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

                                                   PUBLICATION DATE:  08/08/2000
Station ID: 1619000                                SUPERCEDED DATE:   04/21/2003
Name:       JOHNSTON ATOLL, PACIFIC OCEAN                     
NOAA Chart: 83637                                  Latitude:         16° 44.3' N
USGS Quad:  NONE                                   Longitude:       169° 31.8' W


To reach the tidal bench marks, from the Johnston Island airport proceed east on
the perimeter road around the end of the runway for approximately 0.8 km (0.5
mi), make a right turn into the small boat basin.  The bench marks and tide gage
were located in the vicinity of the basin.  The tide house is located on the NW
corner of the pier.  


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


                 PRIMARY BENCH MARK STAMPING:  NO 13 1955
                         DESIGNATION:          161 9000 NO 13

MONUMENTATION:           Tidal Station disk                        VM#:       87
AGENCY:                  US Coast and Geodetic Survey (USC&GS)     PID:         
SETTING CLASSIFICATION:  Concrete bulkhead cap


The primary bench mark is a disk set in a concrete bulkhead cap at the inshore
end of the Small Boat Pier, 17.53 m (57.5 ft) north of the NW corner of Building
#100, 7.92 m (26.0 ft) NW of fire hydrant #14, 4.42 m (14.5 ft) west of the
eastern side of the cement bulkhead of the small boat pier, and flush with
ground.



                         BENCH MARK STAMPING:  NO 12 1955
                         DESIGNATION:          161 9000 NO 12

MONUMENTATION:           Tidal Station disk                        VM#:       60
AGENCY:                  US Coast and Geodetic Survey (USC&GS)     PID:         
SETTING CLASSIFICATION:  Concrete seawall


The bench mark is a disk set in the top of a concrete seawall on the west side
of the Small Boat Pier, 17.07 m (56.0 ft) south of the south edge of the small
concrete pier where the tide house is located, 3 m (10 ft) NW of bollard near
galvanized barrier, 2 m (6 ft) north of galvanized barrier protecting fuel line
painted yellow, and 0.30 m (1.0 ft) south of the south edge of a northern-most
wooden ramp leading from the Navy pier to a wooden boat pier.

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

                                                   PUBLICATION DATE:  08/08/2000
Station ID: 1619000                                SUPERCEDED DATE:   04/21/2003
Name:       JOHNSTON ATOLL, PACIFIC OCEAN                     
NOAA Chart: 83637                                  Latitude:         16° 44.3' N
USGS Quad:  NONE                                   Longitude:       169° 31.8' W


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


                         BENCH MARK STAMPING:  NO 14
                         DESIGNATION:          161 9000 NO 14
                         ALIAS:                USE 14

MONUMENTATION:           Bench Mark disk                           VM#:       61
AGENCY:                  U.S. Army Corps of Engineers (USCOE)      PID:         
SETTING CLASSIFICATION:  Concrete bulkhead cap


The bench mark is a disk set in top of concrete bulkhead cap on the east side of
the Small Boat Pier, 77.72 m (255.0 ft) south of the northeastern corner of the
pier, 59.44 m (195.0 ft) north of the inshore end of the east side of the pier,
5.49 m (18.0 ft) north of a bit, and 0.98 m (3.2 ft) west of the east wooden
face of the Pier.



                         BENCH MARK STAMPING:  NO 28 1964
                         DESIGNATION:          161 9000 NO 28

MONUMENTATION:           Tidal Station disk                        VM#:       62
AGENCY:                  US Coast and Geodetic Survey (USC&GS)     PID#:  TW0253
SETTING CLASSIFICATION:  Concrete sidewalk


The bench mark is a disk set in top of the SE corner of the concrete sidewalk
leading into the doorway to the boiler room on the west side of the west wing of
the former Officer's Club (Building #4), 8.23 m (27.0 ft) north of the SW corner
of the wing, 7.32 m (24.0 ft) south of the NW corner of the wing, 0.30 m (1.0
ft) south of the south edge of the doorway, and 0.12 m (0.4 ft) west of east
facing wall of Building #4.

