U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Datums Page Page 1 of 6
Station ID: 8440369 PUBLICATION DATE: 11/13/2003
Name: MERRIMACPORT, MERRIMACK RIVER
MA
NOAA Chart: 13274 Latitude: 42° 49.5' N ( 42.82500)
USGS Quad: NEWBURYPORT WEST Longitude: 70° 59.3' W ( -70.98830)
To reach the tidal bench marks from the Broad Street exit (# 53) of Interstate
Highway 495, proceed SE on Broad Street for 0.6 km (0.4 mi) to a T-intersection,
with the Wallace Boat Yard directly across the intersection and down a small
hill. The bench marks are along River Road and Broad Street. The tide station
was located on the Wallace Boat Yard bulkhead.
T I D A L B E N C H M A R K S
PRIMARY BENCH MARK STAMPING: 0369 A 1989
DESIGNATION: 844 0369 A
MONUMENTATION: Tidal Station disk VM#: 1448
AGENCY: National Ocean Service (NOS) IDB PID#:
SETTING CLASSIFICATION: Concrete pad OPUS PID:
LATITUDE: ' °deg (0) LONGITUDE: ' °deg (0)
The primary bench mark is a disk set in the NW corner of a 2.35 m x 2.23 m (7.7
ft x 7.3 ft) concrete pad for a large winch at the Wallace Boat Yard, 13 m (43
ft) east of the east wall of the boat yard building, 3.11 m (10.2 ft) NW of the
center of a 1.65 m (5.4 ft) diameter concrete pad adjacent to the winch pad,
0.46 m (1.5 ft) ESE of the NW pad corner, and 0.12 m (0.4 ft) above ground
level.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 2 of 6
Station ID: 8440369 PUBLICATION DATE: 11/13/2003
Name: MERRIMACPORT, MERRIMACK RIVER
MA
NOAA Chart: 13274 Latitude: 42° 49.5' N ( 42.82500)
USGS Quad: NEWBURYPORT WEST Longitude: 70° 59.3' W ( -70.98830)
T I D A L B E N C H M A R K S
BENCH MARK STAMPING: 0369 B 1989
DESIGNATION: 844 0369 B
MONUMENTATION: Tidal Station disk VM#: 1449
AGENCY: National Ocean Service (NOS) IDB PID#:
SETTING CLASSIFICATION: Concrete base OPUS PID:
LATITUDE: ' °deg (0) LONGITUDE: ' °deg (0)
The bench mark is a disk set in the 2 m (6 ft) diameter concrete base of
Merrimack Historic Site #2, 16 m (52 ft) SSE of the centerline of River road,
11.22 m (36.8 ft) south of power pole #6/33, 0.52 m (1.7 ft) SE of the NW edge
of the base, and 0.27 m (0.9 ft) above ground level.
BENCH MARK STAMPING: 0369 C 1989
DESIGNATION: 844 0369 C
MONUMENTATION: Tidal Station disk VM#: 1450
AGENCY: National Ocean Service (NOS) IDB PID#:
SETTING CLASSIFICATION: Concrete wing wall OPUS PID:
LATITUDE: ' °deg (0) LONGITUDE: ' °deg (0)
The bench mark is a disk set flush in the SW concrete wingwall of a culvert
passing under River Road, 19.42 m (63.7 ft) NE of the NE corner of the 2-story
wood frame residence at #1702 River Road, 8.53 m (28.0 ft) south of the
centerline of River Road, and 1.07 m (3.5 ft) NNE of the SW end of the wingwall.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 3 of 6
Station ID: 8440369 PUBLICATION DATE: 11/13/2003
Name: MERRIMACPORT, MERRIMACK RIVER
MA
NOAA Chart: 13274 Latitude: 42° 49.5' N ( 42.82500)
USGS Quad: NEWBURYPORT WEST Longitude: 70° 59.3' W ( -70.98830)
T I D A L B E N C H M A R K S
BENCH MARK STAMPING: 5401
DESIGNATION: 844 0369 5401
MONUMENTATION: Tidal Station disk VM#: 1451
AGENCY: Massachusetts Department of Public Works
(MDPW) IDB PID#:
SETTING CLASSIFICATION: Concrete wheel guard OPUS PID:
LATITUDE: ' °deg (0) LONGITUDE: ' °deg (0)
The bench mark is a disk set flush in the SE concrete wheel guard of the Broad
Street Bridge over Interstate Highway 495, directly below the bronze State Seal,
44.32 m (145.4 ft) south of the Interstate Highway 495 northbound lane, 6.92 m
(22.7 ft) east of the centerline of Broad Street, and 2.41 m (7.9 ft) north of
an unnumbered wooden light pole.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 4 of 6
Station ID: 8440369 PUBLICATION DATE: 11/13/2003
Name: MERRIMACPORT, MERRIMACK RIVER
MA
NOAA Chart: 13274 Latitude: 42° 49.5' N ( 42.82500)
USGS Quad: NEWBURYPORT WEST Longitude: 70° 59.3' W ( -70.98830)
T I D A L B E N C H M A R K S
BENCH MARK STAMPING:
DESIGNATION: 844 0369 MDPW 1
ALIAS: NO STAMPING 1
MONUMENTATION: Tidal Station disk VM#: 1452
AGENCY: Massachusetts Department of Public Works
(MDPW) IDB PID#:
SETTING CLASSIFICATION: Bridge abutment OPUS PID:
LATITUDE: 42° 49.5' N ( 42.82500) LONGITUDE: 70° 59.3' W ( -70.98830)
The bench mark is a disk set flush near the NW end of the Broad Street bridge
over Interstate Highway 495, 8.23 m (27.0 ft) west of the centerline of Broad
Street, 5.36 m (17.6 ft) south of the State Seal at the NW corner of the bridge
rail, and 0.37 m (1.2 ft) west of the west edge of the abutment.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 5 of 6
Station ID: 8440369 PUBLICATION DATE: 11/13/2003
Name: MERRIMACPORT, MERRIMACK RIVER
MA
NOAA Chart: 13274 Latitude: 42° 49.5' N ( 42.82500)
USGS Quad: NEWBURYPORT WEST Longitude: 70° 59.3' W ( -70.98830)
T I D A L D A T U M S
Tidal datums at MERRIMACPORT, MERRIMACK RIVER based on:
LENGTH OF SERIES: 1 MONTH
TIME PERIOD: September 1989 - September 1989
TIDAL EPOCH: 1983-2001
CONTROL TIDE STATION: 8440466 NEWBURYPORT, MERRIMACK RIVER
Elevations of tidal datums referred to Mean Lower Low Water (MLLW), in METERS:
MEAN HIGHER HIGH WATER MHHW = 2.334
MEAN HIGH WATER MHW = 2.201
MEAN SEA LEVEL MSL = 1.141
MEAN TIDE LEVEL MTL = 1.127
MEAN LOW WATER MLW = 0.053
MEAN LOWER LOW WATER MLLW = 0.000
North American Vertical Datum (NAVD88)
Bench Mark Elevation Information In METERS above:
Stamping or Designation MLLW MHW
0369 A 1989 4.935 2.734
0369 B 1989 8.100 5.899
0369 C 1989 5.183 2.982
5401 20.626 18.425
844 0369 MDPW 1 19.248 17.047
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 6 of 6
Station ID: 8440369 PUBLICATION DATE: 11/13/2003
Name: MERRIMACPORT, MERRIMACK RIVER
MA
NOAA Chart: 13274 Latitude: 42° 49.5' N ( 42.82500)
USGS Quad: NEWBURYPORT WEST Longitude: 70° 59.3' W ( -70.98830)
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.