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

                                                                                
Station ID: 9447952                         PUBLICATION DATE:  07/15/2004
Name:       CRESCENT HARBOR, WHIDBEY ISLAND                   
            WA
NOAA Chart: 18428                           Latitude:   48° 17.2' N (  48.28670)
USGS Quad:  DECEPTION PASS                  Longitude: 122° 37.0' W (-122.61700)


To reach the tidal bench marks from Mukilteo, proceed by ferry to Whidbey
Island, then travel WNW on State Highway 525/20 for about 48 km (30 mi) to Oak
Harbor, then proceed ENE on SE Pioneer Way for about 2.2 km (1.4 mi) to Coral
Sea Drive, then turn right and proceed SSE on Coral Sea Drive for 0.5 km (0.3
mi) to Tulag Avenue, then turn left and proceed east on Tulag Avenue to the end
of the road and the U.S. Navy Fuel and Recreation Pier, on the west side of
Crescent Harbor.  The bench marks are located on the pier and along the approach
to the pier.  The tide gage and staff were located at the east end of the pier.


                         T I D A L   B E N C H   M A R K S
                          U.S. DEPARTMENT OF COMMERCE
                National Oceanic and Atmospheric Administration
                            National Ocean Service
                                                                   Page  2 of  6

                                                                                
Station ID: 9447952                         PUBLICATION DATE:  07/15/2004
Name:       CRESCENT HARBOR, WHIDBEY ISLAND                   
            WA
NOAA Chart: 18428                           Latitude:   48° 17.2' N (  48.28670)
USGS Quad:  DECEPTION PASS                  Longitude: 122° 37.0' W (-122.61700)


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


                 PRIMARY BENCH MARK STAMPING:  NO 2 1951
                         DESIGNATION:          TIDAL 2

MONUMENTATION:           Bench Mark disk                       VM#:         9239
AGENCY:                  US Coast & Geodetic Survey
                         (USC&GS)                                 IDB PID#:  TR0440
SETTING CLASSIFICATION:  Concrete bollard                      OPUS PID:        
LATITUDE:   48° 17.1' N (  48.28500)          LONGITUDE: 122° 37.2' W (-122.62000)


The primary bench mark is a disk set in a concrete filled bollard south of the
concrete roadway approach to the pier, 23 m (76 ft) west of the west end of the
pier, 9.57 m (31.4 ft) west of the NW corner of a 2 m x 4 m (7 ft x 13 ft)
concrete water drain basin, 8.08 m (26.5 ft) south of the centerline of the
road, 8 m (25 ft) north of the approximate shoreline, and 1 m (2 ft) above the
ground.



                         BENCH MARK STAMPING:  NO 3 1951
                         DESIGNATION:          944 7952 TIDAL 3

MONUMENTATION:           Bench Mark disk                       VM#:         9240
AGENCY:                  US Coast & Geodetic Survey
                         (USC&GS)                                 IDB PID#:  TR0438
SETTING CLASSIFICATION:  Concrete base                         OPUS PID:        
LATITUDE:   48° 17.1' N (  48.28500)          LONGITUDE: 122° 37.4' W (-122.62300)


The bench mark is a disk set in the SE corner of the concrete base for fuel oil
station No. 306, 37 m (122 ft) south of the centerline of Tulagi Avenue, 34 m
(110 ft) west of the rock filled approach to the pier, and 5 m (17 ft) north of
the NE corner of a 2 m (5 ft) square concrete manhole with steel plate cover.

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

                                                                                
Station ID: 9447952                         PUBLICATION DATE:  07/15/2004
Name:       CRESCENT HARBOR, WHIDBEY ISLAND                   
            WA
NOAA Chart: 18428                           Latitude:   48° 17.2' N (  48.28670)
USGS Quad:  DECEPTION PASS                  Longitude: 122° 37.0' W (-122.61700)


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


                         BENCH MARK STAMPING:  7952 A 1977
                         DESIGNATION:          944 7952 A TIDAL

MONUMENTATION:           Tidal Station disk                    VM#:         9241
AGENCY:                  National Ocean Survey (NOS)           IDB PID#:        
SETTING CLASSIFICATION:  Concrete pier                         OPUS PID:        
LATITUDE:   48° 17.1' N (  48.28500)          LONGITUDE: 122° 37.0' W (-122.61700)


The bench mark is a disk set in the concrete deck at the seaward end of the
pier, about 9 m (30 ft) west of the SE corner of the seaward end of the pier,
0.3 m (1 ft) north of the timber curb along the south side of the pier, and
level with the pier.



