U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Datums Page Page 1 of 8
Station ID: 8761305 PUBLICATION DATE: 03/07/2018
Name: SHELL BEACH, LAKE BORGNE
LA
NOAA Chart: 11371 Latitude: 29° 52.1' N ( 29.86811)
USGS Quad: YSCLOSKEY KEY Longitude: 89° 40.4' W ( -89.67325)
To reach the tidal bench marks from the boat launch facilities near the north
end of State Highway 46 in Shell Beach, proceed by boat north on Bayou Yscloskey
and across the Gulf Outlet Canal for 1.8 km (1.0 nm) to the ruins at Old Shell
Beach. The bench marks are located at the ruins to the east of Bayou Yscloskey,
and along the old road parallel to Bayou Yscloskey. The tide gage and staff
were located on a 7m x 4 m (22 ft x 14 ft) concrete platform at the mouth of the
bayou.
T I D A L B E N C H M A R K S
PRIMARY BENCH MARK STAMPING: 1305 E 2008
DESIGNATION: 876 1305 E
MONUMENTATION: Flange-encased Rod VM#: 18815
AGENCY: NOS IDB PID#:
SETTING CLASSIFICATION: Stainless steel rod in sleeve OPUS PID#: BBFP49
LATITUDE: 29° 52.0' N ( 29.86650) LONGITUDE: 89° 40.4' W ( -89.67369)
The primary bench mark is a 3-D rod, 45.1 m (148.0 ft) south of the 45 degree
curve in the centerline of the rock jetty, 29.6 m (97.1 ft) ENE of the 30 degree
curve in the centerline of the rock jetty, 18.9 m (62.0 ft) west of the
centerline of the rock jetty, 3.4m (11.15 ft) west of the west edge of the salt
marsh grass line, 0.3 m (1.0 ft) west of the carsonite witness post. The datum
point is level with the ground, being the top of a 3D rod in a sleeve, driven
27.4 m (90 ft), 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 2 of 8
Station ID: 8761305 PUBLICATION DATE: 03/07/2018
Name: SHELL BEACH, LAKE BORGNE
LA
NOAA Chart: 11371 Latitude: 29° 52.1' N ( 29.86811)
USGS Quad: YSCLOSKEY KEY Longitude: 89° 40.4' W ( -89.67325)
T I D A L B E N C H M A R K S
BENCH MARK STAMPING: 1305 D 2008
DESIGNATION: 876 1305 D
MONUMENTATION: Flange-encased Rod VM#: 18816
AGENCY: NOS IDB PID#:
SETTING CLASSIFICATION: Stainless steel rod in sleeve OPUS PID#: BBCM90
LATITUDE: 29° 52.0' N ( 29.86681) LONGITUDE: 89° 40.4' W ( -89.67278)
The bench mark is a 3-D rod, located 92.0 m (301.8 ft) east of the 45 degree
curve in the centerline of the rock jetty, 36.3 m (119.1 ft) west of the pipe
located in the 45 degree curve in the rock jetty, 18.9 m (62.0 ft) north of the
north edge of the salt marsh grass line, 11.3 m (37.1 ft) south of the rock
jetty centerline, and 0.7 m (2.3 ft) west of the carsonite witness post. The
datum point is set level with the ground, being the top of a stainless steel rod
in a sleeve, driven 27.4 m (90.0 ft) to refusal, and encased in a 5-inch NOS
logo cap.
BENCH MARK STAMPING: 1305 C 2008
DESIGNATION: 876 1305 C
MONUMENTATION: Flange-encased Rod VM#: 18818
AGENCY: NOS IDB PID#:
SETTING CLASSIFICATION: Galvanized steel rod in sleeve OPUS PID:
LATITUDE: 29° 52.0' N ( 29.86619) LONGITUDE: 89° 40.3' W ( -89.67211)
The bench mark is a flange-encased rod, located 74.8 m (245.4 ft) ESE of the
pipe located in the 45 degree curve in the centerline of the rock jetty, 67.1 m
(220.1 ft) west of the 90 degree curve in the centerline of the rock jetty, 45.7
m (149.9 ft) south of the south face of the elevated concrete foundation, 25.1 m
(82.3 ft) North of the North edge of the salt marsh grass line, and 0.6 m (1.97
ft) north of the carsonite witness post. The datum point is set level with the
ground, being the top of a galvenized steel rod in a sleeve, driven 27.4 m (90
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 8
Station ID: 8761305 PUBLICATION DATE: 03/07/2018
Name: SHELL BEACH, LAKE BORGNE
LA
NOAA Chart: 11371 Latitude: 29° 52.1' N ( 29.86811)
USGS Quad: YSCLOSKEY KEY Longitude: 89° 40.4' W ( -89.67325)
T I D A L B E N C H M A R K S
BENCH MARK STAMPING: 1305 F 2008
DESIGNATION: 876 1305 F
MONUMENTATION: Flange-encased Rod VM#: 18819
AGENCY: NOS IDB PID#:
SETTING CLASSIFICATION: Stainless steel rod in sleeve OPUS PID:
LATITUDE: 29° 52.0' N ( 29.86608) LONGITUDE: 89° 40.5' W ( -89.67428)
The bench mark is a flange-encased rod, located 55.2 m (181.1 ft) NNE of the
pole located in the end of the rock jetty, 52.7 m (172.9 ft) SSW of the 30
degree curve in the centerline of the rock jetty, 22.6 m (74.1 ft) East of the
Rock Jetty centerline, 2.4 m (7.9 ft) west of the NE edge of the salt marsh
grass line, and 0.6 m (2.0 ft) WNW of the carsonite witness post. The datum
point is set level with the ground, being the top of a stainless steel rod in a
sleeve, driven 27.4 m (90 ft) to refusal, and encased in a 5-inch PVC pipe with
logo cap.
