U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Datums Page Page 1 of 6
Station ID: 9439026 PUBLICATION DATE: 07/15/2004
Name: ASTORIA, YOUNGS BAY
OR
NOAA Chart: 18521 Latitude: 46° 10.3' N ( 46.17170)
USGS Quad: ASTORIA Longitude: 123° 50.5' W (-123.84200)
To reach the tidal bench marks from Astoria, proceed west on U.S. Highway 30
(Marine Drive) to the Astoria Megler bridge overpass, then west 0.8 km (0.5 mi)
to the junction of U.S. Highway 101 and U.S. Highway 101 Alt., at the "Y" take
the left fork onto U.S. Highway 101 Alt. (Highway 202) and proceed south along
the north shore of Youngs Bay for 1.9 km (1.2 mi), at the Y take left fork
(straight), go one block, turn right onto 5th Street, proceed one block to "Left
Turn Only", turn left onto the winding road leading to U.S. Highway 101 Alt.,
before reaching an underpass bear left to Clatsop Community College Maritime
buildings. The bench marks are located at the Pacific Power and Light Astoria
District Science Center. The tide gage and staff were located on the east side
of the pier, opposite a storage shed 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: 9026 C 1981
DESIGNATION: 943 9026 C TIDAL
MONUMENTATION: Tidal Station disk VM#: 8882
AGENCY: National Ocean Survey (NOS) IDB PID#: SC1024
SETTING CLASSIFICATION: Concrete footing OPUS PID:
LATITUDE: 46° 10.4' N ( 46.17330) LONGITUDE: 123° 50.7' W (-123.84500)
The primary bench mark is a disk set horizontally in an abandoned 0.8 m (2.5 ft)
square concrete footing located near the NW corner of the property in the
transformer compound (sub-station), 66.81 m (219.2 ft) north of the centerline
of the road, 30.69 m (100.7 ft) north of bench mark 9026 B 1981, 23.01 m (75.5
ft) west of the north gate post of the east entrance to the sub-station, 7.89 m
(25.9 ft) north of the large transformer foundation, and 0.3 m (1 ft) above the
road.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 2 of 6
Station ID: 9439026 PUBLICATION DATE: 07/15/2004
Name: ASTORIA, YOUNGS BAY
OR
NOAA Chart: 18521 Latitude: 46° 10.3' N ( 46.17170)
USGS Quad: ASTORIA Longitude: 123° 50.5' W (-123.84200)
T I D A L B E N C H M A R K S
BENCH MARK STAMPING: P 1 1924
DESIGNATION: P 1
MONUMENTATION: Survey disk VM#: 8878
AGENCY: Pacific Power and Light Company
(PP&L) IDB PID#: SC0509
SETTING CLASSIFICATION: Retaining wall OPUS PID:
LATITUDE: 46° 10.3' N ( 46.17170) LONGITUDE: 123° 50.6' W (-123.84300)
The bench mark is a disk set vertically in the east face of the retaining wall
of the old condenser intake of the abandoned Pacific Power and Light Company
building, 60.99 m (200.1 ft) south of the centerline of the road, 11.00 m (36.1
ft) SW of the SE corner of the building, 5.09 m (16.7 ft) south of the south
face of the building, 5.00 m (16.4 ft) north of a fence, 0.30 m (1.0 ft) north
of the SE corner of the retaining wall, and 0.5 m (1.6 ft) above the ground.
