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Datums Page Page 1 of 10
Station ID: 8418150 PUBLICATION DATE: 10/30/2003
Name: PORTLAND, CASCO BAY
ME
NOAA Chart: 13292 Latitude: 43° 39.4' N ( 43.65670)
USGS Quad: PORTLAND EAST Longitude: 70° 14.8' W ( -70.24670)
To reach the tidal bench marks from north bound Interstate 295 in Portland, take
the Waterfront Exit (Alt. U.S. 1) to Commercial Street, then continue NE along
Commercial Street for 2.4 km (1.5 mi) to the Maine State Pier, the last pier-
warehouse along the waterfront. The bench marks are located within 1.6 km (1
mi) radius of tide station. The tide gage is located in the south corner on the
off shore end of the Maine State Pier.
T I D A L B E N C H M A R K S
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 2 of 10
Station ID: 8418150 PUBLICATION DATE: 10/30/2003
Name: PORTLAND, CASCO BAY
ME
NOAA Chart: 13292 Latitude: 43° 39.4' N ( 43.65670)
USGS Quad: PORTLAND EAST Longitude: 70° 14.8' W ( -70.24670)
T I D A L B E N C H M A R K S
PRIMARY BENCH MARK STAMPING: ELEV 14.501 FT TIDAL 31
DESIGNATION: TIDAL 31 STA 84
MONUMENTATION: Tidal Station disk VM#: 173
AGENCY: US Coast and Geodetic Survey
(USC&GS) IDB PID#: OC0005
SETTING CLASSIFICATION: Stone foundation OPUS PID:
LATITUDE: 43° 39.5' N ( 43.65889) LONGITUDE: 70° 14.9' W ( -70.24908)
The primary bench mark is a disk set vertically in the NE face of the stone
foundation of a three story building located along Commercial Street between
India and Franklin Streets, 63 m (206.7 ft) SW of the SW curb of India Street,
12.65 m (41.5 ft) NNE of fire hydrant on the NW side of Commercial Street, 2.71
m (8.9 ft) NW of the NW curb of Commercial Street, and 0.15 m (0.5 ft) above the
sidewalk.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 3 of 10
Station ID: 8418150 PUBLICATION DATE: 10/30/2003
Name: PORTLAND, CASCO BAY
ME
NOAA Chart: 13292 Latitude: 43° 39.4' N ( 43.65670)
USGS Quad: PORTLAND EAST Longitude: 70° 14.8' W ( -70.24670)
T I D A L B E N C H M A R K S
BENCH MARK STAMPING: 38 1919
DESIGNATION: TIDAL 38 STA 84
MONUMENTATION: Tidal Station disk VM#: 174
AGENCY: US Coast and Geodetic Survey
(USC&GS) IDB PID#: OC0011
SETTING CLASSIFICATION: Stone shelf OPUS PID:
LATITUDE: 43° 39.5' N ( 43.65897) LONGITUDE: 70° 15.4' W ( -70.25728)
The bench mark is a disk set in a stone shelf at the west wing of the City Hall,
located at the intersection of Congress and Chestnut Streets, 17.22 m (56.5 ft)
NE of NE curb of Chestnut Street, 8.2 m (27 ft) NW of NW curb of Congress
Street, 1.07 m (3.5 ft) NE of the NE face of the building wing, and 1.2 m (4 ft)
above the level of the sidewalk.
BENCH MARK STAMPING: NO 3 1971
DESIGNATION: 841 8150 TIDAL 3
MONUMENTATION: Tidal Station disk VM#: 175
AGENCY: US Coast and Geodetic Survey
(USC&GS) IDB PID#: AJ2726
SETTING CLASSIFICATION: Granite sea wall OPUS PID#: AJ2726
LATITUDE: 43° 39.5' N ( 43.65824) LONGITUDE: 70° 14.9' W ( -70.24831)
The bench mark is a disk set in the granite seawall located along the NE side of
Commercial Street north of the Bath Iron Works pier, 17.83 m (58.5 ft) NE of the
NE corner formed by the pier and seawall intersection, 6.10 m (20.0 ft) SW of
the NW corner formed by the edge of the seawall and a projection out from the
seawall, and 0.3 m (1 ft) east of the concrete parking lot barrier.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 4 of 10
Station ID: 8418150 PUBLICATION DATE: 10/30/2003
Name: PORTLAND, CASCO BAY
ME
NOAA Chart: 13292 Latitude: 43° 39.4' N ( 43.65670)
USGS Quad: PORTLAND EAST Longitude: 70° 14.8' W ( -70.24670)
T I D A L B E N C H M A R K S
BENCH MARK STAMPING: NO 43 1975
DESIGNATION: 841 8150 TIDAL 43
MONUMENTATION: Tidal Station disk VM#: 176
AGENCY: National Ocean Survey (NOS) IDB PID#:
SETTING CLASSIFICATION: Granite step OPUS PID:
LATITUDE: 43° 39.5' N ( 43.65908) LONGITUDE: 70° 15.3' W ( -70.25444)
The bench mark is a disk set in the first step of the stairs at the SE entrance
of the Cumberland County Courthouse, 21.0 m (69 ft) SE of the SE corner of Pearl
and Federal Streets, 12.16 m (39.9 ft) east of the centerline of Pearl Street,
and 0.76 m (2.5 ft) west of the west wall of the courthouse.
