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National Ocean Service
Datums Page Page 1 of 5
Station ID: 9454616 PUBLICATION DATE: 04/21/2003
Name: MONTAGUE ISLAND
AK
NOAA Chart: 16701 Latitude: 60° 1.5' N ( 60.02500)
USGS Quad: SEWARD (A-4) Longitude: 147° 35.5' W (-147.59200)
To reach the tidal bench marks, from Cordova head north out of Orca Inlet to
Orca Bay, continue west through Orca Bay to Prince William Sound, upon passage
of Applegate Rock, head SSW, upon passing The Needle, head SE toward Montague
Island. The tide station was located 9 km (5 nm) NE of Point Bazil. The bench
marks were installed in the vicinity along the shore.
T I D A L B E N C H M A R K S
PRIMARY BENCH MARK STAMPING: 4616 A 1999
DESIGNATION: 945 4616 A
MONUMENTATION: Tidal Station disk VM#: 15981
AGENCY: National Ocean Service (NOS) IDB PID#:
SETTING CLASSIFICATION: Bedrock OPUS PID:
LATITUDE: 60° 1.5' N ( 60.02500) LONGITUDE: 147° 34.5' W (-147.57500)
The primary bench mark is a disk set in a flat bedrock, 83 m (272 ft) NE (40
degrees magnetic) of bench mark 4616 B 1999, 15 m (49 ft) from the vegetation
line, 3 m (10 ft) above the apparent high water line.
BENCH MARK STAMPING: 4616 B 1999
DESIGNATION: 945 4616 B
MONUMENTATION: Tidal Station disk VM#: 15982
AGENCY: National Ocean Service (NOS) IDB PID#:
SETTING CLASSIFICATION: Boulder OPUS PID:
LATITUDE: 60° 1.5' N ( 60.02500) LONGITUDE: 147° 34.5' W (-147.57500)
The bench mark is a disk set in a large boulder, set directly in front of a
grass area, 83 m (272 ft) SW (220 degrees magnetic) of bench mark 4616 A 1999,
42 m (138 ft) north (360 degrees magnetic) of bench mark 4616 C 1999, 7 m (23
ft) from the tree line, and 4 m (13 ft) above the apparent high water line.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 2 of 5
Station ID: 9454616 PUBLICATION DATE: 04/21/2003
Name: MONTAGUE ISLAND
AK
NOAA Chart: 16701 Latitude: 60° 1.5' N ( 60.02500)
USGS Quad: SEWARD (A-4) Longitude: 147° 35.5' W (-147.59200)
T I D A L B E N C H M A R K S
BENCH MARK STAMPING: 4616 C 1999
DESIGNATION: 945 4616 C
MONUMENTATION: Tidal Station disk VM#: 15983
AGENCY: National Ocean Service (NOS) IDB PID#:
SETTING CLASSIFICATION: Boulder OPUS PID:
LATITUDE: 60° 1.5' N ( 60.02500) LONGITUDE: 147° 34.5' W (-147.57500)
The bench mark is a disk set in a mid-size boulder, set directly in front of a
grass area, 44 m (144 ft) NE (40 degrees magnetic) of bench mark 4616 D 1999, 42
m (138 ft) south (180 degrees magnetic) of bench mark 4616 B 1999, 8 m (26 ft)
from the tree line, and approximately 2 m (7 ft) above the apparent high water
line.
BENCH MARK STAMPING: 4616 D 1999
DESIGNATION: 945 4616 D
MONUMENTATION: Tidal Station disk VM#: 15984
AGENCY: National Ocean Service (NOS) IDB PID#:
SETTING CLASSIFICATION: Bedrock OPUS PID:
LATITUDE: 60° 1.5' N ( 60.02500) LONGITUDE: 147° 34.5' W (-147.57500)
The bench mark is a disk set in bedrock upon a ledge, set directly in front of a
small stream and grassy area, 44 m (144 ft) SW (220 degrees magnetic) of bench
mark 4616 C 1999, 34 m (112 ft) NE (80 degrees magnetic) of bench mark 4616 E
1999, 5 m (16 ft) from the tree line, and approximately 8 m (26 ft) above the
apparent high water line.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 3 of 5
Station ID: 9454616 PUBLICATION DATE: 04/21/2003
Name: MONTAGUE ISLAND
AK
NOAA Chart: 16701 Latitude: 60° 1.5' N ( 60.02500)
USGS Quad: SEWARD (A-4) Longitude: 147° 35.5' W (-147.59200)
T I D A L B E N C H M A R K S
BENCH MARK STAMPING: 4616 E 1999
DESIGNATION: 945 4616 E
MONUMENTATION: Tidal Station disk VM#: 15985
AGENCY: National Ocean Service (NOS) IDB PID#:
SETTING CLASSIFICATION: Boulder OPUS PID:
LATITUDE: 60° 1.5' N ( 60.02500) LONGITUDE: 147° 34.5' W (-147.57500)
The bench mark is a disk set in a mid-size boulder on a stony beach, 34 m (112
ft) SW (260 degrees magnetic) of bench mark 4616 D 1999, 5 m (15 ft) from the
vegetation line, and approximately 1 m (3 ft) above the apparent high water
line.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 4 of 5
Station ID: 9454616 PUBLICATION DATE: 04/21/2003
Name: MONTAGUE ISLAND
AK
NOAA Chart: 16701 Latitude: 60° 1.5' N ( 60.02500)
USGS Quad: SEWARD (A-4) Longitude: 147° 35.5' W (-147.59200)
T I D A L D A T U M S
Tidal datums at MONTAGUE ISLAND based on:
LENGTH OF SERIES: 1 Month
TIME PERIOD: September 1999 - September 1999
TIDAL EPOCH: 1983-2001
CONTROL TIDE STATION: 9454050 CORDOVA, ORCA INLET, PRINCE WILLIAM SD
Elevations of tidal datums referred to Mean Lower Low Water (MLLW), in METERS:
HIGHEST OBSERVED WATER LEVEL (09/23/1999) = 3.905
MEAN HIGHER HIGH WATER MHHW = 3.506
MEAN HIGH WATER MHW = 3.227
MEAN SEA LEVEL MSL = 1.853
MEAN TIDE LEVEL MTL = 1.834
MEAN LOW WATER MLW = 0.441
MEAN LOWER LOW WATER MLLW = 0.000
LOWEST OBSERVED WATER LEVEL (09/28/1999) = -0.618
North American Vertical Datum (NAVD88)
Bench Mark Elevation Information In METERS above:
Stamping or Designation MLLW MHW
4616 A 1999 4.817 1.590
4616 B 1999 5.618 2.391
4616 C 1999 5.027 1.800
4616 D 1999 5.711 2.484
4616 E 1999 4.017 0.790
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 5 of 5
Station ID: 9454616 PUBLICATION DATE: 04/21/2003
Name: MONTAGUE ISLAND
AK
NOAA Chart: 16701 Latitude: 60° 1.5' N ( 60.02500)
USGS Quad: SEWARD (A-4) Longitude: 147° 35.5' W (-147.59200)
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.