U.S. DEPARTMENT OF COMMERCE
                National Oceanic and Atmospheric Administration
                            National Ocean Service
Datums Page                                                        Page  1 of  4

                                                                                
Station ID: 9415447                         PUBLICATION DATE:  02/26/2004
Name:       SONOMA CREEK, WINGO                               
            CA
NOAA Chart: 18654                           Latitude:   38° 12.6' N (  38.21000)
USGS Quad:  SONOMA                          Longitude: 122° 25.6' W (-122.42700)


To reach the tidal bench marks from the intersection of State Routes 121 and 37,
proceed north along Route 121 to Sonoma Rock Company property, then turn right
and proceed east on the driveway and toward the railroad tracks, then turn left
and proceed north along a dirt road to the railroad bridge over the creek.  The
bench marks were located at the Wingo Railroad Bridge and extend south along
dirt road between railroad tracks and Sonoma Creek.  The tide gage and staff
were located on fender piling at NE corner of drawspan of railroad bridge over
creek.


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


                 PRIMARY BENCH MARK STAMPING:  5447 C 1979
                         DESIGNATION:          941 5447 C TIDAL

MONUMENTATION:           Tidal Station disk                    VM#:         8680
AGENCY:                  National Ocean Survey (NOS)           IDB PID#:        
SETTING CLASSIFICATION:  Galvanized steel rod                  OPUS PID:        
LATITUDE:   38° 12.6' N (  38.21000)          LONGITUDE: 122° 25.6' W (-122.42700)


The primary bench mark is a disk located 161 m (528 ft) south along dirt road
from SE end of railroad bridge over creek, 2 m (6 ft) east of eastern edge of
road, and 0.30 m (1 ft) north of wooden post.  The bench mark is set at grade
level, crimped to the top of a galvanized steel deep rod driven 16.5 m (54 ft)
to refusal, encased in PVC pipe.

                          U.S. DEPARTMENT OF COMMERCE
                National Oceanic and Atmospheric Administration
                            National Ocean Service
                                                                   Page  2 of  4

                                                                                
Station ID: 9415447                         PUBLICATION DATE:  02/26/2004
Name:       SONOMA CREEK, WINGO                               
            CA
NOAA Chart: 18654                           Latitude:   38° 12.6' N (  38.21000)
USGS Quad:  SONOMA                          Longitude: 122° 25.6' W (-122.42700)


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


                         BENCH MARK STAMPING:  5447 A 1979
                         DESIGNATION:          941 5447 A TIDAL

MONUMENTATION:           Tidal Station disk                    VM#:         8678
AGENCY:                  National Ocean Survey (NOS)           IDB PID#:        
SETTING CLASSIFICATION:  Pier of railroad bridge               OPUS PID:        
LATITUDE:   38° 12.6' N (  38.21000)          LONGITUDE: 122° 25.6' W (-122.42700)


The bench mark is a disk set on top of the SE pier of the railroad bridge over
Sonoma Creek, 31 m (101 ft) north of south end of bridge, 2 m (6 ft) east of
easternmost rail, 15 cm (0.5 ft) from edge of pier, and 3 cm (0.1 ft) south of
south end of drawspan.



                         BENCH MARK STAMPING:  5447 B 1979
                         DESIGNATION:          941 5447 B TIDAL

MONUMENTATION:           Tidal Station disk                    VM#:         8679
AGENCY:                  National Ocean Survey (NOS)           IDB PID#:        
SETTING CLASSIFICATION:  Galvanized steel rod                  OPUS PID:        
LATITUDE:   38° 12.6' N (  38.21000)          LONGITUDE: 122° 25.6' W (-122.42700)


The bench mark is a disk located 80 m (264 ft) south along the road from the SE
end of railroad bridge, 3 m (10 ft) SW of west side of road, and 0.76 m (2.5 ft)
SW of witness post.  The bench mark is crimped to the top of a galvanized steel
deep rod, driven 14.9 m (49 ft) to refusal, encased in PVC pipe extending 15 cm
(0.5 ft) above grade.

                          U.S. DEPARTMENT OF COMMERCE
                National Oceanic and Atmospheric Administration
                            National Ocean Service
                                                                   Page  3 of  4

                                                                                
Station ID: 9415447                         PUBLICATION DATE:  02/26/2004
Name:       SONOMA CREEK, WINGO                               
            CA
NOAA Chart: 18654                           Latitude:   38° 12.6' N (  38.21000)
USGS Quad:  SONOMA                          Longitude: 122° 25.6' W (-122.42700)


                            T I D A L   D A T U M S 


Tidal datums at SONOMA CREEK, WINGO based on:

     LENGTH OF SERIES:      1 MONTH
     TIME PERIOD:           October 1979 - October 1979
     TIDAL EPOCH:           1983-2001
     CONTROL TIDE STATION:  9414290 SAN FRANCISCO, SAN FRANCISCO BAY


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

     MEAN HIGHER HIGH WATER                     MHHW   =  1.786
     MEAN HIGH WATER                            MHW    =  1.613
     MEAN SEA LEVEL                             MSL    =  0.931
     MEAN TIDE LEVEL                            MTL    =  0.929
     MEAN LOW WATER                             MLW    =  0.245
     MEAN LOWER LOW WATER                       MLLW   =  0.000

North American Vertical Datum (NAVD88)

Bench Mark Elevation Information                In METERS above:

     Stamping or Designation                    MLLW        MHW

     5447 C 1979                                 0.687   -0.926
     5447 A 1979                                 2.251    0.638
     5447 B 1979                                 0.559   -1.054


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

                                                                                
Station ID: 9415447                         PUBLICATION DATE:  02/26/2004
Name:       SONOMA CREEK, WINGO                               
            CA
NOAA Chart: 18654                           Latitude:   38° 12.6' N (  38.21000)
USGS Quad:  SONOMA                          Longitude: 122° 25.6' W (-122.42700)


                             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.