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Datums Page Page 1 of 7
Station ID: 9455920 PUBLICATION DATE: 07/03/2019
Name: ANCHORAGE, KNIK ARM, COOK INLET
AK
NOAA Chart: 16664 Latitude: 61° 14.2' N ( 61.23750)
USGS Quad: ANCHORAGE A-8 Longitude: 149° 53.4' W (-149.89040)
To reach the tidal bench marks from the Ted Stevens Anchorage International
Airport, follow International Airport Road 3.8 km (2.4 mi) east to the
northbound Minnesota exit, proceed north 5.5 km (3.4 mi) to 6th Avenue and turn
right, proceed 0.9 km (0.5 mi) east to A Street and turn left, proceed north 0.9
km (0.6 mi) and to the Port Exit in the right lane, follow this curving exit
road which becomes Ocean Dock Road 1.0 km (0.6 mi) through two security check
points, veer to the right as the road becomes Anchorage Port Road and continue
north 0.8 km (0.5 mi) to the POL-1 dock. The tide house is located in the green
metal building at the very south end of the POL-1 dock. The bench marks are
located from the Port of Anchorage Building south 1.3 km (0.8 mi) to the
railroad yard near the Port Exit from A Street.
T I D A L B E N C H M A R K S
PRIMARY BENCH MARK STAMPING: NO 15 RESET 1966
DESIGNATION: 945 5920 TIDAL 15 1966
MONUMENTATION: Bench Mark disk VM#: 1332
AGENCY: US Coast and Geodetic Survey
(USC&GS) IDB PID#: TT0711
SETTING CLASSIFICATION: Concrete dock OPUS PID:
LATITUDE: 61° 14.4' N ( 61.23953) LONGITUDE: 149° 53.3' W (-149.88769)
The primary bench mark is a disk set flush with the concrete surface of the
Anchorage City Dock, 101 m ( (330 ft) NW of bench mark 5920 B 1980, 9.45 m (31.0
ft) S of the N edge of the dock, 4.85 m (15.9 ft) NW of the NE corner of the
Port of Anchorage Office building, 3.84 m (12.6 ft) NE of the N door of the
office, and 2.87 m (9.4 ft) E of a 1 m (4 ft) high concrete deck landing for the
office N door.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 2 of 7
Station ID: 9455920 PUBLICATION DATE: 07/03/2019
Name: ANCHORAGE, KNIK ARM, COOK INLET
AK
NOAA Chart: 16664 Latitude: 61° 14.2' N ( 61.23750)
USGS Quad: ANCHORAGE A-8 Longitude: 149° 53.4' W (-149.89040)
T I D A L B E N C H M A R K S
BENCH MARK STAMPING: 5920 B 1980
DESIGNATION: 945 5920 B
MONUMENTATION: Tidal Station disk VM#: 1336
AGENCY: National Ocean Survey (NOS) IDB PID:
SETTING CLASSIFICATION: Copper-clad steel rod OPUS PID:
LATITUDE: 61° 14.3' N ( 61.23914) LONGITUDE: 149° 53.2' W (-149.88586)
The bench mark is a disk set near the NW corner of the blue and white repair
shop building belonging to the Port of Anchorage, 101 m (330 ft) SE of bench
mark NO 15 RESET 1966, 27 m (90 ft) S of light pole LP 5, 0.98 m (3.2 ft) N of
the NW edge of a 5 m (15 ft) wide doorway, and 0.37 m (1.2 ft) NE of NW corner
of the repair shop. The bench mark is 0.06 m (0.2 ft) below ground, being the
top of a disk set on a copper-clad steel rod driven to a depth of 21.6 m (71 ft)
and encased in a 4-inch PVC pipe.
