U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Datums Page Page 1 of 5
Station ID: 8466791 PUBLICATION DATE: 08/07/2009
Name: SNIFFENS POINT, HOUSATONIC RIVER
CT
NOAA Chart: 12370 Latitude: 41° 11.2' N ( 41.18670)
USGS Quad: MILFORD Longitude: 73° 6.8' W ( -73.11330)
To reach the tidal bench marks from the intersection of U.S. Highway 1 and Main
Street (State Highway 113) in Stratford, proceed south on Main Street for 3.7 km
(2.3 mi) to the TEXTRON LYCOMING plant, then turn left on Sniffens Lane and
continue east for 1.0 km (0.6 mi) to the Breakwater Key Condominiums at Sniffens
Point. The bench marks are located along Sniffens Lane and the tide gage and
staff were located on the west side of the Breakwater Key marina.
T I D A L B E N C H M A R K S
PRIMARY BENCH MARK STAMPING: 6791 B 1993
DESIGNATION: 846 6791 B
MONUMENTATION: Tidal Station disk VM#: 12456
AGENCY: National Ocean Service (NOS) IDB PID#:
SETTING CLASSIFICATION: Concrete pad OPUS PID:
LATITUDE: 41° 11.2' N ( 41.18670) LONGITUDE: 73° 6.8' W ( -73.11330)
The primary bench mark is a disk set in the NW corner of a 1.62 m x 1.31 m (5.3
ft x 4.3 ft) concrete pad west of Breakwater Key Condominiums, 27.52 m (90.3 ft)
west of a fire hydrant, 6.22 m (20.4 ft) south of the centerline of Sniffens
Lane, 1.98 m (6.5 ft) ESE of power pole Number 3828, and at ground level.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 2 of 5
Station ID: 8466791 PUBLICATION DATE: 08/07/2009
Name: SNIFFENS POINT, HOUSATONIC RIVER
CT
NOAA Chart: 12370 Latitude: 41° 11.2' N ( 41.18670)
USGS Quad: MILFORD Longitude: 73° 6.8' W ( -73.11330)
T I D A L B E N C H M A R K S
BENCH MARK STAMPING: 6791 A 1993
DESIGNATION: 846 6791 A
MONUMENTATION: Tidal Station disk VM#: 12455
AGENCY: National Ocean Service (NOS) IDB PID#:
SETTING CLASSIFICATION: Concrete catch basin OPUS PID:
LATITUDE: 41° 11.2' N ( 41.18670) LONGITUDE: 73° 6.8' W ( -73.11330)
The bench mark is a disk set in the SE end of a concrete catch basin at the SE
end of the westernmost row of condominiums at Breakwater Key development, 15.33
m (50.3 ft) SSE of the SW corner of condo Number 220, 15.09 m (49.5 ft) SW of
the west edge of the marina bulkhead, 3.96 m (13.0 ft) NE of the centerline of
the driveway, and 0.18 m (0.6 ft) above the pavement.
