U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Datums Page Page 1 of 8
Station ID: 9455920 PUBLICATION DATE: 04/21/2003
Name: ANCHORAGE, KNIK ARM, COOK INLET
ALASKA
NOAA Chart: 16664 Latitude: 61° 14.3' N
USGS Quad: ANCHORAGE A-8 Longitude: 149° 53.4' W
To reach the tidal bench marks from the Anchorage airport, follow International
Road to the Minnesota exit and turn north, proceed 5 km (3 mi) to 6th Avenue and
then left (north) on A Street, then follow A Street for 0.6 km (0.4 mi) and take
the Port exit which turns onto Ocean Dock Road, then follow Ocean Dock Road
until it dead ends at the Port of Anchorage. The bench marks are in the general
vicinity. The tide house is located in the green metal building at the very
south end of the concrete fuel pier.
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) PID#: TT0711
SETTING CLASSIFICATION: Concrete dock
The primary bench mark is a disk set at the Anchorage City Dock at the north end
of the double railroad tracks, 9.45 m (31.0 ft) south of the north end of the
dock, 4.85 m (15.9 ft) NW of the NE corner of the new Port Office, 3.84 m (12.6
ft) NE of the north door of the Port Office, 2.87 m (9.4 ft) east of a 1 m (4
ft) high concrete deck landing for Port Office north door, and set flush with
the concrete surface.
BENCH MARK STAMPING: B 75 1964
DESIGNATION: B 75
MONUMENTATION: Bench Mark disk VM#: 1334
AGENCY: US Coast and Geodetic Survey (USC&GS) PID#: TT0712
SETTING CLASSIFICATION: Concrete dock
The bench mark is a disk set near the SE corner of Anchorage City Dock, 25 m (81
ft) SSE of the southerly corner of the Port of Anchorage Building, 12 m (40 ft)
SE of the east railroad track, 4 m (12 ft) east of the NE corner of the north
end of the approach to the dock, 0.30 m (1.0 ft) north of the north side of a
concrete bull rail at the point where it makes an oblique turn to the NE, and
set flush with the concrete surface.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 2 of 8
Station ID: 9455920 PUBLICATION DATE: 04/21/2003
Name: ANCHORAGE, KNIK ARM, COOK INLET
ALASKA
NOAA Chart: 16664 Latitude: 61° 14.3' N
USGS Quad: ANCHORAGE A-8 Longitude: 149° 53.4' W
T I D A L B E N C H M A R K S
BENCH MARK STAMPING: TIDAL 16 1966
DESIGNATION: 945 5920 TIDAL 16
MONUMENTATION: Bench Mark disk VM#: 1335
AGENCY: US Coast and Geodetic Survey (USC&GS) PID#: TT0713
SETTING CLASSIFICATION: Concrete deck
The bench mark is a disk set on the west side of the Anchorage POL Dock near the
south end, 10.24 m (33.6 ft) west of the SW corner of the 3 m x 4 m (10 ft x 12
ft) building which houses the tide gauges, 3.35 m (11.0 ft) north of the SW
corner of the dock, 1.52 m (5.0 ft) north of the center of a mooring bit, 0.30 m
(1.0 ft) south of the south end of the west bull rail, and flush with the
concrete surface. Note: There is a USACE survey disk within a meter of this
mark, so make sure to survey to the correct mark.
BENCH MARK STAMPING: 5920 B 1980
DESIGNATION: 945 5920 B
MONUMENTATION: Tidal Station disk VM#: 1336
AGENCY: National Ocean Survey (NOS) PID:
SETTING CLASSIFICATION: Copper-clad steel rod
The bench mark is a disk set about 101 m (330 ft) SE of bench mark 15 RESET
1966, 27 m (90 ft) south of light pole LP 5, 0.98 m (3.2 ft) north of the NW
edge of a 5 m (15 ft) wide doorway, and 0.37 m (1.2 ft) NE of NW corner of blue
and white repair shop belonging to the Port of Anchorage. The bench mark is 6
cm (0.2 ft) below asphalt level, set on a copper-clad steel rod driven to a
depth of 21.6 m (71 ft).
