U.S. DEPARTMENT OF COMMERCE
                National Oceanic and Atmospheric Administration
                            National Ocean Service
Datums Page                                                        Page  1 of  7

                                                                                
Station ID: 9439040                                PUBLICATION DATE:  04/21/2003
Name:       ASTORIA, TONGUE POINT, COLUMBIA RIVER             
            OREGON
NOAA Chart: 18521                                  Latitude:         46° 12.5' N
USGS Quad:  ASTORIA                                Longitude:       123° 46.0' W


To reach the tidal bench marks from Astoria, go east on  Highway 30 for about 5
km (3 mi), turn north onto Tongue Point Road and proceed 1.4 km (0.9 mi) to the
U.S. Coast Guard Base.  The tidal bench marks are located on the U. S. Coast
Guard base.  The Tide House is located near the SW corner of the U.S. Coast
Guard Pier.


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


                 PRIMARY BENCH MARK STAMPING:  TIDAL 11 1959
                         DESIGNATION:          943 9040 TIDAL 11

MONUMENTATION:           Tidal Station disk                        VM#:     1071
AGENCY:                  US Coast and Geodetic Survey (USC&GS)     PID#:  SC1053
SETTING CLASSIFICATION:  Concrete pavement


The primary bench mark is a disk set in the concrete pavement, 33 m (108 ft)
east of bench mark Tidal NO 12 1962, 23.62 m (77.5 ft) SE of the SE corner of
headquarters and machine shops building, 14 m (46 ft) south of bench mark Tidal
13 1964, 0.67 m (2.2 ft) SE of a fire hydrant, and 0.09 m (0.3 ft) west of a 1 m
(3 ft) high concrete retaining wall.



                         BENCH MARK STAMPING:  7 1939
                         DESIGNATION:          943 9040 TIDAL 7

MONUMENTATION:           Tidal Station disk                        VM#:     1068
AGENCY:                  US Coast and Geodetic Survey (USC&GS)     PID#:  SC0478
SETTING CLASSIFICATION:  Concrete retaining wall


The bench mark is a disk set in the top at the SW corner of concrete retaining
wall around the hill located north of Building No. 3 (crew's quarters and mess),
9 m (29 ft) NW of the NW corner of Building No 3, 5 m (15 ft) east of the west
edge of the roadway, and about 1 m (3 ft) above road level.  Note: Mark is
painted white.

                          U.S. DEPARTMENT OF COMMERCE
                National Oceanic and Atmospheric Administration
                            National Ocean Service
                                                                   Page  2 of  7

                                                                                
Station ID: 9439040                                PUBLICATION DATE:  04/21/2003
Name:       ASTORIA, TONGUE POINT, COLUMBIA RIVER             
            OREGON
NOAA Chart: 18521                                  Latitude:         46° 12.5' N
USGS Quad:  ASTORIA                                Longitude:       123° 46.0' W


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


                         BENCH MARK STAMPING:  8 1940
                         DESIGNATION:          943 9040 TIDAL 8

MONUMENTATION:           Tidal Station disk                        VM#:     1069
AGENCY:                  US Coast and Geodetic Survey (USC&GS)     PID#:  SC0479
SETTING CLASSIFICATION:  Concrete walkway


The bench mark is a disk set in SW corner of concrete walkway at south entrance
to combination headquarters and main shops building, 29.72 m ( 97.5 ft) NNE of
bench mark TIDAL NO 12 1962, 1.37 m (4.5 ft) south from the foundation wall of
building, and 0.15 m (0.5 ft) east of the west edge of the  walkway, and 0.06 m
(0.2 ft) above concrete deck pavement.  Note: Mark is painted green.    



                         BENCH MARK STAMPING:  NO 10 1958
                         DESIGNATION:          943 9040 TIDAL 10

MONUMENTATION:           Tidal Station disk                        VM#:     1070
AGENCY:                  US Coast and Geodetic Survey (USC&GS)     PID#:  SC0480
SETTING CLASSIFICATION:  Concrete slab


The bench mark is a disk set in concrete slab of USCG Building NO 6 (Engine
Repair Shop) which is the northern-most building of the Tongue Point Coast Guard
Station, 2.13 m (7.0 ft) west of east side of a roll up door, 0.15 m (0.5 ft) in
front of roll-up door and 1 m (2 ft) from the west side of the entrance.

