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National Ocean Service
Datums Page Page 1 of 5
Station ID: 9456901 PUBLICATION DATE: 05/12/2004
Name: AGUCHIK ISLAND
AK
NOAA Chart: 16603 Latitude: 58° 17.4' N ( 58.29000)
USGS Quad: MOUNT KATMAI (B-1) Longitude: 154° 16.2' W (-154.27000)
To reach the tidal bench marks from Kodiak, navigate north 110 km (60 nm) around
the north side of Shuyak Island using Stevenson Entrance, then from Stevenson
Entrance head 110 km (60 nm) SW to the mouth of Kukak Bay, then head SW to the
head of Kukak Bay then around the south side of Aguchik Island to the NE corner
of Aguchik Island. Then inshore of a small island and just south of where
Aguchik Island joins the mainland at low water was the site of the tide station.
The bench marks are located along the rock outcrop along the beach.
T I D A L B E N C H M A R K S
PRIMARY BENCH MARK STAMPING: 6901 A 2000
DESIGNATION: 945 6901 A
MONUMENTATION: Tidal Station disk VM#: 16205
AGENCY: National Ocean Service (NOS) IDB PID#:
SETTING CLASSIFICATION: Boulder OPUS PID:
LATITUDE: 58° 17.4' N ( 58.29000) LONGITUDE: 154° 16.2' W (-154.27000)
The primary bench mark is a disk set in a boulder below a large bedrock cliff,
300 m (984 ft) SW of the bar that connects Aguchik Island to the mainland at low
water, 42 m (138 ft) SW of a flat-topped boulder that is slightly offshore and
directly across the cove from the NE tip of a small island which connects to
shore at low tide, 2.50 m (8.2 ft) from the tree line, 1 m (3 ft) from the grass
line, and 2 m (5 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: 9456901 PUBLICATION DATE: 05/12/2004
Name: AGUCHIK ISLAND
AK
NOAA Chart: 16603 Latitude: 58° 17.4' N ( 58.29000)
USGS Quad: MOUNT KATMAI (B-1) Longitude: 154° 16.2' W (-154.27000)
T I D A L B E N C H M A R K S
BENCH MARK STAMPING: 6901 B 2000
DESIGNATION: 945 6901 B
MONUMENTATION: Tidal Station disk VM#: 16206
AGENCY: National Ocean Service (NOS) IDB PID#:
SETTING CLASSIFICATION: Boulder OPUS PID:
LATITUDE: 58° 17.4' N ( 58.29000) LONGITUDE: 154° 16.2' W (-154.27000)
The bench mark is a disk set in a 4 m x 5 m ( 13ft x 16 ft) boulder located
directly north of the SW tip of the small island offshore, 92 m (302 ft) SW of
bench mark 6901 A 2000, and 1 m (3 ft) above apparent high water line.
BENCH MARK STAMPING: 6901 C 2000
DESIGNATION: 945 6901 C
MONUMENTATION: Tidal Station disk VM#: 16207
AGENCY: National Ocean Service (NOS) IDB PID#:
SETTING CLASSIFICATION: Boulder OPUS PID:
LATITUDE: 58° 17.4' N ( 58.29000) LONGITUDE: 154° 16.2' W (-154.27000)
The bench mark is a disk set in a 1 m x 2 m (3 ft x 6 ft) boulder located
directly across the water from the SW tip of the small island offshore, 72 m
(236 ft) SW of bench mark 6901 B 2000, 11 m (36 ft) from the tree line, and 0.50
m (1.6 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: 9456901 PUBLICATION DATE: 05/12/2004
Name: AGUCHIK ISLAND
AK
NOAA Chart: 16603 Latitude: 58° 17.4' N ( 58.29000)
USGS Quad: MOUNT KATMAI (B-1) Longitude: 154° 16.2' W (-154.27000)
T I D A L B E N C H M A R K S
BENCH MARK STAMPING: 6901 D 2000
DESIGNATION: 945 6901 D
MONUMENTATION: Tidal Station disk VM#: 16208
AGENCY: National Ocean Service (NOS) IDB PID#:
SETTING CLASSIFICATION: Boulder OPUS PID:
LATITUDE: 58° 17.4' N ( 58.29000) LONGITUDE: 154° 16.2' W (-154.27000)
The bench mark is a disk set in a 1 m x 2 m (3 ft x 6 ft) angular boulder that
is part of a rock pile located at the base of the western-most rocky cliff at
the site, north of a major gully, 17 m (56 ft) west of bench mark 6901 C 2000, 7
m (23 ft) inshore of the apparent high water line, and 5 m (16 ft) from the tree
line.
BENCH MARK STAMPING: 6901 E 2000
DESIGNATION: 945 6901 E
MONUMENTATION: Tidal Station disk VM#: 16209
AGENCY: National Ocean Service (NOS) IDB PID#:
SETTING CLASSIFICATION: Bedrock OPUS PID:
LATITUDE: 58° 17.4' N ( 58.29000) LONGITUDE: 154° 16.2' W (-154.27000)
The bench mark is a disk set flush in a bedrock located at the base on the
eastern side of a small islet that is 120 m (394 ft) SW of the small offshore
island and east of a major gully on Aguchik Island, 158 m (518 ft) south of
bench mark 6901 D 2000, and 8 m (25 ft) inshore of the apparent high water line.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 4 of 5
Station ID: 9456901 PUBLICATION DATE: 05/12/2004
Name: AGUCHIK ISLAND
AK
NOAA Chart: 16603 Latitude: 58° 17.4' N ( 58.29000)
USGS Quad: MOUNT KATMAI (B-1) Longitude: 154° 16.2' W (-154.27000)
T I D A L D A T U M S
Tidal datums at AGUCHIK ISLAND based on:
LENGTH OF SERIES: 2 MONTHS
TIME PERIOD: May 2000 - June 2000
TIDAL EPOCH: 1983-2001
CONTROL TIDE STATION: 9459450 SAND POINT, POPOF ISLAND
Elevations of tidal datums referred to Mean Lower Low Water (MLLW), in METERS:
MEAN HIGHER HIGH WATER MHHW = 4.193
MEAN HIGH WATER MHW = 3.944
MEAN TIDE LEVEL MTL = 2.215
MEAN SEA LEVEL MSL = 2.201
MEAN LOW WATER MLW = 0.486
MEAN LOWER LOW WATER MLLW = 0.000
North American Vertical Datum (NAVD88)
Bench Mark Elevation Information In METERS above:
Stamping or Designation MLLW MHW
6901 A 2000 4.065 0.121
6901 B 2000 3.557 -0.388
6901 C 2000 3.244 -0.701
6901 D 2000 4.414 0.470
6901 E 2000 5.120 1.176
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 5 of 5
Station ID: 9456901 PUBLICATION DATE: 05/12/2004
Name: AGUCHIK ISLAND
AK
NOAA Chart: 16603 Latitude: 58° 17.4' N ( 58.29000)
USGS Quad: MOUNT KATMAI (B-1) Longitude: 154° 16.2' W (-154.27000)
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.