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

                                                                                
Station ID: 1630000                                PUBLICATION DATE:  04/21/2003
Name:       GUAM, APRA HARBOR                                 
NOAA Chart: 81054                                  Latitude:         13° 26.5' N
USGS Quad:  APRA HARBOR                            Longitude:       144° 39.2' E


To reach the tidal bench marks, from the Guam airport travel east on Chalan
Passajeros (Route 10A) for 2.9 km (1.8 mi) where it dead ends at Marine Drive
(Route 1), turn left and proceed on Marine Drive for approximately 19 km (12 mi)
until you reach the main gate of the Naval Station Guam.  Obtain a visitor's
pass and continue on Marine Drive for 2.9 km (1.8 mi) until you reach San Luis
Road, turn right (east) and follow to the boat channel on your right to its
entrance.    The bench marks are located between Small Boat Channel and Fleet
Landing Channel.  The tide house is located on the east corner of the entrance
to the Sunny Cove Marina boat harbor.


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


                 PRIMARY BENCH MARK STAMPING:  NO 4 1949
                         DESIGNATION:          163 0000 TIDAL 4

MONUMENTATION:           Tidal Station disk                        VM#:     1684
AGENCY:                  US Coast and Geodetic Survey (USC&GS)     PID#:  TW0041
SETTING CLASSIFICATION:  Concrete valve box


The primary bench mark is a disk set in the NW side of a 2 m x 4 m (6 ft x 12
ft) concrete valve box with steel plates projecting 0.15 m (0.5 ft) in the
center of road between remains of Fleet Post Office Building and Fleet Landing
Channel, 81 m (266 ft) south of the NE corner of the remains of the building,
24.17 m (79.3 ft) NW of the last light pole along the SE bulkhead, and 7.92 m
(26.0 ft) NW of the SE bulkhead of the old Fleet Landing Channel.  Note: A white
square is painted around mark.



                         BENCH MARK STAMPING:  NO 5 1949
                         DESIGNATION:          163 0000 TIDAL 5

MONUMENTATION:           Tidal Station disk                        VM#:     1685
AGENCY:                  US Coast and Geodetic Survey (USC&GS)     PID#:  TW0042
SETTING CLASSIFICATION:  Concrete bulkhead


The bench mark is a disk set inside a 6-inch diameter iron pipe handhold at the
end of Small Boat Channel, about 29 m (95 ft) west of Fleet Landing Channel
bulkhead, 1.98 m (6.5 ft) SW of east corner of boat channel, and 0.21 m (0.7 ft)
below level of concrete bulkhead.

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

                                                                                
Station ID: 1630000                                PUBLICATION DATE:  04/21/2003
Name:       GUAM, APRA HARBOR                                 
NOAA Chart: 81054                                  Latitude:         13° 26.5' N
USGS Quad:  APRA HARBOR                            Longitude:       144° 39.2' E


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


                         BENCH MARK STAMPING:  NO 6 1949
                         DESIGNATION:          163 0000 TIDAL 6

MONUMENTATION:           Tidal Station disk                        VM#:     1686
AGENCY:                  US Coast and Geodetic Survey (USC&GS)     PID#:  TW0043
SETTING CLASSIFICATION:  Concrete culvert head wall


The bench mark is a disk set in top of the south end of a concrete culvert
headwall on the south side of San Luis Road, 95.40 m (313.0 ft) south of bench
mark NO 5 1949, 82.30 m (270.0 ft) east of the centerline of Marine Drive, 12.19
m (40.0 ft) south of the centerline of San Luis Road, and 9.14 m (30.0 ft) north
of telephone pole 2-H-22-6-19-2.



                         BENCH MARK STAMPING:  NO 11 1964
                         DESIGNATION:          163 0000 NO 11

MONUMENTATION:           Tidal Station disk                        VM#:     1688
AGENCY:                  US Coast and Geodetic Survey (USC&GS)     PID#:  AA4394
SETTING CLASSIFICATION:  Concrete foundation


The bench mark is a disk set in concrete foundation which used to support a -
now destroyed - walkway to tide house, 12.80 m (42.0 ft) south of the NE end of
Pier K, 4.03 m (13.2 ft) east of SE corner of tidehouse, 0.91 m (3.0 ft) west of
the steel piling bulkhead on  the west side of Fleet Landing Channel, and 0.29 m
(1.0 ft) SE of the SE corner of the concrete step that used to lead to the - now
destroyed - walkway.

