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Datums Page Page 1 of 9
Station ID: 9439221 PUBLICATION DATE: 02/13/2012
Name: PORTLAND, MORRISON STREET BRIDGE
OR
NOAA Chart: 18526 Latitude: 45° 30.6' N ( 45.51000)
USGS Quad: PORTLAND Longitude: 122° 40.4' W (-122.67300)
To reach the tidal bench marks from U.S. Interstate 5 in Portland, take exit
302A (Rose Quarter), and follow city center signs over the Broadway Bridge.
Stay in left lane, which will put you south bound on NW Broadway Avenue. When
you cross West Burnside Street, NW Broadway will become SW Broadway Avenue.
Continue south to SW Market Street and turn left. When you cross Naito Parkway,
Market will curve right and turn into Harbor Drive. Turn left on Montgomery
from Harbor Drive and follow it until it ends at a cul-de-sac with River Drive.
The bench marks are located to the north along the sea wall on the west side of
the Willamette River. The tide gauge and staff are located inside the gated
River Place Marina, across from the Harbor Master Office.
T I D A L B E N C H M A R K S
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 2 of 9
Station ID: 9439221 PUBLICATION DATE: 02/13/2012
Name: PORTLAND, MORRISON STREET BRIDGE
OR
NOAA Chart: 18526 Latitude: 45° 30.6' N ( 45.51000)
USGS Quad: PORTLAND Longitude: 122° 40.4' W (-122.67300)
T I D A L B E N C H M A R K S
PRIMARY BENCH MARK STAMPING: MAR 1938 NO 1
DESIGNATION: MAR RM 1
MONUMENTATION: Reference Mark disk VM#: 16634
AGENCY: US Coast and Geodetic Survey
(USC&GS) IDB PID#: RD0449
SETTING CLASSIFICATION: Sea wall OPUS PID:
LATITUDE: 45° 30.8' N ( 45.51330) LONGITUDE: 122° 40.4' W (-122.67300)
The primary bench mark is a disk set in the top of a sea wall west of a metal
railing on the west side of Willamette River, 14.70 m (48.2 ft) north of the
north side of Hawthorne Bridge, 10.48 m (34.4 ft) NE of a concrete partition
between two public rest room doors beneath the stairs down from Hawthorne
Bridge, 2.10 m (6.9 ft) north of bench mark MAR 1938 NO 2, 0.68 m (2.2 ft) west
of the edge of the sea wall, and 0.14 m (0.5 ft) south of concrete railing
support post 377.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 3 of 9
Station ID: 9439221 PUBLICATION DATE: 02/13/2012
Name: PORTLAND, MORRISON STREET BRIDGE
OR
NOAA Chart: 18526 Latitude: 45° 30.6' N ( 45.51000)
USGS Quad: PORTLAND Longitude: 122° 40.4' W (-122.67300)
T I D A L B E N C H M A R K S
BENCH MARK STAMPING: MAR 1938 NO 2
DESIGNATION: MAR RM 2
MONUMENTATION: Reference Mark disk VM#: 16635
AGENCY: US Coast and Geodetic Survey
(USC&GS) IDB PID#: RD0448
SETTING CLASSIFICATION: Sea wall OPUS PID:
LATITUDE: 45° 30.8' N ( 45.51330) LONGITUDE: 122° 40.4' W (-122.67300)
The bench mark is a disk set in the top of a sea wall east of a metal railing on
the west side of the Willamette River, 12.60 m (41.3 ft) north of the north side
of Hawthorne Bridge, 10.60 m (34.8 ft) NE of a concrete partition between two
public rest room doors beneath the stairs down from Hawthorne Bridge, 2.26 m
(7.4 ft) south of concrete railing support post 377, 2.10 m (6.9 ft) south of
bench mark MAR 1938 NO 1, and 0.1 m (0.3 ft) west of the edge of the sea wall.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 4 of 9
Station ID: 9439221 PUBLICATION DATE: 02/13/2012
Name: PORTLAND, MORRISON STREET BRIDGE
OR
