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National Ocean Service
Datums Page Page 1 of 6
Station ID: 9450914 PUBLICATION DATE: 08/06/2013
Name: BURROUGH BAY, BEHM CANAL
AK
NOAA Chart: 17420 Latitude: 56° 2.3' N ( 56.03830)
USGS Quad: BRADFIELD CANAL Longitude: 131° 5.7' W (-131.09500)
To reach the tidal bench marks from Ketchikan, AK, by boat, start at the rock
jetty entrance to the small boat harbor at and proceed for 5.02 nm (9.29 km)
towards Spire Island, then proceed for 2.72 nm (5.03 km), then proceed for 2.67
nm (4.94 km) past Bold Island, then proceed for 9.17nm (16.98 km) towards the
entrance to Behm Canal, then proceed for 12.99 nm (24.06 km) past Stag Island,
then proceed for 8.81 nm (16.31 km) Winstanley Island, then proceed for 9.08 nm
(16.82 km) Manzanita Island, then proceed for 9.64 nm (17.86 km) the Channel
Islands, then proceed for 15.21 nm (28.17 km), finally proceed for 5.89 nm
(10.92 km) 56 2'13.76"N, 131 6'3.39"W. The bench marks are located on the
south side of the northeastern arm of Behm Canal.The tide staff was installed
just north of BM 1 1891. The tide gauge was installed just east of BM 1 1891.
T I D A L B E N C H M A R K S
PRIMARY BENCH MARK STAMPING: 0914 A 2013
DESIGNATION: 945 0914 A
MONUMENTATION: Tidal Station disk VM#: 20750
AGENCY: National Ocean Service (NOS) IDB PID#:
SETTING CLASSIFICATION: Bedrock outcrop OPUS PID:
LATITUDE: 56° 2.2' N ( 56.03746) LONGITUDE: 131° 6.0' W (-131.09956)
The primary benchmark is a disk set flush in bedrock, located SE of the flat
mountain peak across the bay, 347 m (1,137 ft) NE of the first prominent point
of land jutting into the bay to the SW, 58.72 m (192.64 ft) SSW of benchmark
Burroughs Mag 1931, and 41.41 m (135.86 ft) north of benchmark 945 0914 B.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 2 of 6
Station ID: 9450914 PUBLICATION DATE: 08/06/2013
Name: BURROUGH BAY, BEHM CANAL
AK
NOAA Chart: 17420 Latitude: 56° 2.3' N ( 56.03830)
USGS Quad: BRADFIELD CANAL Longitude: 131° 5.7' W (-131.09500)
T I D A L B E N C H M A R K S
BENCH MARK STAMPING: BM
DESIGNATION: Tidal Benchmark 1 1891
ALIAS: BM 1 1891
MONUMENTATION: Chiseled Circle VM#: 20748
AGENCY: US Coast and Geodetic Survey
(USC&GS) IDB PID#: TT8329
SETTING CLASSIFICATION: Rocky bluff OPUS PID:
LATITUDE: 56° 2.3' N ( 56.03845) LONGITUDE: 131° 5.9' W (-131.09916)
The benchmark is a circle with a hole in the center and 4 radial lines to center
located directly below the tree and vegetation line, SE of the obvious flat
mountain peak across the bay, 448 m (1,470 ft) NE of the first prominent point
of land jutting into the bay to the SW, and 70.17 m (230.21 ft) north of
benchmark Burroughs Mag 1931.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 3 of 6
Station ID: 9450914 PUBLICATION DATE: 08/06/2013
Name: BURROUGH BAY, BEHM CANAL
AK
NOAA Chart: 17420 Latitude: 56° 2.3' N ( 56.03830)
USGS Quad: BRADFIELD CANAL Longitude: 131° 5.7' W (-131.09500)
T I D A L B E N C H M A R K S
BENCH MARK STAMPING: BURROUGS
DESIGNATION: Burroughs Mag 1931
ALIAS: BM 2
MONUMENTATION: Magnetic station disk VM#: 20749
AGENCY: US Coast and Geodetic Survey
(USC&GS) IDB PID#: TT8328
SETTING CLASSIFICATION: Bedrock outcrop OPUS PID:
LATITUDE: 56° 2.3' N ( 56.03795) LONGITUDE: 131° 6.0' W (-131.09933)
The benchmark is a magnetic disk set flush in bedrock, located SE of the flat
mountain peak across the bay, 397 m (1,303 ft) NE of the first prominent point
of land jutting into the bay to the SW, 70.17 m (230.21 ft) south of benchmark
Tidal Benchmark 1 1891, and 58.72 m (192.64 ft) NNE of benchmark 945 0914 A.
