U.S. DEPARTMENT OF COMMERCE
                National Oceanic and Atmospheric Administration
                            National Ocean Service
Datums Page                                                        Page  1 of  6

                                                                                
Station ID: 9440574                         PUBLICATION DATE:  01/06/2004
Name:       NORTH JETTY                                       
            WA
NOAA Chart: 18521                           Latitude:   46° 16.4' N (  46.27330)
USGS Quad:  CAPE DISAPPOINTMENT             Longitude: 124°  4.3' W (-124.07200)


To reach the tidal bench marks from the center of town of Ilwaco (where U.S.
Highway 101 marks a turn to north), proceed west one block and turn left at sign
CAPE DISAPPOINTMENT, continue south for 2.7 km (1.7 mi) to "Y" intersection,
turn left, and continue for 0.8 km (0.5 mi) to the entrance of Fort Canby State
Park; turn right into the park and proceed 2.1 km (1.3 mi) to a parking lot on
the left.  The bench marks are located on the jetty east of the parking lot and
along the road between the parking lot and the camping area.  The tide gage and
staff were located on the top of the rock jetty SE of the parking lot.


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


                 PRIMARY BENCH MARK STAMPING:  0574 A 1982
                         DESIGNATION:          944 0574 A TIDAL

MONUMENTATION:           Tidal Station disk                    VM#:         8938
AGENCY:                  National Ocean Survey (NOS)           IDB PID#:  SD0299
SETTING CLASSIFICATION:  Stainless steel rod                   OPUS PID:        
LATITUDE:   46° 16.4' N (  46.27330)          LONGITUDE: 124°  4.4' W (-124.07300)


The primary bench mark is a disk located along the south side of the Jetty Road
in Fort Canby State Park, 1.9 km (1.2 mi) west along the jetty road from the
park entrance, 50 m (163 ft) east of the east edge of an entrance road into a
parking lot south of the Jetty Road, 7 m (23 ft) south of the south edge of the
jetty road, and 1 m (3 ft) NW of a witness post.  The bench mark is set 6 cm
(0.2 ft) below the ground, crimped to the top of a stainless steel rod driven
14.6 m (48 ft) to refusal, and encased in a 4-inch PVC pipe and concrete
kickblock.

                          U.S. DEPARTMENT OF COMMERCE
                National Oceanic and Atmospheric Administration
                            National Ocean Service
                                                                   Page  2 of  6

                                                                                
Station ID: 9440574                         PUBLICATION DATE:  01/06/2004
Name:       NORTH JETTY                                       
            WA
NOAA Chart: 18521                           Latitude:   46° 16.4' N (  46.27330)
USGS Quad:  CAPE DISAPPOINTMENT             Longitude: 124°  4.3' W (-124.07200)


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


                         BENCH MARK STAMPING:  0574 B 1982
                         DESIGNATION:          944 0574 B TIDAL

MONUMENTATION:           Tidal Station disk                    VM#:         8939
AGENCY:                  National Ocean Survey (NOS)           IDB PID#:  SD0298
SETTING CLASSIFICATION:  Stainless steel rod                   OPUS PID:        
LATITUDE:   46° 16.4' N (  46.27330)          LONGITUDE: 124°  4.3' W (-124.07200)


The bench mark is a disk located along the south side of the jetty road in Fort
Canby State Park, 1.6 km (1.0 mi) west along jetty road from the park entrance,
8 m (27 ft) south of the southern edge of the jetty road, and 1 m (2 ft) NW of a
witness post.  The bench mark is set 15 cm (0.5 ft) below the ground, crimped to
the top of a stainless steel rod driven 14.6 m (48 ft) to refusal, and encased
in a 4-inch PVC pipe and concrete kickblock.



                         BENCH MARK STAMPING:  0574 C 1982
                         DESIGNATION:          944 0574 C TIDAL

MONUMENTATION:           Tidal Station disk                    VM#:         8940
AGENCY:                  National Ocean Survey (NOS)           IDB PID#:  SD0297
SETTING CLASSIFICATION:  Stainless steel rod                   OPUS PID:        
LATITUDE:   46° 16.6' N (  46.27670)          LONGITUDE: 124°  4.0' W (-124.06700)


The bench mark is a disk located along the south side of the jetty road in Fort
Canby State Park, 1.1 km (0.7 mi) west along the jetty road from the park
entrance, 3 m (11 ft) south of the southern edge of jetty road, and 1 m (2 ft)
NW of a witness post.  The bench mark is set 15 cm (0.5 ft) below the ground,
crimped to the top of a stainless steel rod driven 13.4 m (44 ft) to refusal,
and encased in a 4-inch PVC pipe and concrete kickblock.

