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Datums Page Page 1 of 5
Station ID: 9452346 PUBLICATION DATE: 06/21/2018
Name: COVE POINT, BERNER'S BAY
AK
NOAA Chart: 17316 Latitude: 58° 45.1' N ( 58.75170)
USGS Quad: JUNEAU (D-4) Longitude: 135° 1.7' W (-135.02800)
To reach the tidal bench marks, proceed to the southern edge of Cove Point in
Berner's Bay, AK. The bench marks are located along the beach in the vicinity,
and the tide gauge was located on a high rock ledge jutting out from the tree
line, and set 15 m (49 ft) above the apparent high water line.
T I D A L B E N C H M A R K S
PRIMARY BENCH MARK STAMPING: 2346 C 1998
DESIGNATION: 945 2346 C
MONUMENTATION: Tidal Station disk VM#: 14036
AGENCY: National Ocean Service (NOS) IDB PID#:
SETTING CLASSIFICATION: Bedrock OPUS PID:
LATITUDE: 58° 45.1' N ( 58.75170) LONGITUDE: 135° 1.9' W (-135.03200)
The primary bench mark is a disk set on top of a 0.46 m x 0.46 m (1.5 ft x 1.5
ft) flat black bedrock shelf-like feature, just at the base of the cliff before
it begins a gradual rise, on the southern edge of Cove Point, at the tip of a
prominent, wedge-shaped, 5 m to 9 m (15 ft to 30 ft) high rock cliff that juts
out from below the treeline, 30 m (98 ft) SE (160 degrees magnetic) from bench
mark 2346 D 1998, and approximately at or slightly below the apparent highwater
line.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 2 of 5
Station ID: 9452346 PUBLICATION DATE: 06/21/2018
Name: COVE POINT, BERNER'S BAY
AK
NOAA Chart: 17316 Latitude: 58° 45.1' N ( 58.75170)
USGS Quad: JUNEAU (D-4) Longitude: 135° 1.7' W (-135.02800)
T I D A L B E N C H M A R K S
BENCH MARK STAMPING: 2346 A 1998
DESIGNATION: 945 2346 A
MONUMENTATION: Tidal Station disk VM#: 14034
AGENCY: National Ocean Service (NOS) IDB PID#:
SETTING CLASSIFICATION: Boulder OPUS PID:
LATITUDE: 58° 45.2' N ( 58.75330) LONGITUDE: 135° 1.6' W (-135.02700)
The bench mark is a disk set on top of a boulder at the base of a rock cliff on
the southern edge of Cove Point, 65 m (213 ft) NE (135 degrees magnetic) from
bench mark 2346 B 1998, and approximately 1 m (3 ft) above the apparent high
water line.
BENCH MARK STAMPING: 2346 B 1998
DESIGNATION: 945 2346 B
MONUMENTATION: Tidal Station disk VM#: 14035
AGENCY: National Ocean Service (NOS) IDB PID#:
SETTING CLASSIFICATION: Rock outcrop OPUS PID:
LATITUDE: 58° 45.1' N ( 58.75170) LONGITUDE: 135° 1.6' W (-135.02700)
The bench mark is a disk set on top of a 0.3 m (1 ft) wide rock shelf feature at
the base of a rock cliff, at knee level, on the southern edge of Cove Point, 42
m (138 ft) NE (078 degrees magnetic) from bench mark 2346 C 1998, and
approximately 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 5
Station ID: 9452346 PUBLICATION DATE: 06/21/2018
Name: COVE POINT, BERNER'S BAY
AK
NOAA Chart: 17316 Latitude: 58° 45.1' N ( 58.75170)
USGS Quad: JUNEAU (D-4) Longitude: 135° 1.7' W (-135.02800)
T I D A L B E N C H M A R K S
BENCH MARK STAMPING: 2346 D 1998
DESIGNATION: 945 2346 D
MONUMENTATION: Tidal Station disk VM#: 14037
AGENCY: National Ocean Service (NOS) IDB PID#:
SETTING CLASSIFICATION: Boulder OPUS PID#: BBDF44
LATITUDE: 58° 45.1' N ( 58.75170) LONGITUDE: 135° 1.9' W (-135.03200)
The bench mark is a disk set on top of a 1 m x 1 m (3 ft x 3 ft) flat section of
a boulder cluster among the cluster of angular dark-colored boulders located 30
m (98 ft) due west of the tip of the prominent wedge-shaped rock cliff on the
southern edge of Cove Point, 27 m (89 ft) NE (065 degrees magnetic) from bench
mark 2346 E 1998, and approximately at or slightly above the apparent high water
line.
BENCH MARK STAMPING: 2346 E 1998
DESIGNATION: 945 2346 E
MONUMENTATION: Tidal Station disk VM#: 14038
AGENCY: National Ocean Service (NOS) IDB PID#:
SETTING CLASSIFICATION: Rock outcrop OPUS PID:
LATITUDE: 58° 45.1' N ( 58.75170) LONGITUDE: 135° 1.9' W (-135.03200)
The bench mark is a disk set on top of a gray rock outcrop that is partially
obscured by grass and weeds, 1 m to 2 m (3 ft to 6 ft) into the tree line, at a
small rocky beach area, on the southern edge of Cove Point, 27 m (89 ft) SW (245
degrees magnetic) from bench mark 2346 D 1998, and approximately 2 m (6 ft)
above the apparent high water line.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 4 of 5
Station ID: 9452346 PUBLICATION DATE: 06/21/2018
Name: COVE POINT, BERNER'S BAY
AK
NOAA Chart: 17316 Latitude: 58° 45.1' N ( 58.75170)
USGS Quad: JUNEAU (D-4) Longitude: 135° 1.7' W (-135.02800)
T I D A L D A T U M S
Tidal datums at COVE POINT, BERNER'S BAY based on:
LENGTH OF SERIES: 1 MONTH
TIME PERIOD: May 1999 - May 1999
TIDAL EPOCH: 2012-2016
CONTROL TIDE STATION: 9452210 JUNEAU, GASTINEAU CHANNEL, STEPHENS PASS
Elevations of tidal datums referred to Mean Lower Low Water (MLLW), in METERS:
MEAN HIGHER HIGH WATER MHHW = 4.927
MEAN HIGH WATER MHW = 4.634
MEAN SEA LEVEL MSL = 2.600
MEAN TIDE LEVEL MTL = 2.561
MEAN LOW WATER MLW = 0.488
MEAN LOWER LOW WATER MLLW = 0.000
North American Vertical Datum (NAVD88)
Bench Mark Elevation Information In METERS above:
Stamping or Designation MLLW MHW
2346 C 1998 5.175 0.541
2346 A 1998 7.221 2.587
2346 B 1998 5.363 0.729
2346 D 1998 5.758 1.124
2346 E 1998 7.757 3.123
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 5 of 5
Station ID: 9452346 PUBLICATION DATE: 06/21/2018
Name: COVE POINT, BERNER'S BAY
AK
NOAA Chart: 17316 Latitude: 58° 45.1' N ( 58.75170)
USGS Quad: JUNEAU (D-4) Longitude: 135° 1.7' W (-135.02800)
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.