U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Datums Page Page 1 of 5
PUBLICATION DATE: 08/21/1991
Station ID: 8513825 SUPERCEDED DATE: 04/21/2003
Name: SMITH POINT BRIDGE, NARROW BAY
NEW YORK
NOAA Chart: 12353 Latitude: 40° 44.3' N
USGS Quad: PATTERSQUASHISLAND Longitude: 72° 52.1' W
To reach the tidal bench marks from the intersection of Sunrise Highway (State
Highway 27) and William Floyd Parkway (County Highway 46), proceed south on
William Floyd Parkway for 4.6 miles (7.4 km) to the north end of the higway
bridge over Narrow Bay. The tidal bench marks are along William Floyd Parkway
and at Smith Point Park. The tide gage and staff were on the north side of the
NE bridge fender.
T I D A L B E N C H M A R K S
PRIMARY BENCH MARK STAMPING: 3825 B 1989
MONUMENTATION: Survey Disk VM#: 4855
AGENCY: PID:
SETTING CLASSIFICATION: Concrete Sidewalk
The bench mark is set flush in the concrete sidewalk over the NE corner abutment
of Smith Point Bridge, 20.1 feet (6.1 m) south of the northeasternmost steel
handrail post, 17.8 feet (5.4 m) east of the centeline of William Floyd Parkway,
and 0.8 foot (0.2 m) south of the SE corner of a square steel manhole cover in
the sidewalk.
BENCH MARK STAMPING: H 378 1956
MONUMENTATION: Survey Disk VM#: 4852
AGENCY: PID#: KU0235
SETTING CLASSIFICATION: Concrete Monument
The bench mark is set in a concrete monument, 2.55 miles (4.11 km) south along
William Floyd Parkway from its intersection with State Highway 27, at the SW
corner of the intersection of William Floyd Parkway and West Minster Drive, 23
feet (7 m) south of the center- line of West Minster Drive, 3.6 feet (1.1 m)
south of power pole #18, and 0.1 foot (0.03 m) above ground level.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 2 of 5
PUBLICATION DATE: 08/21/1991
Station ID: 8513825 SUPERCEDED DATE: 04/21/2003
Name: SMITH POINT BRIDGE, NARROW BAY
NEW YORK
NOAA Chart: 12353 Latitude: 40° 44.3' N
USGS Quad: PATTERSQUASHISLAND Longitude: 72° 52.1' W
T I D A L B E N C H M A R K S
BENCH MARK STAMPING: END NO 1 1962
MONUMENTATION: Survey Disk VM#: 4853
AGENCY: PID#: AE4708
SETTING CLASSIFICATION: Concrete Sidewalk
The bench mark is set flush in the concrete sidewalk at the SW end of the Smith
Point Bridge, 21.0 feet (6.4 m) SSE of the SE corner of the southwestern corner
concrete block of the bridge, 18.6 feet (5.7 m) west of the centerline of
William Floyd Parkway, and 6.0 feet (1.8 m) east of a wooden railing.
BENCH MARK STAMPING: 3825 A 1989
MONUMENTATION: Survey Disk VM#: 4854
AGENCY: PID:
SETTING CLASSIFICATION: Concrete Base
The bench mark is set flush in the SW corner of the 6 x 6-foot (2x2 m) concrete
base of an antenna at the administration building of Smith Point Bridge, 25.0
feet (7.6 m) SSW of the SE corner of the building, 15 feet (4 m) SSE of the SW
corner of the building, 15.4 feet (4.7 m) ENE of the east curb of the southbound
lane of the highway, and 0.5 foot (0.2 m) above ground level.
