U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Datums Page Page 1 of 8
Station ID: 9462620 PUBLICATION DATE: 06/17/2019
Name: UNALASKA, DUTCH HARBOR
AK
NOAA Chart: 16529 Latitude: 53° 52.8' N ( 53.87919)
USGS Quad: UNALASKA Longitude: 166° 32.4' W (-166.54031)
To reach the tidal bench marks from the Airport at Dutch Harbor where there is
only one road leading from the Airport to the bridge that crosses over the inlet
to Unalaska, once over the bridge, stay on main road till you come to a "T"
intersection (Generator Plant and school should be directly ahead), make a left
turn and go to the end of road to Alyeska Seafoods, Inc. Tide gauge is located
on pier of fisheries property. The bench marks are located in the general
vicinity.
T I D A L B E N C H M A R K S
PRIMARY BENCH MARK STAMPING: 2620 M 1992
DESIGNATION: 946 2620 M
MONUMENTATION: Tidal Station disk VM#: 11821
AGENCY: National Ocean Survey (NOS) IDB PID:
SETTING CLASSIFICATION: Stainless steel rod OPUS PID#: BBFP54
LATITUDE: 53° 52.6' N ( 53.87597) LONGITUDE: 166° 32.2' W (-166.53636)
The primary bench mark is set between 7th and 8th 4" x 4" vertical fence
supports from the northern-most harbor side corner of the wood picket fence that
surrounds the Russian Orthodox Church -- the Church of the Holy Ascension, 34.70
m (113.8 ft) NE of the northern-most corner of the church, 5.50 m (18.0 ft) SW
of the centerline of the road that fronts the harbor, and 0.80 m (2.6 ft) east
of the north corner of the wood picket fence with an attached witness post
located inside the church property and facing the water. The bench mark is
crimped to the top of a stainless steel rod driven 7.3 m (24 ft) to substantial
resistance, and encased by a 4-inch diameter black ABS pipe with cover
projecting 8 cm (0.25 ft) above natural grade.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 2 of 8
Station ID: 9462620 PUBLICATION DATE: 06/17/2019
Name: UNALASKA, DUTCH HARBOR
AK
NOAA Chart: 16529 Latitude: 53° 52.8' N ( 53.87919)
USGS Quad: UNALASKA Longitude: 166° 32.4' W (-166.54031)
T I D A L B E N C H M A R K S
BENCH MARK STAMPING: NO 7 1956
DESIGNATION: 946 2620 TIDAL 7
MONUMENTATION: Tidal Station disk VM#: 11814
AGENCY: US Coast and Geodetic Survey
(USC&GS) IDB PID:
SETTING CLASSIFICATION: Concrete foundation OPUS PID#: BBFR76
LATITUDE: 53° 52.7' N ( 53.87753) LONGITUDE: 166° 32.3' W (-166.53897)
The bench mark is a disk set in concrete within the TelAlaska locked gate, 46.00
m (150.9 ft) NE of bench mark 946 2620 Tidal 20, 11.30 m (37.1 ft) west of a
chain link fence on the east side of the Alascom compound, 6.17 m (20.2 ft) SSE
of the door knob leading to the AT&T Alascom building, 0.36 m (1.2 ft) north of
a hollowed out stump flush with the ground, and 0.09 m (0.3 ft) below grade.
BENCH MARK STAMPING: NO 16 1958
DESIGNATION: 946 2620 TIDAL 16
MONUMENTATION: Tidal Station disk VM#: 11815
AGENCY: US Coast and Geodetic Survey
(USC&GS) IDB PID:
SETTING CLASSIFICATION: Concrete gun-box OPUS PID:
LATITUDE: 53° 52.4' N ( 53.87400) LONGITUDE: 166° 31.9' W (-166.53122)
The bench mark is a disk set in the north (seaside) corner of an old concrete
gun box on the south side of Bayview Avenue between Fourth and Fifth streets,
116.7 m (383.0 ft) SE of bench mark 946 2620 Tidal 19, 45.7 m (150.0 ft) north
of the Unalaska School House in middle of the fence along the NE side of the
school yard (the fence jogs around the bunker), 4.60 m (15.1 ft) SSW of the
centerline of Bayview Avenue, 0.30 m (1.0 ft) SE of the north corner of the
bunker, and 1.00 m (3.3 ft) above ground.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 3 of 8
Station ID: 9462620 PUBLICATION DATE: 06/17/2019
Name: UNALASKA, DUTCH HARBOR
AK
NOAA Chart: 16529 Latitude: 53° 52.8' N ( 53.87919)
USGS Quad: UNALASKA Longitude: 166° 32.4' W (-166.54031)
T I D A L B E N C H M A R K S
BENCH MARK STAMPING: NO 19 1973
DESIGNATION: 946 2620 TIDAL 19
MONUMENTATION: Tidal Station disk VM#: 11816
AGENCY: National Ocean Survey (NOS) IDB PID:
SETTING CLASSIFICATION: Concrete gun-box OPUS PID#: BBBB51
LATITUDE: 53° 52.5' N ( 53.87444) LONGITUDE: 166° 32.0' W (-166.53281)
The bench mark is set in the top center of an hexagonal World War II concrete
gun-box in front of an apartment building on south side of Bayview Avenue
between Third and Fourth Streets, 117 m (383 ft) NW of bench mark 946 2620 TIDAL
16, 6.71 m (22.0 ft) SW of the centerline of Bayview Avenue, and 0.80 m (2.6 ft)
above the ground level.
