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Datums Page Page 1 of 6
Station ID: 9450581 PUBLICATION DATE: 07/21/2003
Name: KASAAN, KASAAN BAY, CLARENCE STRAIT
AK
NOAA Chart: 17426 Latitude: 55° 32.1' N ( 55.53500)
USGS Quad: CRAIG (C-2) Longitude: 132° 23.8' W (-132.39700)
To reach the tidal bench marks from Ketchikan, go NW approximately 56 km (30 nm)
near the village of Kasaan. Then to a point 0.5 km (0.3 nm) SE of the village
of Kasaan, at the historic location of the U.S. Coast Guard light and day
marker. The tidal bench marks are located along the beach. The tide gauge was
located near the historic site.
T I D A L B E N C H M A R K S
PRIMARY BENCH MARK STAMPING:
DESIGNATION: 945 0581 TIDAL 2
ALIAS: 2 1911
MONUMENTATION: Chiseled Triangle VM#: 16716
AGENCY: US Coast and Geodetic Survey
(USC&GS) IDB PID#:
SETTING CLASSIFICATION: Rock outcrop OPUS PID:
LATITUDE: 55° 32.2' N ( 55.53670) LONGITUDE: 132° 23.8' W (-132.39700)
The primary bench mark is a chiseled triangle with 0.05 m (0.2 ft) sides cut
about 0.02 m (0.1 ft) into a flat reddish rock on first prominent rock outcrop
SE of south end of gravel road, 4.21 m (13.8 ft) ESE of bench mark 0581 A 2002,
1.40 m (4.6 ft) north of the southern edge of the rock outcrop, 0.79 m (2.6 ft)
west of eastern edge rock outcrop, and 0.61 m (2.0 ft) ESE of the nearest
vertical face.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 2 of 6
Station ID: 9450581 PUBLICATION DATE: 07/21/2003
Name: KASAAN, KASAAN BAY, CLARENCE STRAIT
AK
NOAA Chart: 17426 Latitude: 55° 32.1' N ( 55.53500)
USGS Quad: CRAIG (C-2) Longitude: 132° 23.8' W (-132.39700)
T I D A L B E N C H M A R K S
BENCH MARK STAMPING: KASAAN NO 7 1963
DESIGNATION: 945 0581 TIDAL 7
MONUMENTATION: Tidal Station disk VM#: 16867
AGENCY: US Coast and Geodetic Survey
(USC&GS) IDB PID#:
SETTING CLASSIFICATION: Rock outcrop OPUS PID:
LATITUDE: 55° 32.2' N ( 55.53670) LONGITUDE: 132° 23.8' W (-132.39700)
The bench mark is a disk set in a depression in a rock outcrop, 36 m (118 ft)
south of bench mark 0581 A 2002, 23.29 m (76.4 ft) NNW of bench mark 0581 B
2002, 2 m (7 ft) north of rock drop off, 0.70 m (2.3 ft) east of rock drop off,
and near the apparent high water line.
BENCH MARK STAMPING: 0581 A 2002
DESIGNATION: 945 0581 A
MONUMENTATION: Tidal Station disk VM#: 16868
AGENCY: National Ocean Service (NOS) IDB PID#:
SETTING CLASSIFICATION: Rock ledge OPUS PID:
LATITUDE: 55° 32.1' N ( 55.53500) LONGITUDE: 132° 23.8' W (-132.39700)
The bench mark is a disk set in the flat extent of the first bedrock ledge north
of a small gravel cove, 59.41 m (194.9 ft) south of the southern end of the
gravel road, 36 m (118 ft) north of bench mark KASAAN NO 7 1963, 4.21 m (13.8
ft) WNW of bench mark 945 0581 TIDAL 2, 3.0 m (9.8 ft) west of a 1 m (3 ft) high
vertical rock face, 0.18 m (0.6 ft) east of a ledge drop off, and 1 m (3 ft)
above the apparent high water line.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 3 of 6
Station ID: 9450581 PUBLICATION DATE: 07/21/2003
Name: KASAAN, KASAAN BAY, CLARENCE STRAIT
AK
NOAA Chart: 17426 Latitude: 55° 32.1' N ( 55.53500)
USGS Quad: CRAIG (C-2) Longitude: 132° 23.8' W (-132.39700)
T I D A L B E N C H M A R K S
BENCH MARK STAMPING: 0581 B 2002
DESIGNATION: 945 0581 B
MONUMENTATION: Tidal Station disk VM#: 16869
AGENCY: National Ocean Service (NOS) IDB PID#:
SETTING CLASSIFICATION: Rock outcrop OPUS PID:
LATITUDE: 55° 32.1' N ( 55.53500) LONGITUDE: 132° 23.8' W (-132.39700)
The bench mark is a disk set in a rock outcrop, the second largest rock south of
the gravel cove, 33 m (109 ft) WNW of bench mark 0581 C 2002, 23.29 m (76.4 ft)
SSE of bench mark KASAAN NO 7 1963, 21 m (69 ft) SSW of the vegetation line, and
1 m (3 ft) NE of rock drop off near the high water line.