                          U.S. DEPARTMENT OF COMMERCE
                National Oceanic and Atmospheric Administration
                            National Ocean Service
                                                                   Page  3 of  7

                                                                                
Station ID: 9439040                                PUBLICATION DATE:  04/21/2003
Name:       ASTORIA, TONGUE POINT, COLUMBIA RIVER             
            OREGON
NOAA Chart: 18521                                  Latitude:         46° 12.5' N
USGS Quad:  ASTORIA                                Longitude:       123° 46.0' W


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


                         BENCH MARK STAMPING:  TIDAL NO 12 1962
                         DESIGNATION:          943 9040 TIDAL 12

MONUMENTATION:           Tidal Station disk                        VM#:     1072
AGENCY:                  US Coast and Geodetic Survey (USC&GS)     PID#:  SC1055
SETTING CLASSIFICATION:  Concrete wall


The bench mark is a disk set in top of the concrete guard wall at south side of
the main dock, 33 m (108 ft) west of bench mark Tidal NO 12 1962, 29.72 m ( 97.5
ft) SSW of bench mark 8 1940, 4.72 m (15.5 ft) west of the east end of the wall,
0.5 m (1.5 ft) east of the flagpole, and 0.3 m (1 ft) above dock level.



                         BENCH MARK STAMPING:  TIDAL 13 1964
                         DESIGNATION:          943 9040 TIDAL 13

MONUMENTATION:           Tidal Station disk                        VM#:     1073
AGENCY:                  US Coast and Geodetic Survey (USC&GS)     PID#:  SC1054
SETTING CLASSIFICATION:  Concrete step


The bench mark is a disk set in top of first concrete step leading up to
Building No 3 (crew's quarters and mess), 38 m (126 ft) NE of the flag pole,
13.72 m (45.0 ft) SE of SE corner of the headquarters and machine shops
building, 11.73 m (38.5 ft) SE of the SE corner of Building No 7, and 0.15 m
(0.5 ft) SW of the NE end of the first step.

                          U.S. DEPARTMENT OF COMMERCE
                National Oceanic and Atmospheric Administration
                            National Ocean Service
                                                                   Page  4 of  7

                                                                                
Station ID: 9439040                                PUBLICATION DATE:  04/21/2003
Name:       ASTORIA, TONGUE POINT, COLUMBIA RIVER             
            OREGON
NOAA Chart: 18521                                  Latitude:         46° 12.5' N
USGS Quad:  ASTORIA                                Longitude:       123° 46.0' W


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


                         BENCH MARK STAMPING:  9040 A 1981
                         DESIGNATION:          943 9040 A TIDAL

MONUMENTATION:           Tidal Station disk                        VM#:     1077
AGENCY:                  National Ocean Survey (NOS)               PID#:  SC1048
SETTING CLASSIFICATION:  Galvanized steel rod


The bench mark is a disk located 30 m (97 ft) north of the centerline of Vista
Way, 10 m (34 ft) east of the centerline of Tongue Point Road, 5 m (18 ft) SE of
the SE corner of a steam valve cover of 1.37 x 1.37 m (4.5 x 4.5 ft) opening,
0.55 m (1.8 ft) SW of the SE corner of the curb surrounding an asphalt area
south of the railroad bridge, and 0.15 m (0.5 ft) south of a NOS wooden witness
post.  The bench mark is set 9 cm (0.3 ft) below ground, crimped to the top of a
1/2-inch galvanized steel rod, driven to a depth of 7.3 m (24 ft) and protected
by a 4-inch PVC plastic pipe with cover that is encased in concrete.



                         BENCH MARK STAMPING:  9040 B 1981
                         DESIGNATION:          943 9040 B TIDAL

MONUMENTATION:           Tidal Station disk                        VM#:     1078
AGENCY:                  National Ocean Survey (NOS)               PID#:  SC1050
SETTING CLASSIFICATION:  Galvanized steel rod


The bench mark is a disk located 6.25 m (20.5 ft) west of the centerline of
Tongue Point Road, 0.94 m (3.1 ft) SW of the southeastern-most corner of the
fence around the US Coast Guard Base, 0.73 m (2.4 ft) SE of an orange witness
post, and 0.64 m (2.1 ft) west of the concrete edge of Tongue Point Road.  The
bench mark is set 0.1 m (0.3 ft) below ground, crimped to the top of a 1/2-inch
galvanized steel rod, driven to a depth of 6.4 m (21 ft) and protected by a
4-inch PVC plastic pipe and cap that is encased in concrete.

