U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Datums Page Page 1 of 5
PUBLICATION DATE: 02/22/1990
Station ID: 9414575 SUPERCEDED DATE: 04/21/2003
Name: COYOTE CREEK, ALVISO SLOUGH
CALIFORNIA
NOAA Chart: 18651 Latitude: 37° 27.8' N
USGS Quad: MOUNTAINVIEW Longitude: 122° 1.4' W
To reach the tidal bench marks proceed south on U.S. Highway 101 to SR 237, 3.6
miles (5.8 km) east on SR 237 to stop light, left turn onto Gold Street, two
blocks to dead end, right turn to Alviso Marina, then by boat northwesterly down
Alviso Slough 3.5 miles (5.6 km) to Coyote Creek. The bench marks are along
line of tall power transmission towers across the slough. The tide gage and
staff were located on tower number 323 NEWARIC-MAGNESIUM CIR 2 (southeasternmost
of three towers of the second set NE of the land on the west edge of Alviso
Slough).
T I D A L B E N C H M A R K S
PRIMARY BENCH MARK STAMPING: TIDAL BM 1 1975
MONUMENTATION: Survey Disk VM#: 8354
AGENCY: PID:
SETTING CLASSIFICATION: Concrete
The bench mark is set flush in concrete atop the east corner of the concrete
foundation of the Pacific Gas and Electric Companys power transmission tower
NEWARK-MAGNESIUM 2123 CIR 2, in Coyote Creek at the mouth of Alviso Slough, and
2 feet (1 m) west of the east steel leg of the tower on the centerline of the
east-west diagonal concrete brace.
BENCH MARK STAMPING: NO STAMPING NO 1
MONUMENTATION: Survey Disk VM#: 8355
AGENCY: PID:
SETTING CLASSIFICATION: Concrete
The bench mark is the upper face of a galvanized steel bolt set horizontally in
concrete, on the top of the uppermost bolt supporting the SE side of the ladder
on the west leg of tower NEWARK-MAGNESIUM CIR 2 3123, and that portion of the
bolt immediately adjacent to the concrete foundation.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 2 of 5
PUBLICATION DATE: 02/22/1990
Station ID: 9414575 SUPERCEDED DATE: 04/21/2003
Name: COYOTE CREEK, ALVISO SLOUGH
CALIFORNIA
NOAA Chart: 18651 Latitude: 37° 27.8' N
USGS Quad: MOUNTAINVIEW Longitude: 122° 1.4' W
T I D A L B E N C H M A R K S
BENCH MARK STAMPING: NO STAMPING NO 2
MONUMENTATION: Survey Disk VM#: 8356
AGENCY: PID:
SETTING CLASSIFICATION: Concrete Foundation
The bench mark is the top of the head of a galvanized lag bolt which is the
northernmost of two in the northeasternmost of two steel brackets attaching the
top of the float well to the concrete foundation structure.
BENCH MARK STAMPING: D 555 1956
MONUMENTATION: Survey Disk VM#: 8357
AGENCY: PID#: HT1412
SETTING CLASSIFICATION: Concrete Base
The bench mark is set in the top of the SE side of the cylindrical concrete base
for the south leg of steel power line transmission tower 3124, 23.6 feet (7.2 m)
NW of the NW edge of the boardwalk, and 4 feet (1 m) above the boardwalk.
BENCH MARK STAMPING: E 555 1956
MONUMENTATION: Survey Disk VM#: 8358
AGENCY: PID#: HT1413
SETTING CLASSIFICATION: Concrete Base
The bench mark is set in the top of the NE side of the cylindrical concrete base
for the east leg of steel power line transmission tower 3124, 18.3 feet (5.6 m)
SE of the SE edge of the boardwalk, and level with the boardwalk.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 3 of 5
PUBLICATION DATE: 02/22/1990
Station ID: 9414575 SUPERCEDED DATE: 04/21/2003
Name: COYOTE CREEK, ALVISO SLOUGH
CALIFORNIA
NOAA Chart: 18651 Latitude: 37° 27.8' N
USGS Quad: MOUNTAINVIEW Longitude: 122° 1.4' W
T I D A L B E N C H M A R K S
BENCH MARK STAMPING: F 555 1956
MONUMENTATION: Survey Disk VM#: 8359
AGENCY: PID#: HT1411
SETTING CLASSIFICATION: Concrete Base
The bench mark is set in the top of the north corner of the concrete base of the
north leg of steel power line transmission tower 3124, 90.3 feet (27.5 m) SE of
the SE edge of the boardwalk leading SE to the tower, and 2.3 feet (0.7 m) above
the ground.
BENCH MARK STAMPING: H 555 1956
MONUMENTATION: Survey Disk VM#: 8360
AGENCY: PID#: HT1409
SETTING CLASSIFICATION: Concrete Base
The bench mark is set in the top of the east corner of the concrete base for the
east steel leg of steel power line transmission tower 3126, 52 feet (16 m) SE of
the SE edge of the boardwalk, and 1.9 feet (0.6 m) above the ground.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 4 of 5
PUBLICATION DATE: 02/22/1990
Station ID: 9414575 SUPERCEDED DATE: 04/21/2003
Name: COYOTE CREEK, ALVISO SLOUGH
CALIFORNIA
NOAA Chart: 18651 Latitude: 37° 27.8' N
USGS Quad: MOUNTAINVIEW Longitude: 122° 1.4' W
T I D A L D A T U M S
Tidal datums at COYOTE CREEK, ALVISO SLOUGH based on:
LENGTH OF SERIES: 13 MONTHS
TIME PERIOD: MARCH 1975-MARCH 1976
TIDAL EPOCH: 1960-1978
CONTROL TIDE STATION: 9414750 ALAMEDA
Elevations of tidal datums referred to Mean Lower Low Water (MLLW), in FEET:
HIGHEST OBSERVED WATER LEVEL (12/03/1983) = 12.51
MEAN HIGHER HIGH WATER MHHW = 9.00
MEAN HIGH WATER MHW = 8.40
MEAN TIDE LEVEL MTL = 4.83
MEAN LOW WATER MLW = 1.25
MEAN LOWER LOW WATER MLLW = 0.00
LOWEST OBSERVED WATER LEVEL (06/02/1977) = -2.18
North American Vertical Datum (NAVD88)
Bench Mark Elevation Information In FEET above:
Stamping or Designation MLLW MHW
TIDAL BM 1 1975 18.25 9.85
NO STAMPING NO 1 17.18 8.78
NO STAMPING NO 2 18.23 9.83
D 555 1956 17.66 9.26
E 555 1956 15.25 6.85
F 555 1956 11.34 2.94
H 555 1956 8.36 -0.04
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 5 of 5
PUBLICATION DATE: 02/22/1990
Station ID: 9414575 SUPERCEDED DATE: 04/21/2003
Name: COYOTE CREEK, ALVISO SLOUGH
CALIFORNIA
NOAA Chart: 18651 Latitude: 37° 27.8' N
USGS Quad: MOUNTAINVIEW Longitude: 122° 1.4' 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.