U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Datums Page Page 1 of 7
Station ID: 9449639 PUBLICATION DATE: 06/16/2016
Name: POINT ROBERTS, PUGET SOUND
WA
NOAA Chart: 18421 Latitude: 48° 58.5' N ( 48.97500)
USGS Quad: POINT ROBERTS Longitude: 123° 5.0' W (-123.08300)
To reach the station from the US Border Crossing Station in Point Roberts,
proceed south 2.2 km (1.4 mi)on Tyee Drive, turn left onto APA Road and proceed
east 0.3 km (0.2 mi), turn right onto Simundson Drive and proceed south 0.5 km
(0.3 mi) to the Point Roberts Marina building on the right. The tide station is
on the commercial fishing dock and the bench marks are on the marina grounds.
T I D A L B E N C H M A R K S
PRIMARY BENCH MARK STAMPING: 9639 C 2015
DESIGNATION: 944 9639 C
MONUMENTATION: Flange-encased Rod VM#: 21746
AGENCY: CO-OPS IDB PID#:
SETTING CLASSIFICATION: OPUS PID#: BBDY51
LATITUDE: 48° 58.5' N ( 48.97553) LONGITUDE: 123° 3.8' W (-123.06261)
The mark is a flange encased rod set in the southern end of the lawn S of the
marina building near the channel entrance, 61.01 m (200.2 ft) SSE of a fire
hydrant along the rip rap channel shoreline, 51.70 m (169.6 ft) W of a fire
hydrant along a dirt road, 17.80 m (58.4 ft) E of the edge of vegetation above
the rip rap and 14.90 m (48.9 ft) NNW of the drop down to the small embayment N
of the eastern jetty. The datum point is set 4 cm (2 inches) below grade, being
the top of a stainless steel rod driven 18.8 m (61.7 ft) to refusal, in a sleeve
extending to a depth of 0.9 m (3.0 ft), and encased in a 6-inch (15 cm) pvc pipe
with NOS logo cover.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 2 of 7
Station ID: 9449639 PUBLICATION DATE: 06/16/2016
Name: POINT ROBERTS, PUGET SOUND
WA
NOAA Chart: 18421 Latitude: 48° 58.5' N ( 48.97500)
USGS Quad: POINT ROBERTS Longitude: 123° 5.0' W (-123.08300)
T I D A L B E N C H M A R K S
BENCH MARK STAMPING: 9639 B 2015
DESIGNATION: 944 9639 B
MONUMENTATION: Bench Mark disk VM#: 21747
AGENCY: CO-OPS IDB PID#:
SETTING CLASSIFICATION: Base of flag pole OPUS PID:
LATITUDE: 48° 58.6' N ( 48.97681) LONGITUDE: 123° 3.8' W (-123.06333)
The mark is a disk set flush near the center of the 2.4 m (7.9 ft) x 3.9 m (12.8
ft) concrete pad foundation of the flag pole at the SW corner of the marina
building, 20.08 m (65.9 ft) ESE of a fire hydrant along the W side of the lawn
near the base of the fixed pier, 19.00 m (62.3 ft) NE of the center of the top
of the ramp down to the floating dock SW of the marina building, 15.24 m (50.0
ft) SSW of the SW corner of the marina building, 1.38 m (4.5 ft) WSW of the E
side of the concrete pad and 0.96 m (3.1 ft) S of the flag pole.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 3 of 7
Station ID: 9449639 PUBLICATION DATE: 06/16/2016
Name: POINT ROBERTS, PUGET SOUND
WA
NOAA Chart: 18421 Latitude: 48° 58.5' N ( 48.97500)
USGS Quad: POINT ROBERTS Longitude: 123° 5.0' W (-123.08300)
T I D A L B E N C H M A R K S
BENCH MARK STAMPING: 9639 D 2015
DESIGNATION: 944 9639 D
MONUMENTATION: Flange-encased Rod VM#: 21748
AGENCY: CO-OPS IDB PID#:
SETTING CLASSIFICATION: OPUS PID:
LATITUDE: 48° 58.6' N ( 48.97653) LONGITUDE: 123° 3.7' W (-123.06219)
The mark is a flange encased rod set on the eastern side of a low chain link
fence that generally runs N to S on the western side of Simundson Drive, SE of
the marina building, 43.68 m (143.3 ft) S of the northern end of the low fence,
42.27 m (138.7 ft) S of the western post of the marina restaurant sign on S side
of southern parking lot, 30.03 m (98.5 ft) NNW of the southern end of the low
fence, 14.01 m (46.0 ft) NE of the post of the lone basketball hoop on half
court SSE of marina building, 6.31 m (20.7 ft) SSE of gateless opening in fence
and 1.20 m (3.9 ft) E of the fence. The datum point is set 3 cm (1 inch) below
