U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Datums Page Page 1 of 4
PUBLICATION DATE: 05/18/1982
Station ID: 9447856 SUPERCEDED DATE: 04/21/2003
Name: SANDY POINT, SARATOGA PASSAGE
WASHINGTON
NOAA Chart: 18441 Latitude: 48° 2.1' N
USGS Quad: LANGLEY Longitude: 122° 22.6' W
To reach the tidal bench marks from Everett, Washington, proceed by boat, 10
miles northwest to Sandy Point, which is located on the southeast side of
Whidbey Island. The bench marks are located on the sidewalk directly behind the
pier and extend east toward the lighthouse. The tide gage and staff were
located on the west side of the pier.
T I D A L B E N C H M A R K S
PRIMARY BENCH MARK STAMPING: 7856 1977A
MONUMENTATION: Survey Disk VM#: 9231
AGENCY: PID:
SETTING CLASSIFICATION: Pavement (Concrete)
The bench mark is set flush in a concrete sidewalk, south of the pier at Sandy
Point, which is located 1 mile east-southeast of Langley, Washington, 264 feet
(80 m) west of the light station, 20 feet (6 m) south of the berm line, and 5.0
feet (1.5 m) south of the east end of the west ramp leading to the pier.
BENCH MARK STAMPING: 7856 1977B
MONUMENTATION: Survey Disk VM#: 9232
AGENCY: PID:
SETTING CLASSIFICATION: Pavement (Concrete)
The bench mark is set flush in a concrete sidewalk, southeast of the pier, 183
feet (56 m) west of the light station, 81.5 feet (24.8 m) east of Bench Mark
7856 1977 A, 24 feet (7 m) west-northwest of the blue house with five large
picture windows facing the water, and 20 feet (6 m) south of the berm line.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 2 of 4
PUBLICATION DATE: 05/18/1982
Station ID: 9447856 SUPERCEDED DATE: 04/21/2003
Name: SANDY POINT, SARATOGA PASSAGE
WASHINGTON
NOAA Chart: 18441 Latitude: 48° 2.1' N
USGS Quad: LANGLEY Longitude: 122° 22.6' W
T I D A L B E N C H M A R K S
BENCH MARK STAMPING: 7856 1977C
MONUMENTATION: Survey Disk VM#: 9233
AGENCY: PID:
SETTING CLASSIFICATION: Pavement (Concrete)
The bench mark is set flush in a concrete sidewalk, southeast of the pier, 152
feet (46 m) west of the light station, 31 feet (9 m) east of Bench Mark 7856
1977 B, and 10 feet (3 m) north of a grey stained wood house.
BENCH MARK STAMPING: 7856 1977D
MONUMENTATION: Survey Disk VM#: 9234
AGENCY: PID:
SETTING CLASSIFICATION: Pavement (Concrete)
The bench mark is set flush in a concrete sidewalk, southeast of the pier, 200
feet (30 m) west of the light station, 52 feet (16 m) east of Bench Mark 7856
1977 C, and 25 feet (8 m) west of the northwest corner of a yellow house in line
with the sidewalk leading south.
BENCH MARK STAMPING: SANDY POINT 2, NO 3
MONUMENTATION: Survey Disk VM#: 9235
AGENCY: PID:
SETTING CLASSIFICATION: Concrete Post
The bench mark is set flush in a concrete post, near the Sandy Point Light
Station, 152 feet (46 m) east of Bench Mark 7856 1977 D, 70 feet (21 m) south of
the southeast corner of the cement base of the Sandy Point Light Station, and 10
feet (3 m) north of the northeast corner of the grey house, which is the
northeastern most house, bordered by water on two sides.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 3 of 4
PUBLICATION DATE: 05/18/1982
Station ID: 9447856 SUPERCEDED DATE: 04/21/2003
Name: SANDY POINT, SARATOGA PASSAGE
WASHINGTON
NOAA Chart: 18441 Latitude: 48° 2.1' N
USGS Quad: LANGLEY Longitude: 122° 22.6' W
T I D A L D A T U M S
Tidal datums at SANDY POINT, SARATOGA PASSAGE based on:
LENGTH OF SERIES: 1 MONTH
TIME PERIOD: FEBRUARY 1977
TIDAL EPOCH: 1960-1978
CONTROL TIDE STATION: 9447130 SEATTLE
Elevations of tidal datums referred to Mean Lower Low Water (MLLW), in FEET:
HIGHEST OBSERVED WATER LEVEL (02/10/1977) = 12.89
MEAN HIGHER HIGH WATER MHHW = 11.25
MEAN HIGH WATER MHW = 10.38
MEAN TIDE LEVEL MTL = 6.60
MEAN LOW WATER MLW = 2.82
MEAN LOWER LOW WATER MLLW = 0.00
LOWEST OBSERVED WATER LEVEL (04/07/1977) = -1.49
Bench Mark Elevation Information In FEET above:
Stamping or Designation MLLW MHW
7856 1977A 13.94 3.56
7856 1977B 13.65 3.27
7856 1977C 13.76 3.38
7856 1977D 13.88 3.50
SANDY POINT 2, NO 3 14.19 3.81
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 4 of 4
PUBLICATION DATE: 05/18/1982
Station ID: 9447856 SUPERCEDED DATE: 04/21/2003
Name: SANDY POINT, SARATOGA PASSAGE
WASHINGTON
NOAA Chart: 18441 Latitude: 48° 2.1' N
USGS Quad: LANGLEY Longitude: 122° 22.6' W
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 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.