U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Datums Page Page 1 of 5
Station ID: 8761534 PUBLICATION DATE: 04/30/2009
Name: BIG POINT, LAKE PONTCHARTRAIN
LA
NOAA Chart: 11369 Latitude: 30° 13.7' N ( 30.22830)
USGS Quad: NORTH SHORE Longitude: 89° 51.2' W ( -89.85330)
To reach the tidal bench marks from the intersection of Carr Drive and U.S.
Highway 11 near the north end of the U.S. Highway 11 bridge over Lake
Pontchartrain, proceed west on Carr Drive for 3.9 km (2.4 mi) to #387 Carr Drive
(Mocklin residence) on the left. The bench marks are to the SE along Carr
Drive. The tide gauge and staff were near the north corner of the covered porch
at the SW end of the pier behind house #387.
T I D A L B E N C H M A R K S
PRIMARY BENCH MARK STAMPING: 1534 A 1982
DESIGNATION: 876 1534 A TIDAL
MONUMENTATION: Tidal Station disk VM#: 11616
AGENCY: National Ocean Survey (NOS) IDB PID#:
SETTING CLASSIFICATION: Stainless steel rod OPUS PID:
LATITUDE: 30° 13.7' N ( 30.22830) LONGITUDE: 89° 51.2' W ( -89.85330)
The primary bench mark is a disk located in front of 387 Carr Drive, 41 m (133
ft) NE of the NE corner of the two-story brick residence, 29 m (94 ft) north of
utility pole #45, 19 m (63 ft) SW of the SW side of the Mocklin dockhouse on the
north side of Carr Drive, 7 m (22 ft) SW of the centerline of Carr Drive, and 3
m (9 ft) SE of a 0.37 m (1.2 ft) diameter oak tree at the NE corner of the
Mocklin property. The bench mark is set 9 cm (0.3 ft) below ground level,
crimped to the top of a stainless steel rod driven 17.1 m (56 ft) 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 5
Station ID: 8761534 PUBLICATION DATE: 04/30/2009
Name: BIG POINT, LAKE PONTCHARTRAIN
LA
NOAA Chart: 11369 Latitude: 30° 13.7' N ( 30.22830)
USGS Quad: NORTH SHORE Longitude: 89° 51.2' W ( -89.85330)
T I D A L B E N C H M A R K S
BENCH MARK STAMPING: 1534 B 1982
DESIGNATION: 876 1534 B TIDAL
MONUMENTATION: Tidal Station disk VM#: 11617
AGENCY: National Ocean Survey (NOS) IDB PID#: AB7178
SETTING CLASSIFICATION: Stainless steel rod OPUS PID:
LATITUDE: 30° 13.8' N ( 30.23000) LONGITUDE: 89° 51.1' W ( -89.85170)
The bench mark is a disk located 84 m (276 ft) SSE of bench mark 1534 A 1982, 80
m (261 ft) ENE of the shore of the lake, 9 m (31 ft) NNW of the centerline of a
boat ramp north of Carr Drive, 6 m (19 ft) ENE of the centerline of Carr Drive,
and 5 m (15 ft) WSW of the SW shore of Facine Canal. The bench mark is set 9 cm
(0.3 ft) below ground level, crimped to the top of a stainless steel rod driven
18.3 m (60 ft) to substantial resistance, and encased in a 4-inch PVC pipe and
concrete kickblock.
