Published Bench Mark Sheet for 8515921 LLOYD HARBOR NEW LIGHTHOUSE, LONG ISLAND SOUND NEW YORK
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Datums Page Page 1 of 4
PUBLICATION DATE: 02/10/1992
Station ID: 8515921 SUPERCEDED DATE: 04/21/2003
Name: LLOYD HARBOR NEW LIGHTHOUSE, LONG ISLAND SOUND
NEW YORK
NOAA Chart: 12365 Latitude: 40° 54.6' N
USGS Quad: LLOYD HARBOR Longitude: 73° 25.9' W
To reach the tidal bench marks from New York City, proceed east on Long Island
Expressway for 22 miles (35 km) to State Highway 110, go north on State Highway
110 to Huntington Harbor in Huntington, then continue by boat along the
privately maintained harbor channel for approximately 2.5 miles (4.0 km) to
Lloyd Harbor. The bench marks are in the lighthouse foundation and in the
boulders surrounding the lighthouse base. The tide gauge and staff were about
30 feet (9 m) SW of the lighthouse.
T I D A L B E N C H M A R K S
PRIMARY BENCH MARK STAMPING: 5921 A 1990
MONUMENTATION: Survey Disk VM#: 5101
AGENCY: PID:
SETTING CLASSIFICATION: Boulder
The primary bench mark is set in a 6-foot (2 x 2 m) boulder, 5.0 feet (1.5 m)
east of the SE corner of the lighthouse.
BENCH MARK STAMPING: 5921 B 1990
MONUMENTATION: Survey Disk VM#: 5102
AGENCY: PID:
SETTING CLASSIFICATION: Concrete Foundation
The bench mark is set in the foundation of the lighthouse, 2.0 feet (0.6 m) east
of the NE corner of the lighthouse.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 2 of 4
PUBLICATION DATE: 02/10/1992
Station ID: 8515921 SUPERCEDED DATE: 04/21/2003
Name: LLOYD HARBOR NEW LIGHTHOUSE, LONG ISLAND SOUND
NEW YORK
NOAA Chart: 12365 Latitude: 40° 54.6' N
USGS Quad: LLOYD HARBOR Longitude: 73° 25.9' W
T I D A L B E N C H M A R K S
BENCH MARK STAMPING: 5921 C 1990
MONUMENTATION: Survey Disk VM#: 5103
AGENCY: PID:
SETTING CLASSIFICATION: Boulder
The bench mark is set in a 4 x 6-foot (1 x 2 m) boulder, 30 feet (9 m) north of
the NW corner of the lighthouse.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 3 of 4
PUBLICATION DATE: 02/10/1992
Station ID: 8515921 SUPERCEDED DATE: 04/21/2003
Name: LLOYD HARBOR NEW LIGHTHOUSE, LONG ISLAND SOUND
NEW YORK
NOAA Chart: 12365 Latitude: 40° 54.6' N
USGS Quad: LLOYD HARBOR Longitude: 73° 25.9' W
T I D A L D A T U M S
Tidal datums at LLOYD HARBOR NEW LIGHTHOUSE, LONG ISLAND SOUND based on:
LENGTH OF SERIES: 2 MONTHS
TIME PERIOD: JULY-AUGUST 1990
TIDAL EPOCH: 1960-1978
CONTROL TIDE STATION: 8518490 NEW ROCHELLE
Elevations of tidal datums referred to Mean Lower Low Water (MLLW), in FEET:
HIGHEST OBSERVED WATER LEVEL (08/20/1990) = 9.52
MEAN HIGHER HIGH WATER (MHHW) = 7.60
MEAN HIGH WATER (MHW) = 7.24
MEAN TIDE LEVEL (MTL) = 3.73
MEAN LOW WATER (MLW) = 0.22
MEAN LOWER LOW WATER (MLLW) = 0.00
LOWEST OBSERVED WATER LEVEL (06/22/1990) = -0.63
National Geodetic Vertical Datum (NGVD 29)
Bench Mark Elevation Information In FEET above:
Stamping or Designation MLLW MHW
5921 A 1990 7.05 -0.19
5921 B 1990 11.03 3.79
5921 C 1990 10.95 3.71
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 4 of 4
PUBLICATION DATE: 02/10/1992
Station ID: 8515921 SUPERCEDED DATE: 04/21/2003
Name: LLOYD HARBOR NEW LIGHTHOUSE, LONG ISLAND SOUND
NEW YORK
NOAA Chart: 12365 Latitude: 40° 54.6' N
USGS Quad: LLOYD HARBOR Longitude: 73° 25.9' 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 (NAVD 88).
NGVD 29 is a fixed datum adopted as a national standard geodetic reference for
heights but is now considered superseded. NGVD 29 is sometimes referred to as
Sea Level Datum of 1929 or as Mean Sea Level on some early issues of Geological
Survey Topographic Quads. NGVD 29 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 NGVD 29 are available from the National
Geodetic Survey (NGS) data base via the World Wide Web at
National Geodetic Survey.
NAVD 88 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. NAVD 88 replaces NGVD 29 as the national
standard geodetic reference for heights. Bench mark elevations relative to
NAVD 88 are available from NGS through the World Wide Web at
National Geodetic Survey.
NGVD 29 and NAVD 88 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 NAVD 88 elevation is shown on the Elevations of Tidal Datums Table Referred
to MLLW only when two or more of the bench marks listed have NAVD 88 elevations.
The NAVD 88 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, NAVD 88 bench mark elevations computed indirectly from the tidal
datums elevation table may differ slightly from NAVD 88 elevations listed for
each bench mark in the NGS database.
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