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Bench Mark Sheet for 9414818, ANGEL ISLAND, EAST GARRISON, S.F. 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Superseded Epoch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Small blue map location marker Unpublished bench mark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: 9414818                         PUBLICATION DATE:  03/09/2004
Name:       ANGEL ISLAND, EAST GARRISON, S.F. BAY             
            CA
NOAA Chart: 18649                           Latitude:   37° 51.8' N (  37.86330)
USGS Quad:  SAN FRANCISCO NORTH             Longitude: 122° 25.2' W (-122.42000)


To reach the tidal bench marks from San Francisco, proceed north by boat (or
alternately, from Sausalito, proceed east by boat) to Quarry Point on the south
side of the Island at Fort McDowell, then proceed east to the east barracks on
the base.  The bench marks are located on Fort Dowell.  The tide gage was
located on an old wooden dock at Old East Garrison of Fort McDowell at Point
Blunt and the staff was 6 m (20 ft) west of the south corner of the dock.


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


                 PRIMARY BENCH MARK STAMPING:  4818 F 1980
                         DESIGNATION:          941 4818 F TIDAL

MONUMENTATION:           Tidal Station disk                    VM#:         8430
AGENCY:                  National Ocean Survey (NOS)           IDB PID#:        
SETTING CLASSIFICATION:  Cement at base of pier                OPUS PID#: BBCN58
LATITUDE:   37° 51.6' N (  37.86000)          LONGITUDE: 122° 26.6' W (-122.44300)


The primary bench mark is a disk set flush in cement at the base of the U.S.
Coast Guard pier located on Point Blunt, Angel Island, on the south side of the
foot of the pier, 3 m (11 ft) north of a short telephone pole with a power box
attatched, and 0.46 m (1.5 ft) west of the southern pier sill.

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

                                                                                
Station ID: 9414818                         PUBLICATION DATE:  03/09/2004
Name:       ANGEL ISLAND, EAST GARRISON, S.F. BAY             
            CA
NOAA Chart: 18649                           Latitude:   37° 51.8' N (  37.86330)
USGS Quad:  SAN FRANCISCO NORTH             Longitude: 122° 25.2' W (-122.42000)


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


                         BENCH MARK STAMPING:  4818 G 1980
                         DESIGNATION:          941 4818 G TIDAL

MONUMENTATION:           Tidal Station disk                    VM#:        15715
AGENCY:                  National Ocean Survey (NOS)           IDB PID#:        
SETTING CLASSIFICATION:  Sand stone ledge                      OPUS PID:        
LATITUDE:   37° 51.6' N (  37.86000)          LONGITUDE: 122° 26.6' W (-122.44300)


The bench mark is a disk set flush with the surface of a grey sandstone ledge,
91 m (300 ft) north of bench mark 4818 F 1980, 54.86 m (180 ft) south of bench
mark 4818 H 1980, 1 m (3 ft) east of the edge of a cliff, 0.3 m (1 ft) above the
approximate mean high water line.  Note: There is a prominent rock ledge due
east of the mark which is exposed at approximate mean high water line.      



                         BENCH MARK STAMPING:  4818 H 1980
                         DESIGNATION:          941 4818 H TIDAL

MONUMENTATION:           Tidal Station disk                    VM#:        15716
AGENCY:                  National Ocean Survey (NOS)           IDB PID#:        
SETTING CLASSIFICATION:  Sandstone bedrock                     OPUS PID:        
LATITUDE:   37° 51.6' N (  37.86000)          LONGITUDE: 122° 26.6' W (-122.44300)


The bench mark is a disk set in a grey sandstone bedrock 1 m (2 ft) above the
mean high water level, 137 m (450 ft) NNW of the end of the Coast Guard Pier,
122 m (400 ft) SSW of bench mark 4818 I 1980, 61 m (200 ft) north of bench mark
4818 G 1980, 27.43 m (90 ft) NW of a 4 m (12 ft) x 4 m (12 ft) ledge of rocks,
and 1 m (2 ft) above the approximate mean high water line.          