BENCH MARK STAMPING: 8150 A 1978
DESIGNATION: 841 8150 A
MONUMENTATION: Tidal Station disk VM#: 177
AGENCY: National Ocean Survey (NOS) IDB PID#:
SETTING CLASSIFICATION: Concrete loading pad OPUS PID:
LATITUDE: 43° 39.5' N ( 43.65781) LONGITUDE: 70° 14.9' W ( -70.24892)
The bench mark is a disk set in a concrete loading pad near the NW corner of the
Maine State Pier located on the NE side of Commercial Street, 23.77 m (78.0 ft)
east of the east face of a parking garage, 12.01 m (39.4 ft) SW of the NW corner
of a warehouse, 1.68 m (5.5 ft) west of the west side of a building, and 0.3 m
(1.0 ft) above ground.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 5 of 10
Station ID: 8418150 PUBLICATION DATE: 10/30/2003
Name: PORTLAND, CASCO BAY
ME
NOAA Chart: 13292 Latitude: 43° 39.4' N ( 43.65670)
USGS Quad: PORTLAND EAST Longitude: 70° 14.8' W ( -70.24670)
T I D A L B E N C H M A R K S
BENCH MARK STAMPING: 841-8150 C 1979
DESIGNATION: 841 8150 C
MONUMENTATION: Tidal Station disk VM#: 179
AGENCY: National Ocean Survey (NOS) IDB PID#:
SETTING CLASSIFICATION: Granite step OPUS PID:
LATITUDE: 43° 39.5' N ( 43.65781) LONGITUDE: 70° 15.2' W ( -70.25278)
The bench mark is a disk set in the granite step at the doorway leading to the
building at 40 Pearl Street located between Middle and Milk Streets, 19.75 m
(64.8 ft) NW of the centerline of Milk Street, 9.8 m (32 ft) SW of the
centerline of Pearl Street, 6.00 m (19.7 ft) SE of the north corner of the
building, and 0.24 m (0.8 ft) above ground.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 6 of 10
Station ID: 8418150 PUBLICATION DATE: 10/30/2003
Name: PORTLAND, CASCO BAY
ME
NOAA Chart: 13292 Latitude: 43° 39.4' N ( 43.65670)
USGS Quad: PORTLAND EAST Longitude: 70° 14.8' W ( -70.24670)
T I D A L B E N C H M A R K S
BENCH MARK STAMPING:
DESIGNATION: TIDAL 2 USE STA 84
ALIAS: NO 2 USE 1901
MONUMENTATION: Drill Hole VM#: 181
AGENCY: IDB PID#: OC0003
SETTING CLASSIFICATION: Water table OPUS PID:
LATITUDE: 43° 39.4' N ( 43.65706) LONGITUDE: 70° 15.1' W ( -70.25092)
The bench mark is a drill hole in the top of a water table between the bases of
two stone columns at the NE side of the entrance to the U.S. Custom House
located at the intersection of Commercial and Pearl Streets, 20.00 m (65.6 ft)
NW of the centerline of Commercial Street, 12.50 m (41.0 ft) NE of the SW corner
of the Custom House, 8.70 m (28.5 ft) SW of the NE corner of the Custom House,
and 0.3 m (1.0 ft) above the sidewalk.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 7 of 10
Station ID: 8418150 PUBLICATION DATE: 10/30/2003
Name: PORTLAND, CASCO BAY
ME
NOAA Chart: 13292 Latitude: 43° 39.4' N ( 43.65670)
USGS Quad: PORTLAND EAST Longitude: 70° 14.8' W ( -70.24670)
T I D A L B E N C H M A R K S
BENCH MARK STAMPING:
DESIGNATION: TIDAL 30 STA 84
ALIAS: NO 30 (1910)
MONUMENTATION: Chiseled Cross VM#: 182
AGENCY: IDB PID#: OC0006
SETTING CLASSIFICATION: Granite sill OPUS PID:
LATITUDE: 43° 39.6' N ( 43.65939) LONGITUDE: 70° 14.9' W ( -70.24836)
The bench mark is a chiseled cross in the granite sill at the SE corner of the
foundation for the Grand Trunk Railway building located at the intersection of
Commerce and India Streets, 10.61 m (34.8 ft) north of power pole numbered 1.11,
7.99 m (26.2 ft) ESE of the emergency telephone at the intersection of Commerce
