,
11 m (35 ft) NE of the centerline of the boardwalk leading to fuel tank # 5, and
8 m (26 ft) east of the east face of fuel tank #5. The bench mark is set 0.27 m
(0.9 ft) above ground level, crimped to the top of a stainless steel rod driven
15.2 m (50 ft) to refusal, and encased in a 4-inch PVC pipe.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 4 of 5
Station ID: 8760412 PUBLICATION DATE: 06/23/2003
Name: NORTH PASS
LA
NOAA Chart: 11361 Latitude: 29° 12.3' N ( 29.20500)
USGS Quad: PASS A LOUTRE EAST Longitude: 89° 2.2' W ( -89.03670)
T I D A L D A T U M S
Tidal datums at NORTH PASS based on:
LENGTH OF SERIES: 1 Year
TIME PERIOD: January 1981 - December 1981
TIDAL EPOCH: 1983-2001
CONTROL TIDE STATION: 8747437 BAY WAVELAND YC, BAY ST. LOUIS
Elevations of tidal datums referred to Mean Lower Low Water (MLLW), in METERS:
HIGHEST OBSERVED WATER LEVEL (05/07/1981) = 0.666
MEAN HIGHER HIGH WATER MHHW = 0.336
MEAN HIGH WATER MHW = 0.331
MEAN TIDE LEVEL MTL = 0.167
MEAN SEA LEVEL MSL = 0.166
MEAN LOW WATER MLW = 0.003
MEAN LOWER LOW WATER MLLW = 0.000
LOWEST OBSERVED WATER LEVEL (06/27/1980) = -0.312
North American Vertical Datum (NAVD88)
Bench Mark Elevation Information In METERS above:
Stamping or Designation MLLW MHW
0412 B 1980 0.517 0.186
0412 A 1980 0.762 0.431
0412 C 1980 0.222 -0.109
0412 D 1980 -0.088 -0.419
0412 E 1980 -0.231 -0.562
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 5 of 5
Station ID: 8760412 PUBLICATION DATE: 06/23/2003
Name: NORTH PASS
LA
NOAA Chart: 11361 Latitude: 29° 12.3' N ( 29.20500)
USGS Quad: PASS A LOUTRE EAST Longitude: 89° 2.2' W ( -89.03670)
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.