U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Datums Page Page 1 of 7
Station ID: 8513825 PUBLICATION DATE: 05/31/2005
Name: SMITH POINT BRIDGE, NARROW BAY
NY
NOAA Chart: 12353 Latitude: 40° 44.3' N ( 40.73830)
USGS Quad: PATTERSQUASH ISLAND Longitude: 72° 52.1' W ( -72.86830)
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 7.4 km (4.6 mi) 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
DESIGNATION: 851 3825 B
MONUMENTATION: Bench Mark disk VM#: 4855
AGENCY: US Coastal and Geodetic Survey
(USC&GS) IDB PID#:
SETTING CLASSIFICATION: Concrete sidewalk OPUS PID:
LATITUDE: 40° 44.3' N ( 40.73830) LONGITUDE: 72° 52.1' W ( -72.86830)
The primary bench mark is a disk set flush in the concrete sidewalk over the NE
corner abutment of Smith Point Bridge, 6 m (20 ft) south of the northeasternmost
steel handrail post, 5.43 m (17.8 ft) east of the centeline of William Floyd
Parkway, and 0.24 m (0.8 ft) south of the SE corner of a square steel manhole
cover in the sidewalk.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 2 of 7
Station ID: 8513825 PUBLICATION DATE: 05/31/2005
Name: SMITH POINT BRIDGE, NARROW BAY
NY
NOAA Chart: 12353 Latitude: 40° 44.3' N ( 40.73830)
USGS Quad: PATTERSQUASH ISLAND Longitude: 72° 52.1' W ( -72.86830)
T I D A L B E N C H M A R K S
BENCH MARK STAMPING: H 378 1956
DESIGNATION: 851 3825 H 378
MONUMENTATION: Bench Mark disk VM#: 4852
AGENCY: US Coastal and Geodetic Survey
(USC&GS) IDB PID#: KU0235
SETTING CLASSIFICATION: Concrete monument OPUS PID:
LATITUDE: 40° 45.1' N ( 40.75170) LONGITUDE: 72° 52.3' W ( -72.87170)
The bench mark is a disk set in a concrete monument, 4.1 km (2.6 mi) 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, 7 m
(23 ft) south of the center- line of West Minster Drive, 1.10 m (3.6 ft) south
of power pole #18, and 0.03 m (0.1 ft) above ground level.
BENCH MARK STAMPING: END NO 1 1962
DESIGNATION: 851 3825 END TIDAL 1
MONUMENTATION: Bench Mark disk VM#: 4853
AGENCY: US Coastal and Geodetic Survey
(USC&GS) IDB PID#: AE4708
SETTING CLASSIFICATION: Concrete sidwalk OPUS PID:
LATITUDE: 40° 44.3' N ( 40.73830) LONGITUDE: 72° 52.1' W ( -72.86830)
The bench mark is a disk set flush in the concrete sidewalk at the SW end of the
Smith Point Bridge, 6.40 m (21.0 ft) SE of the SE corner of the southwestern
corner concrete block of the bridge, 5.67 m (18.6 ft) west of the centerline of
William Floyd Parkway, and 1.83 m (6.0 ft) east of a wooden railing.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 3 of 7
Station ID: 8513825 PUBLICATION DATE: 05/31/2005
Name: SMITH POINT BRIDGE, NARROW BAY
NY
NOAA Chart: 12353 Latitude: 40° 44.3' N ( 40.73830)
USGS Quad: PATTERSQUASH ISLAND Longitude: 72° 52.1' W ( -72.86830)
T I D A L B E N C H M A R K S
BENCH MARK STAMPING: 3825 A 1989
DESIGNATION: 851 3825 A
MONUMENTATION: Bench Mark disk VM#: 4854
AGENCY: US Coastal and Geodetic Survey
(USC&GS) IDB PID#:
SETTING CLASSIFICATION: Concrete base OPUS PID#: BBDB78
LATITUDE: 40° 44.3' N ( 40.73830) LONGITUDE: 72° 52.1' W ( -72.86830)
The bench mark is a disk set flush in the SW corner of the 2 m x 2 m (6 ft x 6
ft) concrete base of an antenna at the administration building of Smith Point
Bridge, 7.62 m (25.0 ft) SSW of the SE corner of the building, 4 m (15 ft) SSE
of the SW corner of the building, 4.69 m (15.4 ft) ENE of the east curb of the
southbound lane of the highway, and 0.15 m (0.5 ft) above ground level.