BENCH MARK STAMPING: 0914 B 2013
DESIGNATION: 945 0914 B
MONUMENTATION: Tidal Station disk VM#: 20751
AGENCY: National Ocean Service (NOS) IDB PID#:
SETTING CLASSIFICATION: Bedrock outcrop OPUS PID:
LATITUDE: 56° 2.2' N ( 56.03710) LONGITUDE: 131° 6.0' W (-131.09948)
The benchmark is a disk set flush in a bedrock outcrop, located SE of the flat
mountain peak across the bay, 321 m (1,053 ft) NE of the the first prominent
point of land jutting into the bay to the SW, 153.79 m (504.55 ft) north of
benchmark 945 0914 C, and 41.41 m (135.86 ft) south of benchmark 945 0914 A.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 4 of 6
Station ID: 9450914 PUBLICATION DATE: 08/06/2013
Name: BURROUGH BAY, BEHM CANAL
AK
NOAA Chart: 17420 Latitude: 56° 2.3' N ( 56.03830)
USGS Quad: BRADFIELD CANAL Longitude: 131° 5.7' W (-131.09500)
T I D A L B E N C H M A R K S
BENCH MARK STAMPING: 0914 C 2013
DESIGNATION: 945 0914 C
MONUMENTATION: Tidal Station disk VM#: 20758
AGENCY: National Ocean Service (NOS) IDB PID#:
SETTING CLASSIFICATION: Bedrock outcrop OPUS PID:
LATITUDE: 56° 2.1' N ( 56.03576) LONGITUDE: 131° 6.0' W (-131.09958)
The benchmark is a disk set flush in bedrock, located on the northern edge of
the un-named creek, SE of the flat mountain peak across the bay, 153.79 m
(504.55 ft) south of benchmark 945 0914 B, and 100 m (328 ft) upriver from where
the creek meets the ocean at low tide.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 5 of 6
Station ID: 9450914 PUBLICATION DATE: 08/06/2013
Name: BURROUGH BAY, BEHM CANAL
AK
NOAA Chart: 17420 Latitude: 56° 2.3' N ( 56.03830)
USGS Quad: BRADFIELD CANAL Longitude: 131° 5.7' W (-131.09500)
T I D A L D A T U M S
Tidal datums at BURROUGH BAY, BEHM CANAL based on:
LENGTH OF SERIES: 30 Days
TIME PERIOD: May 18 2013 - June 16 2013
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 = 4.846
MEAN HIGH WATER MHW = 4.572
MEAN TIDE LEVEL MTL = 2.523
MEAN SEA LEVEL MSL = 2.517
MEAN LOW WATER MLW = 0.474
MEAN LOWER LOW WATER MLLW = 0.000
North American Vertical Datum (NAVD88)
Bench Mark Elevation Information In METERS above:
Stamping or Designation MLLW MHW
0914 A 2013 5.092 0.520
BM 5.997 1.426
BURROUGS 5.998 1.426
0914 B 2013 5.537 0.966
0914 C 2013 5.484 0.912
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 6 of 6
Station ID: 9450914 PUBLICATION DATE: 08/06/2013
Name: BURROUGH BAY, BEHM CANAL
AK
NOAA Chart: 17420 Latitude: 56° 2.3' N ( 56.03830)
USGS Quad: BRADFIELD CANAL Longitude: 131° 5.7' W (-131.09500)
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.