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National Ocean Service
Datums Page Page 1 of 5
Station ID: 9468261 PUBLICATION DATE: 10/20/2020
Name: KAVALGHAK BAY, ST LAWRENCE ISLAND, AK
AK
NOAA Chart: US3AK89M Latitude: 63° 41.0' N ( 63.68286)
USGS Quad: ST LAWRENCE, AK Longitude: 171° 45.0' W (-171.75019)
The station is located about 38.7 mi (62.4 km) west of Savoonga and 6.4 mi (10.3
km) south of Gambell. To reach the tidal bench marks from the southern end of
the airstrip in Gambell, proceed south by boat or ATV 9 km (5.5 mi) to the north
end of Kavalaghak Bay. The bench marks and tide gauge are located on a bedrock
outcrop at the north end of the bay just south of Kaghoopalik point. The tide
gauge is a dual bubbler orifice mounted to bedrock.
T I D A L B E N C H M A R K S
PRIMARY BENCH MARK STAMPING: 8261 A 2019
DESIGNATION: 946 8261 A
MONUMENTATION: Tidal Station disk VM#: 23105
AGENCY: National Ocean Service IDB PID:
SETTING CLASSIFICATION: OPUS PID#: BBGM57
LATITUDE: 63° 41.0' N ( 63.68283) LONGITUDE: 171° 45.0' W (-171.75008)
The primary bench mark is a disk set in a bedrock outcrop 0.5 km (0.3 mi) SE of
Kaghoopalik Point, 74.57 m (244.7 ft) SE of bench mark 8261 B 2019, 33.65 m
(110.4 ft) SSE of a wood seal hiunting blind, and 1.30 m (4.3 ft) SE of the N
edge of the bedrock outcrop which is a rock crevice that leads down to the
water.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 2 of 5
Station ID: 9468261 PUBLICATION DATE: 10/20/2020
Name: KAVALGHAK BAY, ST LAWRENCE ISLAND, AK
AK
NOAA Chart: US3AK89M Latitude: 63° 41.0' N ( 63.68286)
USGS Quad: ST LAWRENCE, AK Longitude: 171° 45.0' W (-171.75019)
T I D A L B E N C H M A R K S
BENCH MARK STAMPING: 8261 B 2019
DESIGNATION: 946 8261 B
MONUMENTATION: Tidal Station disk VM#: 23106
AGENCY: National Ocean Service IDB PID:
SETTING CLASSIFICATION: OPUS PID:
LATITUDE: 63° 41.0' N ( 63.68336) LONGITUDE: 171° 45.1' W (-171.75103)
The bench mark is a disk set in a bedrock outcrop 0.4 km (0.2 mi) SE of
Kaghoopalik Point, 74.57 m (244.7 ft) NW of bench mark 8261 A 2019, 58.06 m
(190.5 ft) WNW of a wood seal hunting blind, 3.20 m (10.5 ft) ENE of the ocean
end of the outcrop, 0.37 m (1.2 ft) SSE of the N side or face of the outcrop,
and 1.18 m (3.9 ft) above the sand beach of bench mark 8261 A 2019.
