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National Ocean Service
Datums Page Page 1 of 6
Station ID: 9458849 PUBLICATION DATE: 11/09/2011
Name: CHANKLIUT ISLAND
AK
NOAA Chart: 16566 Latitude: 56° 8.8' N ( 56.14670)
USGS Quad: CHIGNIK (A-1) Longitude: 158° 6.4' W (-158.10700)
To reach the tidal bench marks from the eastern tip of Castle Cape, proceed 10.5
km (6.6 mi) south to the concave northern shore of Chankliut Island. The bench
marks and tide gauge were located in the general vicinity of the eastern end of
the concave beach.
T I D A L B E N C H M A R K S
PRIMARY BENCH MARK STAMPING: 8849 B 1997
DESIGNATION: 945 8849 B
MONUMENTATION: Tidal Station disk VM#: 13717
AGENCY: National Ocean Service (NOS) IDB PID#:
SETTING CLASSIFICATION: Granite bedrock OPUS PID:
LATITUDE: 56° 8.8' N ( 56.14670) LONGITUDE: 158° 6.4' W (-158.10700)
The primary bench mark is a disk set in a black rock granite bedrock, beneath a
ravine in a rock face east of a sand and rock beach, 35.93 m (117.9 ft) NNE of
bench mark 8849 C 1997, 32.12 m (105 4 ft) SSW of bench mark 8849 A 1997, 8.20 m
(26.9 ft) north of a 1980 BLM meander corner, 4.30 m (14.1 ft) west of a
vertical rock face, and 3.20 m (10.5 ft) west of a bent aluminum rod protruding
0.66 m (2.1 ft) from a rock, and 5 m (16 ft) above the apparent high water line.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 2 of 6
Station ID: 9458849 PUBLICATION DATE: 11/09/2011
Name: CHANKLIUT ISLAND
AK
NOAA Chart: 16566 Latitude: 56° 8.8' N ( 56.14670)
USGS Quad: CHIGNIK (A-1) Longitude: 158° 6.4' W (-158.10700)
T I D A L B E N C H M A R K S
BENCH MARK STAMPING: 8849 A 1997
DESIGNATION: 945 8849 A
MONUMENTATION: Tidal Station disk VM#: 13716
AGENCY: National Ocean Service (NOS) IDB PID#:
SETTING CLASSIFICATION: Granite bedrock OPUS PID:
LATITUDE: 56° 8.8' N ( 56.14670) LONGITUDE: 158° 6.4' W (-158.10700)
The bench mark is a disk set in the tan granite bedrock on a boulder beach east
of a sand and rock beach, 549 m (1801 ft) ENE of bench mark 8849 E 2001, 32.12 m
(105.4 ft) NNE of bench mark 8849 B 1997, 6 m (21 ft) west of a vertical rock
cliff, 1 m (3 ft) above the apparent high water line, and 0.01 m (0.03 ft) above
the surface of the rock outcrop.
BENCH MARK STAMPING: 8849 C 1997
DESIGNATION: 945 8849 C
MONUMENTATION: Tidal Station disk VM#: 13718
AGENCY: National Ocean Service (NOS) IDB PID#:
SETTING CLASSIFICATION: Granite bedrock OPUS PID:
LATITUDE: 56° 8.8' N ( 56.14670) LONGITUDE: 158° 6.4' W (-158.10700)
The bench mark is a disk set in a tan granite bedrock on the western end of the
concave rocky beach, on a boulder beach east of a sand and rock beach, 72.33 m
(237.3 ft) NE of bench mark 8849 D 2001, 35.94 m (117.9 ft) SSW (205 degrees
magntic) of bench mark 8849 B 1997, 9 m (28 ft) south of the center of a talus
slope, 3 m (10 ft) west of a vertical rock cliff face, and 2 m (7 ft) from the
apparent high water line.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 3 of 6
Station ID: 9458849 PUBLICATION DATE: 11/09/2011
Name: CHANKLIUT ISLAND
AK
NOAA Chart: 16566 Latitude: 56° 8.8' N ( 56.14670)
USGS Quad: CHIGNIK (A-1) Longitude: 158° 6.4' W (-158.10700)
T I D A L B E N C H M A R K S
BENCH MARK STAMPING: 8849 D 2001
DESIGNATION: 945 8849 D
MONUMENTATION: Tidal Station disk VM#: 16604
AGENCY: National Ocean Service (NOS) IDB PID#:
SETTING CLASSIFICATION: Rock outcrop OPUS PID:
LATITUDE: 56° 8.8' N ( 56.14670) LONGITUDE: 158° 6.4' W (-158.10700)
The bench mark is a disk set in a tan rock outcrop on a boulder beach at the
south end of a rock face east of a sand and rock beach, 435 m (1427 ft) ENE of
bench mark 8849 E 2001, 72.34 m (237.3 ft) SW of bench mark 8849 C 1997, 0.70 m
(2.3 ft) west of vertical rock face, 1 m (3 ft) above the boulder beach, and
0.05 m (0.2 ft) beneath the rock outcrop surface.
