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Datums Page Page 1 of 6
Station ID: 9451317 PUBLICATION DATE: 11/13/2003
Name: ANCHOR POINT, WRANGELL NARROWS
AK
NOAA Chart: 17375 Latitude: 56° 38.3' N ( 56.63830)
USGS Quad: PETERSBURG (C-3) Longitude: 132° 55.6' W (-132.92700)
To reach the tidal bench marks from the Petersburg, Alaska, South Harbor public
boat launch, proceed 16.0 km (8.7 nm) south down Wrangell Narrows past Papke's
Landing state wharf, Then 4.6 km (2.5 nm) south to Anchor Point. The tide
gauge was located on the northern most extent of Anchor Point on the east bank
of Wrangell Narrows, and the tidal bench marks were located on the beach.
T I D A L B E N C H M A R K S
PRIMARY BENCH MARK STAMPING: NO 45 5
DESIGNATION: 945 1317 TIDAL 5
MONUMENTATION: Triangulation Station disk VM#: 17252
AGENCY: US Army Corps of Engineers (USACOE) IDB PID#:
SETTING CLASSIFICATION: Bedrock OPUS PID:
LATITUDE: 56° 38.3' N ( 56.63830) LONGITUDE: 132° 55.7' W (-132.92800)
The bench mark is a disk set in bedrock on the tip of Anchor Point in the grass
above high water, and 5.36 m (17.6 ft) SE of bench mark NO 45 1929 4.
BENCH MARK STAMPING: TIDAL BM 1317-A 1977
DESIGNATION: 945 1317 A
MONUMENTATION: Tidal Station disk VM#: 17246
AGENCY: National Ocean Service (NOS) IDB PID#:
SETTING CLASSIFICATION: Boulder OPUS PID:
LATITUDE: 56° 38.2' N ( 56.63670) LONGITUDE: 132° 55.7' W (-132.92800)
The bench mark is a disk set in top of 1 m x 1 m x 0.49 m (3 ft x 3 ft x 1.5 ft)
high boulder on beach on west side of Anchor Point, 137 m (450 ft) south of
TIDAL BM 1317-B 1977, 37 m (120 ft) south of a cabin on the beach, 6 m (20 ft)
west of grass line, and just below apparent high water line.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 2 of 6
Station ID: 9451317 PUBLICATION DATE: 11/13/2003
Name: ANCHOR POINT, WRANGELL NARROWS
AK
NOAA Chart: 17375 Latitude: 56° 38.3' N ( 56.63830)
USGS Quad: PETERSBURG (C-3) Longitude: 132° 55.6' W (-132.92700)
T I D A L B E N C H M A R K S
BENCH MARK STAMPING: TIDAL BM 1317-B 1977
DESIGNATION: 945 1317 B
MONUMENTATION: Tidal Station disk VM#: 17247
AGENCY: National Ocean Service (NOS) IDB PID#:
SETTING CLASSIFICATION: Boulder OPUS PID:
LATITUDE: 56° 38.3' N ( 56.63830) LONGITUDE: 132° 55.7' W (-132.92800)
The bench mark is a disk set in a 1 m x 1 m x 0.49 m (3 ft x 3 ft x 1.5 ft) high
boulder in a boulder strewn beach, 46 m (150 ft) south of bench mark NO 45 1929
4, 137 m (450 ft) north of TIDAL BM 1317-A 1977, 6 m (20 ft) west of grass line,
and just below apparent high water line.
BENCH MARK STAMPING: 1317 C 2003
DESIGNATION: 945 1317 C
MONUMENTATION: Tidal Station disk VM#: 17248
AGENCY: National Ocean Service (NOS) IDB PID#:
SETTING CLASSIFICATION: Boulder OPUS PID#: BBBC59
LATITUDE: 56° 38.3' N ( 56.63830) LONGITUDE: 132° 55.6' W (-132.92700)
The bench mark is a disk set in top of 1 m x 1 m x 1 m (4 ft x 3 ft x 2 ft) high
flat topped boulder on north tip of Anchor Point, 14.87 m (48.8 ft) north of
bench mark NO 45 1929 4, 8.05 m (26.4 ft) west of bench mark 1317 D 2003, 7 m
(22 ft) from grass line, and 6.13 m (20.1 ft) WSW of bench mark 3 1929.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 3 of 6
Station ID: 9451317 PUBLICATION DATE: 11/13/2003
Name: ANCHOR POINT, WRANGELL NARROWS
AK
NOAA Chart: 17375 Latitude: 56° 38.3' N ( 56.63830)
USGS Quad: PETERSBURG (C-3) Longitude: 132° 55.6' W (-132.92700)
T I D A L B E N C H M A R K S
BENCH MARK STAMPING: 1317 D 2003
DESIGNATION: 945 1317 D
MONUMENTATION: Tidal Station disk VM#: 17249
AGENCY: National Ocean Service (NOS) IDB PID#:
SETTING CLASSIFICATION: Boulder OPUS PID:
LATITUDE: 56° 38.3' N ( 56.63830) LONGITUDE: 132° 55.6' W (-132.92700)
The bench mark is a disk set in 2 m x 1 m (5 ft x 4 ft) large sloping boulder,
flush with beach on NW side and 1 ft high on SE side, on north tip of Anchor
Point at grass line, 16 m (51 ft) NE of bench mark NO 45 1929 4, 8.05 m (26.4
ft) east of bench mark 1317 C 2003, and 4.42 m (14.5 ft) south of bench mark 3
1929.
