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

                                                   PUBLICATION DATE:  02/15/1985
Station ID: 9415096                                SUPERCEDED DATE:   04/21/2003
Name:       PITTSBURG, NEW YORK SLOUGH, SUISUN BAY            
            CALIFORNIA
NOAA Chart: 18656                                  Latitude:         38°  2.2' N
USGS Quad:  HONKER BAY                             Longitude:       121° 52.8' W


To reach the tidal bench marks proceed east on Highway 4 to Railroad Avenue exit
in Pittsburg, Railroad Avenue north to Third Street and then left turn into dirt
parking lot opposite the John S. Manville Plant.  The tide gage and staff were
located on the Diablo Service Corporation mooring wharf on the west reach of New
York Slough.


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


                 PRIMARY BENCH MARK STAMPING:  TIDAL 4 1937

MONUMENTATION:           Survey Disk                               VM#:     8535
AGENCY:                                                            PID#:  JS1881
SETTING CLASSIFICATION:  Concrete Step


The bench mark is set in top of the south end of the top concrete step at the
post office leading to the basement on the north side of the building, 27 feet
(8 m) east of the NW corner of the building, 0.4 foot (0.1 m) north of the north
wall, and 1 foot (0.3 m) above the road.



                         BENCH MARK STAMPING:  5096 A 1979

MONUMENTATION:           Survey Disk                               VM#:     8536
AGENCY:                                                            PID:         
SETTING CLASSIFICATION:  Copper-coated Steel Rod


The bench mark is on the Diablo Service Corporation property, 135 feet (41.1 m)
NNW of the corner of the chain link fence at the east end of First Street, 23
feet (7 m) SSE of the shore and a small dock with concrete deck, and 1.5 feet
(0.5 m) SSW of a power pole.  The bench mark is on a rod driven 24 feet (7 m)
and encased in a PVC pipe projecting 1.5 feet (0.5 m) above the grade.

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

                                                   PUBLICATION DATE:  02/15/1985
Station ID: 9415096                                SUPERCEDED DATE:   04/21/2003
Name:       PITTSBURG, NEW YORK SLOUGH, SUISUN BAY            
            CALIFORNIA
NOAA Chart: 18656                                  Latitude:         38°  2.2' N
USGS Quad:  HONKER BAY                             Longitude:       121° 52.8' W


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


                         BENCH MARK STAMPING:  5096 B 1979

MONUMENTATION:           Survey Disk                               VM#:     8537
AGENCY:                                                            PID:         
SETTING CLASSIFICATION:  Building Ledge


The bench mark is set in the top of the ledge on the north side of the old bank
building, 81.5 feet (24.8 m) ESE of the centerline of Railroad Avenue, 25 feet
(8 m) SSW of the centerline of Fourth Street, 8 feet (2.4 m) WSW of the NE
corner of the building, and 2 feet (1 m) above the sidewalk.



                         BENCH MARK STAMPING:  5096 D 1979

MONUMENTATION:           Survey Disk                               VM#:     8538
AGENCY:                                                            PID:         
SETTING CLASSIFICATION:  Copper-coated Steel Rod


The bench mark is located in the back of the parking lot in an island at the
Pittsburg Post Office at 835 Railroad Avenue, 79 feet (24 m) SSW of the SW
corner of the post office, 43 feet (13 m) ESE of the centerline of Railroad
Avenue, and 1.2 feet (0.4 m) SSW of the driveway curb.  The bench mark is on a
copper-coated steel rod driven 13 feet (4 m) to refusal and encased in a PVC
pipe projecting 0.5 foot (0.2 m) above the grade.



                         BENCH MARK STAMPING:  R 10 1930

MONUMENTATION:           Survey Disk                               VM#:     8539
AGENCY:                                                            PID#:  JS1883
SETTING CLASSIFICATION:  Concrete Wall


The bench mark is set in top of the concrete retaining wall along the north side
of the Southern Pacific Company Railroad track, 54.5 feet (16.6 m) east of
milepole 49, 31.8 feet (9.7 m) north of the north rail of the main track, 16
feet (5 m) east of a large pole for the loading crane, 4.9 feet (1.5 m) west of
the east end of the retaining wall, and 3.5 feet (1.1 m) above the track.

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

                                                   PUBLICATION DATE:  02/15/1985
Station ID: 9415096                                SUPERCEDED DATE:   04/21/2003
Name:       PITTSBURG, NEW YORK SLOUGH, SUISUN BAY            
            CALIFORNIA
NOAA Chart: 18656                                  Latitude:         38°  2.2' N
USGS Quad:  HONKER BAY                             Longitude:       121° 52.8' W


                            T I D A L   D A T U M S 


Tidal datums at PITTSBURG, NEW YORK SLOUGH, SUISUN BAY based on:

     LENGTH OF SERIES:      5 MONTHS
     TIME PERIOD:           APRIL-AUGUST 1979
     TIDAL EPOCH:           1960-1978
     CONTROL TIDE STATION:  9415111 BENICIA, CA


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

     HIGHEST OBSERVED WATER LEVEL (08/07/1979)         =   4.84
     MEAN HIGHER HIGH WATER                     MHHW   =   4.14
     MEAN HIGH WATER                            MHW    =   3.64
     MEAN TIDE LEVEL                            MTL    =   2.13
   * NATIONAL GEODETIC VERTICAL DATUM           NGVD29 =   1.14
     MEAN LOW WATER                             MLW    =   0.62
     MEAN LOWER LOW WATER                       MLLW   =   0.00
     LOWEST  OBSERVED WATER LEVEL (04/19/1979)         =  -0.93

   * NGVD reference based on adjustment of 1967 and NOS levels of 1979. 
North American Vertical Datum (NAVD88)

Bench Mark Elevation Information                In FEET above:

     Stamping or Designation                    MLLW        MHW

     TIDAL 4 1937                               23.41     19.77
     5096 A 1979                                 6.26      2.62
     5096 B 1979                                21.89     18.25
     5096 D 1979                                25.06     21.42
     R 10 1930                                  33.67     30.03


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

                                                   PUBLICATION DATE:  02/15/1985
Station ID: 9415096                                SUPERCEDED DATE:   04/21/2003
Name:       PITTSBURG, NEW YORK SLOUGH, SUISUN BAY            
            CALIFORNIA
NOAA Chart: 18656                                  Latitude:         38°  2.2' N
USGS Quad:  HONKER BAY                             Longitude:       121° 52.8' 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 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 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.