BENCH MARK STAMPING: 3825 C 1989
DESIGNATION: 851 3825 C
MONUMENTATION: Bench Mark disk VM#: 4856
AGENCY: US Coastal and Geodetic Survey
(USC&GS) IDB PID#:
SETTING CLASSIFICATION: Stainless steel rod OPUS PID:
LATITUDE: 40° 44.3' N ( 40.73830) LONGITUDE: 72° 52.1' W ( -72.86830)
The bench mark is a disk 76.05 m (249.5 ft) south of the SW corner of the
southwestern corner concrete block of Smith Point Bridge, 23.47 m (77.0 ft) west
of the centerline of William Floyd Parkway, and 1.31 m (4.3 ft) east of a 1 m (4
ft) high chain link fence and witness post. The bench mark is 0.09 m (0.3 ft)
below ground level, crimped to a stainless steel rod driven 21 m (68 ft) 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 4 of 7
Station ID: 8513825 PUBLICATION DATE: 05/31/2005
Name: SMITH POINT BRIDGE, NARROW BAY
NY
NOAA Chart: 12353 Latitude: 40° 44.3' N ( 40.73830)
USGS Quad: PATTERSQUASH ISLAND Longitude: 72° 52.1' W ( -72.86830)
T I D A L B E N C H M A R K S
BENCH MARK STAMPING: SMITH POINT SET 1989
DESIGNATION: 851 3825 SMITH POINT SET
MONUMENTATION: Bench Mark disk VM#: 4857
AGENCY: US Coastal and Geodetic Survey
(USC&GS) IDB PID#:
SETTING CLASSIFICATION: Concrete sidewalk OPUS PID:
LATITUDE: 40° 44.3' N ( 40.73830) LONGITUDE: 72° 52.1' W ( -72.86830)
The bench mark is a disk set flush in the concrete sidewalk over the easternmost
of two pedestrian underpasses at Smith Point Park, 5.79 m (19.0 ft) NW of the
centerline of the westbound lanes of the park, 0.98 m (3.2 ft) SE of the
concrete handrail, and 0.82 m (2.7 ft) NE of the SW edge of the sidewalk.
BENCH MARK STAMPING: 2 993
DESIGNATION: 851 3825 2 993
MONUMENTATION: Bench Mark disk VM#: 4858
AGENCY: US Coastal and Geodetic Survey
(USC&GS) IDB PID#:
SETTING CLASSIFICATION: Concrete monument OPUS PID:
LATITUDE: 40° 44.3' N ( 40.73830) LONGITUDE: 72° 52.1' W ( -72.86830)
The bench mark is a disk set in a concrete monument at the eastern turnaround at
Smith Point Park, 21.46 m (70.4 ft) SSE of the centerline of the westbound
lanes, 20.63 m (67.7 ft) SSW of the center of an hexagonal-shaped flower garden
ringed by railroad ties and posts, 6.55 m (21.5 ft) NNW of the centerline of the
eastbound lanes, and at ground level.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 5 of 7
Station ID: 8513825 PUBLICATION DATE: 05/31/2005
Name: SMITH POINT BRIDGE, NARROW BAY
NY
NOAA Chart: 12353 Latitude: 40° 44.3' N ( 40.73830)
USGS Quad: PATTERSQUASH ISLAND Longitude: 72° 52.1' W ( -72.86830)
T I D A L B E N C H M A R K S
BENCH MARK STAMPING: 2 994
DESIGNATION: 851 3825 2 994
MONUMENTATION: Bench Mark disk VM#: 4859
AGENCY: US Coastal and Geodetic Survey
(USC&GS) IDB PID#:
SETTING CLASSIFICATION: Concrete Monument OPUS PID:
LATITUDE: 40° 44.3' N ( 40.73830) LONGITUDE: 72° 52.1' W ( -72.86830)
The bench mark is a disk 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, 23.29 m (76.4 ft) north of the south end of
the triangle, 21.88 m (71.8 ft) SE of the NW end of the triangle, 8.63 m (28.3
ft) 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 6 of 7
Station ID: 8513825 PUBLICATION DATE: 05/31/2005
Name: SMITH POINT BRIDGE, NARROW BAY
NY
NOAA Chart: 12353 Latitude: 40° 44.3' N ( 40.73830)
USGS Quad: PATTERSQUASH ISLAND Longitude: 72° 52.1' W ( -72.86830)
T I D A L D A T U M S
Tidal datums at SMITH POINT BRIDGE, NARROW BAY based on:
LENGTH OF SERIES: 1 YEAR
TIME PERIOD: February 1990 - January 1991
TIDAL EPOCH: 1983-2001
CONTROL TIDE STATION: 8510560 MONTAUK, FORT POND BAY
Elevations of tidal datums referred to Mean Lower Low Water (MLLW), in METERS:
HIGHEST OBSERVED WATER LEVEL (12/04/1990) = 0.978
MEAN HIGHER HIGH WATER MHHW = 0.446
MEAN HIGH WATER MHW = 0.397
MEAN SEA LEVEL MSL = 0.224
MEAN TIDE LEVEL MTL = 0.216
MEAN LOW WATER MLW = 0.036
MEAN LOWER LOW WATER MLLW = 0.000
LOWEST OBSERVED WATER LEVEL (02/21/1990) = -0.372
North American Vertical Datum (NAVD88)
Bench Mark Elevation Information In METERS above:
Stamping or Designation MLLW MHW
3825 B 1989 4.645 4.248
H 378 1956 2.389 1.992
END NO 1 1962 3.999 3.602
3825 A 1989 2.806 2.409
3825 C 1989 1.565 1.168
SMITH POINT SET 1989 5.511 5.114
2 993 4.941 4.544
2 994 5.755 5.358
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 7 of 7
Station ID: 8513825 PUBLICATION DATE: 05/31/2005
Name: SMITH POINT BRIDGE, NARROW BAY
NY
NOAA Chart: 12353 Latitude: 40° 44.3' N ( 40.73830)
USGS Quad: PATTERSQUASH ISLAND Longitude: 72° 52.1' W ( -72.86830)
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.