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

                                                   PUBLICATION DATE:  08/08/2000
Station ID: 1619000                                SUPERCEDED DATE:   04/21/2003
Name:       JOHNSTON ATOLL, PACIFIC OCEAN                     
NOAA Chart: 83637                                  Latitude:         16° 44.3' N
USGS Quad:  NONE                                   Longitude:       169° 31.8' W


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


                         BENCH MARK STAMPING:  MON JOHN
                         DESIGNATION:          161 9000 MON JOHN

MONUMENTATION:           Triangulation Station disk                VM#:       66
AGENCY:                  Unknown                                   PID#:  TW0231
SETTING CLASSIFICATION:  Concrete monument


The bench mark is a disk set in a 0.30 m (1.0 ft) diameter concrete hole located
approximately midway between Apartment D and Apartment E, 37.34 m (122.5 ft) NE
of a fire hydrant on Arnold Avenue corner, 23.93 m (78.5 ft) SW of the SE corner
of Building #291, 11.43 m (37.5 ft) west from 1 m (3 ft) diameter electric
manhole cover on south side of Arnold Avenue, 3.05 m (10.0 ft) SE of street
curbing, 0.24 m (0.8 ft) below street level, and protected by a 0.3 m (1 ft)
circular steel cover.   



                         BENCH MARK STAMPING:  9000 L 1979
                         DESIGNATION:          161 9000 L

MONUMENTATION:           Tidal Station disk                        VM#:       67
AGENCY:                  National Ocean Survey (NOS)               PID:         
SETTING CLASSIFICATION:  Concrete loading ramp


The bench mark is a disk set horizontally in the northeastern corner of the
raised concrete loading ramp on the SW side of Building #100, 14.33 m (47.0 ft)
east of the SW corner of the building, 4.05 m (13.3 ft) north of south edge of
raised compressor platform, 0.15 m (0.5 ft) from south facing edge of building,
and 1.07 m (3.5 ft) above ground level. 

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

                                                   PUBLICATION DATE:  08/08/2000
Station ID: 1619000                                SUPERCEDED DATE:   04/21/2003
Name:       JOHNSTON ATOLL, PACIFIC OCEAN                     
NOAA Chart: 83637                                  Latitude:         16° 44.3' N
USGS Quad:  NONE                                   Longitude:       169° 31.8' W


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


                         BENCH MARK STAMPING:  NO 21 1964
                         DESIGNATION:          161 9000 NO 21

MONUMENTATION:           Tidal Station disk                        VM#:       88
AGENCY:                  US Coast and Geodetic Survey (USC&GS)     PID#:  TW0252
SETTING CLASSIFICATION:  Concrete wall


The bench mark is a disk set in top of a 1 m (2 ft) high concrete foundation
wall, 23.47 m (77.0 ft) east from the NW corner of the west wing of the former
Officer's Club (Building #4), and 1.22 m (4.0 ft) west from west edge of a
doorway on the north side of the wing, and 0.12 m (0.4 ft) north of north facing
wall of building #4.



                         BENCH MARK STAMPING:  9000 M 1990
                         DESIGNATION:          161 9000 M

MONUMENTATION:           Tidal Station disk                        VM#:     1487
AGENCY:                  National Ocean Service (NOS)              PID:         
SETTING CLASSIFICATION:  Building foundation


The bench mark is a disk set in the foundation on the south side in the west
corner of the second bay door on the western side of the Painting Building #33,
7.10 m (23.3 ft) east of SW corner of the Building #33, 4.05 m (13.3 ft) of east
side of cargo bay door, 1.91 m (6.25 ft) north of the southern edge of the
concrete pad forming the ramp into the bay, and 0.21 m (0.7 ft) east of the
western edge of the bay door.