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

                                                                                
Station ID: 9414818                         PUBLICATION DATE:  03/09/2004
Name:       ANGEL ISLAND, EAST GARRISON, S.F. BAY             
            CA
NOAA Chart: 18649                           Latitude:   37° 51.8' N (  37.86330)
USGS Quad:  SAN FRANCISCO NORTH             Longitude: 122° 25.2' W (-122.42000)


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


                         BENCH MARK STAMPING:  4818 I 1980
                         DESIGNATION:          941 4818 I TIDAL

MONUMENTATION:           Tidal Station disk                    VM#:        15717
AGENCY:                  National Ocean Survey (NOS)           IDB PID#:        
SETTING CLASSIFICATION:  Boulder                               OPUS PID:        
LATITUDE:   37° 51.6' N (  37.86000)          LONGITUDE: 122° 26.6' W (-122.44300)


The bench mark is a disk set in the western portion of a 4 m (12 ft) x 2 m (6
ft) boulder at approximate mean high water line located on the first prominent
point of land north of the Coast Guard pier at Pt. Blunt,  91 m (300 ft) SSE of
bench mark 4818 J 1980, 122 m (400 ft) NNE of bench mark 4818 H 1980, and 6.80 m
(22.3 ft) SW of a white "KEEP OUT-Do Not Enter Beyond This Point-USCG Station
Pt. Blunt" sign set in concrete in a large boulder.      



                         BENCH MARK STAMPING:  4818 J 1980
                         DESIGNATION:          941 4818 J TIDAL

MONUMENTATION:           Tidal Station disk                    VM#:        15718
AGENCY:                  National Ocean Survey (NOS)           IDB PID#:        
SETTING CLASSIFICATION:  Sand stone outcrop                    OPUS PID:        
LATITUDE:   37° 51.6' N (  37.86000)          LONGITUDE: 122° 26.6' W (-122.44300)


The bench mark is a disk set flush in a sandstone rock surface, 91 m (300 ft)
NNW of bench mark 4818 I 1980, 2 m (5 ft) east of a prominent rock cliff, 1 m (3
ft) east of the range line formed by bench mark 4818 I 1980 and the Echo span of
the Oakland-Bay Bridge (the Echo span is the span just to the west of Yerba
Buena Island), and 1 m (3 ft) above the approximate mean high water line.       


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

                                                                                
Station ID: 9414818                         PUBLICATION DATE:  03/09/2004
Name:       ANGEL ISLAND, EAST GARRISON, S.F. BAY             
            CA
NOAA Chart: 18649                           Latitude:   37° 51.8' N (  37.86330)
USGS Quad:  SAN FRANCISCO NORTH             Longitude: 122° 25.2' W (-122.42000)


                            T I D A L   D A T U M S 


Tidal datums at ANGEL ISLAND, EAST GARRISON, S.F. BAY based on:

     LENGTH OF SERIES:      7 MONTHS
     TIME PERIOD:           May 1980 - November 1980
     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   =  1.799
     MEAN HIGH WATER                            MHW    =  1.616
     MEAN TIDE LEVEL                            MTL    =  0.981
     MEAN SEA LEVEL                             MSL    =  0.972
     MEAN LOW WATER                             MLW    =  0.346
     MEAN LOWER LOW WATER                       MLLW   =  0.000

North American Vertical Datum (NAVD88)

Bench Mark Elevation Information                In METERS above:

     Stamping or Designation                    MLLW        MHW

     4818 F 1980                                 3.445    1.829
     4818 G 1980                                 2.111    0.495
     4818 H 1980                                 2.342    0.726
     4818 I 1980                                 1.793    0.177
     4818 J 1980                                 2.434    0.818


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

                                                                                
Station ID: 9414818                         PUBLICATION DATE:  03/09/2004
Name:       ANGEL ISLAND, EAST GARRISON, S.F. BAY             
            CA
NOAA Chart: 18649                           Latitude:   37° 51.8' N (  37.86330)
USGS Quad:  SAN FRANCISCO NORTH             Longitude: 122° 25.2' W (-122.42000)


                             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 9414818 ANGEL ISLAND, EAST GARRISON, S.F. BAY, CA

Revised: 10/15/2013
NOAA / National Ocean Service
Web site owner: Center for Operational Oceanographic Products and Services