BENCH MARK STAMPING: 1305 G 2008
DESIGNATION: 876 1305 G
MONUMENTATION: Flange-encased Rod VM#: 18820
AGENCY: IDB PID#:
SETTING CLASSIFICATION: Stainless steel rod in sleeve OPUS PID:
LATITUDE: 29° 51.9' N ( 29.86564) LONGITUDE: 89° 40.5' W ( -89.67486)
The bench mark is a flange-encased rod, located 61.3 m (201.1 ft) SSW of the 15
degree curve in the centerline of the rock jetty, 39.0 m (128.0 ft) NNE of the
north edge of the salt marsh grass line, 22.9 m (75.1 ft) SSW of the pole
located in the end of the Rock Jetty, 8.5 m (27.9 ft) west of the west edge of
the salt marsh grass line, and 0.7 m (2.3 ft) west of the carsonite witness
post. The datum point is set level with the ground, being the top of a
stainless steel rod in a sleeve, driven to 27.4 m (90 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 8
Station ID: 8761305 PUBLICATION DATE: 03/07/2018
Name: SHELL BEACH, LAKE BORGNE
LA
NOAA Chart: 11371 Latitude: 29° 52.1' N ( 29.86811)
USGS Quad: YSCLOSKEY KEY Longitude: 89° 40.4' W ( -89.67325)
T I D A L B E N C H M A R K S
BENCH MARK STAMPING: 1305 SPIP 2008
DESIGNATION: 876 1305 SPIP
MONUMENTATION: Bench Mark disk VM#: 18822
AGENCY: NOS IDB PID#:
SETTING CLASSIFICATION: Davit plate on platform OPUS PID:
LATITUDE: 29° 52.1' N ( 29.86811) LONGITUDE: 89° 40.4' W ( -89.67325)
The bench mark is a disk set flush in the top of the SE corner of the davit
plate located on the NW corner of the 10m x 10m raised platform, 3.2 m (10.5 ft)
NW of the SE corner of the 10m x 10m raised platform, 2.3 m (7.5 ft) NE of the
SW corner of the 10m x 10m raised platform, 2.2 m (7.2 ft) SW of the NE corner
of the 10m x 10m raised platform, and 1.6 m (5.2 ft) SE of the NW corner of the
10m x 10m raised platform.
BENCH MARK STAMPING: 1305 H 2009
DESIGNATION: 876 1305 H
MONUMENTATION: Flange-encased Rod VM#: 19422
AGENCY: National Ocan Survey/Sevic (NOS) IDB PID#:
SETTING CLASSIFICATION: Stainless steel rod in sleeve OPUS PID:
LATITUDE: 29° 51.9' N ( 29.86511) LONGITUDE: 89° 40.5' W ( -89.67528)
The bench mark is a flange-encased rod located 60.00 m (196.8 ft) south of bench
mark 1305 G 2008, 20.30 m (66.6 ft) south of a triangular shaped piece of
concrete sticking out of the water, 2.0 m (6.5 ft) east of the waterline, 1.0 m
(3.3 ft) west of the witness post, and 0.7 m (2.3 ft) west of the carsonite
witness post. The datum point is set level with the ground, being the top of a
stainless steel rod in a sleeve, driven 27.4 m (90 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 5 of 8
Station ID: 8761305 PUBLICATION DATE: 03/07/2018
Name: SHELL BEACH, LAKE BORGNE
LA
NOAA Chart: 11371 Latitude: 29° 52.1' N ( 29.86811)
USGS Quad: YSCLOSKEY KEY Longitude: 89° 40.4' W ( -89.67325)
T I D A L B E N C H M A R K S
BENCH MARK STAMPING: 1305 J 2009
DESIGNATION: 876 1305 J
MONUMENTATION: Flange-encased Rod VM#: 19423
AGENCY: National Ocean Survey/Service (NOS) IDB PID#:
SETTING CLASSIFICATION: Stainless steel rod in sleeve OPUS PID:
LATITUDE: 29° 51.9' N ( 29.86458) LONGITUDE: 89° 40.5' W ( -89.67528)
The bench mark is a flange-encased rod, located 60.00 m (196.8 ft) SSW of bench
mark 1305 H 2009, 4.0 m (13.12 ft) east of the waterline, 3.5 m (11.5 ft) east
of the edge of the old road, 0.30 m (0.98 ft) west of the witness post, and 0.30
(0.98 ft) west of the carsonite witness post. The datum point is set level with
the ground, being the top of a stainless steel rod in a sleeve, driven 27.4 m
(90 ft) to refusal, and encased in a 5-inch PVC pipe with logo cap.