NOAA Chart: 18526 Latitude: 45° 30.6' N ( 45.51000)
USGS Quad: PORTLAND Longitude: 122° 40.4' W (-122.67300)
T I D A L B E N C H M A R K S
BENCH MARK STAMPING: KET 1938 NO 1
DESIGNATION: KET RM 1
MONUMENTATION: Reference Mark disk VM#: 16636
AGENCY: US Coast and Geodetic Survey
(USC&GS) IDB PID#: RD0454
SETTING CLASSIFICATION: Sea wall OPUS PID:
LATITUDE: 45° 31.0' N ( 45.51670) LONGITUDE: 122° 40.3' W (-122.67200)
The bench mark is a disk set in the top of a sea wall east of a metal railing on
the west side of Willamette River, located 49.04 m (160.9 ft) south of the SE
corner of a concrete plaque describing the historic Morrison Bridge, 1.98 m (6.5
ft) south of concrete railing support post 295, 1.94 m (6.4 ft) south of bench
mark KET 1938 NO 2, and 0.10 m (0.3 ft) west of the edge of the sea wall.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 5 of 9
Station ID: 9439221 PUBLICATION DATE: 02/13/2012
Name: PORTLAND, MORRISON STREET BRIDGE
OR
NOAA Chart: 18526 Latitude: 45° 30.6' N ( 45.51000)
USGS Quad: PORTLAND Longitude: 122° 40.4' W (-122.67300)
T I D A L B E N C H M A R K S
BENCH MARK STAMPING: KET 1938 NO 2
DESIGNATION: KET RM 2
MONUMENTATION: Reference Mark disk VM#: 16637
AGENCY: US Coast and Geodetic Survey
(USC&GS) IDB PID#: RD0455
SETTING CLASSIFICATION: Sea wall OPUS PID:
LATITUDE: 45° 31.0' N ( 45.51670) LONGITUDE: 122° 40.3' W (-122.67200)
The bench mark is a disk set in the top of a sea wall west of a metal railing on
the west side of the Willamette River, 43.0 m (141.1 ft) south of the south side
of the Morrison Street Bridge, 1.94 m (6.4 ft) north of bench mark KET 1938 NO
1, 0.72 m (2.4 ft) west of the edge of the sea wall, and 0.08 m (0.3 ft) south
of the concrete railing support post 295.
BENCH MARK STAMPING:
DESIGNATION: 943 9221 UNSTAMPED
MONUMENTATION: Bench Mark disk VM#: 16638
AGENCY: US Coast and Geodetic Survey
(USC&GS) IDB PID#:
SETTING CLASSIFICATION: Sea wall OPUS PID:
LATITUDE: 45° 31.1' N ( 45.51766) LONGITUDE: 122° 40.3' W (-122.67149)
The bench mark is a disk set in top of a sea wall on the west side of a metal
railing on the west side of the Willamette River, 52.90 m (173.6 ft) south of
the south side of the Morrison Street Bridge, 0.71 m (2.3 ft) south of concrete
railing support post 268, and 0.70 m (2.3 ft) west of the outside edge of a sea
wall.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 6 of 9
Station ID: 9439221 PUBLICATION DATE: 02/13/2012
Name: PORTLAND, MORRISON STREET BRIDGE
OR
NOAA Chart: 18526 Latitude: 45° 30.6' N ( 45.51000)
USGS Quad: PORTLAND Longitude: 122° 40.4' W (-122.67300)
T I D A L B E N C H M A R K S
BENCH MARK STAMPING: 9221 A 2008
DESIGNATION: 943 9221 A
MONUMENTATION: Tidal Station disk VM#: 19119
AGENCY: National Ocean Service (NOS) IDB PID#:
SETTING CLASSIFICATION: Concrete seawall OPUS PID:
LATITUDE: 45° 30.8' N ( 45.51317) LONGITUDE: 122° 40.4' W (-122.67331)
The bench mark is a disk set flush in concrete at the top of the south end of a
sea wall in the corner where the north to south sea wall turns west on the west
side of Willamette River, 73.98 m (242.7 ft) south of the centerline of the
Hawthorne Bridge, 1.75 m (5.7 ft) east of the center of a dark green Bollard,
1.04 m (3.4 ft) WNW of the outside edge of the sea wall, and 0.14 m (0.46 ft)
west of the west corner of concrete railing support post 404.
