Superseded Bench Mark Sheet for 9413623, ELKHORN SLOUGH, ENTRANCE BRIDGE CA

Present Epoch

Printable version

                          U.S. DEPARTMENT OF COMMERCE
                National Oceanic and Atmospheric Administration
                            National Ocean Service
Datums Page                                                        Page  1 of  5

                                                   PUBLICATION DATE:  05/19/1982
Station ID: 9413623                                SUPERCEDED DATE:   04/21/2003
Name:       ELKHORN SLOUGH HIGHWAY 1 BRIDGE,MOSS LANDING      
            CALIFORNIA
NOAA Chart: 18685                                  Latitude:         36° 48.6' N
USGS Quad:  MOSS LANDING                           Longitude:       121° 47.1' W


To reach the tidal bench marks proceed 0.2 mile north from the Elkhorn Slough
Highway Bridge along Highway 1 on Pauls Island thence west on road to the yacht
club.  The tide gage and staff were located west of west side of bridge near
floating fish pier.


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


                 PRIMARY BENCH MARK STAMPING:  3623 A 1976

MONUMENTATION:           Survey Disk                               VM#:     8057
AGENCY:                                                            PID:         
SETTING CLASSIFICATION:  Abutment


The bench mark is set horizontally in the abutment at the north end of bridge,
on west of Highway 1 bridge across slough, 75 feet northeast from front door of
Harbor Inn, 17.5 feet south southwest from centerline of bridge, 1.5 feet south
of concrete seawall running west from north end of the bridge and 3.7 feet below
level of curb.



                         BENCH MARK STAMPING:  3623 C 1976

MONUMENTATION:           Survey Disk                               VM#:     8058
AGENCY:                                                            PID:         
SETTING CLASSIFICATION:  Copper-Clad Steel Rod


The bench mark is set on a copper- clad steel rod driven to 60 feet, inside a
PVC pipe, on east side of Highway 1 (Cabrillo Highway), 650 feet north of Bench
Mark 3623 A 1976, 600 feet north of bridge over slough, 375 feet southwest of
Bench Mark 3623 D 1976, 80 feet west of wood bulkhead of salt pond, 43 feet east
of centerline of Highway 1, 1.5 feet south of a telephone pole and level with
ground.

                          U.S. DEPARTMENT OF COMMERCE
                National Oceanic and Atmospheric Administration
                            National Ocean Service
                                                                   Page  2 of  5

                                                   PUBLICATION DATE:  05/19/1982
Station ID: 9413623                                SUPERCEDED DATE:   04/21/2003
Name:       ELKHORN SLOUGH HIGHWAY 1 BRIDGE,MOSS LANDING      
            CALIFORNIA
NOAA Chart: 18685                                  Latitude:         36° 48.6' N
USGS Quad:  MOSS LANDING                           Longitude:       121° 47.1' W


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


                         BENCH MARK STAMPING:  3623 D 1976

MONUMENTATION:           Survey Disk                               VM#:     8059
AGENCY:                                                            PID:         
SETTING CLASSIFICATION:  Copper-Clad Steel Rod


The bench mark is set in a copper-clad steel rod, inside a PVC pipe, on the east
side of the highway near the Monterey Bay Salt Company Office, 0.2 mile north of
Highway 1 across the slough, 600 feet southeast of Bench Mark 3623 E 1976, 375
feet northeast of Bench Mark 3623 C 1976, 250 feet east of the centerline of
Highway 1, 35.6 feet north of a wooden power pole, and 11.7 feet northwest of
the southwest corner of the Office.



                         BENCH MARK STAMPING:  3623 E 1976

MONUMENTATION:           Survey Disk                               VM#:     8060
AGENCY:                                                            PID:         
SETTING CLASSIFICATION:  Copper-Clad Steel Rod


The bench mark is set on a copper-clad steel rod driven to 40 feet, inside a PVC
pipe, on the west side of Highway 1, on north side of access road to Moss
Landing Yacht Club, 0.3 mile north of bridge across the slough, 241 feet west of
center of highway, 236 feet east of entrance gate of yacht club piers, 50 feet
north of northeast corner of fenced boat storage area, and 1.7 feet north of a
telephone pole.