BENCH MARK STAMPING: 1305 K 2009
DESIGNATION: 876 1305 K
MONUMENTATION: Flange-encased Rod VM#: 19424
AGENCY: National Ocean Survey/Service (NOS) IDB PID#:
SETTING CLASSIFICATION: Stainless steel rod in sleeve OPUS PID:
LATITUDE: 29° 51.8' N ( 29.86400) LONGITUDE: 89° 40.5' W ( -89.67500)
The bench mark is a flange-encased rod located 60.00 m (196.8 ft) SSW of bench
mark 1305 J 2009, 14.7 m (48.2 ft) west of two old fence posts, 3 m (9.8 ft)
east of the waterline, 1.0 m (3.28 ft) west of the witness post, and 1.0 m (
3.28 ft) west of the carsonite witness post. The datum point is evel with the
ground, being the top of a stainless steel rod in a sleeve, driven 27.4 m (90
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 6 of 8
Station ID: 8761305 PUBLICATION DATE: 03/07/2018
Name: SHELL BEACH, LAKE BORGNE
LA
NOAA Chart: 11371 Latitude: 29° 52.1' N ( 29.86811)
USGS Quad: YSCLOSKEY KEY Longitude: 89° 40.4' W ( -89.67325)
T I D A L B E N C H M A R K S
BENCH MARK STAMPING: 1305 M 2016
DESIGNATION: 876 1305 M
MONUMENTATION: Metal Rod VM#: 21885
AGENCY: National Ocean Service (NOS) IDB PID#:
SETTING CLASSIFICATION: Flange encased rod OPUS PID:
LATITUDE: 29° 51.8' N ( 29.86306) LONGITUDE: 89° 40.5' W ( -89.67456)
The bench mark is a rod ,10.00 m (32.8 ft) SE of the waterline, 22.5 m (73.8 ft)
S of No Tresspassing sign post, 2.91 m (9.55 ft) S of timber piling stump, and
0.45 m (1.5 ft) W of the witness post. The top of the rod is level with the
ground, encased in a 5-inch pvc pipe with logo cap 0.45 m (1.5 ft) W of the
carsonite witness post, driven 33.5m (110 ft) into the ground.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 7 of 8
Station ID: 8761305 PUBLICATION DATE: 03/07/2018
Name: SHELL BEACH, LAKE BORGNE
LA
NOAA Chart: 11371 Latitude: 29° 52.1' N ( 29.86811)
USGS Quad: YSCLOSKEY KEY Longitude: 89° 40.4' W ( -89.67325)
T I D A L D A T U M S
Tidal datums at SHELL BEACH, LAKE BORGNE based on:
LENGTH OF SERIES: 6 YEARS
TIME PERIOD: 7/09-6/11,1/12-12/12,1/14-12/15,6/16-5/17
TIDAL EPOCH: 1983-2001
CONTROL TIDE STATION: 8747437 BAY WAVELAND YACHT CLUB, BAY ST. LOUIS
Elevations of tidal datums referred to Mean Lower Low Water (MLLW), in METERS:
HIGHEST OBSERVED WATER LEVEL (08/29/2012) = 3.302
MEAN HIGHER HIGH WATER MHHW = 0.447
MEAN HIGH WATER MHW = 0.425
MEAN SEA LEVEL MSL = 0.229
MEAN TIDE LEVEL MTL = 0.225
North American Vertical Datum NAVD88 = 0.218
MEAN LOW WATER MLW = 0.025
MEAN LOWER LOW WATER MLLW = 0.000
LOWEST OBSERVED WATER LEVEL (08/25/2008) = -0.825
North American Vertical Datum (NAVD88)
Bench Mark Elevation Information In METERS above:
Stamping or Designation MLLW MHW
1305 E 2008 0.444 0.019
1305 D 2008 0.629 0.204
1305 C 2008 0.586 0.161
1305 F 2008 0.507 0.082
1305 G 2008 0.504 0.079
1305 SPIP 2008 8.045 7.620
1305 H 2009 0.725 0.300
1305 J 2009 0.735 0.310
1305 K 2009 0.775 0.350
1305 M 2016 0.545 0.120
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 8 of 8
Station ID: 8761305 PUBLICATION DATE: 03/07/2018
Name: SHELL BEACH, LAKE BORGNE
LA
NOAA Chart: 11371 Latitude: 29° 52.1' N ( 29.86811)
USGS Quad: YSCLOSKEY KEY Longitude: 89° 40.4' W ( -89.67325)
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.