Bench Mark Sheet for 9440572, JETTY A, COLUMBIA RIVER WA

Superseded Epoch

Large map location marker Station Location
Small red map location marker Published bench mark
Small blue map location marker Unpublished bench mark

Bench mark positions only appear on the map if their coordinates in the CO-OPS database are at the precision of degrees/minutes/seconds/and tenths of seconds. If the coordinates are less precise, the mark will not appear.

Printable version

                          U.S. DEPARTMENT OF COMMERCE
                National Oceanic and Atmospheric Administration
                            National Ocean Service
Datums Page                                                        Page  1 of  5

                                                                                
Station ID: 9440572                         PUBLICATION DATE:  12/12/2003
Name:       JETTY A, COLUMBIA RIVER                           
            WA
NOAA Chart: 18521                           Latitude:   46° 16.1' N (  46.26830)
USGS Quad:  CAPE DISAPPOINTMENT             Longitude: 124°  2.2' W (-124.03700)


To reach the tidal bench marks from Astoria, Oregon, proceed towards Washington
on U.S. Highway 101, cross the Astoria-Megler bridge, turn left (west) at the
north end of the bridge and follow U.S. Highway 101 for 16 km (10 mi) to the
town of Illwaco.  At the main intersection in the town of Illwaco, turn left,
follow the signs posted to the Cape Disappointment Coast Guard Station.  Stay on
the main road through the coast guard station to an unpaved road, pass a firing
range on the right and a helicopter pad on the left to the end of the unpaved
road and the beginning of the jetty.  Most of the bench marks are located on the
jetty and one is located at the very beginning of the jetty.  The tide gauge was
located on a U.S. Army Corps of Engineers dredging marker 30 m (100 ft)
offshore.


                         T I D A L   B E N C H   M A R K S


                 PRIMARY BENCH MARK STAMPING:  MID 1970
                         DESIGNATION:          944 0572 MID

MONUMENTATION:           Tidal Station disk                    VM#:         8922
AGENCY:                  National Ocean Survey (NOS)           IDB PID#:        
SETTING CLASSIFICATION:  Boulder                               OPUS PID:        
LATITUDE:   46° 16.1' N (  46.26830)          LONGITUDE: 124°  2.2' W (-124.03700)


The primary bench mark is a disk set flush in a large flat boulder marked by an
aerial survey cross in the middle of Jetty A, 457 m (1500 ft) SE of bench mark
0572 A 1981, 457 m (1500 ft) NW of bench mark BEND 1970 U.S.E., 114 m (374 ft)
SE of a turning point stamped 5 which is a lag bolt cemented in boulder and
marked by aerial survey cross.

                          U.S. DEPARTMENT OF COMMERCE
                National Oceanic and Atmospheric Administration
                            National Ocean Service
                                                                   Page  2 of  5

                                                                                
Station ID: 9440572                         PUBLICATION DATE:  12/12/2003
Name:       JETTY A, COLUMBIA RIVER                           
            WA
NOAA Chart: 18521                           Latitude:   46° 16.1' N (  46.26830)
USGS Quad:  CAPE DISAPPOINTMENT             Longitude: 124°  2.2' W (-124.03700)


                         T I D A L   B E N C H   M A R K S


                         BENCH MARK STAMPING:  BETTY M 1976
                         DESIGNATION:          BETTY M

MONUMENTATION:           Survey disk                           VM#:         8923
AGENCY:                  Pacific County                        IDB PID#:  SD0640
SETTING CLASSIFICATION:  Concrete monument                     OPUS PID:        
LATITUDE:   46° 16.6' N (  46.27670)          LONGITUDE: 124°  2.5' W (-124.04200)


The bench mark is a disk set flush in a concrete monument at the intersection of
two roads just north of the jetty, and 1 m (3 ft) east of a witness post.



                         BENCH MARK STAMPING:  0572 A 1981
                         DESIGNATION:          944 0572 A

MONUMENTATION:           Tidal Station disk                    VM#:         8926
AGENCY:                  National Ocean Survey (NOS)           IDB PID#:        
SETTING CLASSIFICATION:  Boulder                               OPUS PID:        
LATITUDE:   46° 16.1' N (  46.26830)          LONGITUDE: 124°  2.2' W (-124.03700)


The bench mark is a disk set flush in a large flat boulder, 457 m (1500 ft) NW
of bench mark MID 1970, 110 m (360 ft) NW of a turning point stamped 6 which is
a stainless steel lag bolt cemented in boulder, and marked by aerial survey
cross.

