U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Datums Page Page 1 of 4
PUBLICATION DATE: 06/04/1992
Station ID: 8762273 SUPERCEDED DATE: 04/21/2003
Name: EAST END, PASS MANCHAC
LOUISIANA
NOAA Chart: 11369 Latitude: 30° 17.8' N
USGS Quad: PONCHATOULA SE Longitude: 90° 18.7' W
To reach the tidal bench marks from the public boat ramp just north of Manchac
on U.S. Highway 51, proceed by boat 1.0 mile (1.6 km) south on a canal parallel
to Interstate Highway 55 to Pass Manchac, then continue east on Pass Manchac for
6.1 miles (9.8 km) to the Murray camp on the north shore. The bench marks are
both east and west of the Murray camp. The tide gage and staff were at the SE
corner of the Murray pier.
T I D A L B E N C H M A R K S
PRIMARY BENCH MARK STAMPING: 2273 B 1982
MONUMENTATION: Survey Disk VM#: 11599
AGENCY: PID:
SETTING CLASSIFICATION: Stainless Steel Rod
The primary bench mark is 76 feet (23 m) north of the approximate high water
mark on Pass Manchac, 76 feet (23 m) SE of utility pole #535, 65 feet (20 m) ENE
of the NE corner of Starvation Landing camp house, and 65 feet (20 m) WNW of the
NW corner of the Murray camp house. The bench mark is 0.3 foot (0.1 m) below
ground level, crimped to a stainless steel rod driven 64 feet (20 m) to
substantial resistance, and encased in a 4-inch PVC pipe and concrete kickblock.
BENCH MARK STAMPING: 2273 C 1982
MONUMENTATION: Survey Disk VM#: 11600
AGENCY: PID:
SETTING CLASSIFICATION: Stainless Steel Rod
The bench mark is 182 feet (55 m) west of Bench Mark 2273 B 1982, 109 feet (33
m) south of utility pole #534, and 27 feet (8 m) NNE of a wooden bulkhead. The
bench mark is 0.3 foot (0.1 m) below ground level, crimped to a stainless steel
rod driven 68 feet (21 m) to substantial resistance, and encased in a 4-inch PVC
pipe and concrete kickblock.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 2 of 4
PUBLICATION DATE: 06/04/1992
Station ID: 8762273 SUPERCEDED DATE: 04/21/2003
Name: EAST END, PASS MANCHAC
LOUISIANA
NOAA Chart: 11369 Latitude: 30° 17.8' N
USGS Quad: PONCHATOULA SE Longitude: 90° 18.7' W
T I D A L B E N C H M A R K S
BENCH MARK STAMPING: 2273 D 1982
MONUMENTATION: Survey Disk VM#: 11601
AGENCY: PID:
SETTING CLASSIFICATION: Stainless Steel Rod
The bench mark is NW of Bench Mark 2273 C 1982, 75 feet (23 m) NW of an unmarked
light pole, 55 feet (17 m) WNW of the SW corner of the second camp west of
Starvation Landing camp, 32 feet (10 m) NNE of the approximate high water mark
on the north shore of Pass Manchac, and 19 feet (6 m) ESE of the SE corner of
the third camp west of Starvation Landing camp. The bench mark is 0.3 foot
(0.1 m) below ground level, crimped to a stainless steel rod driven 64 feet (20
m) to substantial resistance, and encased in a 4-inch PVC pipe and concrete
kickblock.
BENCH MARK STAMPING: 2273 E 1982
MONUMENTATION: Survey Disk VM#: 11602
AGENCY: PID:
SETTING CLASSIFICATION: Stainless Steel Rod
The bench mark is 204 feet (62 m) WNW of Bench Mark 2273 D 1982, 85 feet (26 m)
NW of the NW corner of a small wooden camp house, 18 feet (5 m) NNE of a
1.5-foot (0.5 m) diameter oak tree, and 7 feet (2 m) ESE of the approximate high
water mark on the east bank of a small unnamed bayou. The bench mark is 0.3
foot (0.1 m) below ground level, crimped to a stainless steel rod driven 64 feet
(20 m) to substantial resistance, and encased in a 4-inch PVC pipe and
concrete kickblock.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 3 of 4
PUBLICATION DATE: 06/04/1992
Station ID: 8762273 SUPERCEDED DATE: 04/21/2003
Name: EAST END, PASS MANCHAC
LOUISIANA
NOAA Chart: 11369 Latitude: 30° 17.8' N
USGS Quad: PONCHATOULA SE Longitude: 90° 18.7' W
T I D A L D A T U M S
Tidal datums at EAST END, PASS MANCHAC based on:
LENGTH OF SERIES: 50 MONTHS
TIME PERIOD: 1983-1987
TIDAL EPOCH: 1960-1978
CONTROL TIDE STATION: 8761927 NEW CANAL
Elevations of tidal datums referred to Mean Lower Low Water (MLLW), in FEET:
HIGHEST OBSERVED WATER LEVEL (01/20/1983) = 3.04
MEAN HIGHER HIGH WATER MHHW = 0.52
MEAN HIGH WATER MHW = 0.52
MEAN TIDE LEVEL MTL = 0.26
MEAN LOW WATER MLW = 0.00
MEAN LOWER LOW WATER MLLW = 0.00
LOWEST OBSERVED WATER LEVEL (04/12/1988) = -2.43
Bench Mark Elevation Information In FEET above:
Stamping or Designation MLLW MHW
2273 B 1982 1.30 0.78
2273 C 1982 1.30 0.78
2273 D 1982 1.32 0.80
2273 E 1982 1.76 1.24
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 4 of 4
PUBLICATION DATE: 06/04/1992
Station ID: 8762273 SUPERCEDED DATE: 04/21/2003
Name: EAST END, PASS MANCHAC
LOUISIANA
NOAA Chart: 11369 Latitude: 30° 17.8' N
USGS Quad: PONCHATOULA SE Longitude: 90° 18.7' 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 (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 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.