U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Datums Page Page 1 of 6
Station ID: 8466573 PUBLICATION DATE: 09/15/2004
Name: SHELTON, HOUSATONIC RIVER
CT
NOAA Chart: 12370 Latitude: 41° 18.1' N ( 41.30170)
USGS Quad: ANSONIA Longitude: 73° 4.3' W ( -73.07170)
To reach the tidal bench marks from the intersection of Routes 8 and 110 in
Shelton, proceed south on Route 110 (River Road) for 1.9 km (1.2 mi) to 202
River Road. The bench marks are located along Route 110 north of the property
at 202 River Road and on the property, and the tide gauge and staff were located
at the end of a walkway leading to floating docks on the east end of the
property.
T I D A L B E N C H M A R K S
PRIMARY BENCH MARK STAMPING: 6573 A 1993
DESIGNATION: 846 6573 A
MONUMENTATION: Tidal Station disk VM#: 12429
AGENCY: National Ocean Service (NOS) IDB PID#:
SETTING CLASSIFICATION: Concrete sewer culvert OPUS PID:
LATITUDE: 41° 18.1' N ( 41.30170) LONGITUDE: 73° 4.3' W ( -73.07170)
The primary bench mark is a disk set in the top of a concrete sewer culvert in
the back yard of 202 River Road, 49 m (161 ft) SSE of the south corner of the
house, 7.65 m (25.1 ft) SW of the concrete dam, and 7 m (23 ft) east of the
centerline of a dirt road leading to the river.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 2 of 6
Station ID: 8466573 PUBLICATION DATE: 09/15/2004
Name: SHELTON, HOUSATONIC RIVER
CT
NOAA Chart: 12370 Latitude: 41° 18.1' N ( 41.30170)
USGS Quad: ANSONIA Longitude: 73° 4.3' W ( -73.07170)
T I D A L B E N C H M A R K S
BENCH MARK STAMPING: 6573 B 1993
DESIGNATION: 846 6573 B
MONUMENTATION: Tidal Station disk VM#: 12430
AGENCY: National Ocean Service (NOS) IDB PID#:
SETTING CLASSIFICATION: Concrete sewer drain OPUS PID:
LATITUDE: 41° 18.1' N ( 41.30170) LONGITUDE: 73° 4.3' W ( -73.07170)
The bench mark is a disk set in the top of a sewer drain at the SW corner of the
intersection of River Road (Route 110) and Nettleton Court, 8.50 m (27.9 ft)
west of the river road centerline, 7.47 m (24.5 ft) north of the Nettleton Court
centerline, 4.94 m (16.2 ft) east of SNET utility pole #952, and 0.21 m (0.7 ft)
above the road.
BENCH MARK STAMPING: 6573 C 1993
DESIGNATION: 846 6573 C
MONUMENTATION: Tidal Station disk VM#: 12431
AGENCY: National Ocean Service (NOS) IDB PID#:
SETTING CLASSIFICATION: Bedrock outcrop OPUS PID:
LATITUDE: 41° 18.1' N ( 41.30170) LONGITUDE: 73° 4.3' W ( -73.07170)
The bench mark is a disk set in the top of a bedrock outcrop on the west side of
Route 110, 22.31 m (73.2 ft) SW of SNET utility pole #939, 8.17 m (26.8 ft) west
of the Route 110 centerline, 2.04 m (6.7 ft) east of vertical rock wall, and 1 m
(2 ft) above the road.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 3 of 6
Station ID: 8466573 PUBLICATION DATE: 09/15/2004
Name: SHELTON, HOUSATONIC RIVER
CT
NOAA Chart: 12370 Latitude: 41° 18.1' N ( 41.30170)
USGS Quad: ANSONIA Longitude: 73° 4.3' W ( -73.07170)
T I D A L B E N C H M A R K S
BENCH MARK STAMPING: 6573 D 1993
DESIGNATION: 846 6573 D
MONUMENTATION: Tidal Station disk VM#: 12432
AGENCY: National Ocean Service (NOS) IDB PID#:
SETTING CLASSIFICATION: Bedrock outcrop OPUS PID:
LATITUDE: 41° 18.1' N ( 41.30170) LONGITUDE: 73° 4.3' W ( -73.07170)
The bench mark is a disk set in the top of a bedrock outcrop along the west side
of Route 110, 85 m (279 ft) south of the Trolley Bridge Road centerline, 47 m
(154 ft) SW of snet utility pole #930, 8.56 m (28.1 ft) west of the Route 110
centerline, and 1.22 m (4.0 ft) above the road.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 4 of 6
Station ID: 8466573 PUBLICATION DATE: 09/15/2004
Name: SHELTON, HOUSATONIC RIVER
CT
NOAA Chart: 12370 Latitude: 41° 18.1' N ( 41.30170)
USGS Quad: ANSONIA Longitude: 73° 4.3' W ( -73.07170)
T I D A L B E N C H M A R K S
BENCH MARK STAMPING: J 77 1985
DESIGNATION: J 77
MONUMENTATION: Bench Mark disk VM#: 12433
AGENCY: US Coast and Geodetic Survey
(USC&GS) IDB PID#: LX2523
SETTING CLASSIFICATION: Bedrock outcrop OPUS PID:
LATITUDE: 41° 18.5' N ( 41.30830) LONGITUDE: 73° 4.8' W ( -73.08000)
The bench mark is a disk set in top of a bedrock outcrop along the west side of
Route 110, 85 m (279 ft) NNW the Trolley Bridge Road centerline, 9.14 m (30.0
ft) SW of the Route 110 centerline, 5.49 m (18.0 ft) NW of the SE end of the
rock cut, and 1.19 m (3.9 ft) above the road.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 5 of 6
Station ID: 8466573 PUBLICATION DATE: 09/15/2004
Name: SHELTON, HOUSATONIC RIVER
CT
NOAA Chart: 12370 Latitude: 41° 18.1' N ( 41.30170)
USGS Quad: ANSONIA Longitude: 73° 4.3' W ( -73.07170)
T I D A L D A T U M S
Tidal datums at SHELTON, HOUSATONIC RIVER based on:
LENGTH OF SERIES: 2 MONTHS
TIME PERIOD: July 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 = 2.317
MEAN HIGH WATER MHW = 2.209
MEAN TIDE LEVEL MTL = 1.140
North American Vertical Datum NAVD88 = 1.109
MEAN SEA LEVEL MSL = 1.087
MEAN LOW WATER MLW = 0.071
MEAN LOWER LOW WATER MLLW = 0.000
North American Vertical Datum (NAVD88)
Bench Mark Elevation Information In METERS above:
Stamping or Designation MLLW MHW
6573 A 1993 19.381 17.172
6573 B 1993 32.952 30.743
6573 C 1993 32.675 30.466
6573 D 1993 34.066 31.857
J 77 1985 33.748 31.539
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 6 of 6
Station ID: 8466573 PUBLICATION DATE: 09/15/2004
Name: SHELTON, HOUSATONIC RIVER
CT
NOAA Chart: 12370 Latitude: 41° 18.1' N ( 41.30170)
USGS Quad: ANSONIA Longitude: 73° 4.3' W ( -73.07170)
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.