NOTE: Suspected destroyed. (US Power Squadron, 2001)
BENCH MARK STAMPING: 9026 A 1981
DESIGNATION: 943 9026 A TIDAL
MONUMENTATION: Tidal Station disk VM#: 8880
AGENCY: National Ocean Survey (NOS) IDB PID#:
SETTING CLASSIFICATION: Concrete footing OPUS PID:
LATITUDE: 46° 10.2' N ( 46.17000) LONGITUDE: 123° 50.1' W (-123.83500)
The bench mark is a disk set horizontally in the concrete footing located near
the SE corner of the Pacific Power and Light Science Center property, on the
east side of the main plant building, close to a doorway which has been sealed
with cement, 30 m (100 ft) SW of the SW corner of the vehicle maintenance
garage, 6.52 m (21.4 ft) north of the SE corner of the main plant building, and
0.12 m (0.4 ft) east of the main plant building.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 3 of 6
Station ID: 9439026 PUBLICATION DATE: 07/15/2004
Name: ASTORIA, YOUNGS BAY
OR
NOAA Chart: 18521 Latitude: 46° 10.3' N ( 46.17170)
USGS Quad: ASTORIA Longitude: 123° 50.5' W (-123.84200)
T I D A L B E N C H M A R K S
BENCH MARK STAMPING: 9026 B 1981
DESIGNATION: 943 9026 B TIDAL
MONUMENTATION: Tidal Station disk VM#: 8881
AGENCY: National Ocean Survey (NOS) IDB PID#: SC1025
SETTING CLASSIFICATION: Manhole foundation OPUS PID:
LATITUDE: 46° 10.4' N ( 46.17330) LONGITUDE: 123° 50.6' W (-123.84300)
The bench mark is a disk set flush in the top of a manhole foundation located
inside of the electric sub-station, 65.38 m (214.5 ft) SW of the center of the
south wall of an old tank farm foundation, 62 m (205 ft) north of the NE corner
of the old generator building, 36.09 m (118.4 ft) north of the centerline of the
road, 30.72 m (100.8 ft) SE of bench mark 9026 C 1981, 30.51 m (100.1 ft) north
of the east gate post of the south entrance to the sub-station, 17.59 m (57.7
ft) SW of the north post of the east entrance gate to the sub-station, 12.86 m
(42.2 ft) west of a utility pole located outside the sub-station, 1.89 m (6.2
ft) west of the SE corner of the foundation, and 0.49 m (1.6 ft) east of the
east edge of the steel manhole cover.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 4 of 6
Station ID: 9439026 PUBLICATION DATE: 07/15/2004
Name: ASTORIA, YOUNGS BAY
OR
NOAA Chart: 18521 Latitude: 46° 10.3' N ( 46.17170)
USGS Quad: ASTORIA Longitude: 123° 50.5' W (-123.84200)
T I D A L B E N C H M A R K S
BENCH MARK STAMPING: 9026 D 1981
DESIGNATION: 943 9026 D TIDAL
MONUMENTATION: Tidal Station disk VM#: 8883
AGENCY: National Ocean Survey (NOS) IDB PID#: SC1026
SETTING CLASSIFICATION: Boat ramp OPUS PID:
LATITUDE: 46° 10.2' N ( 46.17000) LONGITUDE: 123° 50.2' W (-123.83700)
The bench mark is a disk set in the NW corner of the boat ramp located at the
Clatsop Community College Maritime Science Center, 78.30 m (256.9 ft) SE of the
flag pole, 53.89 m (176.8 ft) south of the SE corner of the building, 10.91 m
(35.8 m) south of the centerline of the road, 1.40 m (4.6 ft) south of the NW
corner of the boat ramp, 0.21 m (0.7 ft) west of the west edge of the boat ramp,
and 0.3 m (1 ft) below the road.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 5 of 6
Station ID: 9439026 PUBLICATION DATE: 07/15/2004
Name: ASTORIA, YOUNGS BAY
OR
NOAA Chart: 18521 Latitude: 46° 10.3' N ( 46.17170)
USGS Quad: ASTORIA Longitude: 123° 50.5' W (-123.84200)
T I D A L D A T U M S
Tidal datums at ASTORIA, YOUNGS BAY based on:
LENGTH OF SERIES: 1 MONTH
TIME PERIOD: July 1981 - July 1981
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 = 2.681
MEAN HIGH WATER MHW = 2.468
MEAN SEA LEVEL MSL = 1.425
MEAN TIDE LEVEL MTL = 1.424
MEAN LOW WATER MLW = 0.380
North American Vertical Datum NAVD88 = 0.051
MEAN LOWER LOW WATER MLLW = 0.000
North American Vertical Datum (NAVD88)
Bench Mark Elevation Information In METERS above:
Stamping or Designation MLLW MHW
9026 C 1981 4.886 2.418
P 1 1924 5.070 2.602
9026 A 1981 5.385 2.917
9026 B 1981 4.457 1.989
9026 D 1981 3.826 1.358
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 6 of 6
Station ID: 9439026 PUBLICATION DATE: 07/15/2004
Name: ASTORIA, YOUNGS BAY
OR
NOAA Chart: 18521 Latitude: 46° 10.3' N ( 46.17170)
USGS Quad: ASTORIA Longitude: 123° 50.5' W (-123.84200)
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.