BENCH MARK STAMPING: 0581 C 2002
DESIGNATION: 945 0581 C
MONUMENTATION: Tidal Station disk VM#: 16870
AGENCY: National Ocean Service (NOS) IDB PID#:
SETTING CLASSIFICATION: Rock outcrop OPUS PID:
LATITUDE: 55° 32.1' N ( 55.53500) LONGITUDE: 132° 23.8' W (-132.39700)
The bench mark is a disk set on the SW portion of the same rock outcrop as the
red and white USCG light, 17.0 m (55.8 ft) WSW of bench mark 0581 D 2002, 5.21 m
(17.1 ft) SSW of the USCG light, 1.71 m (5.6 ft) north of rock drop off, and
1.31 m (4.3 ft) SSW of vertical rock at the base USCG light.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 4 of 6
Station ID: 9450581 PUBLICATION DATE: 07/21/2003
Name: KASAAN, KASAAN BAY, CLARENCE STRAIT
AK
NOAA Chart: 17426 Latitude: 55° 32.1' N ( 55.53500)
USGS Quad: CRAIG (C-2) Longitude: 132° 23.8' W (-132.39700)
T I D A L B E N C H M A R K S
BENCH MARK STAMPING: 0581 D 2002
DESIGNATION: 945 0581 D
MONUMENTATION: Tidal Station disk VM#: 16871
AGENCY: National Ocean Service (NOS) IDB PID#:
SETTING CLASSIFICATION: Rock outcrop OPUS PID:
LATITUDE: 55° 32.2' N ( 55.53670) LONGITUDE: 132° 23.8' W (-132.39700)
The bench mark is a disk set in a shear rock outcrop that drops off to the south
and the east, 14.60 m (47.9 ft) east of the center of the red and white USCG
light, 0.70 m (2.3 ft) south of a 1 m (3 ft) high vertical outcrop, 0.42 m (1.4
ft) west of the east edge of a rock outcrop, and 0.25 m (0.8 ft) north of south
edge of a rock outcrop.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 5 of 6
Station ID: 9450581 PUBLICATION DATE: 07/21/2003
Name: KASAAN, KASAAN BAY, CLARENCE STRAIT
AK
NOAA Chart: 17426 Latitude: 55° 32.1' N ( 55.53500)
USGS Quad: CRAIG (C-2) Longitude: 132° 23.8' W (-132.39700)
T I D A L D A T U M S
Tidal datums at KASAAN, KASAAN BAY, CLARENCE STRAIT based on:
LENGTH OF SERIES: 2 MONTHS
TIME PERIOD: July 2002 - August 2002
TIDAL EPOCH: 1983-2001
CONTROL TIDE STATION: 9450460 KETCHIKAN, TONGASS NARROWS
Elevations of tidal datums referred to Mean Lower Low Water (MLLW), in METERS:
MEAN HIGHER HIGH WATER MHHW = 4.781
MEAN HIGH WATER MHW = 4.506
MEAN TIDE LEVEL MTL = 2.494
MEAN SEA LEVEL MSL = 2.490
MEAN LOW WATER MLW = 0.482
MEAN LOWER LOW WATER MLLW = 0.000
North American Vertical Datum (NAVD88)
Bench Mark Elevation Information In METERS above:
Stamping or Designation MLLW MHW
945 0581 TIDAL 2 6.789 2.283
KASAAN NO 7 1963 6.551 2.045
0581 A 2002 5.027 0.521
0581 B 2002 5.767 1.261
0581 C 2002 6.831 2.325
0581 D 2002 7.218 2.712
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 6 of 6
Station ID: 9450581 PUBLICATION DATE: 07/21/2003
Name: KASAAN, KASAAN BAY, CLARENCE STRAIT
AK
NOAA Chart: 17426 Latitude: 55° 32.1' N ( 55.53500)
USGS Quad: CRAIG (C-2) Longitude: 132° 23.8' W (-132.39700)
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.