                          U.S. DEPARTMENT OF COMMERCE
                National Oceanic and Atmospheric Administration
                            National Ocean Service
                                                                   Page  3 of  6

                                                                                
Station ID: 9440574                         PUBLICATION DATE:  01/06/2004
Name:       NORTH JETTY                                       
            WA
NOAA Chart: 18521                           Latitude:   46° 16.4' N (  46.27330)
USGS Quad:  CAPE DISAPPOINTMENT             Longitude: 124°  4.3' W (-124.07200)


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


                         BENCH MARK STAMPING:  0574 D 1982
                         DESIGNATION:          944 0574 D TIDAL

MONUMENTATION:           Tidal Station disk                    VM#:         8941
AGENCY:                  National Ocean Survey (NOS)           IDB PID#:  SD0296
SETTING CLASSIFICATION:  Concrete bunker                       OPUS PID:        
LATITUDE:   46° 16.9' N (  46.28170)          LONGITUDE: 124°  3.4' W (-124.05700)


The bench mark is a disk set in the NW corner of a World War II machine gun 
bunker, 45 m (146 ft) SE of the SE corner of the restroom building, 0.3 m (1 ft)
east of the west edge of the 2 m (8ft) square concrete bunker, 0.27 m (0.9 ft)
south of the north edge of the bunker, and 1.16 m (3.8 ft) above the ground.



                         BENCH MARK STAMPING:  BM 1 1958
                         DESIGNATION:          944 0574 TIDAL 1

MONUMENTATION:           Tidal Station disk                    VM#:         8942
AGENCY:                  US Coast and Geodetic Survey
                         (USC&GS)                              IDB PID#:  SD0302
SETTING CLASSIFICATION:  Boulder                               OPUS PID:        
LATITUDE:   46° 16.3' N (  46.27170)          LONGITUDE: 124°  4.3' W (-124.07200)


The bench mark is a disk set in the top of a large light colored rock located at
the edge of the Columbia River, 69 m (225 ft) east of the parking lot, 3 m (10
ft) towards the river from a set of burned-out pilings, and 3 m (10 ft) below
the top of a levee. Note: The high point on the disk is "R" in MARK.

                          U.S. DEPARTMENT OF COMMERCE
                National Oceanic and Atmospheric Administration
                            National Ocean Service
                                                                   Page  4 of  6

                                                                                
Station ID: 9440574                         PUBLICATION DATE:  01/06/2004
Name:       NORTH JETTY                                       
            WA
NOAA Chart: 18521                           Latitude:   46° 16.4' N (  46.27330)
USGS Quad:  CAPE DISAPPOINTMENT             Longitude: 124°  4.3' W (-124.07200)


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


                         BENCH MARK STAMPING:  BM 3 1958
                         DESIGNATION:          944 0574 TIDAL 3

MONUMENTATION:           Tidal Station disk                    VM#:         8944
AGENCY:                  US Coast and Geodetic Survey
                         (USC&GS)                              IDB PID#:  SD0300
SETTING CLASSIFICATION:  Boulder                               OPUS PID:        
LATITUDE:   46° 16.3' N (  46.27170)          LONGITUDE: 124°  4.3' W (-124.07200)


The bench mark is a disk set in the top of a large jetty rock located at the
edge of the Columbia River, 82 m (270 ft) east of the parking lot, 7 m (23 ft)
NE of bench mark BM 2 1958, and 3 m (10 ft) below the top of a levee.  Note: The
high point on the disk is "D" in GEODETIC.

                          U.S. DEPARTMENT OF COMMERCE
                National Oceanic and Atmospheric Administration
                            National Ocean Service
                                                                   Page  5 of  6

                                                                                
Station ID: 9440574                         PUBLICATION DATE:  01/06/2004
Name:       NORTH JETTY                                       
            WA
NOAA Chart: 18521                           Latitude:   46° 16.4' N (  46.27330)
USGS Quad:  CAPE DISAPPOINTMENT             Longitude: 124°  4.3' W (-124.07200)


                            T I D A L   D A T U M S 


Tidal datums at NORTH JETTY based on:

     LENGTH OF SERIES:      4 MONTHS
     TIME PERIOD:           July 1983 - October 1983
     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   =  2.361
     MEAN HIGH WATER                            MHW    =  2.156
     MEAN TIDE LEVEL                            MTL    =  1.265
     MEAN SEA LEVEL                             MSL    =  1.246
     MEAN LOW WATER                             MLW    =  0.374
     North American Vertical Datum              NAVD88 =  0.077
     MEAN LOWER LOW WATER                       MLLW   =  0.000

North American Vertical Datum (NAVD88)

Bench Mark Elevation Information                In METERS above:

     Stamping or Designation                    MLLW        MHW

     0574 A 1982                                 4.949    2.793
     0574 B 1982                                 4.782    2.626
     0574 C 1982                                 4.754    2.598
     0574 D 1982                                 7.447    5.291
     BM 1 1958                                   5.900    3.744
     BM 3 1958                                   4.327    2.171


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

                                                                                
Station ID: 9440574                         PUBLICATION DATE:  01/06/2004
Name:       NORTH JETTY                                       
            WA
NOAA Chart: 18521                           Latitude:   46° 16.4' N (  46.27330)
USGS Quad:  CAPE DISAPPOINTMENT             Longitude: 124°  4.3' W (-124.07200)


                             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.