                         BENCH MARK STAMPING:  7952 B 1977
                         DESIGNATION:          944 7952 B TIDAL

MONUMENTATION:           Tidal Station disk                    VM#:         9242
AGENCY:                  National Ocean Survey (NOS)           IDB PID#:        
SETTING CLASSIFICATION:  Concrete bollard base                 OPUS PID:        
LATITUDE:   48° 17.1' N (  48.28500)          LONGITUDE: 122° 37.0' W (-122.61700)


The bench mark is a disk set flush in the SE corner of a concrete base for a
bollard on the south side of the pier, 48 m (156 ft) west of bench mark 7952 A
1977, and 0.3 m (1 ft) north of the timber curb along the south side of the
pier.

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

                                                                                
Station ID: 9447952                         PUBLICATION DATE:  07/15/2004
Name:       CRESCENT HARBOR, WHIDBEY ISLAND                   
            WA
NOAA Chart: 18428                           Latitude:   48° 17.2' N (  48.28670)
USGS Quad:  DECEPTION PASS                  Longitude: 122° 37.0' W (-122.61700)


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


                         BENCH MARK STAMPING:  7952 C 1977
                         DESIGNATION:          944 7952 C TIDAL

MONUMENTATION:           Tidal Station disk                    VM#:         9243
AGENCY:                  National Ocean Survey (NOS)           IDB PID#:        
SETTING CLASSIFICATION:  Concrete bollard base                 OPUS PID:        
LATITUDE:   48° 17.1' N (  48.28500)          LONGITUDE: 122° 37.0' W (-122.61700)


The bench mark is a disk set flush in the SE corner of a concrete base for a
bollard on the south side of the pier, 51 m (167 ft) west of bench mark 7952 B
1977, and 0.3 m (1 ft) north of the timber curb along the south side of the
pier.

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

                                                                                
Station ID: 9447952                         PUBLICATION DATE:  07/15/2004
Name:       CRESCENT HARBOR, WHIDBEY ISLAND                   
            WA
NOAA Chart: 18428                           Latitude:   48° 17.2' N (  48.28670)
USGS Quad:  DECEPTION PASS                  Longitude: 122° 37.0' W (-122.61700)


                            T I D A L   D A T U M S 


Tidal datums at CRESCENT HARBOR, WHIDBEY ISLAND based on:

     LENGTH OF SERIES:      1 MONTH
     TIME PERIOD:           March 1977 - March 1977
     TIDAL EPOCH:           1983-2001
     CONTROL TIDE STATION:  9447130 SEATTLE, PUGET SOUND


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

     MEAN HIGHER HIGH WATER                     MHHW   =  3.554
     MEAN HIGH WATER                            MHW    =  3.281
     MEAN SEA LEVEL                             MSL    =  2.072
     MEAN TIDE LEVEL                            MTL    =  2.068
     MEAN LOW WATER                             MLW    =  0.855
     North American Vertical Datum              NAVD88 =  0.675
     MEAN LOWER LOW WATER                       MLLW   =  0.000

North American Vertical Datum (NAVD88)

Bench Mark Elevation Information                In METERS above:

     Stamping or Designation                    MLLW        MHW

     NO 2 1951                                   5.707    2.426
     NO 3 1951                                   5.546    2.265
     7952 A 1977                                 5.095    1.814
     7952 B 1977                                 5.148    1.867
     7952 C 1977                                 5.098    1.817


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

                                                                                
Station ID: 9447952                         PUBLICATION DATE:  07/15/2004
Name:       CRESCENT HARBOR, WHIDBEY ISLAND                   
            WA
NOAA Chart: 18428                           Latitude:   48° 17.2' N (  48.28670)
USGS Quad:  DECEPTION PASS                  Longitude: 122° 37.0' W (-122.61700)


                             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.