BENCH MARK STAMPING: NO 20 1974
DESIGNATION: 946 2620 TIDAL 20
MONUMENTATION: Tidal Station disk VM#: 11817
AGENCY: US Coast and Geodetic Survey IDB PID:
SETTING CLASSIFICATION: Concrete foundation OPUS PID:
LATITUDE: 53° 52.6' N ( 53.87722) LONGITUDE: 166° 32.4' W (-166.53931)
The bench mark is a disk set vertically in the eastern corner of an Alyeska Bunk
House, 46.02 m (151.0 ft) SW of bench mark 946 2620 TIDAL 7, 3.51 m (11.5 ft) SW
of the main gate hige post on the fence to the AT&T Alascom Facility, 2.71 m
(8.9 ft) NNW of the northernmost support to the neighboring "10 Units Bunk
House", 0.09 m (0.3 ft) west of NE corner of the Alyeska bunkhouse, and 0.61 m
(2.0 ft) above ground level.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 4 of 8
Station ID: 9462620 PUBLICATION DATE: 06/17/2019
Name: UNALASKA, DUTCH HARBOR
AK
NOAA Chart: 16529 Latitude: 53° 52.8' N ( 53.87919)
USGS Quad: UNALASKA Longitude: 166° 32.4' W (-166.54031)
T I D A L B E N C H M A R K S
BENCH MARK STAMPING: TIDAL BM 21 1975
DESIGNATION: 946 2620 TIDAL BM 21
MONUMENTATION: Tidal Station disk VM#: 11818
AGENCY: US Coast and Geodetic Survery
(USC&GS) IDB PID:
SETTING CLASSIFICATION: Concrete slab OPUS PID:
LATITUDE: 53° 52.7' N ( 53.87775) LONGITUDE: 166° 32.3' W (-166.53900)
The bench mark is a disk set in the north corner of a 1.37 m x 1.37 m (4.5 ft x
4.5 ft) concrete base, 9.00 m (29.5 ft) east of the west support leg of a large
satellite dish, 11.70 m (38.4 ft) west of the NW corner of the Alascom Building,
2.80 m (9.2 ft) north of the NE corner of a 1.70 m x 3.40 m x 1.30 m (5.6 ft x
11.2 ft x 4.3 ft) rectangular green diesel fuel tank, and 0.30 m (1.0 ft) above
ground level and directly under a cable raceway.
BENCH MARK STAMPING: 2620 P 1997
DESIGNATION: 946 2620 P
MONUMENTATION: Tidal Station disk VM#: 13866
AGENCY: National Ocean Service (NOS) IDB PID:
SETTING CLASSIFICATION: Concrete vault OPUS PID#: BBFR66
LATITUDE: 53° 52.6' N ( 53.87653) LONGITUDE: 166° 32.3' W (-166.53778)
The bench mark is set flush in the east corner of a concrete electrical vault at
the corner of West Broadway Avenue and Cathedral Way, 15.50 m (50.9 ft) NE of
the stop sign at the intersection, 9.50 m (31.2 ft) north of a metal light pole,
0.20 m (0.7 ft) west of the east corner of concrete vault, and 0.20 m (0.7 ft)
above ground.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 5 of 8
Station ID: 9462620 PUBLICATION DATE: 06/17/2019
Name: UNALASKA, DUTCH HARBOR
AK
NOAA Chart: 16529 Latitude: 53° 52.8' N ( 53.87919)
USGS Quad: UNALASKA Longitude: 166° 32.4' W (-166.54031)
T I D A L B E N C H M A R K S
BENCH MARK STAMPING: 2620 Q 2002
DESIGNATION: 946 2620 Q
MONUMENTATION: Tidal Station disk VM#: 16848
AGENCY: National Ocean Service (NOS) IDB PID:
SETTING CLASSIFICATION: Concrete foundation OPUS PID:
LATITUDE: 53° 52.4' N ( 53.87267) LONGITUDE: 166° 31.7' W (-166.52897)
The bench mark is a disk set flush in a concrete foundation located on the north
side of Unalaska High School, 10.50 m (34.4 ft) south of the center line of
Mission Avenue, and 0.22 m (0.7 ft) west of the east edge of a driveway for a 3
m (10 ft) wide white roll-up door.