BENCH MARK STAMPING: 5920 G 2011
DESIGNATION: 945 5920 G
MONUMENTATION: Tidal Station disk VM#: 20098
AGENCY: National Ocean Service (NOS) IDB PID:
SETTING CLASSIFICATION: Utility vault OPUS PID#: BBFH14
LATITUDE: 61° 14.1' N ( 61.23506) LONGITUDE: 149° 53.2' W (-149.88714)
The bench mark is a disk set in a 1.80 m X 2.10 m concrete utility vault located
on the W side of Tidewater Road, 25.30 m (83.0 ft) E of the most eastern rail of
the railroad tracks that run N and S 8.30 m (27.2 ft) W of the centerline of
Tidewater Road, and 7.30 m (23.9 ft) S of a yellow fire hydrant.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 3 of 7
Station ID: 9455920 PUBLICATION DATE: 07/03/2019
Name: ANCHORAGE, KNIK ARM, COOK INLET
AK
NOAA Chart: 16664 Latitude: 61° 14.2' N ( 61.23750)
USGS Quad: ANCHORAGE A-8 Longitude: 149° 53.4' W (-149.89040)
T I D A L B E N C H M A R K S
BENCH MARK STAMPING: 5920 H 2011
DESIGNATION: 945 5920 H
MONUMENTATION: Tidal Station disk VM#: 20099
AGENCY: National Ocean Service (NOS) IDB PID:
SETTING CLASSIFICATION: Concrete sidewalk OPUS PID#: BBFH52
LATITUDE: 61° 13.8' N ( 61.23025) LONGITUDE: 149° 53.4' W (-149.89022)
The bench mark is a disk set in a concrete sidewalk on the W side of Chevron
Corporation at 459 W Bluff Road, 12.25 m (40.1 ft) N of the centerline of W
Bluff Road, 1.60 m (5.2 ft) NW of the SW corner of the Chevron Building, 1.20 m
(3.9 ft) E of the most eastern rail road track, and 0.20 m (0.65 ft) above
ground level.
BENCH MARK STAMPING: 945 5920 J 2014
DESIGNATION: 945 5920 J
MONUMENTATION: Bench Mark disk VM#: 21300
AGENCY: National Ocean Service IDB PID:
SETTING CLASSIFICATION: Concrete step OPUS PID:
LATITUDE: 61° 14.2' N ( 61.23667) LONGITUDE: 149° 53.2' W (-149.88597)
The bench mark is a surface disk set in a large concrete stair pad at the
entrance to the horizon lines building at 1717 port road, 20 m (65.6 ft) S of NW
corner of brick building, 6.5 m (21.3 ft) east of N of 2 flag poles, 2.5 m (8.2
ft) W of main building wall, 0.7 m (2.3 ft) above grade.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 4 of 7
Station ID: 9455920 PUBLICATION DATE: 07/03/2019
Name: ANCHORAGE, KNIK ARM, COOK INLET
AK
NOAA Chart: 16664 Latitude: 61° 14.2' N ( 61.23750)
USGS Quad: ANCHORAGE A-8 Longitude: 149° 53.4' W (-149.89040)
T I D A L B E N C H M A R K S
BENCH MARK STAMPING: 945 5920 K 2014
DESIGNATION: 945 5920 K
MONUMENTATION: Bench Mark disk VM#: 21301
AGENCY: National Ocean Service IDB PID:
SETTING CLASSIFICATION: Top of concrete base OPUS PID:
LATITUDE: 61° 13.9' N ( 61.23250) LONGITUDE: 149° 53.3' W (-149.88834)
The bench mark is a disk set in a 2 m (6.6 ft) x 2 meter concrete base of a 3.5
m (11.5 ft) bronze propeller monument SW of the port security building at 311
Anchorage port road. Set in the NW corner of the concrete pad, 19.5 m (64.0 ft)
SW of the SW corner of the port security building, 14.7 m (48.2 ft) E of the E
spur railroad tracks, 3.5 m (11.5 ft) WSW of fire hydrant 1030 #904.
BENCH MARK STAMPING: 945 5920 L 2014
DESIGNATION: 945 5920 L
MONUMENTATION: Bench Mark disk VM#: 21302
AGENCY: National Ocean Service IDB PID:
SETTING CLASSIFICATION: Disk set in concrete silo base OPUS PID:
LATITUDE: 61° 13.9' N ( 61.23228) LONGITUDE: 149° 53.5' W (-149.89153)
The bench mark is W of the port security building at 311 Anchorage port road and
NW of the intersection of roger graves and Anchorage port rd. The bench mark
disk set in SW corner of 20 m (65.6 ft) x 30 m (98.4 ft) concrete pad with 6
cement powder storage silos. 10.5 m (34.4 ft) W of centerline of concrete pad.