BENCH MARK STAMPING: 8261 C 2019
DESIGNATION: 946 8261 C
MONUMENTATION: Tidal Station disk VM#: 23107
AGENCY: National Ocean Service IDB PID:
SETTING CLASSIFICATION: OPUS PID:
LATITUDE: 63° 41.1' N ( 63.68417) LONGITUDE: 171° 44.9' W (-171.74772)
The bench mark is a disk set in a boulder that is 1.05 m (3.4 ft) in width and
2.10 m (6.9 ft) in length, 0.5 km (0.3 mi) ESE of Koghoopalik Point, 318.5 m
(1044.9 ft) SE of bench mark 8261 D 2019, 189.64 m (622.2 ft) NE of bench mark
8261 A 2019, 20.32 m (66.7 ft) WNW of the center of an ATV trail, 0.75 m (2.5
ft) W of the E edge of the boulder, 0.51 m (1.7 ft) S of the N edge of the
boulder, and 0.26 m (0.9 ft) above the ground.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 3 of 5
Station ID: 9468261 PUBLICATION DATE: 10/20/2020
Name: KAVALGHAK BAY, ST LAWRENCE ISLAND, AK
AK
NOAA Chart: US3AK89M Latitude: 63° 41.0' N ( 63.68286)
USGS Quad: ST LAWRENCE, AK Longitude: 171° 45.0' W (-171.75019)
T I D A L B E N C H M A R K S
BENCH MARK STAMPING: 8261 D 2019
DESIGNATION: 946 8261 D
MONUMENTATION: Tidal Station disk VM#: 23108
AGENCY: National Ocean Service IDB PID:
SETTING CLASSIFICATION: OPUS PID:
LATITUDE: 63° 41.2' N ( 63.68583) LONGITUDE: 171° 45.2' W (-171.75289)
The bench mark is a disk set at the south tip of a bedrock outcrop 3.7 m (12.1
ft) in length, 0.2 km (o.1 mi) ESE of Kaghoopalik Point, 318.50 m (1044.9 ft) NW
of bench mark 8261 C 2019, 162.09 m (531.8 ft) ESE of bench mark 8261 E 2019,
5.57 m (18.3 ft) SSE of the high point of a rock outcrop or hill with the WSW
face of the outcrop to the ocean, 0.54 m (1.8 ft) NW of the S end of the rock,
and 0.66 m (2.2 ft) above the ground.
BENCH MARK STAMPING: 8261 E 2019
DESIGNATION: 946 8261 E
MONUMENTATION: Tidal Station disk VM#: 23109
AGENCY: National Ocean Service IDB PID:
SETTING CLASSIFICATION: OPUS PID#: BBGM58
LATITUDE: 63° 41.2' N ( 63.68678) LONGITUDE: 171° 45.3' W (-171.75536)
The bench mark is a disk set in a 3.94 m (12.9 ft) by 4.33 m (14.2 ft) large
rock or boulder 80 m (260 ft) E of Kaghoopalik Point, 162.09 m (531.8 ft) NW of
bench mark 8261 D 2019, 44.4 m (145.7 ft) WSW of the top of the hill behind this
point of land, 42.06 m (138.0 ft) ENE of a stone blind for seal hunting at the
edge of tundra bluff overlooking rock point, 1.50 m (4.9 ft) NE of the SW point
of rock which the bench mark is set, 0.33 m (1.1 ft) WSW of a boulder on top of
the rock which the bench mark is set and 0.77 m (2.5 ft) above the ground.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 4 of 5
Station ID: 9468261 PUBLICATION DATE: 10/20/2020
Name: KAVALGHAK BAY, ST LAWRENCE ISLAND, AK
AK
NOAA Chart: US3AK89M Latitude: 63° 41.0' N ( 63.68286)
USGS Quad: ST LAWRENCE, AK Longitude: 171° 45.0' W (-171.75019)
T I D A L D A T U M S
Tidal datums at KAVALGHAK BAY, ST LAWRENCE ISLAND, AK based on:
LENGTH OF SERIES: 2 MONTHS
TIME PERIOD: July 2019 - August 2019
TIDAL EPOCH: 1983-2001
CONTROL TIDE STATION: 9491094 RED DOG DOCK
Elevations of tidal datums referred to Mean Lower Low Water (MLLW), in METERS:
MEAN HIGHER HIGH WATER MHHW = 0.737
MEAN HIGH WATER MHW = 0.684
MEAN TIDE LEVEL MTL = 0.398
MEAN SEA LEVEL MSL = 0.374
MEAN LOW WATER MLW = 0.111
MEAN LOWER LOW WATER MLLW = 0.000
North American Vertical Datum NAVD88 = -0.216
North American Vertical Datum (NAVD88)
Bench Mark Elevation Information In METERS above:
Stamping or Designation MLLW MHW
8261 A 2019 2.558 1.874
8261 B 2019 2.354 1.670
8261 C 2019 25.689 25.005
8261 D 2019 18.633 17.949
8261 E 2019 9.164 8.480
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 5 of 5
Station ID: 9468261 PUBLICATION DATE: 10/20/2020
Name: KAVALGHAK BAY, ST LAWRENCE ISLAND, AK
AK
NOAA Chart: US3AK89M Latitude: 63° 41.0' N ( 63.68286)
USGS Quad: ST LAWRENCE, AK Longitude: 171° 45.0' W (-171.75019)
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.