U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Datums Page Page 1 of 6
Station ID: 8466664 PUBLICATION DATE: 04/21/2003
Name: MURPHY'S BOAT YARD, HOUSATONIC RIVER
CT
NOAA Chart: 12370 Latitude: 41° 16.5' N ( 41.27500)
USGS Quad: ANSONIA Longitude: 73° 5.3' W ( -73.08830)
To reach the tidal bench marks from the intersection of U.S. Highway 1 and State
Highway 110 in Stratford, proceed north on State Highway 110 for 8.5 km (5.3 mi)
to Murphy's Boat Yard on the right. The bench marks are located north and south
of the Boat Yard along State Highway 110. The tide gage and staff were located
on the second and first floating docks, respectively, from the south end of the
boat yard.
T I D A L B E N C H M A R K S
PRIMARY BENCH MARK STAMPING: 6664 B 1993
DESIGNATION: 846 6664 B
MONUMENTATION: Tidal Station disk VM#: 12443
AGENCY: National Ocean Service (NOS) IDB PID#:
SETTING CLASSIFICATION: Rock outcrop OPUS PID:
LATITUDE: 40° 16.4' N ( 40.27330) LONGITUDE: 73° 5.4' W ( -73.09000)
The primary bench mark is a disk set in a rock outcrop across State Highway 100
from the driveway of the Autoswage Plant, 59 m (194 ft) north of a fire hydrant
located near power pole Number 1442, 44 m (145 ft) WSW of power pole Nunber
1438, 11.13 m (36.5 ft) WNW of the centerline of the highway, and 1.07 m (3.5
ft) above the base of the outcropping.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 2 of 6
Station ID: 8466664 PUBLICATION DATE: 04/21/2003
Name: MURPHY'S BOAT YARD, HOUSATONIC RIVER
CT
NOAA Chart: 12370 Latitude: 41° 16.5' N ( 41.27500)
USGS Quad: ANSONIA Longitude: 73° 5.3' W ( -73.08830)
T I D A L B E N C H M A R K S
BENCH MARK STAMPING: 6664 A 1993
DESIGNATION: 846 6664 A
MONUMENTATION: Tidal Station disk VM#: 12442
AGENCY: National Ocean Service (NOS) IDB PID#:
SETTING CLASSIFICATION: Concrete block OPUS PID:
LATITUDE: 40° 16.4' N ( 40.27330) LONGITUDE: 73° 5.4' W ( -73.09000)
The bench mark is a disk set in a 2 m x 1 m (6 ft x 3 ft) concrete block at the
south end of Murphy's Boat Yard, 24.69 m (81.0 ft) WSW of the most southerly
dock ramp, 7.13 m (23.4 ft) ENE of the SE corner of the concrete block retaining
wall, 4.51 m (14.8 ft) NW of the centerline of the entrance drive to the boat
yard, and 0.40 m (1.3 ft) above the ground level.
BENCH MARK STAMPING: 6664 C 1993
DESIGNATION: 846 6664 C
MONUMENTATION: Tidal Station disk VM#: 12444
AGENCY: National Ocean Service (NOS) IDB PID#:
SETTING CLASSIFICATION: Concrete pad OPUS PID:
LATITUDE: 40° 16.4' N ( 40.27330) LONGITUDE: 73° 5.4' W ( -73.09000)
The bench mark is a disk set in the NE corner of a 1.83 m x 1.07 m (6.0 ft x 3.5
ft) concrete pad, 27 m (89 ft) east of power pole Number 1443, 25.48 m (83.6 ft)
south of the fire hydrant on the east side of State Highway 110, 17.74 m (58.2
ft) west of the SW corner of the Autoswage Plant, and 0.09 m (0.3 ft) above
ground level.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 3 of 6
Station ID: 8466664 PUBLICATION DATE: 04/21/2003
Name: MURPHY'S BOAT YARD, HOUSATONIC RIVER
CT
NOAA Chart: 12370 Latitude: 41° 16.5' N ( 41.27500)
USGS Quad: ANSONIA Longitude: 73° 5.3' W ( -73.08830)
T I D A L B E N C H M A R K S
BENCH MARK STAMPING: 6664 D 1993
DESIGNATION: 846 6664 D
MONUMENTATION: Tidal Station disk VM#: 12445
AGENCY: National Ocean Service (NOS) IDB PID#:
SETTING CLASSIFICATION: Concrete head wall OPUS PID:
LATITUDE: 40° 16.4' N ( 40.27330) LONGITUDE: 73° 5.4' W ( -73.09000)
The bench mark is a disk set in the SW end of a concrete headwall just south of
the Saddler Restaurant on State Highway 110, 36 m (118 ft) SW of power pole
Number 1446, 13 m (43 ft) WNW of the centerline of State Highway 110, 12 m (39
ft) ESE of the base of a small waterfall, and 2 m (7 ft) below the level of the
highway.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 4 of 6
Station ID: 8466664 PUBLICATION DATE: 04/21/2003
Name: MURPHY'S BOAT YARD, HOUSATONIC RIVER
CT
NOAA Chart: 12370 Latitude: 41° 16.5' N ( 41.27500)
USGS Quad: ANSONIA Longitude: 73° 5.3' W ( -73.08830)
T I D A L B E N C H M A R K S
BENCH MARK STAMPING: F 77 1985
DESIGNATION: F 77
MONUMENTATION: Bench Mark disk VM#: 12446
AGENCY: National Geodetic Survey (NGS) IDB PID#: LX2526
SETTING CLASSIFICATION: Rock outcrop OPUS PID:
LATITUDE: 41° 15.9' N ( 41.26500) LONGITUDE: 73° 5.6' W ( -73.09330)
The bench mark is a disk set vertically near the NE end of a long rock outcrop,
60 m (197 ft) south along State Highway 110 from bench mark 6664 B 1993, 18.68 m
(61.3 ft) NW and directly across the highway from power pole Number 1458, 9.14 m
(30.0 ft) NW of the centerline of the highway, 8.53 m (28.0 ft) SW of the NE end
of the rock cut, and 0.21 m (0.7 ft) above the level of the highway.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 5 of 6
Station ID: 8466664 PUBLICATION DATE: 04/21/2003
Name: MURPHY'S BOAT YARD, HOUSATONIC RIVER
CT
NOAA Chart: 12370 Latitude: 41° 16.5' N ( 41.27500)
USGS Quad: ANSONIA Longitude: 73° 5.3' W ( -73.08830)
T I D A L D A T U M S
Tidal datums at MURPHY'S BOAT YARD, 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 = 2.264
MEAN HIGH WATER MHW = 2.162
MEAN TIDE LEVEL MTL = 1.119
North American Vertical Datum NAVD88 = 1.082
MEAN SEA LEVEL MSL = 1.062
MEAN LOW WATER MLW = 0.075
MEAN LOWER LOW WATER MLLW = 0.000
North American Vertical Datum (NAVD88)
Bench Mark Elevation Information In METERS above:
Stamping or Designation MLLW MHW
6664 B 1993 20.252 18.090
6664 A 1993 5.693 3.531
6664 C 1993 18.325 16.163
6664 D 1993 18.578 16.416
F 77 1985 20.996 18.834
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 6 of 6
Station ID: 8466664 PUBLICATION DATE: 04/21/2003
Name: MURPHY'S BOAT YARD, HOUSATONIC RIVER
CT
NOAA Chart: 12370 Latitude: 41° 16.5' N ( 41.27500)
USGS Quad: ANSONIA Longitude: 73° 5.3' W ( -73.08830)
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.