BENCH MARK STAMPING: NO 10 1948
DESIGNATION: 946 2620 TIDAL 10
MONUMENTATION: Tidal Station disk VM#: 16849
AGENCY: US Coast and Geodetic Survey
(USC&GS) IDB PID:
SETTING CLASSIFICATION: Concrete foundation OPUS PID#: BBFR77
LATITUDE: 53° 52.4' N ( 53.87269) LONGITUDE: 166° 31.4' W (-166.52400)
The bench mark is a disk set in the south side of the 3.30 m (10.8 ft) diameter
concrete foundation of a three stepped base for a wood pole (now gone) in the
City of Unalaska Memorial Park, 17.20 m (56.4 ft) SE of a marble monument
dedicated to lost mariners, 17.20 m (56.4 ft) west of a hexagonal concrete
machine-gun bunker, and 15.80 m (51.8 ft) SW of a square marble monument
inscribed as "World War II in the Aleutians".
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 6 of 8
Station ID: 9462620 PUBLICATION DATE: 06/17/2019
Name: UNALASKA, DUTCH HARBOR
AK
NOAA Chart: 16529 Latitude: 53° 52.8' N ( 53.87919)
USGS Quad: UNALASKA Longitude: 166° 32.4' W (-166.54031)
T I D A L B E N C H M A R K S
BENCH MARK STAMPING: 2620 R 2014
DESIGNATION: 946 2620 R
MONUMENTATION: Bench Mark disk VM#: 21203
AGENCY: National Ocean Service (NOS) IDB PID:
SETTING CLASSIFICATION: Concrete mat OPUS PID#: BBFR67
LATITUDE: 53° 52.4' N ( 53.87397) LONGITUDE: 166° 31.1' W (-166.51778)
The bench mark is a disk set in the NE corner of a 3.3 m (10.8 ft) x 10.9 m
(35.8 ft) concrete foundation, 64.70 m (212.3 ft) NE of a 0.80 m (2.6 ft)
diameter orange culvert which runs beneath the road at the intersection with a
driveway, 29.25 m (96.0 ft) SW of a 1.22 m (4.0 ft) high yellow wooden bollard
the W most of a group of three yellow bollards, 6.78 m (22.2 ft) S from the top
of a 0.44 m (1.4 ft) diameter culvert with orange flag which runs beneath the
road, 6.20 m (20.3 ft) SE from the should of the road, 5.51 m (18.1 ft) E from
an orange carsonite survey marker post, 1.19 m (3.9 ft) SE from the NW edge of
the concrete, 0.82 m (2.7 ft) SW from the NE edge of the concrete.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 7 of 8
Station ID: 9462620 PUBLICATION DATE: 06/17/2019
Name: UNALASKA, DUTCH HARBOR
AK
NOAA Chart: 16529 Latitude: 53° 52.8' N ( 53.87919)
USGS Quad: UNALASKA Longitude: 166° 32.4' W (-166.54031)
T I D A L D A T U M S
Tidal datums at UNALASKA, DUTCH HARBOR based on:
LENGTH OF SERIES: 19 YEARS
TIME PERIOD: Jan '83-Dec '01 & Jan '97-Dec '01
TIDAL EPOCH: 1983-2001
CONTROL TIDE STATION:
Elevations of tidal datums referred to Mean Lower Low Water (MLLW), in METERS:
HIGHEST OBSERVED WATER LEVEL (01/27/1960) = 2.043
MEAN HIGHER HIGH WATER MHHW = 1.098
MEAN HIGH WATER MHW = 1.011
MEAN TIDE LEVEL MTL = 0.647
MEAN SEA LEVEL MSL = 0.635
MEAN LOW WATER MLW = 0.283
MEAN LOWER LOW WATER MLLW = 0.000
North American Vertical Datum NAVD88 = -0.080
LOWEST OBSERVED WATER LEVEL (12/13/2008) = -0.847
North American Vertical Datum (NAVD88)
Bench Mark Elevation Information In METERS above:
Stamping or Designation MLLW MHW
2620 M 1992 3.345 2.334
NO 7 1956 2.805 1.794
NO 16 1958 5.598 4.587
NO 19 1973 5.007 3.996
NO 20 1974 4.723 3.712
TIDAL BM 21 1975 3.242 2.231
2620 P 1997 3.574 2.563
2620 Q 2002 5.889 4.878
NO 10 1948 5.774 4.763
2620 R 2014 3.423 2.412
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 8 of 8
Station ID: 9462620 PUBLICATION DATE: 06/17/2019
Name: UNALASKA, DUTCH HARBOR
AK
NOAA Chart: 16529 Latitude: 53° 52.8' N ( 53.87919)
USGS Quad: UNALASKA Longitude: 166° 32.4' W (-166.54031)
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.