U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Datums Page Page 1 of 4
PUBLICATION DATE: 10/07/1982
Station ID: 9414818 SUPERCEDED DATE: 04/21/2003
Name: ANGEL ISLAND, SAN FRANCISCO BAY
CALIFORNIA
NOAA Chart: 18649 Latitude: 37° 51.8' N
USGS Quad: SAN FRANCISCO NORTH Longitude: 122° 25.1' W
To reach the tidal bench marks proceed north by boat from San Francisco or east
from Sausalito to Quarry Point on south side of the Island at Fort McDowell,
then to east of east barracks on the base. The bench marks are located on the
property of 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 20 feet (0.00 m)
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:
MONUMENTATION: VM#: 8430
AGENCY: PID:
SETTING CLASSIFICATION:
BENCH MARK STAMPING: 5 1936
MONUMENTATION: Survey Disk VM#: 8425
AGENCY: PID#: AC6343
SETTING CLASSIFICATION: Concrete Enclosure
The bench mark is in SE corner of square concrete enclosure on NW side of
sloping gravel road, 200 feet (61 m) SE of Channel Marker N0 5, at Quarry Point,
and 30 feet (9.1 m) SE of SE corner of square concrete block building.
BENCH MARK STAMPING: 6 1936
MONUMENTATION: Survey Disk VM#: 8426
AGENCY: PID#: AC6341
SETTING CLASSIFICATION: Concrete Base
The bench mark is in concrete base with stamp of old flagpole on NE side of
guard house (Building #20) at East Garrison, and 400 feet (122 m) west of Quarry
Point.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 2 of 4
PUBLICATION DATE: 10/07/1982
Station ID: 9414818 SUPERCEDED DATE: 04/21/2003
Name: ANGEL ISLAND, SAN FRANCISCO BAY
CALIFORNIA
NOAA Chart: 18649 Latitude: 37° 51.8' N
USGS Quad: SAN FRANCISCO NORTH Longitude: 122° 25.1' W
T I D A L B E N C H M A R K S
BENCH MARK STAMPING: 7 1936
MONUMENTATION: Survey Disk VM#: 8427
AGENCY: PID#: AC6340
SETTING CLASSIFICATION: Retaining Wall
The bench mark is in top of concrete retaining wall 550 feet (168 m) WNW of
Channel Marker N0 5 at Quarry Point, and 15 feet (4.6 m) south of south entrance
to old mess hall at Old East Garrison.
BENCH MARK STAMPING: 4818 D 1979
MONUMENTATION: Survey Disk VM#: 8428
AGENCY: PID#: AC6342
SETTING CLASSIFICATION: Sand Stone Cliff
The bench mark is set vertically in north face of sand stone cliff, 400 feet
(122 m) WNE of Channel Marker N0 5 at Quarry Point, 85 feet (26 m) WSW of
building marked Director of Supplies, 8 feet (2.4 m) west of chainlink fence and
6.0 feet (1.8 m) above ground level.
BENCH MARK STAMPING: 4818 E 1979
MONUMENTATION: Survey Disk VM#: 8429
AGENCY: PID:
SETTING CLASSIFICATION: Sand Stone Cliff
The bench mark is set horizontally in NW corner of an outcropping of sandstone
cliff, 225 feet (0.00 m) west of Channel Marker N0 5 at Quarry Point, 100 feet
(30.5 m) NW of SE end of cliff, 61 feet (18.6 m) NW of NW corner of square
concrete block building marked Point Storage, and 3 feet (0.00 m) above ground
level.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 3 of 4
PUBLICATION DATE: 10/07/1982
Station ID: 9414818 SUPERCEDED DATE: 04/21/2003
Name: ANGEL ISLAND, SAN FRANCISCO BAY
CALIFORNIA
NOAA Chart: 18649 Latitude: 37° 51.8' N
USGS Quad: SAN FRANCISCO NORTH Longitude: 122° 25.1' W
T I D A L D A T U M S
Tidal datums at ANGEL ISLAND, SAN FRANCISCO BAY based on:
LENGTH OF SERIES: 9 MONTHS
TIME PERIOD: FEBRUARY-OCTOBER 1979
TIDAL EPOCH: 1960-1978
CONTROL TIDE STATION: 9414290 SAN FRANCISCO
Elevations of tidal datums referred to Mean Lower Low Water (MLLW), in FEET:
HIGHEST OBSERVED WATER LEVEL (03/27/1979) = 7.18
MEAN HIGHER HIGH WATER MHHW = 5.92
MEAN HIGH WATER MHW = 5.33
MEAN TIDE LEVEL MTL = 3.25
MEAN LOW WATER MLW = 1.17
MEAN LOWER LOW WATER MLLW = 0.00
LOWEST OBSERVED WATER LEVEL (07/11/1979) = -1.56
North American Vertical Datum (NAVD88)
Bench Mark Elevation Information In FEET above:
Stamping or Designation MLLW MHW
0 0.00 0.00
5 1936 35.61 30.28
6 1936 50.11 44.78
7 1936 71.98 66.65
4818 D 1979 28.80 23.47
4818 E 1979 30.83 25.50
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 4 of 4
PUBLICATION DATE: 10/07/1982
Station ID: 9414818 SUPERCEDED DATE: 04/21/2003
Name: ANGEL ISLAND, SAN FRANCISCO BAY
CALIFORNIA
NOAA Chart: 18649 Latitude: 37° 51.8' N
USGS Quad: SAN FRANCISCO NORTH Longitude: 122° 25.1' 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.