grade being the top of a stainless steel rod driven 13.2 m (43.3 ft) to refusal
and encased in a 6 inch (15 cm) nos logo cover with concrete kick block.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 4 of 7
Station ID: 9449639 PUBLICATION DATE: 06/16/2016
Name: POINT ROBERTS, PUGET SOUND
WA
NOAA Chart: 18421 Latitude: 48° 58.5' N ( 48.97500)
USGS Quad: POINT ROBERTS Longitude: 123° 5.0' W (-123.08300)
T I D A L B E N C H M A R K S
BENCH MARK STAMPING: 9639 E 2015
DESIGNATION: 944 9639 E
MONUMENTATION: Flange-encased Rod VM#: 21749
AGENCY: CO-OPS IDB PID#:
SETTING CLASSIFICATION: OPUS PID:
LATITUDE: 48° 58.7' N ( 48.97794) LONGITUDE: 123° 3.8' W (-123.06292)
The mark is a flange encased rod set near the NE corner of the grass island
created by the northern boundary of the marina building parking lot, the public
parking lot to the N and Simundson Drive to the E, 15.53 m (51.0 ft) E of a tree
along northern side of the grass island, 14.19 m (46.6 ft) N of the northern
metal gate post of the northern road entrance to marina parking lot, 10.09 m
(33.1 ft) WSW of the centerline of Simundson Drive, 4.50 m (14.8 ft) SSW of
evergreen bush trunk in NE corner of grass island, 3.30 m (10.8 ft) S of the
inside southeastern corner of pavement of public parking lot N of marina
building. The datum point is set 9 cm (4 inches) below grade being the top of a
stainless steel rod driven 8.5 m (27.9 ft) to refusal and encased in a 6 inch
(15 cm) NOS logo cover with concrete kick block.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 5 of 7
Station ID: 9449639 PUBLICATION DATE: 06/16/2016
Name: POINT ROBERTS, PUGET SOUND
WA
NOAA Chart: 18421 Latitude: 48° 58.5' N ( 48.97500)
USGS Quad: POINT ROBERTS Longitude: 123° 5.0' W (-123.08300)
T I D A L B E N C H M A R K S
BENCH MARK STAMPING: 9639 A 2015
DESIGNATION: 944 9639 A
MONUMENTATION: Bench Mark disk VM#: 21750
AGENCY: CO-OPS IDB PID#:
SETTING CLASSIFICATION: Concrete abutment OPUS PID:
LATITUDE: 48° 58.6' N ( 48.97742) LONGITUDE: 123° 3.8' W (-123.06394)
The mark is a disk set flush in the top of a concrete abutment for a ramp to the
floating dock, 50.60 m (166.0 ft) NNW of the southern edge of parking lot W of
the marina building, 18.83 m (61.8 ft) S of a fire hydrant at the S end of the
brick pedestrian walkway, 4.43 m (14.5 ft) W of the SE wooden vertical support
of the boat hoist, 3.90 m (12.8 ft) NW of the northern most of three white
bollards on W side of parking lot, 0.21 m (0.7 ft) SSE of the northern end of
the abutment and 0.6 m (2.0 ft) above the adjacent boat ramp.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 6 of 7
Station ID: 9449639 PUBLICATION DATE: 06/16/2016
Name: POINT ROBERTS, PUGET SOUND
WA
NOAA Chart: 18421 Latitude: 48° 58.5' N ( 48.97500)
USGS Quad: POINT ROBERTS Longitude: 123° 5.0' W (-123.08300)
T I D A L D A T U M S
Tidal datums at POINT ROBERTS, PUGET SOUND based on:
LENGTH OF SERIES: 3 MONTHS
TIME PERIOD: August 2015 - October 2015
TIDAL EPOCH: 1983-2001
CONTROL TIDE STATION: 9449424 CHERRY POINT, STRAIT OF GEORGIA
Elevations of tidal datums referred to Mean Lower Low Water (MLLW), in METERS:
MEAN HIGHER HIGH WATER MHHW = 2.983
MEAN HIGH WATER MHW = 2.719
MEAN TIDE LEVEL MTL = 1.773
MEAN SEA LEVEL MSL = 1.718
MEAN LOW WATER MLW = 0.826
MEAN LOWER LOW WATER MLLW = 0.000
North American Vertical Datum (NAVD88)
Bench Mark Elevation Information In METERS above:
Stamping or Designation MLLW MHW
9639 C 2015 4.976 2.257
9639 B 2015 5.124 2.405
9639 D 2015 4.599 1.880
9639 E 2015 5.015 2.296
9639 A 2015 4.830 2.111
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 7 of 7
Station ID: 9449639 PUBLICATION DATE: 06/16/2016
Name: POINT ROBERTS, PUGET SOUND
WA
NOAA Chart: 18421 Latitude: 48° 58.5' N ( 48.97500)
USGS Quad: POINT ROBERTS Longitude: 123° 5.0' W (-123.08300)
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.