BENCH MARK STAMPING: 1534 C 1982
DESIGNATION: 876 1534 C TIDAL
MONUMENTATION: Tidal Station disk VM#: 11618
AGENCY: National Ocean Survey (NOS) IDB PID#:
SETTING CLASSIFICATION: Stainless steel rod OPUS PID:
LATITUDE: 30° 13.7' N ( 30.22830) LONGITUDE: 89° 51.2' W ( -89.85330)
The bench mark is a disk located 64 m (210 ft) south of bench mark 1534 B 1982,
30 m (100 ft) ENE of the NE corner of a two-story contemporary wood house, 16 m
(53 ft) SW of the approximate high water mark of the SW bank of Facine Canal, 8
m (25 ft) SSW of utility pole #43, and 6 m (19 ft) WSW of the centerline of Carr
Drive. The bench mark is set 9 cm (0.3 ft) below ground level, crimped to the
top of a stainless steel rod driven 20.7 m (68 ft) 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 5
Station ID: 8761534 PUBLICATION DATE: 04/30/2009
Name: BIG POINT, LAKE PONTCHARTRAIN
LA
NOAA Chart: 11369 Latitude: 30° 13.7' N ( 30.22830)
USGS Quad: NORTH SHORE Longitude: 89° 51.2' W ( -89.85330)
T I D A L B E N C H M A R K S
BENCH MARK STAMPING: 1534 D 1982
DESIGNATION: 876 1534 D TIDAL
MONUMENTATION: Tidal Station disk VM#: 11619
AGENCY: National Ocean Survey (NOS) IDB PID#:
SETTING CLASSIFICATION: Stainless steel rod OPUS PID:
LATITUDE: 30° 13.7' N ( 30.22830) LONGITUDE: 89° 51.2' W ( -89.85330)
The bench mark is a disk located 75 m (247 ft) SE of bench mark 1534 C 1982, 20
m (65 ft) east of utility pole #42, 9 m (28 ft) SSE of a 0.43 m (1.4 ft)
diameter oak tree located between Carr Drive and Facine Canal, 7 m (24 ft) ENE
of the centerline of Carr Drive, and 5 m (15 ft) SW of the approximate high
water mark of the SW bank of Facine Canal. The bench mark is set 9 cm (0.3 ft)
below ground level, crimped to the top of a stainless steel rod driven 23.2 m
(76 ft) to substantial resistance, and encased in a 4-inch PVC pipe and concrete
kickblock.
BENCH MARK STAMPING: 1534 E 1982
DESIGNATION: 876 1534 E TIDAL
MONUMENTATION: Tidal Station disk VM#: 11620
AGENCY: National Ocean Survey (NOS) IDB PID#:
SETTING CLASSIFICATION: Stainless steel rod OPUS PID:
LATITUDE: 30° 13.7' N ( 30.22830) LONGITUDE: 89° 51.2' W ( -89.85330)
The bench mark is a disk located 81 m (267 ft) SSE of bench mark 1534 D 1982, 29
m (94 ft) SE of utility pole #41, 16 m (54 ft) SSW of utility pole #630, 15 m
(50 ft) WSW of the SW corner of a wood dockhouse located on the SW bank of
Facine Canal, and 5 m (18 ft) WSW of the centerline of Carr Drive. The bench
mark is set 9 cm (0.3 ft) below ground level, crimped to the top of a stainless
steel rod driven 19.5 m (64 ft) 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 4 of 5
Station ID: 8761534 PUBLICATION DATE: 04/30/2009
Name: BIG POINT, LAKE PONTCHARTRAIN
LA
NOAA Chart: 11369 Latitude: 30° 13.7' N ( 30.22830)
USGS Quad: NORTH SHORE Longitude: 89° 51.2' W ( -89.85330)
T I D A L D A T U M S
Tidal datums at BIG POINT, LAKE PONTCHARTRAIN based on:
LENGTH OF SERIES: 1 YEAR
TIME PERIOD: January 1983 - December 1983
TIDAL EPOCH: 1983-2001
CONTROL TIDE STATION: 8761927 USCG NEW CANAL STA., LAKE PONT.
Elevations of tidal datums referred to Mean Lower Low Water (MLLW), in METERS:
MEAN HIGHER HIGH WATER MHHW = 0.155
MEAN HIGH WATER MHW = 0.153
MEAN SEA LEVEL MSL = 0.083
MEAN TIDE LEVEL MTL = 0.077
MEAN LOW WATER MLW = 0.001
MEAN LOWER LOW WATER MLLW = 0.000
North American Vertical Datum (NAVD88)
Bench Mark Elevation Information In METERS above:
Stamping or Designation MLLW MHW
1534 A 1982 0.846 0.693
1534 B 1982 0.793 0.640
1534 C 1982 0.743 0.590
1534 D 1982 0.686 0.533
1534 E 1982 1.083 0.930
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 5 of 5
Station ID: 8761534 PUBLICATION DATE: 04/30/2009
Name: BIG POINT, LAKE PONTCHARTRAIN
LA
NOAA Chart: 11369 Latitude: 30° 13.7' N ( 30.22830)
USGS Quad: NORTH SHORE Longitude: 89° 51.2' W ( -89.85330)
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.