U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Datums Page Page 1 of 5
PUBLICATION DATE: 10/23/2000
Station ID: 8441571 SUPERCEDED DATE: 04/21/2003
Name: LOBSTER COVE, ANNISQUAM RIVER
MASSACHUSETTS
NOAA Chart: 13281 Latitude: 42° 39.3' N
USGS Quad: GLOUCESTER Longitude: 70° 40.6' W
To reach the bench marks from the State Route 128 Grant Circle Rotary
(Interchange 11), proceed NNE on SR 127 North for 5 km (3 mi) to Leonard Street,
then SW on Leonard Street for 1.1 km (0.7 mi) to Bridgewater Street, then SE on
Bridgewater Street for 0.1 km (0.06 mi) to the west end of the Lobster Cove
footbridge. The bench marks are located near the west end of the footbridge and
at the southern end of the peninsula around the Annisquam Yacht Club and the
tide gage and staff were located near the center of the footbridge on opposite
sides (gage on south, staff on north side).
T I D A L B E N C H M A R K S
PRIMARY BENCH MARK STAMPING: NO 1 1928
DESIGNATION: 844 1571 NO 1
MONUMENTATION: Tidal Station disk VM#: 2016
AGENCY: US Coast and Geodetic Survey (USC&GS) PID:
SETTING CLASSIFICATION: Rock outcrop
The primary bench mark is a disk set in a reddish rock outcrop at the Annisquam
Yacht Club located at the southern end of the peninsula on which the town of
Annisquam is located, at the southern end of the low marshy area between the
Yacht Club and the mainland, 29 m (95 ft) south of the walkway centerline, 16.31
m (53.5 ft) SE of the SE corner of the Yacht Club, and 27.71 m (90.9 ft) NNW of
a large stone navigational beacon built up crib fashion from large granite posts
with the interior filled with large irregular blocks of rock.
BENCH MARK STAMPING: NO 2 1928
DESIGNATION: 844 1571 NO 2
MONUMENTATION: Tidal Station disk VM#: 2017
AGENCY: US Coast and Geodetic Survey (USC&GS) PID:
SETTING CLASSIFICATION: Rock outcrop
The bench mark is a disk set in a large gray rock outcrop located immediately
inshore from the Yacht Clubhouse, about 70 m (230 ft) NE of a stone navigational
beacon, about 15 m (49 ft) WSW from telephone pole 003767-13 on River Drive, and
5.00 m (16.4 ft) south of the walkway railing leading to the Yacht Club.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 2 of 5
PUBLICATION DATE: 10/23/2000
Station ID: 8441571 SUPERCEDED DATE: 04/21/2003
Name: LOBSTER COVE, ANNISQUAM RIVER
MASSACHUSETTS
NOAA Chart: 13281 Latitude: 42° 39.3' N
USGS Quad: GLOUCESTER Longitude: 70° 40.6' W
T I D A L B E N C H M A R K S
BENCH MARK STAMPING: NO 3 1928
DESIGNATION: 844 1571 NO 3
MONUMENTATION: Tidal Station disk VM#: 2018
AGENCY: US Coast and Geodetic Survey (USC&GS) PID:
SETTING CLASSIFICATION: Rock outcrop
The bench mark is a disk set in a rock outcrop located near the NW corner of a
sea wall surrounding the Annisquam Yacht Club Tennis Courts, about 100 m (328
ft) NW of a stone navigational beacon, 40 m (131 ft) NW of the walk leading to
the club, and 2.59 m (8.5 ft) SE of the NW corner of the tennis court sea wall.
BENCH MARK STAMPING: NO 4 1967
DESIGNATION: 844 1571 NO 4
MONUMENTATION: Tidal Station disk VM#: 2019
AGENCY: US Coast and Geodetic Survey (USC&GS) PID:
SETTING CLASSIFICATION: Granite wall
The bench mark is a disk set in a 0.30 m (1.0 ft) high granite wall bordering
the north side of the corner lot at River Drive and Bridgewater Street in
Annisquam near the west end of the Lobster Cove Footbridge, 7.10 m (23.3 ft)
west of the River Drive centerline, 5.00 m (16.4 ft) south of the Bridgewater
Street centerline, and 1.01 m (3.3 ft) west of the east corner of the granite
wall.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 3 of 5
PUBLICATION DATE: 10/23/2000
Station ID: 8441571 SUPERCEDED DATE: 04/21/2003
Name: LOBSTER COVE, ANNISQUAM RIVER
MASSACHUSETTS
NOAA Chart: 13281 Latitude: 42° 39.3' N
USGS Quad: GLOUCESTER Longitude: 70° 40.6' W
T I D A L B E N C H M A R K S
BENCH MARK STAMPING: YACHT
DESIGNATION: 841 1571 YACHT
MONUMENTATION: Survey disk VM#: 2020
AGENCY: US Army Corps of Engineers (COE) PID:
SETTING CLASSIFICATION: Rock outcrop
The bench mark is a disk set in a rock outcrop located on the seaward side of
the Annisquam Yacht Club, 8.81 m (28.9 ft) WSW of the NW corner of the club,
3.81 m (12.5 ft) north of the west corner of a large flagpole base, and 2.99 m
(9.8 ft) west of an eyebolt protruding from a rock.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 4 of 5
PUBLICATION DATE: 10/23/2000
Station ID: 8441571 SUPERCEDED DATE: 04/21/2003
Name: LOBSTER COVE, ANNISQUAM RIVER
MASSACHUSETTS
NOAA Chart: 13281 Latitude: 42° 39.3' N
USGS Quad: GLOUCESTER Longitude: 70° 40.6' W
T I D A L D A T U M S
Tidal datums at LOBSTER COVE, ANNISQUAM RIVER based on:
LENGTH OF SERIES: 5 MONTHS
TIME PERIOD: May 1994 - September 1994
TIDAL EPOCH: 1960-1978
CONTROL TIDE STATION: 8443970 BOSTON, BOSTON HARBOR
Elevations of tidal datums referred to Mean Lower Low Water (MLLW), in METERS:
MEAN HIGHER HIGH WATER MHHW = 2.936
MEAN HIGH WATER MHW = 2.806
MEAN SEA LEVEL MSL = 1.458
MEAN TIDE LEVEL MTL = 1.454
MEAN LOW WATER MLW = 0.103
MEAN LOWER LOW WATER MLLW = 0.000
Bench Mark Elevation Information In METERS above:
Stamping or Designation MLLW MHW
NO 1 1928 2.819 0.013
NO 2 1928 6.470 3.664
NO 3 1928 3.664 0.858
NO 4 1967 6.874 4.068
YACHT 1.867 -0.939
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 5 of 5
PUBLICATION DATE: 10/23/2000
Station ID: 8441571 SUPERCEDED DATE: 04/21/2003
Name: LOBSTER COVE, ANNISQUAM RIVER
MASSACHUSETTS
NOAA Chart: 13281 Latitude: 42° 39.3' N
USGS Quad: GLOUCESTER Longitude: 70° 40.6' 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.