U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Datums Page Page 1 of 7
Station ID: 9440483 PUBLICATION DATE: 01/25/2017
Name: BARLOW POINT, COLUMBIA RIVER
WA
NOAA Chart: 18524 Latitude: 46° 9.1' N ( 46.15222)
USGS Quad: COAL CREEK Longitude: 123° 2.4' W (-123.03917)
To reach the bench marks from the intersection of Ocean Beach Highway (SR 4) and
Willow Grove Connection Road (SR 432) in Longview, proceed south on Willow Grove
Connection Road (SR 432) for 1.3 km (0.8 mi) to its intersection with Barlow
Point Road on the left. Turn left and proceed south on Barlow Point Road for
1.1 km (0.7 mi) to the driveway for 274 Barlow Point Road. The bench marks are
located at 274 Barlow Point Road, on the dike road to the south of the residence
and across the street at 273 Barlow Point Road. The tide station Is located at
the end of the pier.
T I D A L B E N C H M A R K S
PRIMARY BENCH MARK STAMPING: 0483 C 2016
DESIGNATION: 944 0483 C
MONUMENTATION: Flange-encased Rod VM#: 22065
AGENCY: National Ocean Service IDB PID#:
SETTING CLASSIFICATION: OPUS PID:
LATITUDE: 46° 9.2' N ( 46.15297) LONGITUDE: 123° 2.3' W (-123.03789)
The primary bench mark is a flange encased rod located in the back yard of the
residence of 274 Barlow Point road, 52.85 m (173.4 ft) W of the SW building
corner, 47.95 m (157.3 ft) WNW of a 1-foot diameter decorative tree in the
backyard, 45.72 m (150.0 ft) SW of the NW corner of a concrete walkway, 38.55 m
(126.5 ft) NNW of the N face of a pier to dock, and 19.25 m (63.2 ft) ESE of the
E fence post for a gate to the N. The datum point is set 4 cm (2 inches) below
grade, being the top of a stainless steel rod driven 19.05 m (62.5 ft) to
refusal, in a sleeve extending to a depth of 1.1 m (3.6 ft) and encased in a
7-inch (18 cm) nos logo cover with kick block.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 2 of 7
Station ID: 9440483 PUBLICATION DATE: 01/25/2017
Name: BARLOW POINT, COLUMBIA RIVER
WA
NOAA Chart: 18524 Latitude: 46° 9.1' N ( 46.15222)
USGS Quad: COAL CREEK Longitude: 123° 2.4' W (-123.03917)
T I D A L B E N C H M A R K S
BENCH MARK STAMPING: 0483 B 2016
DESIGNATION: 944 0483 B
MONUMENTATION: Flange-encased Rod VM#: 22066
AGENCY: National Ocean Service IDB PID#:
SETTING CLASSIFICATION: OPUS PID#: BBFG95
LATITUDE: 46° 9.2' N ( 46.15367) LONGITUDE: 123° 2.1' W (-123.03447)
The bench mark is a flange encased rod set in the back yard of the private
residence of 273 Barlow Point road, 49.72 m (163.1 ft) E of the SE corner of the
solar farm, 33.65 m (110.4 ft) WSW of the end fence post at the E corner of the
lot, 19.45 m (63.8 ft) W of a fence post at the intersection of two fences, 5.75
m (18.9 ft) WSW of the centerline of the gravel driveway, and 5.65 m (18.5 ft) S
of the N end of a drainage bank. The bench mark is set 4 cm (2 inches) below
grade being the top of a stainless steel rod driven 15.2 m (49.9 ft) to refusal,
in a sleeve extending to 1.1 m (3.6 ft) and encased in a 7-inch NOS logo cover
with kick block.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 3 of 7
Station ID: 9440483 PUBLICATION DATE: 01/25/2017
Name: BARLOW POINT, COLUMBIA RIVER
WA
NOAA Chart: 18524 Latitude: 46° 9.1' N ( 46.15222)
USGS Quad: COAL CREEK Longitude: 123° 2.4' W (-123.03917)
T I D A L B E N C H M A R K S
BENCH MARK STAMPING: 0483 A 2016
DESIGNATION: 944 0483 A
MONUMENTATION: Bench Mark disk VM#: 22067
AGENCY: National Ocean Service IDB PID#:
SETTING CLASSIFICATION: Concrete retaining wall OPUS PID:
LATITUDE: 46° 9.2' N ( 46.15297) LONGITUDE: 123° 2.2' W (-123.03669)