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

                                                   PUBLICATION DATE:  08/08/2000
Station ID: 1619000                                SUPERCEDED DATE:   04/21/2003
Name:       JOHNSTON ATOLL, PACIFIC OCEAN                     
NOAA Chart: 83637                                  Latitude:         16° 44.3' N
USGS Quad:  NONE                                   Longitude:       169° 31.8' W


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


                         BENCH MARK STAMPING:  9000 N 1990
                         DESIGNATION:          161 9000 N

MONUMENTATION:           Tidal Station disk                        VM#:     1488
AGENCY:                  National Ocean Service (NOS)              PID:         
SETTING CLASSIFICATION:  Building foundation


The bench mark is a disk set in the foundation in the eastern-most bay on the
north side of the Vehicle Maintenance Building #40, 3.32 m (10.9 ft) east of the
west side of the cargo bay door, 2.26 m (7.4 ft) south of the end of the
concrete pad serving as an entry into the garage, 1.07 m (3.5 ft) west of the
west side of the entry doorway to the dispatch office, and 0.34 m (1.1 ft) west
of the eastern side of the bay door.



                         BENCH MARK STAMPING:  TRANSVERSE MONUMENT NO 1 JOE ELEV
                                               14.177
                         DESIGNATION:          161 9000 NO 1 JOE
                         ALIAS:                NO 1 JOE 1988

MONUMENTATION:           Bench Mark disk                           VM#:     1489
AGENCY:                  Unknown                                   PID:         
SETTING CLASSIFICATION:  Pavement


The bench mark is a brass disk located in the middle of the road at the
intersection of Arnold Avenue and Mitchell Street, 19.96 m (65.5 ft) east from
yellow hydrant #40, 19.81 m (65.0 ft) SW from SW corner of Building #252, 14.48
m (47.5 ft) west from west corner of Post Office, and flush with surface of the
road.

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

                                                   PUBLICATION DATE:  08/08/2000
Station ID: 1619000                                SUPERCEDED DATE:   04/21/2003
Name:       JOHNSTON ATOLL, PACIFIC OCEAN                     
NOAA Chart: 83637                                  Latitude:         16° 44.3' N
USGS Quad:  NONE                                   Longitude:       169° 31.8' W


                            T I D A L   D A T U M S 


Tidal datums at JOHNSTON ATOLL, PACIFIC OCEAN based on:

     LENGTH OF SERIES:      19 YEARS
     TIME PERIOD:           January 1960 - December 1978
     TIDAL EPOCH:           1960-1978
     CONTROL TIDE STATION:   


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

     HIGHEST OBSERVED WATER LEVEL (01/13/1958)         =  1.542
     MEAN HIGHER HIGH WATER                     MHHW   =  0.686
     MEAN HIGH WATER                            MHW    =  0.613
     MEAN SEA LEVEL                             MSL    =  0.326
     MEAN TIDE LEVEL                            MTL    =  0.323
     MEAN LOW WATER                             MLW    =  0.037
     MEAN LOWER LOW WATER                       MLLW   =  0.000
     LOWEST  OBSERVED WATER LEVEL (03/23/1951)         = -0.530



Bench Mark Elevation Information                In METERS above:

     Stamping or Designation                    MLLW        MHW

     NO 13 1955                                  2.320    1.707
     NO 12 1955                                  2.359    1.746
     NO 14                                       2.325    1.713
     NO 28 1964                                  2.843    2.231
     MON JOHN                                    4.064    3.451
     9000 L 1979                                 3.356    2.743
     NO 21 1964                                  3.260    2.648
     9000 M 1990                                 2.356    1.743
     9000 N 1990                                 2.859    2.246
     TRANSVERSE MONUMENT NO 1 JOE ELEV
     14.177                                      4.217    3.605


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

                                                   PUBLICATION DATE:  08/08/2000
Station ID: 1619000                                SUPERCEDED DATE:   04/21/2003
Name:       JOHNSTON ATOLL, PACIFIC OCEAN                     
NOAA Chart: 83637                                  Latitude:         16° 44.3' N
USGS Quad:  NONE                                   Longitude:       169° 31.8' 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 any other fixed island datum.

This tide station location has a local island datum.  Island datums
are specific fixed geodetic datums whose elevation relationship 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.