BENCH MARK STAMPING: 3825 C 1989
MONUMENTATION: Survey Disk VM#: 4856
AGENCY: PID:
SETTING CLASSIFICATION: Stainless Steel Rod
The bench mark is 249.5 feet (76.0 m) south of the SW corner of the southwestern
corner concrete block of Smith Point Bridge, 77.0 feet (23.5 m) west of the
centerline of William Floyd Parkway, and 4.3 feet (1.3 m) east of a 4-foot (1 m)
high chain link fence and witness post. The bench mark is 0.3 foot (0.1 m)
below ground level, crimped to a stainless steel rod driven 68 feet (21 m) to
substantial resistance, and encased in a 5-inch PVC pipe and concrete kickblock.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 3 of 5
PUBLICATION DATE: 08/21/1991
Station ID: 8513825 SUPERCEDED DATE: 04/21/2003
Name: SMITH POINT BRIDGE, NARROW BAY
NEW YORK
NOAA Chart: 12353 Latitude: 40° 44.3' N
USGS Quad: PATTERSQUASHISLAND Longitude: 72° 52.1' W
T I D A L B E N C H M A R K S
BENCH MARK STAMPING: SMITH POINT SET 1989
MONUMENTATION: Survey Disk VM#: 4857
AGENCY: PID:
SETTING CLASSIFICATION: Concrete Sidewalk
The bench mark is set flush in the concrete sidewalk over the easternmost of two
pedestrian underpasses at Smith Point Park, 19.0 feet (5.8 m) NW of the
centerline of the westbound lanes of the park, 3.2 feet (1.0 m) SE of the
concrete handrail, and 2.7 feet (0.8 m) NE of the SW edge of the sidewalk.
BENCH MARK STAMPING: 2 993
MONUMENTATION: Survey Disk VM#: 4858
AGENCY: PID:
SETTING CLASSIFICATION: Concrete Monument
The bench mark is set in a concrete monument at the eastern turnaround at Smith
Point Park, 70.4 feet (21.5 m) SSE of the centerline of the westbound lanes,
67.7 feet (20.6 m) SSW of the center of an hexagonal-shaped flower garden ringed
by railroad ties and posts, 21.5 feet (6.6 m) NNW of the centerline of the
eastbound lanes, and at ground level.
BENCH MARK STAMPING: 2 994
MONUMENTATION: Survey Disk VM#: 4859
AGENCY: PID:
SETTING CLASSIFICATION: Concrete Monument
The bench mark is set in a concrete monument in the triangular shaped grass
median on the east side of the traffic circle at the south end of William Floyd
Parkway at Smith Point Park, 76.4 feet (23.3 m) north of the south end of the
triangle, 71.8 feet (21.9 m) SE of the NW end of the triangle, 28.3 feet
(8.6 m) east of the centerline of the traffic circle, and at ground level.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 4 of 5
PUBLICATION DATE: 08/21/1991
Station ID: 8513825 SUPERCEDED DATE: 04/21/2003
Name: SMITH POINT BRIDGE, NARROW BAY
NEW YORK
NOAA Chart: 12353 Latitude: 40° 44.3' N
USGS Quad: PATTERSQUASHISLAND Longitude: 72° 52.1' W
T I D A L D A T U M S
Tidal datums at SMITH POINT BRIDGE, NARROW BAY based on:
LENGTH OF SERIES: 12 MONTHS
TIME PERIOD: FEBRUARY 1990-JANUARY1991
TIDAL EPOCH: 1960-1978
CONTROL TIDE STATION: 8518750 THE BATTERY
Elevations of tidal datums referred to Mean Lower Low Water (MLLW), in FEET:
HIGHEST OBSERVED WATER LEVEL (12/04/1990) = 3.41
MEAN HIGHER HIGH WATER MHHW = 1.47
MEAN HIGH WATER MHW = 1.31
MEAN TIDE LEVEL MTL = 0.71
MEAN LOW WATER MLW = 0.12
MEAN LOWER LOW WATER MLLW = 0.00
* NATIONAL GEODETIC VERTICAL DATUM NGVD29 = -0.06
LOWEST OBSERVED WATER LEVEL (12/09/1989) = -1.07
* NGVD reference based on elevations published in Quad 400724, 1968, and NOS
leveling of 1991.
North American Vertical Datum (NAVD88)
Bench Mark Elevation Information In FEET above:
Stamping or Designation MLLW MHW
3825 B 1989 15.44 14.13
H 378 1956 8.04 6.73
END NO 1 1962 13.32 12.01
3825 A 1989 9.41 8.10
3825 C 1989 5.34 4.03
SMITH POINT SET 1989 18.28 16.97
2 993 16.41 15.10
2 994 19.08 17.77
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 5 of 5
PUBLICATION DATE: 08/21/1991
Station ID: 8513825 SUPERCEDED DATE: 04/21/2003
Name: SMITH POINT BRIDGE, NARROW BAY
NEW YORK
NOAA Chart: 12353 Latitude: 40° 44.3' N
USGS Quad: PATTERSQUASHISLAND Longitude: 72° 52.1' 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.