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National Oceanic and Atmospheric Administration
National Ocean Service
Datums Page Page 1 of 5
Station ID: 9446451 PUBLICATION DATE: 06/16/2004
Name: GREEN POINT
WA
NOAA Chart: 18448 Latitude: 47° 18.1' N ( 47.30170)
USGS Quad: FOX ISLAND Longitude: 122° 40.9' W (-122.68200)
To reach the tidal bench marks from Arletta, proceed 1.9 km (1.2 mi) north to
the NE end of Horsehead Bay. The bench marks are located in the sea wall around
the residence of Mr. William Busch. The tide gage and staff were located on the
wooden pier on the property. NOTE: The owner is very privacy conscious, contact
before occupying.
T I D A L B E N C H M A R K S
PRIMARY BENCH MARK STAMPING: 6451 B 1978
DESIGNATION: 944 6451 B TIDAL
MONUMENTATION: Tidal Station disk VM#: 9138
AGENCY: National Ocean Survey (NOS) IDB PID#:
SETTING CLASSIFICATION: Concrete sea wall OPUS PID:
LATITUDE: 47° 18.1' N ( 47.30170) LONGITUDE: 122° 40.9' W (-122.68200)
The primary bench mark is a disk set in the top of a concrete sea wall west of a
private home at the NE end of Horsehead Bay, 21 m (68 ft) north of the NE end of
the pier at a junction with a sidewalk leading to the residence, 4 m (13 ft)
south of a brick firepit, 1 m (4 ft) NW of a large fir tree, and 0.5 m (1.5 ft)
above the beach.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 2 of 5
Station ID: 9446451 PUBLICATION DATE: 06/16/2004
Name: GREEN POINT
WA
NOAA Chart: 18448 Latitude: 47° 18.1' N ( 47.30170)
USGS Quad: FOX ISLAND Longitude: 122° 40.9' W (-122.68200)
T I D A L B E N C H M A R K S
BENCH MARK STAMPING: 6451 A 1978
DESIGNATION: 944 6451 A TIDAL
MONUMENTATION: Tidal Station disk VM#: 9137
AGENCY: National Ocean Survey (NOS) IDB PID#:
SETTING CLASSIFICATION: Concrete sea wall OPUS PID:
LATITUDE: 47° 18.1' N ( 47.30170) LONGITUDE: 122° 40.9' W (-122.68200)
The bench mark is a disk set in the top of the north end of the concrete sea
wall winding north-southeasterly, west of the private home at the NE end of
Horsehead Bay, 50 m (164 ft) north of bench mark 6451 B 1978, 9 m (28 ft) NW of
a 6 m (20 ft) tree stump, and 1 m (3 ft) above the base of the sea wall.
BENCH MARK STAMPING: 6451 C 1978
DESIGNATION: 944 6451 C TIDAL
MONUMENTATION: Tidal Station disk VM#: 9139
AGENCY: National Ocean Survey (NOS) IDB PID#:
SETTING CLASSIFICATION: Concrete sea wall OPUS PID:
LATITUDE: 47° 18.1' N ( 47.30170) LONGITUDE: 122° 40.9' W (-122.68200)
The bench mark is a disk set in the top of a concrete sea wall west of a private
home at the NE end of Horsehead Bay, 50 m (164 ft) SE of bench mark 6451 B 1978,
and 2 m (6 ft) west of the SE end of the sea wall.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 3 of 5
Station ID: 9446451 PUBLICATION DATE: 06/16/2004
Name: GREEN POINT
WA
NOAA Chart: 18448 Latitude: 47° 18.1' N ( 47.30170)
USGS Quad: FOX ISLAND Longitude: 122° 40.9' W (-122.68200)
T I D A L B E N C H M A R K S
BENCH MARK STAMPING: 6451 D 1978
DESIGNATION: 944 6451 D TIDAL
MONUMENTATION: Tidal Station disk VM#: 9140
AGENCY: National Ocean Survey (NOS) IDB PID#:
SETTING CLASSIFICATION: Concrete sea wall OPUS PID:
LATITUDE: 47° 18.1' N ( 47.30170) LONGITUDE: 122° 40.9' W (-122.68200)
The bench mark is a disk set in the top of a concrete sea wall, near the corner
of the junction of a sidewalk cutting through the wall to the beach, 121 m (400
ft) south of the prominent pier leading seaward from the private residence at
the NE end of Horsehead Bay, 70 m (230 ft) south of bench mark 6451 C 1978, and
6 m (20 ft) SSW of a large fir tree.
BENCH MARK STAMPING: 6451 E 1978
DESIGNATION: 944 6451 E TIDAL
MONUMENTATION: Tidal Station disk VM#: 9141
AGENCY: National Ocean Survey (NOS) IDB PID#:
SETTING CLASSIFICATION: Concrete sea wall OPUS PID:
LATITUDE: 47° 18.1' N ( 47.30170) LONGITUDE: 122° 40.9' W (-122.68200)
The bench mark is a disk set in top of a concrete sea wall, 198 m (650 ft) south
of the prominent pier leading seaward from the private residence at the NE end
of Horsehead Bay, 70 m (230 ft) south of bench mark 6451 D 1978, and 20 m (65
ft) south of a sidewalk cut in the sea wall. The bench mark is 2 m (7 ft) above
beach level at the sea wall.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 4 of 5
Station ID: 9446451 PUBLICATION DATE: 06/16/2004
Name: GREEN POINT
WA
NOAA Chart: 18448 Latitude: 47° 18.1' N ( 47.30170)
USGS Quad: FOX ISLAND Longitude: 122° 40.9' W (-122.68200)
T I D A L D A T U M S
Tidal datums at GREEN POINT based on:
LENGTH OF SERIES: 1 MONTH
TIME PERIOD: March 1978 - March 1978
TIDAL EPOCH: 1983-2001
CONTROL TIDE STATION: 9447130 SEATTLE, PUGET SOUND
Elevations of tidal datums referred to Mean Lower Low Water (MLLW), in METERS:
MEAN HIGHER HIGH WATER MHHW = 4.105
MEAN HIGH WATER MHW = 3.825
MEAN TIDE LEVEL MTL = 2.365
MEAN SEA LEVEL MSL = 2.354
MEAN LOW WATER MLW = 0.905
MEAN LOWER LOW WATER MLLW = 0.000
North American Vertical Datum (NAVD88)
Bench Mark Elevation Information In METERS above:
Stamping or Designation MLLW MHW
6451 B 1978 5.296 1.471
6451 A 1978 5.378 1.553
6451 C 1978 5.336 1.511
6451 D 1978 5.344 1.519
6451 E 1978 5.363 1.538
Foot Notes:
Bench marks 6451 A 1978, 6451 C 1978, 6451 D 1978,and 6451 E 1978 are based on
one differential leveling connection and do not meet the quality control
standards of the NOS. Therefore, caution should be used when deriving elevations
for these marks.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 5 of 5
Station ID: 9446451 PUBLICATION DATE: 06/16/2004
Name: GREEN POINT
WA
NOAA Chart: 18448 Latitude: 47° 18.1' N ( 47.30170)
USGS Quad: FOX ISLAND Longitude: 122° 40.9' W (-122.68200)
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.
Station Location
Published bench mark
Unpublished bench mark
