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Datums Page Page 1 of 4
Station ID: 9414958 PUBLICATION DATE: 06/02/2003
Name: BOLINAS, BOLINAS LAGOON
CALIFORNIA
NOAA Chart: 18649 Latitude: 37° 54.6' N
USGS Quad: BOLINAS Longitude: 122° 40.9' W
To reach the tidal bench marks from Stinson Beach, proceed NW along road around
inland perimeter of Bolinas Lagoon, then turn left at end of road and south on a
road leading to Bolina and College of Marin Marine Biological station. The
tidal bench marks were located along the wharf road and on the beach. The tide
station was located on a piling in the channel between Bolina and Kent Island
and the tide staff was located inside below of the "L" shaped dock across the
street from the Marine station.
T I D A L B E N C H M A R K S
PRIMARY BENCH MARK STAMPING: BOLINAS TIDAL 1
DESIGNATION: TIDAL 1
MONUMENTATION: Tidal Station disk VM#: 11860
AGENCY: National Ocean Survey (NOS) PID#: HT1729
SETTING CLASSIFICATION: Concrete wing wall
The primay bench mark is a brass cap set flush in the top of the reinforced
concrete wingwall at the northerly end of timber wall (at the base of the bluff
on the west side of the entrance to the lagoon), and 30 m (100 ft) south from
the south face of the heavy rip-rap at the end of the road leading from the
Village of Bolinas.
BENCH MARK STAMPING: 4958 B 1979
DESIGNATION: 941 4958 B
MONUMENTATION: Tidal Station disk VM#: 11857
AGENCY: National Ocean Survey (NOS) PID:
SETTING CLASSIFICATION: Concrete sea wall
The bench mark is a disk set in top of a concrete seawall, 4 m (13 ft) ENE of
the centerline of Wharf Road, 2.74 m (9.0 ft) NW of the NW corner of the garage
at 95 Wharf Road, and 1.22 m (4.0 ft) NNW of the south end of the seawall.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 2 of 4
Station ID: 9414958 PUBLICATION DATE: 06/02/2003
Name: BOLINAS, BOLINAS LAGOON
CALIFORNIA
NOAA Chart: 18649 Latitude: 37° 54.6' N
USGS Quad: BOLINAS Longitude: 122° 40.9' W
T I D A L B E N C H M A R K S
BENCH MARK STAMPING: 4958 C 1979
DESIGNATION: 941 4958 C
MONUMENTATION: Tidal Station disk VM#: 11858
AGENCY: National Ocean Survey (NOS) PID:
SETTING CLASSIFICATION: Concrete sea wall
The bench mark is a disk set in top of a concrete seawall, 33 m (108 ft) SSE of
the SW corner of the last house on Wharf Road, 12 m (39 ft) NNW of the south end
of the seawall (south end of Wharf Road), and 4.57 m (15.0 ft) ENE of the
centerline of Wharf Road.
BENCH MARK STAMPING: 4958 E 1979
DESIGNATION: 941 4958 E
MONUMENTATION: Tidal Station disk VM#: 11859
AGENCY: National Ocean Survey (NOS) PID:
SETTING CLASSIFICATION: Concrete sea wall
The bench mark is a disk set in top of a concrete bulkhead at the base of the
cliffs along Bolinas Beach, 137 m (450 ft) SSW of the south end of the seawall
at the south end of the Wharf Road, and 0.30 m (1 ft) NE of the SW end of the
U-shaped concrete bulkhead.
BENCH MARK STAMPING: BOLINAS TIDAL 2
DESIGNATION: TIDAL 2
MONUMENTATION: Tidal Station disk VM#: 11861
AGENCY: National Ocean Survey (NOS) PID#: HT1728
SETTING CLASSIFICATION: Concrete curb
The bench mark is a brass cap set flush in the top of the east curb beside the
entrance walk of the Bolina Bay Coast Guard Station, 5.64 m (18.5 ft) east of
the centerline of the station flagpole, and 3.32 m (10.9 ft) from the inner line
of the walk along the Village Street Guard Station.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 3 of 4
Station ID: 9414958 PUBLICATION DATE: 06/02/2003
Name: BOLINAS, BOLINAS LAGOON
CALIFORNIA
NOAA Chart: 18649 Latitude: 37° 54.6' N
USGS Quad: BOLINAS Longitude: 122° 40.9' W
T I D A L D A T U M S
Tidal datums at BOLINAS, BOLINAS LAGOON based on:
LENGTH OF SERIES: 2 MONTHS
TIME PERIOD: November 1979 - December 1979
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) = 1.311
MEAN HIGH WATER (MHW) = 1.120
MEAN TIDE LEVEL (MTL) = 0.667
MEAN SEA LEVEL (MSL) = 0.667
MEAN LOW WATER (MLW) = 0.214
MEAN LOWER LOW WATER (MLLW) = 0.000
National Geodetic Vertical Datum (NGVD 29)
Bench Mark Elevation Information In METERS above:
Stamping or Designation MLLW MHW
BOLINAS TIDAL 1 2.977 1.857
4958 B 1979 3.589 2.469
4958 C 1979 4.314 3.194
4958 E 1979 3.006 1.886
BOLINAS TIDAL 2 2.911 1.791
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 4 of 4
Station ID: 9414958 PUBLICATION DATE: 06/02/2003
Name: BOLINAS, BOLINAS LAGOON
CALIFORNIA
NOAA Chart: 18649 Latitude: 37° 54.6' N
USGS Quad: BOLINAS Longitude: 122° 40.9' 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 (NAVD 88).
NGVD 29 is a fixed datum adopted as a national standard geodetic reference for
heights but is now considered superseded. NGVD 29 is sometimes referred to as
Sea Level Datum of 1929 or as Mean Sea Level on some early issues of Geological
Survey Topographic Quads. NGVD 29 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 NGVD 29 are available from the National
Geodetic Survey (NGS) data base via the World Wide Web at
National Geodetic Survey.
NAVD 88 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. NAVD 88 replaces NGVD 29 as the national
standard geodetic reference for heights. Bench mark elevations relative to
NAVD 88 are available from NGS through the World Wide Web at
National Geodetic Survey.
NGVD 29 and NAVD 88 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 NAVD 88 elevation is shown on the Elevations of Tidal Datums Table Referred
to MLLW only when two or more of the bench marks listed have NAVD 88 elevations.
The NAVD 88 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, NAVD 88 bench mark elevations computed indirectly from the tidal
datums elevation table may differ slightly from NAVD 88 elevations listed for
each bench mark in the NGS database.