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

                                                                                
Station ID: 1630000                                PUBLICATION DATE:  04/21/2003
Name:       GUAM, APRA HARBOR                                 
NOAA Chart: 81054                                  Latitude:         13° 26.5' N
USGS Quad:  APRA HARBOR                            Longitude:       144° 39.2' E


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


                         BENCH MARK STAMPING:  NO 12 1974
                         DESIGNATION:          163 0000 NO 12

MONUMENTATION:           Tidal Station disk                        VM#:     1689
AGENCY:                  National Ocean Survey (NOS)               PID:         
SETTING CLASSIFICATION:  Concrete patio slab


The bench mark is a disk set flush in SW corner of the elevated 9 m x 6 m (28 ft
x 21 ft) concrete patio supporting a yellow flammable storage house of the U.S.
Naval Sea Cadets Headquarters, 57 m (187 ft) west of the west side of the Fleet
Landing Channel, 18.75 m (61.5 ft) east of the east side of the small boat
channel, and 7.32 m (24.0 ft) south of a flagpole.



                         BENCH MARK STAMPING:  TIDAL BM 13 1975
                         DESIGNATION:          163 0000 TIDAL BM 13

MONUMENTATION:           Tidal Station disk                        VM#:     1690
AGENCY:                  National Ocean Survey (NOS)               PID:         
SETTING CLASSIFICATION:  Concrete apron slab


The bench mark is a disk set in the concrete apron fronting the double door
entrance to the Communication Security Material Issuing office, 70 m (230 ft) NW
of the centerline of the intersection of San Luis Road and Marine Drive, 42 m
(139 ft) west of a fire hydrant, 7 m (24 ft) north of the south wall of the
office, and 0.85 m (2.8 ft) east of the office.

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

                                                                                
Station ID: 1630000                                PUBLICATION DATE:  04/21/2003
Name:       GUAM, APRA HARBOR                                 
NOAA Chart: 81054                                  Latitude:         13° 26.5' N
USGS Quad:  APRA HARBOR                            Longitude:       144° 39.2' E


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


                         BENCH MARK STAMPING:  0000 K TIDAL BM 1978
                         DESIGNATION:          163 0000 TIDAL BM K

MONUMENTATION:           Tidal Station disk                        VM#:     1691
AGENCY:                  National Ocean Survey (NOS)               PID:         
SETTING CLASSIFICATION:  Concrete base of a flagpole


The bench mark is a disk set in the NW corner of the concrete base of a flagpole
at the Sumay Cove Marina, 61 m (200 ft) east of bench mark NO 6 1949, 19.96 m
(65.5 ft) east of the SE corner of the Marina Building (#1985), 14.02 m (46.0
ft) east of east edge of a 6 m x 18 m (20 ft x 60 ft) old concrete foundation
used for drydocking small boats, 6.10 m (20.0 ft) west of the eastern-most edge
of a wooden plank deck along west side of Sunny Cove, and 3.05 m (10.0 ft) south
of a small concrete floored picnic shelter.



                         BENCH MARK STAMPING:  USN BM 1
                         DESIGNATION:          163 0000 USN BM 1
                         ALIAS:                14

MONUMENTATION:           Bench Mark disk                           VM#:     1692
AGENCY:                  US Army Corps of Engineers (USE)          PID:         
SETTING CLASSIFICATION:  Iron pipe handhold


The bench mark is a disk set inside a 6-inch diameter iron pipe handhold at end
of Small Boat Channel, 38.10 m (125.0 ft) west of the Fleet Landing Channel
bulkhead, 11.77 m (38.6 ft) SW of the inside east corner of the Small Boat
Channel, 10.00 m (32.8 ft) SW of bench mark NO 5 1949, and 0.21 m (0.7 ft) below
the level of concrete bulkhead. 

