U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Datums Page Page 1 of 4
PUBLICATION DATE: 11/12/1990
Station ID: 9448918 SUPERCEDED DATE: 04/21/2003
Name: TIDE POINT, CYPRESS ISLAND, ROSARIO STRAIT
WASHINGTON
NOAA Chart: 18430 Latitude: 48° 35.2' N
USGS Quad: CYPRESS ISLAND Longitude: 122° 44.4' W
To reach the tidal bench marks from the town of Anacortes on Fidalgo Island,
proceed by boat about 5 nautical miles (9 km) west along Guemes Channel to
Rosario Strait Channel, then about 4 nautical miles (7 km) north along Rosario
Strait Channel to the flashing light (FL 2 1/2 sec 15ft 12) at Tide Point. The
bench marks are along the beach to the NE and SE of the point. The tide gage
was NE of the point and the staff was west of the point.
T I D A L B E N C H M A R K S
PRIMARY BENCH MARK STAMPING: BM 1 1974
MONUMENTATION: Survey Disk VM#: 9269
AGENCY: PID:
SETTING CLASSIFICATION: Large Rock
The bench mark is set in a 4x4x2-foot (1x1x1 m) rock at the SW corner of the
open front log camp shelter NE of Tide Point Light, 290 feet (88 m) ENE of the
NE corner of the boat storage house, and 40 feet (12 m) east of the approximate
high water line.
BENCH MARK STAMPING: BM 2 1974
MONUMENTATION: Survey Disk VM#: 9270
AGENCY: PID:
SETTING CLASSIFICATION: Large Rock
The bench mark is set in a 4x5x3-foot (1x2x1 m) flat rock at the south edge of
a grassy meadow, 1080 feet (329 m) west of Bench Mark BM 1 1974, 300 feet (91 m)
west of a red house on the bluff, and 33 feet (10 m) NE of the approximate high
water line.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 2 of 4
PUBLICATION DATE: 11/12/1990
Station ID: 9448918 SUPERCEDED DATE: 04/21/2003
Name: TIDE POINT, CYPRESS ISLAND, ROSARIO STRAIT
WASHINGTON
NOAA Chart: 18430 Latitude: 48° 35.2' N
USGS Quad: CYPRESS ISLAND Longitude: 122° 44.4' W
T I D A L B E N C H M A R K S
BENCH MARK STAMPING: BM 3 1974
MONUMENTATION: Survey Disk VM#: 9271
AGENCY: PID:
SETTING CLASSIFICATION: Large Rock
The bench mark is set in a rock buried in the gravel beach just south of Tide
Point, 200 feet (61 m) west of the red house on the bluff, 100 feet (30 m) SSE
of Bench Mark BM 2 1974, and 24 feet (7 m) NE of the approximate high water
line.
BENCH MARK STAMPING: BM 4 1974
MONUMENTATION: Survey Disk VM#: 9272
AGENCY: PID:
SETTING CLASSIFICATION: Large Rock
The bench mark is set in a 5x5x6-foot (2x2x2 m) rock outcrop on the beach SE of
Tide Point, and 90 feet (27 m) south of Bench Mark BM 3 1974.
BENCH MARK STAMPING: BM 5 1974
MONUMENTATION: Survey Disk VM#: 9273
AGENCY: PID:
SETTING CLASSIFICATION: Large Rock
The bench mark is set in a 10x10x5-foot (3x3x2 m) solitary rock on the beach SE
of Tide Point, 120 feet (37 m) SSE of Bench Mark BM 4 1974, 20 feet (6 m) west
of the 15x15x15-foot (5x5x5 m) rock nearest to the water, and 16 feet (5 m) SW
of the bluff below the red house.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 3 of 4
PUBLICATION DATE: 11/12/1990
Station ID: 9448918 SUPERCEDED DATE: 04/21/2003
Name: TIDE POINT, CYPRESS ISLAND, ROSARIO STRAIT
WASHINGTON
NOAA Chart: 18430 Latitude: 48° 35.2' N
USGS Quad: CYPRESS ISLAND Longitude: 122° 44.4' W
T I D A L D A T U M S
Tidal datums at TIDE POINT, CYPRESS ISLAND, ROSARIO STRAIT based on:
LENGTH OF SERIES: 1 MONTH
TIME PERIOD: MARCH 1974
TIDAL EPOCH: 1960-1978
CONTROL TIDE STATION: 9449880 FRIDAY HARBOR
Elevations of tidal datums referred to Mean Lower Low Water (MLLW), in FEET:
HIGHEST OBSERVED WATER LEVEL (03/10/1974) = 9.10
MEAN HIGHER HIGH WATER MHHW = 8.08
MEAN HIGH WATER MHW = 7.30
MEAN TIDE LEVEL MTL = 4.86
MEAN LOW WATER MLW = 2.42
MEAN LOWER LOW WATER MLLW = 0.00
LOWEST OBSERVED WATER LEVEL (03/05/1974) = -0.70
Bench Mark Elevation Information In FEET above:
Stamping or Designation MLLW MHW
BM 1 1974 19.48 12.18
BM 2 1974 14.38 7.08
BM 3 1974 12.09 4.79
BM 4 1974 13.47 6.17
BM 5 1974 14.66 7.36
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 4 of 4
PUBLICATION DATE: 11/12/1990
Station ID: 9448918 SUPERCEDED DATE: 04/21/2003
Name: TIDE POINT, CYPRESS ISLAND, ROSARIO STRAIT
WASHINGTON
NOAA Chart: 18430 Latitude: 48° 35.2' N
USGS Quad: CYPRESS ISLAND Longitude: 122° 44.4' 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.