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National Oceanic and Atmospheric Administration
National Ocean Service
Datums Page Page 1 of 7
Station ID: 8764227 PUBLICATION DATE: 10/05/2017
Name: LAWMA, AMERADA PASS
LA
NOAA Chart: 11354 Latitude: 29° 27.0' N ( 29.44961)
USGS Quad: POINTAU FER NE Longitude: 91° 20.3' W ( -91.33811)
To reach the tidal bench marks from the intersection of U.S. Highway 90 and
Berwick Road at the west foot of the Morgan City Bridge, proceed south on
Berwick Road for 1.9 km (1.20 mi) then turn west on River Road for 3.5 km (2.15
mi) to the boat launch facilities. Proceed by boat SW on the Atchafalaya River
for 33.8 km (21.00 mi) to channel marker 47, head right in a westerly direction
for 1.7 km (1.05 mi) then proceed south for approximately 0.5 km (0.30 mi) to
the Louisiana Wildlife Management Area. The bench marks are located in the
vicinity of the wildlife management area. The tide gage is located at the mouth
of the Lawma Canal on a 3.00 m x 3.00 m (9.8 ft x 9.8 ft) raised platform on top
of a single pile structure.
T I D A L B E N C H M A R K S
PRIMARY BENCH MARK STAMPING: 4227 A 2005
DESIGNATION: 876 4227 A
MONUMENTATION: Flange-encased Rod VM#: 18163
AGENCY: National Ocean Service (NOS) IDB PID#:
SETTING CLASSIFICATION: Stainless steel rod OPUS PID:
LATITUDE: 29° 26.9' N ( 29.44825) LONGITUDE: 91° 20.3' W ( -91.33847)
The primary bench mark is a flange-encased located in the vicinity of the
wildlife management area, driven 32 m (105.0 ft) north of the boat shed, 30 m
(98.4 ft) west of the WMA sleeping quarters, and 1 m (3.28 ft) east of the
Carsonite witness post. The datum point is set 0.05 m (0.16 ft) below grade
crimped to a stainless steel rod driven 23 m (75.5 ft) to refusal, and encased
in 5-inch PVC pipe with logo cap.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 2 of 7
Station ID: 8764227 PUBLICATION DATE: 10/05/2017
Name: LAWMA, AMERADA PASS
LA
NOAA Chart: 11354 Latitude: 29° 27.0' N ( 29.44961)
USGS Quad: POINTAU FER NE Longitude: 91° 20.3' W ( -91.33811)
T I D A L B E N C H M A R K S
BENCH MARK STAMPING: 227 B 2006
DESIGNATION: 876 4227 B
MONUMENTATION: Flange-encased Rod VM#: 18164
AGENCY: National Ocean Service (NOS) IDB PID#:
SETTING CLASSIFICATION: Stainless steel rod OPUS PID#: BBBJ02
LATITUDE: 29° 26.9' N ( 29.44869) LONGITUDE: 91° 20.3' W ( -91.33825)
The bench mark is a flange-encased rod located 93.4 m (306.4 ft) north of the
boat shed, 27.7 m (90.9 ft) east of the oak tree, and 2.0 m (6.6 ft) WNW of the
Carsonite witness post. The datum point is set 0.05 m (0.16 ft) below grade,
crimped to a stainless steel rod driven 23 m (75.5 ft) to refusal and encased in
a 5-inch PVC pipe with logo cap.