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 3 of 8
Station ID: 9455920 PUBLICATION DATE: 04/21/2003
Name: ANCHORAGE, KNIK ARM, COOK INLET
ALASKA
NOAA Chart: 16664 Latitude: 61° 14.3' N
USGS Quad: ANCHORAGE A-8 Longitude: 149° 53.4' W
T I D A L B E N C H M A R K S
BENCH MARK STAMPING: 5920 D 1980
DESIGNATION: 945 5920 D
MONUMENTATION: Tidal Station disk VM#: 1337
AGENCY: National Ocean Survey (NOS) PID:
SETTING CLASSIFICATION: Copper-clad steel rod
The bench mark is a disk set at the SE corner of the intersection of Ocean Dock
Road, Loop Road, and Whitney Road, 46.88 m (153.8 ft) east of a fire plug, 19.08
m (62.6 ft) NE of a steel light pole, 10.76 m (35.3 ft) south of the center of a
traffic island of Loop Road, 2.32 m (7.6 ft) north of a cyclone fence, 1.40 m
(4.6 ft) east of the western end of a steel guard rail, and 0.79 m (2.6 ft)
north of a witness post. The bench mark is 6 cm (0.2 ft) below ground level,
set on copper-clad steel rod driven to a depth of 19.5 m (64 ft).
BENCH MARK STAMPING: 5920 E 1986
DESIGNATION: 945 5920 E
MONUMENTATION: Tidal Station disk VM#: 1338
AGENCY: National Ocean Service (NOS) PID:
SETTING CLASSIFICATION: Concrete dock
The bench mark is a disk set in a concrete loading dock at the NE corner of
MAPCO at 1076 Ocean Dock Road, 23.32 m (76.5 ft) west of the centerline of Ocean
Dock Road, 18.78 m (61.6 ft) NW of a fire plug, 18.90 m (62.0 ft) SW of a
utility pole, 0.30 m (1.0 ft) north of the north end of the building, 0.30 m
(1.0 ft) west of the east edge of the loading dock, and 1.22 m (4.0 ft) above
ground level.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 4 of 8
Station ID: 9455920 PUBLICATION DATE: 04/21/2003
Name: ANCHORAGE, KNIK ARM, COOK INLET
ALASKA
NOAA Chart: 16664 Latitude: 61° 14.3' N
USGS Quad: ANCHORAGE A-8 Longitude: 149° 53.4' W
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
MONUMENTATION: Tidal Station disk VM#: 1339
AGENCY: National Ocean Survey (NOS) PID:
SETTING CLASSIFICATION: Thermopile deep rod
The bench mark is an aluminum disk located across the street from Tesoro Alaska
at 1331 Tidewater Road, near the intersection of Tidewater and Ocean Dock, 7.32
m (24.0 ft) NE of a railroad switch signal, 6.92 m (22.7 ft) east of the
eastern-most rail of the railroad tracks, 1.62 m (5.3 ft) west of a 1 m (2 ft)
high 6-inch square concrete post, and 0.46 m (1.5 ft) north of a 4-inch wooden
witness post. The bench mark is 15 cm (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.
BENCH MARK STAMPING: 5920 C 1980
DESIGNATION: 945 5920 C
MONUMENTATION: Tidal Station disk VM#: 12644
AGENCY: National Ocean Survey (NOS) PID:
SETTING CLASSIFICATION: Copper-clad steel rod
The bench mark is a disk set 26 m (86 ft) NW of office door (1601 Tidewater
Road, Tesoro Sales Terminal), 16.61 m (54.5 ft) SW of where SW rail of railroad
tracks cross the NW side of Tidewater Road, 9.60 m (31.5 ft) north of
northern-most of three yellow concrete posts that are 1.04 m (3.4 ft) tall, 7.50
m (24.6 ft) north of utility pole 1030 76G, 7.62 m (25.0 ft) NW of the
centerline of Tidewater Road, and 1.52 m (5.0 ft) NW of a utility pole with
witness post sign. The bench mark is 3 cm (0.1 ft) below ground level, set on a
copper-clad steel rod driven to a depth of 24.4 m (80 ft).
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 5 of 8
Station ID: 9455920 PUBLICATION DATE: 04/21/2003
Name: ANCHORAGE, KNIK ARM, COOK INLET
ALASKA
NOAA Chart: 16664 Latitude: 61° 14.3' N
USGS Quad: ANCHORAGE A-8 Longitude: 149° 53.4' W
T I D A L B E N C H M A R K S
BENCH MARK STAMPING: BM 9 1918
DESIGNATION: 945 5920 TIDAL 9
MONUMENTATION: Bench Mark disk VM#: 12645
AGENCY: US Coast and Geodetic Survey (USC&GS) PID#: TT0719
SETTING CLASSIFICATION: Concrete foundation
The bench mark is a disk set on SE side of the concrete foundation for a 1 m (3
ft) diameter manhole cover in the yard of the Alaska Railroad, 1.5 km (0.9 mi)
south of Port of Anchorage along Port Road, 41 m (136 ft) north of NE corner of
Building No. 3, 40.39 m (132.5 ft) NW of fire hydrant, 27 m (89 ft) SSW of SW
corner of northwestern-most support pillar for elevated road, 15.03 m (49.3 ft)
NW of second most northwesterly support on west side of elevated road, and 0.15
m (0.5 ft) below ground level. Note: A cross has been chiseled on top of the
circular concrete portion of the foundation to indicate where to dig for the
mark.