                          U.S. DEPARTMENT OF COMMERCE
                National Oceanic and Atmospheric Administration
                            National Ocean Service
                                                                   Page  5 of  7

                                                                                
Station ID: 9439040                                PUBLICATION DATE:  04/21/2003
Name:       ASTORIA, TONGUE POINT, COLUMBIA RIVER             
            OREGON
NOAA Chart: 18521                                  Latitude:         46° 12.5' N
USGS Quad:  ASTORIA                                Longitude:       123° 46.0' W


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


                         BENCH MARK STAMPING:  9040 C 1981
                         DESIGNATION:          943 9040 C TIDAL

MONUMENTATION:           Tidal Station disk                        VM#:     1079
AGENCY:                  National Ocean Survey (NOS)               PID#:  SC1051
SETTING CLASSIFICATION:  Galvanized steel rod


The bench mark is a disk 42 m (137 ft) north from the center of the intersection
of Pier Street, Tongue Point Road, and the road leading into Coast Guard Base,
20 m (66 ft) east of centerline of road leading into Coast Guard Base, 14 m (47
ft) SE of the SW corner Coast Guard Exchange Building, 0.98 m (3.2 ft) west of
NOS metal post and survey marker, and 0.58 m (1.9 ft) south of the fence
surrounding U.S. Coast Guard Base, and 0.46 m (1.5 ft) north of orange NOS
witness post. The bench mark is set 0.1 m (0.3 ft) below ground, crimped to the
top of a 1/2-inch galvanized steel rod, driven to a depth of 4.9 m (16 ft) and
protected by a 4-inch PVC plastic pipe with cover which is encased in concrete.



                         BENCH MARK STAMPING:  AQUA REF 9040 1990
                         DESIGNATION:          TBM 943 9040 AQUA REF

MONUMENTATION:           Bench Mark disk                           VM#:    12598
AGENCY:                  National Ocean Service (NOS)              PID:         
SETTING CLASSIFICATION:  Concrete bull rail


The bench mark is a disk set in a concrete bullrail on the south side of Tongue
Point Coast Guard Pier, 27.43 m (90.0 ft) north of the tide gauge protective
well, and 4.11 m (13.5 ft) east of a blue and yellow concrete block, and 0.15 m
(0.5 ft) north of south edge of bull rail.

                          U.S. DEPARTMENT OF COMMERCE
                National Oceanic and Atmospheric Administration
                            National Ocean Service
                                                                   Page  6 of  7

                                                                                
Station ID: 9439040                                PUBLICATION DATE:  04/21/2003
Name:       ASTORIA, TONGUE POINT, COLUMBIA RIVER             
            OREGON
NOAA Chart: 18521                                  Latitude:         46° 12.5' N
USGS Quad:  ASTORIA                                Longitude:       123° 46.0' W


                            T I D A L   D A T U M S 


Tidal datums at ASTORIA, TONGUE POINT, COLUMBIA RIVER based on:

     LENGTH OF SERIES:      19 Years
     TIME PERIOD:           January 1983 - December 2001
     TIDAL EPOCH:           1983-2001
     CONTROL TIDE STATION:   


Elevations of tidal datums referred to Mean Lower Low Water (MLLW), in METERS:

     HIGHEST OBSERVED WATER LEVEL (01/27/1983)         =  3.769
     MEAN HIGHER HIGH WATER                     MHHW   =  2.625
     MEAN HIGH WATER                            MHW    =  2.418
     MEAN TIDE LEVEL                            MTL    =  1.387
     MEAN SEA LEVEL                             MSL    =  1.374
     MEAN LOW WATER                             MLW    =  0.355
     MEAN LOWER LOW WATER                       MLLW   =  0.000
     North American Vertical Datum              NAVD88 = -0.066
     LOWEST  OBSERVED WATER LEVEL (01/28/1979)         = -1.175

North American Vertical Datum (NAVD88)

Bench Mark Elevation Information                In METERS above:

     Stamping or Designation                    MLLW        MHW

     TIDAL 11 1959                               5.253    2.835
     7 1939                                     10.487    8.069
     8 1940                                      5.331    2.913
     NO 10 1958                                  5.430    3.012
     TIDAL NO 12 1962                            5.430    3.011
     TIDAL 13 1964                               5.622    3.204
     9040 A 1981                                16.856   14.438
     9040 B 1981                                 9.298    6.880
     9040 C 1981                                 7.209    4.791
     AQUA REF 9040 1990                          5.311    2.893


                          U.S. DEPARTMENT OF COMMERCE
                National Oceanic and Atmospheric Administration
                            National Ocean Service
                                                                   Page  7 of  7

                                                                                
Station ID: 9439040                                PUBLICATION DATE:  04/21/2003
Name:       ASTORIA, TONGUE POINT, COLUMBIA RIVER             
            OREGON
NOAA Chart: 18521                                  Latitude:         46° 12.5' N
USGS Quad:  ASTORIA                                Longitude:       123° 46.0' W


                             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 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.