U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Datums Page Page 1 of 4
PUBLICATION DATE: 06/07/1985
Station ID: 9450811 SUPERCEDED DATE: 04/21/2003
Name: FIN, WALKER COVE
ALASKA
NOAA Chart: 17424 Latitude: 55° 43.1' N
USGS Quad: KETCHIKAN C-3 Longitude: 130° 47.6' W
To reach the tidal bench marks From Behm Canal, go east by boat about 5 miles (8
km) into Walker Cove. The bench marks are on the south shore of Walker Cove.
The tide gage and staff were on the shore just east of a small water fall
flowing into the cove.
T I D A L B E N C H M A R K S
PRIMARY BENCH MARK STAMPING: FIN 1931
MONUMENTATION: Survey Disk VM#: 9344
AGENCY: PID#: UV5354
SETTING CLASSIFICATION: Boulder
The bench mark is set in a boulder surrounded by water at extreme high water on
the south shore of Walker Cove, 3.5 miles (5.6 km) NE of the ledge point in a
bight located 246 feet (75 m) east of a large stream.
BENCH MARK STAMPING: 0811 A 1984
MONUMENTATION: Survey Disk VM#: 9345
AGENCY: PID:
SETTING CLASSIFICATION: Boulder
The bench mark is set in a large rock, 26 feet (8 m) from the tree line, and 16
feet (5 m) from a large bush that lies between this bench mark and Bench Mark
FIN 1931, and is set about 2 feet (1 m) above the shoreline.
BENCH MARK STAMPING: 0811 B 1984
MONUMENTATION: Survey Disk VM#: 9346
AGENCY: PID:
SETTING CLASSIFICATION: Boulder
The bench mark is set in a boulder, 82 feet (25 m) east of Bench Mark 0811 A
1984, and 49 feet (15 m) from the tree line.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 2 of 4
PUBLICATION DATE: 06/07/1985
Station ID: 9450811 SUPERCEDED DATE: 04/21/2003
Name: FIN, WALKER COVE
ALASKA
NOAA Chart: 17424 Latitude: 55° 43.1' N
USGS Quad: KETCHIKAN C-3 Longitude: 130° 47.6' W
T I D A L B E N C H M A R K S
BENCH MARK STAMPING: 0811 C 1984
MONUMENTATION: Survey Disk VM#: 9347
AGENCY: PID:
SETTING CLASSIFICATION: Boulder
The bench mark is set at the shoreline in a boulder among other small
irregularly shaped boulders, 82 feet (25 m) east of Bench Mark 0811 B 1984, and
66 feet (20 m) from the tree line.
BENCH MARK STAMPING: 0811 D 1984
MONUMENTATION: Survey Disk VM#: 9348
AGENCY: PID:
SETTING CLASSIFICATION: Boulder
The bench mark is set in a large boulder, 131 feet (40 m) east of Bench Mark
0811 C 1984, and 49 feet (15 m) from the tree line.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 3 of 4
PUBLICATION DATE: 06/07/1985
Station ID: 9450811 SUPERCEDED DATE: 04/21/2003
Name: FIN, WALKER COVE
ALASKA
NOAA Chart: 17424 Latitude: 55° 43.1' N
USGS Quad: KETCHIKAN C-3 Longitude: 130° 47.6' W
T I D A L D A T U M S
Tidal datums at FIN, WALKER COVE based on:
LENGTH OF SERIES: 59 HW and 60 LW
TIME PERIOD: April 30 - May 30, 1984
TIDAL EPOCH: 1960-1978
CONTROL TIDE STATION: 9450460 KETCHIKAN
Elevations of tidal datums referred to Mean Lower Low Water (MLLW), in FEET:
HIGHEST OBSERVED WATER LEVEL (05/15/1984) = 18.75
MEAN HIGHER HIGH WATER (MHHW) = 15.98
MEAN HIGH WATER (MHW) = 15.10
MEAN TIDE LEVEL (MTL) = 8.36
MEAN LOW WATER (MLW) = 1.62
MEAN LOWER LOW WATER (MLLW) = 0.00
LOWEST OBSERVED WATER LEVEL (05/15/1984) = -3.23
National Geodetic Vertical Datum (NGVD 29)
Bench Mark Elevation Information In FEET above:
Stamping or Designation MLLW MHW
FIN 1931 18.54 3.44
0811 A 1984 16.92 1.82
0811 B 1984 14.49 -0.61
0811 C 1984 15.05 -0.05
0811 D 1984 14.45 -0.65
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 4 of 4
PUBLICATION DATE: 06/07/1985
Station ID: 9450811 SUPERCEDED DATE: 04/21/2003
Name: FIN, WALKER COVE
ALASKA
NOAA Chart: 17424 Latitude: 55° 43.1' N
USGS Quad: KETCHIKAN C-3 Longitude: 130° 47.6' 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.