BENCH MARK STAMPING:
DESIGNATION: TBM 945 5920 CHANNELSTAFF
MONUMENTATION: See descriptive text VM#: 12648
AGENCY: National Ocean Service (NOS) PID:
SETTING CLASSIFICATION: Bolted to a channel
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 6 of 8
Station ID: 9455920 PUBLICATION DATE: 04/21/2003
Name: ANCHORAGE, KNIK ARM, COOK INLET
ALASKA
NOAA Chart: 16664 Latitude: 61° 14.3' N
USGS Quad: ANCHORAGE A-8 Longitude: 149° 53.4' W
T I D A L D A T U M S
Tidal datums at ANCHORAGE, KNIK ARM, COOK INLET based on:
LENGTH OF SERIES: 5 Years
TIME PERIOD: January 1997 - December 2001
TIDAL EPOCH: 1983-2001
CONTROL TIDE STATION:
Elevations of tidal datums referred to Mean Lower Low Water (MLLW), in METERS:
HIGHEST OBSERVED WATER LEVEL (10/24/1980) = 10.543
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
MEAN LOW WATER (MLW) = 0.685
MEAN LOWER LOW WATER (MLLW) = 0.000
LOWEST OBSERVED WATER LEVEL (12/25/1999) = -1.949
National Geodetic Vertical Datum (NGVD 29)
Bench Mark Elevation Information In METERS above:
Stamping or Designation MLLW MHW
NO 15 RESET 1966 11.320 2.653
B 75 1964 11.223 2.556
TIDAL 16 1966 12.355 3.688
5920 B 1980 11.874 3.207
5920 D 1980 13.621 4.954
5920 E 1986 12.807 4.140
5920 THERMO 1 1988 11.373 2.706
5920 C 1980 11.193 2.526
BM 9 1918 12.569 3.902
TBM 945 5920 CHANNELSTAFF 9.651 0.984
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 7 of 8
Station ID: 9455920 PUBLICATION DATE: 04/21/2003
Name: ANCHORAGE, KNIK ARM, COOK INLET
ALASKA
NOAA Chart: 16664 Latitude: 61° 14.3' N
USGS Quad: ANCHORAGE A-8 Longitude: 149° 53.4' W
Foot Notes:
Cook Inlet, Alaska has anomalous relative sea level trends compared to most
other geographic regions in the United States. This is due to a general uplift
of the land in these areas, which has been occurring at a rapid rate. Because of
the magnitude of the sea level trends in these areas, NOAA has adopted a
procedure for computing accepted tidal datums for the National Water Level
Observation Network (NWLON) using the last several years of sea level data
rather than the 19-year tidal epoch. The tide ranges are still based on the 1983
- 2001 National Tidal Datum EPOCH (NTDE) and are applied to the five year
(1997-2001) Mean Tide Level (MTL) to compute other tidal datums. The adoption of
this procedure was necessary to ensure that these tidal datums accurately
represent the existing stand of sea level.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 8 of 8
Station ID: 9455920 PUBLICATION DATE: 04/21/2003
Name: ANCHORAGE, KNIK ARM, COOK INLET
ALASKA
NOAA Chart: 16664 Latitude: 61° 14.3' N
USGS Quad: ANCHORAGE A-8 Longitude: 149° 53.4' W
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 (NAVD 88).
NGVD 29 is a fixed datum adopted as a national standard geodetic reference for
heights but is now considered superseded. NGVD 29 is sometimes referred to as
Sea Level Datum of 1929 or as Mean Sea Level on some early issues of Geological
Survey Topographic Quads. NGVD 29 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 NGVD 29 are available from the National
Geodetic Survey (NGS) data base via the World Wide Web at
National Geodetic Survey.
NAVD 88 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. NAVD 88 replaces NGVD 29 as the national
standard geodetic reference for heights. Bench mark elevations relative to
NAVD 88 are available from NGS through the World Wide Web at
National Geodetic Survey.
NGVD 29 and NAVD 88 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 NAVD 88 elevation is shown on the Elevations of Tidal Datums Table Referred
to MLLW only when two or more of the bench marks listed have NAVD 88 elevations.
The NAVD 88 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, NAVD 88 bench mark elevations computed indirectly from the tidal
datums elevation table may differ slightly from NAVD 88 elevations listed for
each bench mark in the NGS database.