The bench mark is a disk set in a retaining wall near the pier leading to the
dock on the S side of the residence, 21.73 m (71.3 ft) SE of the SW building
corner of the residence, 15.60 m (51.2 ft) WNW of a consolidated diking
improvement district station sign reading 150+00, 12.16 m (39.9 ft) W of the W
fence post to a gate leading to the S, 10.29 m (33.8 ft) E of the face of the E
most piling for the pier, 1.08 m (3.5 ft) ENE of the SW most corner of the
retaining wall and set 0.4 ft (12 cm) above the driveway level.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 4 of 7
Station ID: 9440483 PUBLICATION DATE: 01/25/2017
Name: BARLOW POINT, COLUMBIA RIVER
WA
NOAA Chart: 18524 Latitude: 46° 9.1' N ( 46.15222)
USGS Quad: COAL CREEK Longitude: 123° 2.4' W (-123.03917)
T I D A L B E N C H M A R K S
BENCH MARK STAMPING: LS 21711 CDID 150+49.4
DESIGNATION: CDID 150+49.4
MONUMENTATION: Survey disk VM#: 22068
AGENCY: IDB PID#:
SETTING CLASSIFICATION: OPUS PID:
LATITUDE: 46° 9.1' N ( 46.15233) LONGITUDE: 123° 2.2' W (-123.03633)
The bench mark is an aluminum disk set on the W side of the dike, 72.72 m (238.6
ft) SSE of the W post of the gate leading from the dike road to the residence
driveway, 61.97 m (203.3 ft) S of CDID station sign 150+00.0, 4.98 m (16.3 ft)
WSW of the centerline of the dike road, 0.55 m (1.8 ft) ENE of CDID survey
marker sign number 25 and about 0.10 m (0.3 ft) below the grade on the uphill
side of the station.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 5 of 7
Station ID: 9440483 PUBLICATION DATE: 01/25/2017
Name: BARLOW POINT, COLUMBIA RIVER
WA
NOAA Chart: 18524 Latitude: 46° 9.1' N ( 46.15222)
USGS Quad: COAL CREEK Longitude: 123° 2.4' W (-123.03917)
T I D A L B E N C H M A R K S
BENCH MARK STAMPING: LS 21711 CDID 147+49.4
DESIGNATION: CDID 147+49.4
MONUMENTATION: Survey disk VM#: 22069
AGENCY: IDB PID#:
SETTING CLASSIFICATION: OPUS PID:
LATITUDE: 46° 9.1' N ( 46.15172) LONGITUDE: 123° 2.1' W (-123.03569)
The bench mark is an aluminum disk set on the W side of the dike, 152.00 m
(498.7 ft) NW of a CDID station sign marked 160+00.0, 37.95 m (124.5 ft) WSW of
the inside corner of two gravel roads, 4.69 m (15.4 ft) WSW of the centerline of
dike road, 1.70 m (5.6 ft) ENE of CDID survey marker sign number 26.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 6 of 7
Station ID: 9440483 PUBLICATION DATE: 01/25/2017
Name: BARLOW POINT, COLUMBIA RIVER
WA
NOAA Chart: 18524 Latitude: 46° 9.1' N ( 46.15222)
USGS Quad: COAL CREEK Longitude: 123° 2.4' W (-123.03917)
T I D A L D A T U M S
Tidal datums at BARLOW POINT, COLUMBIA RIVER based on:
LENGTH OF SERIES: 3 MONTHS
TIME PERIOD: August 2016 - October 2016
TIDAL EPOCH: 1983-2001
CONTROL TIDE STATION: 9439040 ASTORIA, TONGUE POINT, COLUMBIA RIVER
Elevations of tidal datums referred to Mean Lower Low Water (MLLW), in METERS:
MEAN HIGHER HIGH WATER MHHW = 1.540
MEAN HIGH WATER MHW = 1.384
MEAN TIDE LEVEL MTL = 0.755
MEAN SEA LEVEL MSL = 0.693
MEAN LOW WATER MLW = 0.126
MEAN LOWER LOW WATER MLLW = 0.000
North American Vertical Datum (NAVD88)
Bench Mark Elevation Information In METERS above:
Stamping or Designation MLLW MHW
0483 C 2016 2.225 0.841
0483 B 2016 0.757 -0.627
0483 A 2016 6.291 4.907
LS 21711 CDID 150+49.4 7.182 5.798
LS 21711 CDID 147+49.4 7.563 6.179
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 7 of 7
Station ID: 9440483 PUBLICATION DATE: 01/25/2017
Name: BARLOW POINT, COLUMBIA RIVER
WA
NOAA Chart: 18524 Latitude: 46° 9.1' N ( 46.15222)
USGS Quad: COAL CREEK Longitude: 123° 2.4' W (-123.03917)
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.