U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Datums Page Page 1 of 4
Station ID: 9455557 PUBLICATION DATE: 08/11/2003
Name: HOMER
ALASKA
NOAA Chart: 16640 Latitude: 59° 36.2' N
USGS Quad: SELDOVIA C-4-1961 Longitude: 151° 25.2' W
To reach the tidal bench marks from Homer, Alaska, proceed 0.88 km (0.55 mi)
east along road towards Millers Landing, turn right, 1.6 km (1.0 mi) south past
Beluga Lake to Homer Airport, then 5.6 km (3.5 mi) SE along Homer Spit to Homer
Harbor and Coal Point. The tide gage and staff were located on the eastern side
of the Spit at the City Dock and bench marks are located in the vicinity of
Seward Fisheries and Standard Oil Company property.
T I D A L B E N C H M A R K S
PRIMARY BENCH MARK STAMPING: BM 6 1965
DESIGNATION: 945 5557 BM B
MONUMENTATION: Tidal Station disk VM#: 9539
AGENCY: National Ocean Survey (NOS) PID:
SETTING CLASSIFICATION: Concrete floor
The primary bench mark is a disk set flush with the concrete floor in the pump
house, at the Standard Oil Distributing Station at the SE end of Homer Spit near
the city dock, inside the door on the NW end of the pump house, 21.34 m (70.0
ft) south of Bench Mark C103 1965 , and 1.52 m (5.0 ft) from the south wall.
BENCH MARK STAMPING: B 103 1965
DESIGNATION: B 103
MONUMENTATION: Bench Mark disk VM#: 9541
AGENCY: US Coast & Geodetic Survey (USC&GS) PID#: TT0174
SETTING CLASSIFICATION: Copper-coated rod
The bench mark is a disk set on top of a 5/8-inch cooper-coated rod, 84 m (275
ft) SW of the SE end of a loading platform, 91 m (300 ft) south of the SW end of
loading dock and Bench Mark A 103 1965, 0.3 m (1 ft) north of the most westerly
of three oil tanks, and 0.18 m (0.6 ft) south of a metal witness post. The
bench mark is on top of a 5/8-inch cooper-coated rod driven to a depth of 22 m
(72 ft), encased in a 4-inch orangeburg pipe and protruding 0.15 m (0.5 ft)
above the ground.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 2 of 4
Station ID: 9455557 PUBLICATION DATE: 08/11/2003
Name: HOMER
ALASKA
NOAA Chart: 16640 Latitude: 59° 36.2' N
USGS Quad: SELDOVIA C-4-1961 Longitude: 151° 25.2' W
T I D A L B E N C H M A R K S
BENCH MARK STAMPING: C 103 1965
DESIGNATION: C 103
MONUMENTATION: Bench Mark disk VM#: 9542
AGENCY: US Coast & Geodetic Survey (USC&GS) PID#: TT0175
SETTING CLASSIFICATION: Copper-coated rod
The bench mark is a disk set on top of a 5/8-inch cooper-coated rod, 32 m (106
ft) east of Bench Mark B103 1965, 8 m (27 ft) west of the most northerly of six
small tanks, 0.46 m (1.5 ft) north of the most easterly of three oil tanks, and
0.15 m (0.5 ft) south of a metal witness post. The bench mark is set on top of
a 5/8-inch copper-coated rod driven to a depth of 18 m (58 ft) and encased in a
4-inch orangeburg pipe protruding 0.18 m (0.6 ft) above the ground.
BENCH MARK STAMPING: HOMER EAST B 2 NO 1 1963
DESIGNATION: HOMER EAST BASE 2 RM 1
MONUMENTATION: Reference Mark disk VM#: 9543
AGENCY: US Coast & Geodetic Survey (USC&GS) PID#: TT0171
SETTING CLASSIFICATION: Concrete floor
The bench mark is a disk flush in concrete at the foot of a utility pole, 61 m
(200 ft) east of the small boat ramp at the small boat harbor on Homer Spit,
0.76 m (2.5 ft) SW from a power pole witness post, center of three poles in a
north-south line across the Spit, with north end of Spit terminating at Porpoise
Room, and 0.24 m (0.8 ft) below ground level.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 3 of 4
Station ID: 9455557 PUBLICATION DATE: 08/11/2003
Name: HOMER
ALASKA
NOAA Chart: 16640 Latitude: 59° 36.2' N
USGS Quad: SELDOVIA C-4-1961 Longitude: 151° 25.2' W
T I D A L D A T U M S
Tidal datums at HOMER based on:
LENGTH OF SERIES: 2 YEARS
TIME PERIOD: January 1966 - December 1967
TIDAL EPOCH: 1983-2001
CONTROL TIDE STATION: 9455500 SELDOVIA, COOK INLET
Elevations of tidal datums referred to Mean Lower Low Water (MLLW), in METERS:
HIGHEST OBSERVED WATER LEVEL (10/15/1966) = 8.027
MEAN HIGHER HIGH WATER (MHHW) = 5.583
MEAN HIGH WATER (MHW) = 5.328
MEAN SEA LEVEL (MSL) = 2.941
MEAN TIDE LEVEL (MTL) = 2.916
MEAN LOW WATER (MLW) = 0.503
MEAN LOWER LOW WATER (MLLW) = 0.000
LOWEST OBSERVED WATER LEVEL (02/06/1966) = -1.339
National Geodetic Vertical Datum (NGVD 29)
Bench Mark Elevation Information In METERS above:
Stamping or Designation MLLW MHW
BM 6 1965 8.315 2.987
B 103 1965 8.171 2.843
C 103 1965 8.215 2.887
HOMER EAST B 2 NO 1 1963 9.437 4.109
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 4 of 4
Station ID: 9455557 PUBLICATION DATE: 08/11/2003
Name: HOMER
ALASKA
NOAA Chart: 16640 Latitude: 59° 36.2' N
USGS Quad: SELDOVIA C-4-1961 Longitude: 151° 25.2' 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.