and India Streets, 7.6 m (25 ft) NE of the NE curb of India Street, 5.00 m (16.4
ft) SSE of the south side of the steps leading into the Grand Trunk Railway
building, and 0.40 m (1.3 ft) above ground.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 8 of 10
Station ID: 8418150 PUBLICATION DATE: 10/30/2003
Name: PORTLAND, CASCO BAY
ME
NOAA Chart: 13292 Latitude: 43° 39.4' N ( 43.65670)
USGS Quad: PORTLAND EAST Longitude: 70° 14.8' W ( -70.24670)
T I D A L B E N C H M A R K S
BENCH MARK STAMPING:
DESIGNATION: TIDAL 33 STA 84
ALIAS: NO 33 1910
MONUMENTATION: Chiseled Cross VM#: 183
AGENCY: IDB PID#: OC0004
SETTING CLASSIFICATION: Stone window sill OPUS PID:
LATITUDE: 43° 39.4' N ( 43.65750) LONGITUDE: 70° 15.0' W ( -70.25047)
The bench mark is a chiseled cross in the lower stone sill of the second window
SW of the NE corner of the W. L. Blake Building at 19 Commercial Street, 16.18 m
(53.1 ft) SSE of the centerline of Commercial Street, 6.71 m (22.0 ft) SW of the
center of the Blake Building entrance, 4.79 m (15.7 ft) SW of the NE corner of
the building, and 0.91 m (3.0 ft) above the sidewalk.
BENCH MARK STAMPING: 8150 E 1991
DESIGNATION: 841 8150 E
MONUMENTATION: Tidal Station disk VM#: 13803
AGENCY: National Ocean Service (NOS) IDB PID#:
SETTING CLASSIFICATION: Set in pile cap OPUS PID:
LATITUDE: 43° 39.4' N ( 43.65670) LONGITUDE: 70° 14.8' W ( -70.24670)
The bench mark is a disk set on the SE side of the Bath Iron Works concrete pier
located on the NE side of Commercial Street, 39.32 m (129.0 ft) NE of the tide
gauge house, 9.91 m (32.5 ft) ENE of the SE corner of the Bath Iron Works
building, 2.13 m (7.0 ft) SSE of the southernmost bollard, 1.22 m (4.0 ft) WSW
of the eastern edge of the pier, and 0.37 m (1.2 ft) above the pier deck.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 9 of 10
Station ID: 8418150 PUBLICATION DATE: 10/30/2003
Name: PORTLAND, CASCO BAY
ME
NOAA Chart: 13292 Latitude: 43° 39.4' N ( 43.65670)
USGS Quad: PORTLAND EAST Longitude: 70° 14.8' W ( -70.24670)
T I D A L D A T U M S
Tidal datums at PORTLAND, CASCO BAY based on:
LENGTH OF SERIES: 19 YEARS
TIME PERIOD: January 1983 - December 2001
TIDAL EPOCH: 1983-2001
CONTROL TIDE STATION:
Elevations of tidal datums referred to Mean Lower Low Water (MLLW), in METERS:
HIGHEST OBSERVED WATER LEVEL (02/07/1978) = 4.305
MEAN HIGHER HIGH WATER MHHW = 3.019
MEAN HIGH WATER MHW = 2.886
North American Vertical Datum NAVD88 = 1.601
MEAN SEA LEVEL MSL = 1.505
MEAN TIDE LEVEL MTL = 1.495
MEAN LOW WATER MLW = 0.105
MEAN LOWER LOW WATER MLLW = 0.000
LOWEST OBSERVED WATER LEVEL (11/30/1955) = -1.053
North American Vertical Datum (NAVD88)
Bench Mark Elevation Information In METERS above:
Stamping or Designation MLLW MHW
ELEV 14.501 FT TIDAL 31 5.799 2.913
38 1919 22.616 19.730
NO 3 1971 4.733 1.847
NO 43 1975 17.723 14.837
8150 A 1978 4.917 2.031
841-8150 C 1979 12.323 9.437
TIDAL 2 USE STA 84 5.662 2.777
TIDAL 30 STA 84 6.337 3.451
TIDAL 33 STA 84 5.306 2.421
8150 E 1991 5.275 2.389
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 10 of 10
Station ID: 8418150 PUBLICATION DATE: 10/30/2003
Name: PORTLAND, CASCO BAY
ME
NOAA Chart: 13292 Latitude: 43° 39.4' N ( 43.65670)
USGS Quad: PORTLAND EAST Longitude: 70° 14.8' W ( -70.24670)
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.