BENCH MARK STAMPING: 227 D 2006
DESIGNATION: 876 4227 D
MONUMENTATION: Flange-encased Rod VM#: 18166
AGENCY: National Ocean Service (NOS) IDB PID#:
SETTING CLASSIFICATION: Stainless steel rod OPUS PID:
LATITUDE: 29° 26.9' N ( 29.44767) LONGITUDE: 91° 20.3' W ( -91.33883)
The bench mark is a flange-encased rod located 19.2 m (63.0 ft) ESE of a radio
tower beside the game warden office, 17.4 m (57.1 ft) south of the boat ramp,
16.0 m (52.5 ft) NNE of the south corner of the bulkhead, 13.4 m (44.0 ft) south
of the southern edge of a sidewalk running from boathouse to the rangers office,
and 0.3 m (0.98 ft) WNW of the west side of the boat shed. The datum point is
set 0.03 m (0.098 ft) below grade, crimped to a stainless steel rod driven 23 m
(75.5 ft) to refusal, and encased in a 5-inch PVC pipe with logo cap.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 3 of 7
Station ID: 8764227 PUBLICATION DATE: 10/05/2017
Name: LAWMA, AMERADA PASS
LA
NOAA Chart: 11354 Latitude: 29° 27.0' N ( 29.44961)
USGS Quad: POINTAU FER NE Longitude: 91° 20.3' W ( -91.33811)
T I D A L B E N C H M A R K S
BENCH MARK STAMPING: 227 E 2006
DESIGNATION: 876 4227 E
MONUMENTATION: Tidal Station disk VM#: 18167
AGENCY: National Ocean Service (NOS) IDB PID#:
SETTING CLASSIFICATION: Small tower foundation OPUS PID:
LATITUDE: 29° 26.9' N ( 29.44769) LONGITUDE: 91° 20.3' W ( -91.33900)
The bench mark is a disk set flush on the concrete foundation holding the Rohn
tower, 3.2 m (10.5 FT) NW of the orange tree, 2.8 m (9.2 ft) south of the WMA
sleeping quarters, 0.3 m (1.0 ft) NW of the Rohn tower.
BENCH MARK STAMPING: GPS GAGE 36
DESIGNATION: 876 4227 GPS GAGE 36
MONUMENTATION: Flange-encased Rod VM#: 18999
AGENCY: National Ocean Service (NOS) IDB PID#: DJ9384
SETTING CLASSIFICATION: Stainless steel rod in sleeve OPUS PID:
LATITUDE: 29° 27.0' N ( 29.44925) LONGITUDE: 91° 20.3' W ( -91.33764)
The bench mark is flange-encased rod located 38.7 m (126.96 ft) north of the
south woods line of the camp area, 10.1 m (33.1 ft) west of the west bank of
Amerada pass, 1.7 m (5.6 ft) south of the east bank of the eastern most camp
basin on the south side of the LAWMA canal. The datum point is set 0.03 m
(0.098 ft) below grade being a stainless steel rod driven 23 m (75.5 ft) to
refusal and encased in a 5-inch PVC pipe with logo cap.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 4 of 7
Station ID: 8764227 PUBLICATION DATE: 10/05/2017
Name: LAWMA, AMERADA PASS
LA
NOAA Chart: 11354 Latitude: 29° 27.0' N ( 29.44961)
USGS Quad: POINTAU FER NE Longitude: 91° 20.3' W ( -91.33811)
T I D A L B E N C H M A R K S
BENCH MARK STAMPING: 4227 F 2010
DESIGNATION: 876 4227 F
MONUMENTATION: Flange-encased Rod VM#: 19723
AGENCY: National Ocean Survey/Service (NoS) IDB PID#:
SETTING CLASSIFICATION: Stainless steel rod OPUS PID:
LATITUDE: 29° 26.9' N ( 29.44775) LONGITUDE: 91° 20.3' W ( -91.33831)
The flange-encased rod is located 15.2 m (50 ft) SSW of SW corner of public
restrooms, 5.2 m (17 ft) NW of 12 inch diameter cypress tree, 4.7 m (15.5 ft)
south of Louisiana department of wildlife and fisheries designated camping area
sign, 3.0 m (10 ft) ESE of the waters edge, 2.43 m (8 ft) ESE of witness post.
The datum point is set flush to ground, being the top of a stainless steel rod
driven 27.4 m (90 ft) to refusal, and encased in a 6 inch (15 cm) National
Geodetic Survey Logo Cap.