BENCH MARK STAMPING: 8849 E 2001
DESIGNATION: 945 8849 E
MONUMENTATION: Flange-encased Rod VM#: 16605
AGENCY: National Ocean Service (NOS) IDB PID#:
SETTING CLASSIFICATION: Stainless steel rod OPUS PID:
LATITUDE: 56° 8.8' N ( 56.14670) LONGITUDE: 158° 6.4' W (-158.10700)
The bench mark is a stainless steel rod on a grassy rise inland from the middle
of a rock and sand beach, 548.96 m (1801.0 ft) ENE of bench mark 8849 A 1997,
435.07 m (1427.4 ft) WSW of bench mark 8849 D 2001, 13 m (42.6 ft) north of the
vegetation line along a tidal lake, 8.1 m (26.6 ft) south of the vegetation line
along the rock beach, and 1.45 m (4.8 ft) north of a wooden witness post. The
datum point is set 3 cm (0.1 ft) above ground, being the top of a stainless
steel rod with a rounded top and punchmark in the center, driven 8.2 m (27 ft)
to refusal, and encased in a 5-inch PVC pipe with NOS logo cap.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 4 of 6
Station ID: 9458849 PUBLICATION DATE: 11/09/2011
Name: CHANKLIUT ISLAND
AK
NOAA Chart: 16566 Latitude: 56° 8.8' N ( 56.14670)
USGS Quad: CHIGNIK (A-1) Longitude: 158° 6.4' W (-158.10700)
T I D A L B E N C H M A R K S
BENCH MARK STAMPING: 8849 F 2002
DESIGNATION: 945 8849 F
MONUMENTATION: Tidal Station disk VM#: 16775
AGENCY: National Ocean Service (NOS) IDB PID#:
SETTING CLASSIFICATION: Bedrock OPUS PID:
LATITUDE: 56° 8.8' N ( 56.14670) LONGITUDE: 158° 6.4' W (-158.10700)
The bench mark is a disk set flush in a bedrock between two boulder, 58 m (190
ft) SE of bench mark 8849 D 1997, 9 m (30 ft) from the apparent high water mark,
and 4 m (13 ft) from a gravel slope.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 5 of 6
Station ID: 9458849 PUBLICATION DATE: 11/09/2011
Name: CHANKLIUT ISLAND
AK
NOAA Chart: 16566 Latitude: 56° 8.8' N ( 56.14670)
USGS Quad: CHIGNIK (A-1) Longitude: 158° 6.4' W (-158.10700)
T I D A L D A T U M S
Tidal datums at CHANKLIUT ISLAND based on:
LENGTH OF SERIES: 1 MONTH
TIME PERIOD: July 2001 - July 2001
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 = 2.592
MEAN HIGH WATER MHW = 2.351
MEAN TIDE LEVEL MTL = 1.388
MEAN SEA LEVEL MSL = 1.367
MEAN LOW WATER MLW = 0.425
MEAN LOWER LOW WATER MLLW = 0.000
North American Vertical Datum (NAVD88)
Bench Mark Elevation Information In METERS above:
Stamping or Designation MLLW MHW
8849 B 1997 4.175 1.824
8849 A 1997 3.100 0.749
8849 C 1997 3.973 1.622
8849 D 2001 3.513 1.162
8849 E 2001 7.528 5.177
8849 F 2002 4.151 1.800
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 6 of 6
Station ID: 9458849 PUBLICATION DATE: 11/09/2011
Name: CHANKLIUT ISLAND
AK
NOAA Chart: 16566 Latitude: 56° 8.8' N ( 56.14670)
USGS Quad: CHIGNIK (A-1) Longitude: 158° 6.4' W (-158.10700)
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.