                          U.S. DEPARTMENT OF COMMERCE
                National Oceanic and Atmospheric Administration
                            National Ocean Service
                                                                   Page  3 of  5

                                                   PUBLICATION DATE:  05/19/1982
Station ID: 9413623                                SUPERCEDED DATE:   04/21/2003
Name:       ELKHORN SLOUGH HIGHWAY 1 BRIDGE,MOSS LANDING      
            CALIFORNIA
NOAA Chart: 18685                                  Latitude:         36° 48.6' N
USGS Quad:  MOSS LANDING                           Longitude:       121° 47.1' W


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


                         BENCH MARK STAMPING:  PURPLE 1972

MONUMENTATION:           Survey Disk                               VM#:     8061
AGENCY:                                                            PID:         
SETTING CLASSIFICATION:  Concrete Pad


The bench mark is set in a concrete pad 250 feet south southwest of the west
northwest of northwest corner of the Highway 1 bridge over the slough, 23.5 feet
east northeast of the center of the main door to Skippers Restaurant, 4.3 feet
north northeast of fence post on the south side of the sidewalk, and 0.6 foot
from the south edge of the sidewalk.



                         BENCH MARK STAMPING:  UNSTAMPED

MONUMENTATION:           Survey Disk                               VM#:     8062
AGENCY:                                                            PID:         
SETTING CLASSIFICATION:  Retaining Wall


The bench mark is in top of a concrete bridge retaining wall along Highway 1, at
the northeast corner of Highway bridge over the slough and 0.45 mile north of
Dolan Road.

                          U.S. DEPARTMENT OF COMMERCE
                National Oceanic and Atmospheric Administration
                            National Ocean Service
                                                                   Page  4 of  5

                                                   PUBLICATION DATE:  05/19/1982
Station ID: 9413623                                SUPERCEDED DATE:   04/21/2003
Name:       ELKHORN SLOUGH HIGHWAY 1 BRIDGE,MOSS LANDING      
            CALIFORNIA
NOAA Chart: 18685                                  Latitude:         36° 48.6' N
USGS Quad:  MOSS LANDING                           Longitude:       121° 47.1' W


                            T I D A L   D A T U M S 


Tidal datums at ELKHORN SLOUGH HIGHWAY 1 BRIDGE,MOSS LANDING based on:

     LENGTH OF SERIES:      4 MONTHS
     TIME PERIOD:           JUNE-JULY 1976, MAY-JUNE 1977
     TIDAL EPOCH:           1960-1978
     CONTROL TIDE STATION:  9413450 MONTEREY


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

     MEAN HIGHER HIGH WATER                     MHHW   =   5.33
     MEAN HIGH WATER                            MHW    =   4.64
     MEAN TIDE LEVEL                            MTL    =   2.86
   * NATIONAL GEODETIC VERTICAL DATUM           NGVD29 =   2.70
     MEAN LOW WATER                             MLW    =   1.08
   * North American Vertical Datum              NAVD88 =   0.00
     MEAN LOWER LOW WATER                       MLLW   =   0.00

   * NGVD reference based on adjustment of 1961 and NOS levels of 1976-78. 


Bench Mark Elevation Information                In FEET above:

     Stamping or Designation                    MLLW        MHW

     3623 A 1976                                 8.77      4.13
     3623 C 1976                                 6.99      2.35
     3623 D 1976                                 7.84      3.20
     3623 E 1976                                10.72      6.08
     PURPLE 1972                                 8.63      3.99
     UNSTAMPED                                  11.29      6.65


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

                                                   PUBLICATION DATE:  05/19/1982
Station ID: 9413623                                SUPERCEDED DATE:   04/21/2003
Name:       ELKHORN SLOUGH HIGHWAY 1 BRIDGE,MOSS LANDING      
            CALIFORNIA
NOAA Chart: 18685                                  Latitude:         36° 48.6' N
USGS Quad:  MOSS LANDING                           Longitude:       121° 47.1' 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.

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