BENCH MARK STAMPING: 4227 G 2010
DESIGNATION: 876 4227 G
MONUMENTATION: Flange-encased Rod VM#: 19724
AGENCY: National Ocean Survey/Service (NOS) IDB PID#:
SETTING CLASSIFICATION: Stainless steel rod OPUS PID#: BBDX31
LATITUDE: 29° 26.9' N ( 29.44831) LONGITUDE: 91° 20.2' W ( -91.33739)
The bench mark is a flange-encased rod located 26.8 m (88 ft) east of NE corner
of pinic table, 12.8 m (42 ft) NE of yellow do not enter sign, 5.8 m (19 ft)
east of 18 in diameter pecan tree, 2.4 m (8 ft) NW of restricted area no
trespassing LDWF sign, 1.1 m (3.5 ft) west of witness post. The datum point is
set flush to ground, being the top of a stainless steel rod driven 27.4 m (90
ft) to refusal, and encased in a 6 inch (15 cm) National Geodetic Survey logo
cap.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 5 of 7
Station ID: 8764227 PUBLICATION DATE: 10/05/2017
Name: LAWMA, AMERADA PASS
LA
NOAA Chart: 11354 Latitude: 29° 27.0' N ( 29.44961)
USGS Quad: POINTAU FER NE Longitude: 91° 20.3' W ( -91.33811)
T I D A L B E N C H M A R K S
BENCH MARK STAMPING: 4227 H 2010
DESIGNATION: 876 4227 H
MONUMENTATION: Flange-encased Rod VM#: 19725
AGENCY: National Ocean Survey/Service (NOS) IDB PID#:
SETTING CLASSIFICATION: Stainless steel rod OPUS PID:
LATITUDE: 29° 26.9' N ( 29.44872) LONGITUDE: 91° 20.2' W ( -91.33714)
The bench mark is a flange-encased rod located 45.1 m (148 ft) ESE of camping
registration box, 30.8 m (101 ft) south of south corner of pinic table, 22.1 m
(72.5 ft) west of large keep out sign, 14.0 m (46 ft) ESE of 1.2 m (4 ft)
diameter pecan tree, 2.1 m (7 ft) north of witness post. The datum point is set
flush to ground, being the top of a stainless steel rod driven 27.4 m (90 ft) to
refusal, and encased in a 6 inch (15 cm) National Geodetic Survey Logo cap.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 6 of 7
Station ID: 8764227 PUBLICATION DATE: 10/05/2017
Name: LAWMA, AMERADA PASS
LA
NOAA Chart: 11354 Latitude: 29° 27.0' N ( 29.44961)
USGS Quad: POINTAU FER NE Longitude: 91° 20.3' W ( -91.33811)
T I D A L D A T U M S
Tidal datums at LAWMA, AMERADA PASS based on:
LENGTH OF SERIES: 8 YEARS
TIME PERIOD: 6/07-5/09, 11/09-0/12, 7/13-6/15, 3/16-2/17
TIDAL EPOCH: 1983-2001
CONTROL TIDE STATION: 8770570 SABINE PASS NORTH
Elevations of tidal datums referred to Mean Lower Low Water (MLLW), in METERS:
HIGHEST OBSERVED WATER LEVEL (09/12/2008) = 2.303
MEAN HIGHER HIGH WATER MHHW = 0.493
MEAN HIGH WATER MHW = 0.447
MEAN TIDE LEVEL MTL = 0.273
MEAN SEA LEVEL MSL = 0.260
North American Vertical Datum NAVD88 = 0.226
MEAN LOW WATER MLW = 0.099
MEAN LOWER LOW WATER MLLW = 0.000
LOWEST OBSERVED WATER LEVEL (12/26/2010) = -0.494
North American Vertical Datum (NAVD88)
Bench Mark Elevation Information In METERS above:
Stamping or Designation MLLW MHW
4227 A 2005 1.619 1.172
227 B 2006 2.243 1.796
227 D 2006 0.921 0.474
227 E 2006 1.645 1.198
GPS GAGE 36 1.169 0.722
4227 F 2010 1.115 0.668
4227 G 2010 0.959 0.512
4227 H 2010 0.988 0.541
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 7 of 7
Station ID: 8764227 PUBLICATION DATE: 10/05/2017
Name: LAWMA, AMERADA PASS
LA
NOAA Chart: 11354 Latitude: 29° 27.0' N ( 29.44961)
USGS Quad: POINTAU FER NE Longitude: 91° 20.3' W ( -91.33811)
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.
Station Location
Published bench mark
Unpublished bench mark
