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National Ocean Service
Datums Page Page 1 of 5
Station ID: 9454674 PUBLICATION DATE: 03/02/2011
Name: MACLEOD HARBOR
AK
NOAA Chart: 16701 Latitude: 59° 53.4' N ( 59.89000)
USGS Quad: BLYING SOUND (D-3) Longitude: 147° 47.7' W (-147.79500)
To reach the tidal bench marks, travel to MacLeod Harbor from the village of
Chenega Bay (located on the shores of Sawmill Bay). Head east out of Sawmill
Bay, then north in Latouche Passage for 9.3 km (5 nm). Round the north tip of
Latouche Island and head south in Montague Strait for 22.2 km (12 nm) to reach
MacLeod Harbor. The tide station and bench marks are located on a prominent,
rocky point on the north shore of Macleod Harbor, Montague Island, Prince
William Sound. The point extends south from the north shore of the bay about
half way between the mouth and the head of the bay. The point is approximately
1.85 km (1 nm) SSE of Point Woodcock.
T I D A L B E N C H M A R K S
PRIMARY BENCH MARK STAMPING: 4674 A 1978
DESIGNATION: 945 4674 A
MONUMENTATION: Tidal Station disk VM#: 14659
AGENCY: National Ocean Survey (NOS) IDB PID#:
SETTING CLASSIFICATION: Rock outcrop OPUS PID:
LATITUDE: 59° 53.4' N ( 59.89000) LONGITUDE: 147° 47.7' W (-147.79500)
The primary bench mark is a disk set on a bare rock point on the north shore of
Macleod Harbor, 24 m (80 ft) NE from the apparent high water mark at the
southern tip of this point.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 2 of 5
Station ID: 9454674 PUBLICATION DATE: 03/02/2011
Name: MACLEOD HARBOR
AK
NOAA Chart: 16701 Latitude: 59° 53.4' N ( 59.89000)
USGS Quad: BLYING SOUND (D-3) Longitude: 147° 47.7' W (-147.79500)
T I D A L B E N C H M A R K S
BENCH MARK STAMPING: 4674 B 1978
DESIGNATION: 945 4674 B
MONUMENTATION: Tidal Station disk VM#: 14660
AGENCY: National Ocean Survey (NOS) IDB PID#:
SETTING CLASSIFICATION: Rock outcrop OPUS PID:
LATITUDE: 59° 53.4' N ( 59.89000) LONGITUDE: 147° 47.7' W (-147.79500)
The bench mark is a disk set on a rocky point, 13.41 m (44.0 ft) NE of bench
mark 4674 A 1978, and 13.11 m (43.0 ft) SW of bench mark RESET C 2000.
BENCH MARK STAMPING: 4674 E 1978
DESIGNATION: 945 4674 E
MONUMENTATION: Tidal Station disk VM#: 14663
AGENCY: National Ocean Survey (NOS) IDB PID#:
SETTING CLASSIFICATION: Rock outcrop OPUS PID:
LATITUDE: 59° 53.4' N ( 59.89000) LONGITUDE: 147° 47.7' W (-147.79500)
The bench mark is a disk set in a steep sloping rock outcrop which rises from
the water to a moss-covered peak, located at the top of the lower half of the
sloping rock outcrop, set in a notch amongst the roots of a small conifer tree,
22.50 m (73.8 ft) SE of bench mark RESET D 2000, and 15 m (50 ft) NE of bench
mark RESET C 2000.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 3 of 5
Station ID: 9454674 PUBLICATION DATE: 03/02/2011
Name: MACLEOD HARBOR
AK
NOAA Chart: 16701 Latitude: 59° 53.4' N ( 59.89000)
USGS Quad: BLYING SOUND (D-3) Longitude: 147° 47.7' W (-147.79500)
T I D A L B E N C H M A R K S
BENCH MARK STAMPING: RESET C 2000
DESIGNATION: 945 4674 RESET C 2000
MONUMENTATION: Tidal Station disk VM#: 16334
AGENCY: National Ocean Service (NOS) IDB PID#:
SETTING CLASSIFICATION: Rock outcrop OPUS PID:
LATITUDE: 59° 53.4' N ( 59.89000) LONGITUDE: 147° 47.7' W (-147.79500)
The bench mark is a disk set at the base of a 9 m (29 ft) high sloping rock
cliff, 37.50 m ( 123.0 ft) SW of bench mark RESET D 2000, and 13.01 m (42.7 ft)
NE of bench mark 4674 B 1978.
BENCH MARK STAMPING: RESET D 2000
DESIGNATION: 945 4674 D 2000
MONUMENTATION: Tidal Station disk VM#: 16335
AGENCY: National Ocean Service (NOS) IDB PID#:
SETTING CLASSIFICATION: Rock outcrop OPUS PID:
LATITUDE: 59° 53.4' N ( 59.89000) LONGITUDE: 147° 47.7' W (-147.79500)
The bench mark is a disk set on a small bedrock ledge 2 m (5 ft) above the base
of a 9 m (29 ft) high sloping rock cliff, 37.50 m (123.0 ft) NE of bench mark
RESET D 2000, and 22.50 m (73.8 ft) NW of bench mark 4674 E 1978.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 4 of 5
Station ID: 9454674 PUBLICATION DATE: 03/02/2011
Name: MACLEOD HARBOR
AK
NOAA Chart: 16701 Latitude: 59° 53.4' N ( 59.89000)
USGS Quad: BLYING SOUND (D-3) Longitude: 147° 47.7' W (-147.79500)
T I D A L D A T U M S
Tidal datums at MACLEOD HARBOR based on:
LENGTH OF SERIES: 33 DAYS
TIME PERIOD: September 23 2000 - October 25 2000
TIDAL EPOCH: 1983-2001
CONTROL TIDE STATION: 9455090 SEWARD, RESURRECTION BAY
Elevations of tidal datums referred to Mean Lower Low Water (MLLW), in METERS:
MEAN HIGHER HIGH WATER MHHW = 3.411
MEAN HIGH WATER MHW = 3.154
MEAN SEA LEVEL MSL = 1.818
MEAN TIDE LEVEL MTL = 1.797
MEAN LOW WATER MLW = 0.441
MEAN LOWER LOW WATER MLLW = 0.000
North American Vertical Datum (NAVD88)
Bench Mark Elevation Information In METERS above:
Stamping or Designation MLLW MHW
4674 A 1978 7.902 4.748
4674 B 1978 7.863 4.710
4674 E 1978 7.224 4.071
RESET C 2000 7.710 4.557
RESET D 2000 8.115 4.962
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 5 of 5
Station ID: 9454674 PUBLICATION DATE: 03/02/2011
Name: MACLEOD HARBOR
AK
NOAA Chart: 16701 Latitude: 59° 53.4' N ( 59.89000)
USGS Quad: BLYING SOUND (D-3) Longitude: 147° 47.7' W (-147.79500)
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.