BENCH MARK STAMPING: 3 1929
DESIGNATION: 945 1317 TIDAL 3
MONUMENTATION: Tidal Station disk VM#: 17250
AGENCY: US Coast & Geodetic Survey
(USC&GS) IDB PID#:
SETTING CLASSIFICATION: Boulder OPUS PID:
LATITUDE: 56° 38.3' N ( 56.63830) LONGITUDE: 132° 55.6' W (-132.92700)
The bench mark is a disk set in the top of the largest rock of size 2 m x 1 m x
1 m high (8 ft x 4 ft x 4 ft) on Anchor Point, 18.04 m (59.2 ft) NNE of bench
mark NO 45 1929 4, 6.13 m (20.1 ft) ENE of bench mark 1317 C 2003, 4.42 m (14.5
ft) north of bench mark 1317 D 2003, and located at the apparent high water
line.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 4 of 6
Station ID: 9451317 PUBLICATION DATE: 11/13/2003
Name: ANCHOR POINT, WRANGELL NARROWS
AK
NOAA Chart: 17375 Latitude: 56° 38.3' N ( 56.63830)
USGS Quad: PETERSBURG (C-3) Longitude: 132° 55.6' W (-132.92700)
T I D A L B E N C H M A R K S
BENCH MARK STAMPING: NO 45 1929 4
DESIGNATION: 945 1317 TIDAL 4
MONUMENTATION: Reference Mark disk VM#: 17251
AGENCY: US Coast & Geodetic Survey
(USC&GS) IDB PID#:
SETTING CLASSIFICATION: Bedrock OPUS PID:
LATITUDE: 56° 38.3' N ( 56.63830) LONGITUDE: 132° 55.7' W (-132.92800)
The bench mark is a disk set in bedrock near the apparent high water line on the
tip of Anchor Point, 18.04 m (59.2 ft) SSW of bench mark 3 1929, 16 m (51 ft) SW
of bench mark 1317 D 2003, 14.87 m (48.8 ft) south of bench mark 1317 C 2003,
5.36 m (17.6 ft) NW of bench mark NO 45 5, and at the grass line.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 5 of 6
Station ID: 9451317 PUBLICATION DATE: 11/13/2003
Name: ANCHOR POINT, WRANGELL NARROWS
AK
NOAA Chart: 17375 Latitude: 56° 38.3' N ( 56.63830)
USGS Quad: PETERSBURG (C-3) Longitude: 132° 55.6' W (-132.92700)
T I D A L D A T U M S
Tidal datums at ANCHOR POINT, WRANGELL NARROWS based on:
LENGTH OF SERIES: 2 MONTHS
TIME PERIOD: August 2003 - September 2003
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 = 4.875
MEAN HIGH WATER MHW = 4.602
MEAN TIDE LEVEL MTL = 2.537
MEAN SEA LEVEL MSL = 2.500
MEAN LOW WATER MLW = 0.473
MEAN LOWER LOW WATER MLLW = 0.000
North American Vertical Datum (NAVD88)
Bench Mark Elevation Information In METERS above:
Stamping or Designation MLLW MHW
NO 45 5 5.875 1.273
TIDAL BM 1317-A 1977 4.588 -0.014
TIDAL BM 1317-B 1977 4.048 -0.554
1317 C 2003 5.121 0.520
1317 D 2003 5.075 0.473
3 1929 5.759 1.158
NO 45 1929 4 5.396 0.794
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 6 of 6
Station ID: 9451317 PUBLICATION DATE: 11/13/2003
Name: ANCHOR POINT, WRANGELL NARROWS
AK
NOAA Chart: 17375 Latitude: 56° 38.3' N ( 56.63830)
USGS Quad: PETERSBURG (C-3) Longitude: 132° 55.6' W (-132.92700)
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.