BENCH MARK STAMPING: 6791 C 1993
DESIGNATION: 846 6791 C
MONUMENTATION: Tidal Station disk VM#: 12457
AGENCY: National Ocean Service (NOS) IDB PID#:
SETTING CLASSIFICATION: Concrete foundation OPUS PID#: BBDD48
LATITUDE: 41° 11.2' N ( 41.18670) LONGITUDE: 73° 6.8' W ( -73.11330)
The bench mark is a disk set in the SW corner of a 2.29 m (7.5 ft) square
concrete foundation for a sewer access, 13.14 m (43.1 ft) east of power pole
Number 6071, 11.92 m (39.1 ft) WSW of the employee's entrance at Number 360
Sniffens Lane (Industrial Heating Company), 11.46 m (37.6 ft) north of the
centerline of Sniffens Lane, and 0.09 m (0.3 ft) below ground level.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 3 of 5
Station ID: 8466791 PUBLICATION DATE: 08/07/2009
Name: SNIFFENS POINT, HOUSATONIC RIVER
CT
NOAA Chart: 12370 Latitude: 41° 11.2' N ( 41.18670)
USGS Quad: MILFORD Longitude: 73° 6.8' W ( -73.11330)
T I D A L B E N C H M A R K S
BENCH MARK STAMPING: 6791 D 1993
DESIGNATION: 846 6791 D
MONUMENTATION: Tidal Station disk VM#: 12458
AGENCY: National Ocean Service (NOS) IDB PID#:
SETTING CLASSIFICATION: Concrete footing OPUS PID:
LATITUDE: 41° 11.2' N ( 41.18670) LONGITUDE: 73° 6.8' W ( -73.11330)
The bench mark is a disk set in the east end of a concrete footing for a
crossover pipeline near the contractor's entrance to the TEXTRON plant, 16.79 m
(55.1 ft) SW of the SW corner of a large stone and aluminum building, 9.33 m
(30.6 ft) NNW of the centerline of Sniffens Lane, 6.22 m (20.4 ft) ENE of the SE
corner of the guard shack, and 0.88 m (2.9 ft) above the pavement.
BENCH MARK STAMPING: 6791 E 1993
DESIGNATION: 846 6791 E
MONUMENTATION: Tidal Station disk VM#: 12459
AGENCY: National Ocean Service (NOS) IDB PID#:
SETTING CLASSIFICATION: Concrete pad OPUS PID:
LATITUDE: 41° 11.2' N ( 41.18670) LONGITUDE: 73° 6.8' W ( -73.11330)
The bench mark is a disk set in the NE corner of a 3 m x 2 m (11 ft x 6 ft)
concrete pad in front of the Engineering Technologies Laboratory (Building 6) at
the TEXTRON plant, 19 m (62 ft) west of the centerline of the front entrance
driveway, 14.72 m (48.3 ft) north of the north wall of the building, 14.05 m
(46.1 ft) south of the centerline of Sniffens Lane, and 0.37 m (1.2 ft) above
ground level.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 4 of 5
Station ID: 8466791 PUBLICATION DATE: 08/07/2009
Name: SNIFFENS POINT, HOUSATONIC RIVER
CT
NOAA Chart: 12370 Latitude: 41° 11.2' N ( 41.18670)
USGS Quad: MILFORD Longitude: 73° 6.8' W ( -73.11330)
T I D A L D A T U M S
Tidal datums at SNIFFENS POINT, HOUSATONIC RIVER based on:
LENGTH OF SERIES: 3 MONTHS
TIME PERIOD: June 1993 - August 1993
TIDAL EPOCH: 1983-2001
CONTROL TIDE STATION: 8467150 BRIDGEPORT, BRIDGEPORT HARBOR
Elevations of tidal datums referred to Mean Lower Low Water (MLLW), in METERS:
MEAN HIGHER HIGH WATER MHHW = 2.134
MEAN HIGH WATER MHW = 2.034
MEAN TIDE LEVEL MTL = 1.053
MEAN SEA LEVEL MSL = 1.043
MEAN LOW WATER MLW = 0.073
MEAN LOWER LOW WATER MLLW = 0.000
North American Vertical Datum (NAVD88)
Bench Mark Elevation Information In METERS above:
Stamping or Designation MLLW MHW
6791 B 1993 3.956 1.922
6791 A 1993 3.893 1.859
6791 C 1993 4.384 2.350
6791 D 1993 3.999 1.965
6791 E 1993 3.436 1.402
Foot Notes:
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 5 of 5
Station ID: 8466791 PUBLICATION DATE: 08/07/2009
Name: SNIFFENS POINT, HOUSATONIC RIVER
CT
NOAA Chart: 12370 Latitude: 41° 11.2' N ( 41.18670)
USGS Quad: MILFORD Longitude: 73° 6.8' W ( -73.11330)
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.