U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Datums Page Page 1 of 4
PUBLICATION DATE: 02/11/1992
Station ID: 8516614 SUPERCEDED DATE: 04/21/2003
Name: GLEN COVE, HEMPSTEAD HARBOR, LONG ISLAND SOUND
NEW YORK
NOAA Chart: 12366 Latitude: 40° 51.8' N
USGS Quad: SEA CLIFF Longitude: 73° 39.3' W
To reach the tidal bench marks from the Glen Cove firehouse at the intersection
of Glen Cove Road and Glen Cove Avenue, proceed south on Glen Cove Avenue, take
the first right onto Charles Street, then left on The Place (bends to right and
becomes Elwood Street), then left on McLoughlin to the end of the street at Glen
Cove Yacht Club. The bench marks are in the retaining wall of the dock. The
tide gauge and staff were at the west end of the dock.
T I D A L B E N C H M A R K S
PRIMARY BENCH MARK STAMPING: NO 3 1934
MONUMENTATION: Survey Disk VM#: 7088
AGENCY: PID#: KU1595
SETTING CLASSIFICATION: Concrete Retaining Wall
The primary bench mark is set in the top of the north concrete retaining wall at
the junction of a low wire fence and a high wire fence, and about 151 feet (46
m) east of Bench Mark NO 2 1934.
BENCH MARK STAMPING: NO 1 1934
MONUMENTATION: Survey Disk VM#: 7086
AGENCY: PID#: KU1594
SETTING CLASSIFICATION: Concrete Retaining Wall
The bench mark is set in the top of the west end of the south concrete retaining
wall at the SW corner of the dock, and about 13 feet (4 m) south of a concrete
ramp leading to a boat landing.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 2 of 4
PUBLICATION DATE: 02/11/1992
Station ID: 8516614 SUPERCEDED DATE: 04/21/2003
Name: GLEN COVE, HEMPSTEAD HARBOR, LONG ISLAND SOUND
NEW YORK
NOAA Chart: 12366 Latitude: 40° 51.8' N
USGS Quad: SEA CLIFF Longitude: 73° 39.3' W
T I D A L B E N C H M A R K S
BENCH MARK STAMPING: NO 2 1934
MONUMENTATION: Survey Disk VM#: 7087
AGENCY: PID#: KU1593
SETTING CLASSIFICATION: Concrete Retaining Wall
The bench mark is set in the top of the north concrete retaining wall, 102 feet
(31 m) north of Bench Mark NO 1 1934, and 39 feet (12 m) east of the west end of
the retaining wall.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 3 of 4
PUBLICATION DATE: 02/11/1992
Station ID: 8516614 SUPERCEDED DATE: 04/21/2003
Name: GLEN COVE, HEMPSTEAD HARBOR, LONG ISLAND SOUND
NEW YORK
NOAA Chart: 12366 Latitude: 40° 51.8' N
USGS Quad: SEA CLIFF Longitude: 73° 39.3' W
T I D A L D A T U M S
Tidal datums at GLEN COVE, HEMPSTEAD HARBOR, LONG ISLAND SOUND based on:
LENGTH OF SERIES: 3 MONTHS
TIME PERIOD: JUNE-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) = 9.88
MEAN HIGHER HIGH WATER MHHW = 7.85
MEAN HIGH WATER MHW = 7.49
MEAN TIDE LEVEL MTL = 3.86
* NATIONAL GEODETIC VERTICAL DATUM NGVD29 = 3.22
MEAN LOW WATER MLW = 0.24
MEAN LOWER LOW WATER MLLW = 0.00
LOWEST OBSERVED WATER LEVEL (06/22/1990) = -0.75
* NGVD reference based on adjustment of 1957 and NOS levels of 1990.
North American Vertical Datum (NAVD88)
Bench Mark Elevation Information In FEET above:
Stamping or Designation MLLW MHW
NO 3 1934 15.41 7.92
NO 1 1934 15.01 7.52
NO 2 1934 14.90 7.41
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 4 of 4
PUBLICATION DATE: 02/11/1992
Station ID: 8516614 SUPERCEDED DATE: 04/21/2003
Name: GLEN COVE, HEMPSTEAD HARBOR, LONG ISLAND SOUND
NEW YORK
NOAA Chart: 12366 Latitude: 40° 51.8' N
USGS Quad: SEA CLIFF Longitude: 73° 39.3' 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.