BENCH MARK STAMPING: 9221 B 2008
DESIGNATION: 943 9221 B
MONUMENTATION: Tidal Station disk VM#: 19120
AGENCY: National Ocean Service (NOS) IDB PID#:
SETTING CLASSIFICATION: Concrete flagpole base OPUS PID:
LATITUDE: 45° 30.7' N ( 45.51158) LONGITUDE: 122° 40.4' W (-122.67386)
The bench mark is a disk set flush in the concrete base of the western most
flagpole in a group of flagpoles in an elevated flowerbed on the NE end of the
River Place Hotel, 0.52 m (1.7 ft) east of the outside edge of the retaining
wall surrounding the flowerbed, 0.48 m (1.6 ft) SSW of the center of the western
most flagpole, and 0.42 m (1.4 ft) above the sidewalk.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 7 of 9
Station ID: 9439221 PUBLICATION DATE: 02/13/2012
Name: PORTLAND, MORRISON STREET BRIDGE
OR
NOAA Chart: 18526 Latitude: 45° 30.6' N ( 45.51000)
USGS Quad: PORTLAND Longitude: 122° 40.4' W (-122.67300)
T I D A L B E N C H M A R K S
BENCH MARK STAMPING: 9221 C 2008
DESIGNATION: 943 9221 C
MONUMENTATION: Tidal Station disk VM#: 19121
AGENCY: National Ocean Service (NOS) IDB PID#:
SETTING CLASSIFICATION: Concrete pad OPUS PID:
LATITUDE: 45° 30.6' N ( 45.50936) LONGITUDE: 122° 40.4' W (-122.67283)
The bench mark is a disk set flush in the concrete pad supporting the ramp to
the floating dock called Riverplace Moorage, 4.26 m (13.9 ft) NNE of the 2.16 m
(7.08 ft) tall wooden retaining wall of the inclined sidewalk to street level,
0.83 m (2.7 ft) WSW of the center of the top of the ramp, and 0.11 m (0.36 ft)
east of the west edge of the concrete pad.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 8 of 9
Station ID: 9439221 PUBLICATION DATE: 02/13/2012
Name: PORTLAND, MORRISON STREET BRIDGE
OR
NOAA Chart: 18526 Latitude: 45° 30.6' N ( 45.51000)
USGS Quad: PORTLAND Longitude: 122° 40.4' W (-122.67300)
T I D A L D A T U M S
Tidal datums at PORTLAND, MORRISON STREET BRIDGE based on:
LENGTH OF SERIES: 5 MONTHS
TIME PERIOD: Sept 2002 - Oct 2002 and Aug 2005 - Oct 2005
TIDAL EPOCH: 1983-2001
CONTROL TIDE STATION: 9439040 ASTORIA, TONGUE POINT, COLUMBIA RIVER
Elevations of tidal datums referred to Columbia River Datum (-2), in METERS:
MEAN HIGHER HIGH WATER MHHW = 1.605
MEAN HIGH WATER MHW = 1.450
MEAN TIDE LEVEL MTL = 1.015
MEAN SEA LEVEL MSL = 0.966
MEAN LOW WATER MLW = 0.580
MEAN LOWER LOW WATER MLLW = 0.503
a River Datum (-2) Columb = 0.000
North American Vertical Datum NAVD88 = -1.640
North American Vertical Datum (NAVD88)
Bench Mark Elevation Information In METERS above:
Stamping or Designation -2 MHW
MAR 1938 NO 1 8.798 7.348
MAR 1938 NO 2 8.784 7.334
KET 1938 NO 1 8.738 7.288
KET 1938 NO 2 8.746 7.296
943 9221 UNSTAMPED 8.801 7.351
9221 A 2008 8.787 7.337
9221 B 2008 10.382 8.932
9221 C 2008 6.308 4.858
Foot Notes:
Data were collected on Columbia River Datum (CRD). Datums were computed using
data from three months of lowest river levels, generally the months
August-October over multiple years. Depending on river flow, water levels can
be significantly higher than Columbia River Datum.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 9 of 9
Station ID: 9439221 PUBLICATION DATE: 02/13/2012
Name: PORTLAND, MORRISON STREET BRIDGE
OR
NOAA Chart: 18526 Latitude: 45° 30.6' N ( 45.51000)
USGS Quad: PORTLAND Longitude: 122° 40.4' W (-122.67300)
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.