U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Datums Page Page 1 of 5
PUBLICATION DATE: 03/01/1990
Station ID: 8464336 SUPERCEDED DATE: 04/21/2003
Name: MIDDLETOWN, CONNECTICUT RIVER
CONNECTICUT
NOAA Chart: 12377 Latitude: 41° 33.6' N
USGS Quad: MIDDLETOWN Longitude: 72° 38.7' W
To reach the tidal bench marks from the intersection of Main and Union Streets
in Middletown, proceed east on Union Street beneath the State Highway 9 over-
pass to Harbor Drive, then north on Harbor Drive for 0.1 mile (0.2 km) to
Harbour Park Restaurant. The bench marks are NW of Harbour Park Restaurant.
The tide gage and staff were on the wharf behind the restaurant.
T I D A L B E N C H M A R K S
PRIMARY BENCH MARK STAMPING: 4336 E 1987
MONUMENTATION: Survey Disk VM#: 2265
AGENCY: PID:
SETTING CLASSIFICATION: Retaining Wall
The bench mark is set flush in the top of the south end of a retaining wall on
Harbor Drive, 192 feet (59 m) WNW of the Harbour Park Restaurant entrance, 189
feet (57.6 m) west of a handrail along the river, 57.1 feet (17.4 m) ENE of the
east guardrail on State Highway 9, and 4.6 feet (1.4 m) above ground level.
BENCH MARK STAMPING: 92 W 1923 54
MONUMENTATION: Survey Disk VM#: 2262
AGENCY: PID#: LX0580
SETTING CLASSIFICATION: Concrete Steps
The bench mark is set flush in the first step of the west entrance on the south
side of St Johns Catholic Church at Main Street and Hartford Avenue, 103.0 feet
(31.4 m) west of the centerline of St Johns street, 54.0 feet (16.5 m) east
of the entrance to St Johns School, 26.8 feet (8.2 m) north of the north curb of
Hartford Avenue, and 0.4 foot (0.1 m) above the sidewalk.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 2 of 5
PUBLICATION DATE: 03/01/1990
Station ID: 8464336 SUPERCEDED DATE: 04/21/2003
Name: MIDDLETOWN, CONNECTICUT RIVER
CONNECTICUT
NOAA Chart: 12377 Latitude: 41° 33.6' N
USGS Quad: MIDDLETOWN Longitude: 72° 38.7' W
T I D A L B E N C H M A R K S
BENCH MARK STAMPING: MIDDLETOWN 1935
MONUMENTATION: Survey Disk VM#: 2263
AGENCY: PID#: LX0583
SETTING CLASSIFICATION: Concrete Steps
The bench mark is set flush on the first step of the Connecticut Bank & Trust
near the intersection of Main and Court Streets, 79.6 feet (24.3 m) south of the
SE corner of the post office, 41.6 feet (12.7 m) NW of a yellow and green fire
hydrant, 23.3 feet (7.1 m) west of the west curb of Main Street, and 0.65 foot
(0.20 m) above the sidewalk.
BENCH MARK STAMPING: Y 14 1935
MONUMENTATION: Survey Disk VM#: 2264
AGENCY: PID#: LX0579
SETTING CLASSIFICATION: Bridge Abutment
The bench mark is set in the top of the NW corner of the NY, NH, and H Railroad
bridge abutment on the west side of the river, 62.3 feet (19.0 m) east of the
east rail of the north/south railroad tracks, 32.1 feet (9.8 m) NE of the NE
corner of a red brick building, 7.0 feet (2.1 m) north of the north rail of the
east/west tracks, and 2.5 feet (0.8 m) below track level.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 3 of 5
PUBLICATION DATE: 03/01/1990
Station ID: 8464336 SUPERCEDED DATE: 04/21/2003
Name: MIDDLETOWN, CONNECTICUT RIVER
CONNECTICUT
NOAA Chart: 12377 Latitude: 41° 33.6' N
USGS Quad: MIDDLETOWN Longitude: 72° 38.7' W
T I D A L B E N C H M A R K S
BENCH MARK STAMPING: NO STAMPING 1
MONUMENTATION: Survey Disk VM#: 2266
AGENCY: PID:
SETTING CLASSIFICATION: Concrete Monument
The bench mark is set in a concrete monument at the NW corner of Court Street
and Dekoven Drive, near the SE corner of Middletown Municipal Building, 146.9
feet (44.8 m) south of a flagpole, 46.9 feet (14.3 m) north of the centerline of
Court Street, 12.6 feet (3.8 m) east of the SE corner of the stone landing of
the Middletown Municipal Building steps, and 1.2 feet (0.4 m) above ground
level.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 4 of 5
PUBLICATION DATE: 03/01/1990
Station ID: 8464336 SUPERCEDED DATE: 04/21/2003
Name: MIDDLETOWN, CONNECTICUT RIVER
CONNECTICUT
NOAA Chart: 12377 Latitude: 41° 33.6' N
USGS Quad: MIDDLETOWN Longitude: 72° 38.7' W
T I D A L D A T U M S
Tidal datums at MIDDLETOWN, CONNECTICUT RIVER based on:
LENGTH OF SERIES: 8 MONTHS
TIME PERIOD: JUNE-SEPTEMBER 1987, 1988
TIDAL EPOCH: 1960-1978
CONTROL TIDE STATION: 8461490 NEW LONDON
Elevations of tidal datums referred to Mean Lower Low Water (MLLW), in FEET:
HIGHEST OBSERVED WATER LEVEL (05/02/1988) = 9.14
MEAN HIGHER HIGH WATER MHHW = 2.55
MEAN HIGH WATER MHW = 2.30
MEAN TIDE LEVEL MTL = 1.20
MEAN LOW WATER MLW = 0.11
MEAN LOWER LOW WATER MLLW = 0.00
* NATIONAL GEODETIC VERTICAL DATUM NGVD29 = -0.25
LOWEST OBSERVED WATER LEVEL (10/13/1988) = -0.71
* NGVD reference based on elevations published in Quad 410724, 1940, and NOS
leveling of 1988.
North American Vertical Datum (NAVD88)
Bench Mark Elevation Information In FEET above:
Stamping or Designation MLLW MHW
4336 E 1987 19.94 17.64
92 W 1923 54 54.01 51.71
MIDDLETOWN 1935 50.74 48.44
Y 14 1935 33.73 31.43
NO STAMPING 1 37.34 35.04
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 5 of 5
PUBLICATION DATE: 03/01/1990
Station ID: 8464336 SUPERCEDED DATE: 04/21/2003
Name: MIDDLETOWN, CONNECTICUT RIVER
CONNECTICUT
NOAA Chart: 12377 Latitude: 41° 33.6' N
USGS Quad: MIDDLETOWN Longitude: 72° 38.7' W
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 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.