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Bench Mark Sheet for 9415477, SAND POINT, TOMALES BAY CA

Superseded Epoch

Large map location marker Station Location
Small red map location marker Published bench mark
Small blue map location marker Unpublished bench mark

Bench mark positions only appear on the map if their coordinates in the CO-OPS database are at the precision of degrees/minutes/seconds/and tenths of seconds. If the coordinates are less precise, the mark will not appear.

Printable version

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

                                                                                
Station ID: 9415477                         PUBLICATION DATE:  03/14/2006
Name:       SAND POINT, TOMALES BAY                           
            CA
NOAA Chart: 18643                           Latitude:   38° 13.9' N (  38.23170)
USGS Quad:  TOMALES                         Longitude: 122° 58.1' W (-122.96800)


To reach the tidal bench marks from Dillon Beach, proceed SW 0.32 km (0.2 mi)
along the beach road known as Cliff Street from Lawsons Store in Dillons Beach. 
The tide gage is located on the south end of the beach. The bench marks are
located near the pier. 


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


                 PRIMARY BENCH MARK STAMPING:  5477 A 1993
                         DESIGNATION:          941 5477 A

MONUMENTATION:           Tidal Station disk                    VM#:        15723
AGENCY:                  National Ocean Service (NOS)          IDB PID#:        
SETTING CLASSIFICATION:  Concrete fuel bunker                  OPUS PID:        
LATITUDE:   38° 13.9' N (  38.23170)          LONGITUDE: 122° 58.1' W (-122.96800)


The primary bench mark is a disk set in the top of the SW corner of a concrete
fuel bunker located on the west side of the inshore end of the pier, 16.76 m
(55.0 ft) south (180  magnetic) from the SE corner of Lawsons Landing boathouse,
8.23 m (27.0 ft) west (270  magnetic) from the centerline of the pier, and 1.83
m (6.0 ft) above grade.

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

                                                                                
Station ID: 9415477                         PUBLICATION DATE:  03/14/2006
Name:       SAND POINT, TOMALES BAY                           
            CA
NOAA Chart: 18643                           Latitude:   38° 13.9' N (  38.23170)
USGS Quad:  TOMALES                         Longitude: 122° 58.1' W (-122.96800)


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


                         BENCH MARK STAMPING:  5477 B 1993
                         DESIGNATION:          941 5477 B

MONUMENTATION:           Tidal Station disk                    VM#:        15724
AGENCY:                  National Ocean Service (NOS)          IDB PID#:        
SETTING CLASSIFICATION:  Unspecified deep rod                  OPUS PID#: BBCN52
LATITUDE:   38° 13.9' N (  38.23170)          LONGITUDE: 122° 58.1' W (-122.96800)


The bench mark is a disk located on the east side of the main road 0.16 km (0.10
mi) north of the end of the pier, 34.44 m (113.0 ft) NE (060  magnetic) from the
center of the y-intersection of the main, paved, and graveled road, 8.53 m (28.0
ft) east (090  magnetic) from the south corner of a public restroom, and 1.83 m
(6.0 ft) SW (230  magnetic) from power pole #4067.  The bench mark is set flush
with the ground, crimped to the top of a deep rod, hand driven 6.1 m (20 ft) to
refusal, and set in the top of a 0.91 m (3.0 ft) section of a 4-inch ABS pipe
filled with concrete.



                         BENCH MARK STAMPING:  5477 C 1993
                         DESIGNATION:          941 5477 C

MONUMENTATION:           Tidal Station disk                    VM#:        15725
AGENCY:                  National Ocean Service (NOS)          IDB PID#:        
SETTING CLASSIFICATION:  Unspecified deep rod                  OPUS PID:        
LATITUDE:   38° 13.9' N (  38.23170)          LONGITUDE: 122° 58.1' W (-122.96800)


The bench mark is a disk located on the west side of the main road 0.32 km (0.20
mi) north of the end of the pier, 24 m (79 ft) SW (220  magnetic) from power
pole #4065, 10.67 m (35.0 ft) NE (025  magnetic) from a metal power box standing
1.52 m (5.0 ft) high, and 8.84 m (29.0 ft) from the NE corner of a public
restroom.  The bench mark extends 0.15 m (0.5 ft) above ground, crimped to the
top of a deep rod, hand driven 6.7 m (22 ft) to refusal, and set in the top of a
0.61 m (2.0 ft) section of a 4-inch ABS pipe filled with concrete.