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

                                                                                
Station ID: 1630000                                PUBLICATION DATE:  04/21/2003
Name:       GUAM, APRA HARBOR                                 
NOAA Chart: 81054                                  Latitude:         13° 26.5' N
USGS Quad:  APRA HARBOR                            Longitude:       144° 39.2' E


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


                         BENCH MARK STAMPING:   
                         DESIGNATION:          163 0000 TIDAL 7
                         ALIAS:                TIDAL 7 PIE

MONUMENTATION:           Bolt                                      VM#:     1693
AGENCY:                  Unknown                                   PID#:  TW0044
SETTING CLASSIFICATION:  Concrete culvert head wall


The bench mark is a bolt set flush in the north end of a concrete culvert
headwall at the SW corner of the intersection of Marine Drive and San Luis Road,
21.34 m (70.0 ft) south of the centerline of San Luis Road, 10.97 m (36.0 ft)
west of the centerline of Marine Drive, and about 4 m (12 ft) north of a
protruding concrete post labeled "Buried Cable".



                         BENCH MARK STAMPING:  0000 N 1994
                         DESIGNATION:          163 0000 N

MONUMENTATION:           Tidal Station disk                        VM#:    12702
AGENCY:                  National Ocean Service (NOS)              PID:         
SETTING CLASSIFICATION:  Concrete slab


The bench mark is a disk set flush in the SE corner of a 5 m x 8 m x 1 m (16 ft
x 26 ft x 3 ft) utility access pad, 0.2 km (0.1 mi) west of the intersection of
Marine Drive and San Luis Road, 30 m (98 ft) east of the Trans-Pacific Cable
Station sign, 14.50 m (47.6 ft) SE of a 2.5 m x 2 m x 1 m (8 ft x 7 ft x 3 ft)
concrete bunker, 11.75 m (38.5 ft) SW of utility pole "JB-61-9", 10.85 m (35.6
ft) north of the centerline of San Luis, and 1.24 m (4.1 ft) above the natural
grade of the hill.

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

                                                                                
Station ID: 1630000                                PUBLICATION DATE:  04/21/2003
Name:       GUAM, APRA HARBOR                                 
NOAA Chart: 81054                                  Latitude:         13° 26.5' N
USGS Quad:  APRA HARBOR                            Longitude:       144° 39.2' E


                            T I D A L   D A T U M S 


Tidal datums at GUAM, APRA HARBOR 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 (08/28/1992)         =  1.309
     MEAN HIGHER HIGH WATER                     MHHW   =  0.715
     MEAN HIGH WATER                            MHW    =  0.678
     MEAN TIDE LEVEL                            MTL    =  0.432
     MEAN SEA LEVEL                             MSL    =  0.419
     MEAN LOW WATER                             MLW    =  0.185
     MEAN LOWER LOW WATER                       MLLW   =  0.000
     LOWEST  OBSERVED WATER LEVEL (10/24/1972)         = -0.712



Bench Mark Elevation Information                In METERS above:

     Stamping or Designation                    MLLW        MHW

     NO 4 1949                                   2.589    1.911
     NO 5 1949                                   1.002    0.324
     NO 6 1949                                   1.957    1.279
     NO 11 1964                                  2.418    1.740
     NO 12 1974                                  2.612    1.934
     TIDAL BM 13 1975                            3.265    2.587
     0000 K TIDAL BM 1978                        2.127    1.449
     USN BM 1                                    0.958    0.280
     163 0000 TIDAL 7                            2.685    2.007
     0000 N 1994                                13.338   12.660


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

                                                                                
Station ID: 1630000                                PUBLICATION DATE:  04/21/2003
Name:       GUAM, APRA HARBOR                                 
NOAA Chart: 81054                                  Latitude:         13° 26.5' N
USGS Quad:  APRA HARBOR                            Longitude:       144° 39.2' E


                             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 defined island datum (GUVD04).  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.

Guam Vertical Datum of 2004 (GUVD04) is a fixed datum derived from a
simultaneous, least squares, minimum constraint adjustment of leveling
observations.  Local mean sea level relative to the 1983-2001 National Tidal
Datum Epoch observed at tide station 1630000 at Apra  Harbor, Guam, was held
fixed as the single initial constraint.  GUVD04 replaces all previous height
system as the national standard geodetic reference for heights on Guam.  Bench
mark elevations relative to GUVD04 are available from NGS through the
World Wide Web at National Geodetic Survey.

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 GUVD04 elevation is shown on the Elevations of Tidal Datums Table Referred
to MLLW only when two or more of the bench marks listed have GUVD04 elevations.
The GUVD04 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, GUVD04 bench mark elevations computed indirectly from the tidal
datums elevation table may differ slightly from GUVD04 elevations listed for
each bench mark in the NGS database.