U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Datums Page Page 1 of 5
Station ID: 8464445 PUBLICATION DATE: 04/21/2003
Name: GUILFORD, GUILFORD HARBOR
CT
NOAA Chart: 12373 Latitude: 41° 16.3' N ( 41.27170)
USGS Quad: GUILFORD Longitude: 72° 40.0' W ( -72.66670)
To reach the tidal bench marks from the intersection of I-95 and Route 77,
proceed south on Route 77 for 2.3 km (1.4 mi) to the intersection of Routes 77
and 146, continue straight through intersection and proceed south on Whitfield
Street for 1.8 km (1.1 mi) to Guilford Harbor. The bench marks are located in
the harbor parking lot and along Whitfield Street in the vicinity of the harbor
and the tide gauge and staff were located along the harbor bulkhead.
T I D A L B E N C H M A R K S
PRIMARY BENCH MARK STAMPING: 4445 B 1993
DESIGNATION: 846 4445 B
MONUMENTATION: Tidal Station disk VM#: 12436
AGENCY: National Ocean Service (NOS) IDB PID#:
SETTING CLASSIFICATION: Concrete wall OPUS PID:
LATITUDE: 41° 16.3' N ( 41.27170) LONGITUDE: 72° 40.0' W ( -72.66670)
The primary bench mark is a disk set in the SE corner of a small concrete bridge
over an irrigation canal, 17.86 m (58.6 ft) ESE of the south end of the concrete
fuel platform, 12.80 m (42.0 ft) west of SNET utility pole #4248, and 3.35 m
(11.0 ft) SW of the centerline of the bridge.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 2 of 5
Station ID: 8464445 PUBLICATION DATE: 04/21/2003
Name: GUILFORD, GUILFORD HARBOR
CT
NOAA Chart: 12373 Latitude: 41° 16.3' N ( 41.27170)
USGS Quad: GUILFORD Longitude: 72° 40.0' W ( -72.66670)
T I D A L B E N C H M A R K S
BENCH MARK STAMPING: 4445 A 1993
DESIGNATION: 846 4445 A
MONUMENTATION: Tidal Station disk VM#: 12435
AGENCY: National Ocean Service (NOS) IDB PID#:
SETTING CLASSIFICATION: Concrete foundation OPUS PID:
LATITUDE: 41° 16.3' N ( 41.27170) LONGITUDE: 72° 40.0' W ( -72.66670)
The bench mark is a disk set in the SW corner of the 1 m (3 ft) square concrete
flagpole base adjacent to the harbormaster's office, 13.53 m (44.4 ft) north of
SNET utility pole #1084, 3.54 m (11.6 ft) south of the SW support pile for the
office, and 2.53 m (8.3 ft) ENE of the split rail fence bordering the harbor.
BENCH MARK STAMPING: 4445 C 1993
DESIGNATION: 846 4445 C
MONUMENTATION: Tidal Station disk VM#: 12437
AGENCY: National Ocean Service (NOS) IDB PID#:
SETTING CLASSIFICATION: Bedrock outcrop OPUS PID:
LATITUDE: 41° 16.3' N ( 41.27170) LONGITUDE: 72° 40.0' W ( -72.66670)
The bench mark is a disk set near the eastern end of a long strip of exposed
bedrock located in the front yard of the residence at 421 Whitfield Street,
31.46 m (103.2 ft) NE of the NE corner of the residence, 17.68 m (58.0 ft) SE of
SNET utility pole #4604, and 13.41 m (44.0 ft) SSW of the centerline of
Whitfield Street.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 3 of 5
Station ID: 8464445 PUBLICATION DATE: 04/21/2003
Name: GUILFORD, GUILFORD HARBOR
CT
NOAA Chart: 12373 Latitude: 41° 16.3' N ( 41.27170)
USGS Quad: GUILFORD Longitude: 72° 40.0' W ( -72.66670)
T I D A L B E N C H M A R K S
BENCH MARK STAMPING: 4445 D 1993
DESIGNATION: 846 4445 D
MONUMENTATION: Tidal Station disk VM#: 12438
AGENCY: National Ocean Service (NOS) IDB PID#:
SETTING CLASSIFICATION: Concrete storm drain head wall OPUS PID#: BBDC92
LATITUDE: 41° 16.3' N ( 41.27170) LONGITUDE: 72° 40.0' W ( -72.66670)
The bench mark is a disk set in the south end of a 0.46 m x 2.29 m (1.5 ft x 7.5
ft) concrete storm drain headwall located just east of the driveway to the small
row of townhouses at 373 Whitfield Street, 19.05 m (62.5 ft) SSW of SNET utility
pole #7486, 16.25 m (53.3 ft) east of SNET utility pole #b1087, 11.52 m (37.8
ft) NNE of the centerline of Whitfield Street, and 1 m (3 ft) above the ground.
BENCH MARK STAMPING: 4445 E 1993
DESIGNATION: 846 4445 E
MONUMENTATION: Tidal Station disk VM#: 12439
AGENCY: National Ocean Service (NOS) IDB PID#:
SETTING CLASSIFICATION: Concrete bridge abutment OPUS PID:
LATITUDE: 41° 16.3' N ( 41.27170) LONGITUDE: 72° 40.0' W ( -72.66670)
The bench mark is a disk set in the bridge abutment located on the NW corner of
the Whitfield Street bridge over the railroad track, 5.49 m (18.0 ft) SW of the
centerline of Whitfield Street, 1.40 m (4.6 ft) east of the NW end of the
bridge, and 0.30 m (1.0 ft) west of the east edge of the abutment.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 4 of 5
Station ID: 8464445 PUBLICATION DATE: 04/21/2003
Name: GUILFORD, GUILFORD HARBOR
CT
NOAA Chart: 12373 Latitude: 41° 16.3' N ( 41.27170)
USGS Quad: GUILFORD Longitude: 72° 40.0' W ( -72.66670)
T I D A L D A T U M S
Tidal datums at GUILFORD, GUILFORD HARBOR 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 = 1.747
MEAN HIGH WATER MHW = 1.652
MEAN TIDE LEVEL MTL = 0.861
MEAN SEA LEVEL MSL = 0.860
MEAN LOW WATER MLW = 0.070
MEAN LOWER LOW WATER MLLW = 0.000
North American Vertical Datum (NAVD88)
Bench Mark Elevation Information In METERS above:
Stamping or Designation MLLW MHW
4445 B 1993 2.425 0.773
4445 A 1993 2.779 1.127
4445 C 1993 3.597 1.945
4445 D 1993 3.800 2.148
4445 E 1993 11.346 9.694
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 5 of 5
Station ID: 8464445 PUBLICATION DATE: 04/21/2003
Name: GUILFORD, GUILFORD HARBOR
CT
NOAA Chart: 12373 Latitude: 41° 16.3' N ( 41.27170)
USGS Quad: GUILFORD Longitude: 72° 40.0' W ( -72.66670)
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.