                          U.S. DEPARTMENT OF COMMERCE
                National Oceanic and Atmospheric Administration
                            National Ocean Service
                                                                   Page  3 of  5

                                                                                
Station ID: 9440572                         PUBLICATION DATE:  12/12/2003
Name:       JETTY A, COLUMBIA RIVER                           
            WA
NOAA Chart: 18521                           Latitude:   46° 16.1' N (  46.26830)
USGS Quad:  CAPE DISAPPOINTMENT             Longitude: 124°  2.2' W (-124.03700)


                         T I D A L   B E N C H   M A R K S


                         BENCH MARK STAMPING:  0572 B 1997
                         DESIGNATION:          944 0572 B

MONUMENTATION:           Tidal Station disk                    VM#:        13722
AGENCY:                  National Ocean Service (NOS)          IDB PID#:        
SETTING CLASSIFICATION:  Boulder                               OPUS PID:        
LATITUDE:   46° 16.1' N (  46.26830)          LONGITUDE: 124°  2.2' W (-124.03700)


The bench mark is a disk set flush in a large boulder on the west side of Jetty
A, 140 m (459 ft) north of bench mark 0572 A 1981, and 120 m (393 ft) south of
bench mark Betty M 1976.



                         BENCH MARK STAMPING:  BEND 1970 U.S.E
                         DESIGNATION:          944 0572 BEND USE

MONUMENTATION:           Survey disk                           VM#:        13723
AGENCY:                  US Army Corps of Engineers (USE)      IDB PID#:        
SETTING CLASSIFICATION:  Large rock                            OPUS PID:        
LATITUDE:   46° 16.1' N (  46.26830)          LONGITUDE: 124°  2.2' W (-124.03700)


The bench mark is a disk set in a large rock at point where Jetty turns to west
a little, and is  0.76 m (2.5 ft) higher than normal rocks.  Note: The bench
mark is painted with a white cross.

                          U.S. DEPARTMENT OF COMMERCE
                National Oceanic and Atmospheric Administration
                            National Ocean Service
                                                                   Page  4 of  5

                                                                                
Station ID: 9440572                         PUBLICATION DATE:  12/12/2003
Name:       JETTY A, COLUMBIA RIVER                           
            WA
NOAA Chart: 18521                           Latitude:   46° 16.1' N (  46.26830)
USGS Quad:  CAPE DISAPPOINTMENT             Longitude: 124°  2.2' W (-124.03700)


                            T I D A L   D A T U M S 


Tidal datums at JETTY A, COLUMBIA RIVER based on:

     LENGTH OF SERIES:      1 MONTH
     TIME PERIOD:           March 1997 - March 1997
     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   =  2.585
     MEAN HIGH WATER                            MHW    =  2.357
     MEAN TIDE LEVEL                            MTL    =  1.396
     MEAN SEA LEVEL                             MSL    =  1.396
     MEAN LOW WATER                             MLW    =  0.435
     MEAN LOWER LOW WATER                       MLLW   =  0.000

North American Vertical Datum (NAVD88)

Bench Mark Elevation Information                In METERS above:

     Stamping or Designation                    MLLW        MHW

     MID 1970                                    8.026    5.669
     BETTY M 1976                                6.830    4.473
     0572 A 1981                                 7.545    5.188
     0572 B 1997                                 6.954    4.597
     BEND 1970 U.S.E                             8.486    6.129


                          U.S. DEPARTMENT OF COMMERCE
                National Oceanic and Atmospheric Administration
                            National Ocean Service
                                                                   Page  5 of  5

                                                                                
Station ID: 9440572                         PUBLICATION DATE:  12/12/2003
Name:       JETTY A, COLUMBIA RIVER                           
            WA
NOAA Chart: 18521                           Latitude:   46° 16.1' N (  46.26830)
USGS Quad:  CAPE DISAPPOINTMENT             Longitude: 124°  2.2' W (-124.03700)


                             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.

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