5.3 m (17.4 ft) S of center line weld on SW most of 6 steel silos. 0.2 m (0.7
ft) N of SW corner of concrete pad.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 5 of 7
Station ID: 9455920 PUBLICATION DATE: 07/03/2019
Name: ANCHORAGE, KNIK ARM, COOK INLET
AK
NOAA Chart: 16664 Latitude: 61° 14.2' N ( 61.23750)
USGS Quad: ANCHORAGE A-8 Longitude: 149° 53.4' W (-149.89040)
T I D A L B E N C H M A R K S
BENCH MARK STAMPING: 5920 THERMO 1 1988
DESIGNATION: 945 5920 THERMO 1
ALIAS: THERMO 1 RESET
MONUMENTATION: Tidal Station disk VM#: 23023
AGENCY: National Ocean Service IDB PID:
SETTING CLASSIFICATION: Thermopile deep rod OPUS PID#: BBBH31
LATITUDE: 61° 14.0' N ( 61.23358) LONGITUDE: 149° 53.3' W (-149.88781)
The bench mark is an aluminum disk located W of Tesoro Alaska at 1331 Tidewater
Road at the intersection of Terminal Road and Anchorage Port Road, 21.85 m (71.5
ft) W of the first light pole E of the intersection on the N side of Terminal
Rd, 7.06 m (23.2 ft) NNE of the stop sign, 6.92 m (22.7 ft) E of the
eastern-most rail of the railroad tracks, and 1.62 m (5.3 ft) W of a 0.6 m (2
ft) high 6-inch square concrete post. The bench mark is set 0.15 m (0.5 ft)
above ground level, attached to a 1-inch diameter 3.20 m (10.5 ft) long
thermopile cylinder driven to a depth of 3.1 m (10 ft), and encased in a 4-inch
PVC pipe with concrete kick block.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 6 of 7
Station ID: 9455920 PUBLICATION DATE: 07/03/2019
Name: ANCHORAGE, KNIK ARM, COOK INLET
AK
NOAA Chart: 16664 Latitude: 61° 14.2' N ( 61.23750)
USGS Quad: ANCHORAGE A-8 Longitude: 149° 53.4' W (-149.89040)
T I D A L D A T U M S
Tidal datums at ANCHORAGE, KNIK ARM, COOK INLET 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 (11/06/2002) = 10.624
MEAN HIGHER HIGH WATER MHHW = 8.889
MEAN HIGH WATER MHW = 8.667
MEAN SEA LEVEL MSL = 5.020
MEAN TIDE LEVEL MTL = 4.676
North American Vertical Datum NAVD88 = 3.284
MEAN LOW WATER MLW = 0.685
MEAN LOWER LOW WATER MLLW = 0.000
LOWEST OBSERVED WATER LEVEL (12/25/1999) = -1.949
North American Vertical Datum (NAVD88)
Bench Mark Elevation Information In METERS above:
Stamping or Designation MLLW MHW
NO 15 RESET 1966 11.320 2.653
5920 B 1980 11.876 3.209
5920 G 2011 11.368 2.701
5920 H 2011 11.702 3.035
945 5920 J 2014 12.288 3.621
945 5920 K 2014 11.835 3.168
945 5920 L 2014 11.974 3.307
5920 THERMO 1 1988 11.337 2.670
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 7 of 7
Station ID: 9455920 PUBLICATION DATE: 07/03/2019
Name: ANCHORAGE, KNIK ARM, COOK INLET
AK
NOAA Chart: 16664 Latitude: 61° 14.2' N ( 61.23750)
USGS Quad: ANCHORAGE A-8 Longitude: 149° 53.4' W (-149.89040)
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.
Station Location
Published bench mark
Unpublished bench mark