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

                                                                                
Station ID: 9415477                         PUBLICATION DATE:  03/14/2006
Name:       SAND POINT, TOMALES BAY                           
            CA
NOAA Chart: 18643                           Latitude:   38° 13.9' N (  38.23170)
USGS Quad:  TOMALES                         Longitude: 122° 58.1' W (-122.96800)


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


                         BENCH MARK STAMPING:  5477 D 1993
                         DESIGNATION:          941 5477 D

MONUMENTATION:           Tidal Station disk                    VM#:        15726
AGENCY:                  National Ocean Service (NOS)          IDB PID#:        
SETTING CLASSIFICATION:  Unspecified deep rod                  OPUS PID:        
LATITUDE:   38° 13.9' N (  38.23170)          LONGITUDE: 122° 58.1' W (-122.96800)


The bench mark is a disk located on the west side of the main road 0.32 km (0.20
mi) north of the end of the pier, 24 m (79 ft) SW (220  magnetic) from power
pole #4065, 10.67 m (35.0 ft) NE (025  magnetic) from a metal power box standing
1.52 m (5.0 ft) high, and 8.84 m (29.0 ft) from the NE corner of a public
restroom.  The bench mark extends 0.09 m (0.3 ft) above ground level, crimped to
the top of a deep rod, hand driven 7 m (23 ft) to refusal, and set in the top of
a 0.76 m (2.5 ft) section of a 4-inch ABS pipe filled with concrete.



                         BENCH MARK STAMPING:  NO 2 1957
                         DESIGNATION:          941 5477 TIDAL 2

MONUMENTATION:           Tidal Station disk                    VM#:        15728
AGENCY:                  US Coast and Geodetic Survey
                         (USC&GS)                              IDB PID#:        
SETTING CLASSIFICATION:  Concrete filled 4-inch tile           OPUS PID:        
LATITUDE:   38° 13.9' N (  38.23170)          LONGITUDE: 122° 58.1' W (-122.96800)


The bench mark is a disk set in top of a concrete filled 4-inch tile located in
the same general vicinity as bench mark NO 1 1957, 89 m (292 ft) NW of the
inshore end of the dock and in range with the inshore end of the dock and Hog
Island just below the top at a small sand dune and projecting 0.30 m (1 ft)
above the ground.

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

                                                                                
Station ID: 9415477                         PUBLICATION DATE:  03/14/2006
Name:       SAND POINT, TOMALES BAY                           
            CA
NOAA Chart: 18643                           Latitude:   38° 13.9' N (  38.23170)
USGS Quad:  TOMALES                         Longitude: 122° 58.1' W (-122.96800)


                            T I D A L   D A T U M S 


Tidal datums at SAND POINT, TOMALES BAY based on:

     LENGTH OF SERIES:      4 MONTHS
     TIME PERIOD:           October 1993 - January 1994
     TIDAL EPOCH:           1983-2001
     CONTROL TIDE STATION:  9415020 POINT REYES, DRAKES BAY


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

     MEAN HIGHER HIGH WATER                     MHHW   =  1.573
     MEAN HIGH WATER                            MHW    =  1.355
     MEAN TIDE LEVEL                            MTL    =  0.827
     MEAN SEA LEVEL                             MSL    =  0.802
     MEAN LOW WATER                             MLW    =  0.298
     MEAN LOWER LOW WATER                       MLLW   =  0.000

North American Vertical Datum (NAVD88)

Bench Mark Elevation Information                In METERS above:

     Stamping or Designation                    MLLW        MHW

     5477 A 1993                                 3.591    2.236
     5477 B 1993                                 3.130    1.775
     5477 C 1993                                 3.189    1.834
     5477 D 1993                                 2.813    1.458
     NO 2 1957                                   4.253    2.898


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

                                                                                
Station ID: 9415477                         PUBLICATION DATE:  03/14/2006
Name:       SAND POINT, TOMALES BAY                           
            CA
NOAA Chart: 18643                           Latitude:   38° 13.9' N (  38.23170)
USGS Quad:  TOMALES                         Longitude: 122° 58.1' W (-122.96800)


                             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.

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Products available at 9415477 SAND POINT, TOMALES BAY, CA

Revised: 08/08/2018
NOAA / National Ocean Service
Web site owner: Center for Operational Oceanographic Products and Services