U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Datums Page Page 1 of 7
Station ID: 9414958 PUBLICATION DATE: 09/07/2018
Name: BOLINAS, BOLINAS LAGOON
CA
NOAA Chart: 18649 Latitude: 37° 54.5' N ( 37.90778)
USGS Quad: BOLINAS Longitude: 122° 40.7' W (-122.67861)
To reach the tidal bench marks from US Highway 101travel NW to Stinson Beach,
turn west onto Calle Del Arroyo, Continue NW approximately 300 meters until you
reach the security gate for the Seadrift Community, pass throught the gate and
veer right on Seadrift Road, travel approximately 0.3 miles to the community
recreation center on the right side of the road, near the tennis courts. The
tide gauge is located behind the building housing the bathrooms. The bench
marks are located along the sea wall, near the end of Seadrift Road, and in the
town of Bolinas.
T I D A L B E N C H M A R K S
PRIMARY BENCH MARK STAMPING: 4958 F 2009
DESIGNATION: 941 4958 F
MONUMENTATION: Tidal Station disk VM#: 19225
AGENCY: National Ocean Survey (NOS) IDB PID#:
SETTING CLASSIFICATION: Stainless steel rod OPUS PID#: BBBK98
LATITUDE: 37° 54.4' N ( 37.90733) LONGITUDE: 122° 40.7' W (-122.67894)
The primary bench mark is a metal rod set 41.50 m (136.2 ft) west of the SW
corner of tennis court "3", 30.70 m (100.7 ft) NW of the north corner of a fence
located at 358 Seadrift Road, and 12.25 m (40.2 ft) south of the southern most
gate post marking a sand road leading to the Bolinas Channel. The datum point is
the top of a stainless steel deep rod driven 15.1 m (49.7 ft) to refusal and
encased in a 6" PVC in a concrete kick block.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 2 of 7
Station ID: 9414958 PUBLICATION DATE: 09/07/2018
Name: BOLINAS, BOLINAS LAGOON
CA
NOAA Chart: 18649 Latitude: 37° 54.5' N ( 37.90778)
USGS Quad: BOLINAS Longitude: 122° 40.7' W (-122.67861)
T I D A L B E N C H M A R K S
BENCH MARK STAMPING: 4958 B 1979
DESIGNATION: 941 4958 B
MONUMENTATION: Tidal Station disk VM#: 11857
AGENCY: National Ocean Survey (NOS) IDB PID#:
SETTING CLASSIFICATION: Concrete sea wall OPUS PID:
LATITUDE: 37° 54.6' N ( 37.90994) LONGITUDE: 122° 41.0' W (-122.68286)
The bench mark is a disk set in top of a concrete seawall, 4.00 m (13.1 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.
BENCH MARK STAMPING: 4958 C 1979
DESIGNATION: 941 4958 C
MONUMENTATION: Tidal Station disk VM#: 11858
AGENCY: National Ocean Survey (NOS) IDB PID#:
SETTING CLASSIFICATION: Concrete sea wall OPUS PID:
LATITUDE: 37° 54.5' N ( 37.90864) LONGITUDE: 122° 40.9' W (-122.68214)
The bench mark is a disk set in top of a concrete seawall, 33.00 m (108.3 ft)
SSE of the SW corner of the last house on Wharf Road, 12.00 m (39.4 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.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 3 of 7
Station ID: 9414958 PUBLICATION DATE: 09/07/2018
Name: BOLINAS, BOLINAS LAGOON
CA
NOAA Chart: 18649 Latitude: 37° 54.5' N ( 37.90778)
USGS Quad: BOLINAS Longitude: 122° 40.7' W (-122.67861)
T I D A L B E N C H M A R K S
BENCH MARK STAMPING: BOLINAS TIDAL 2
DESIGNATION: TIDAL 2
MONUMENTATION: Tidal Station disk VM#: 11861
AGENCY: National Ocean Survey (NOS) IDB PID#: HT1728
SETTING CLASSIFICATION: Concrete curb wall OPUS PID:
LATITUDE: 37° 54.6' N ( 37.91003) LONGITUDE: 122° 41.0' W (-122.68403)
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.
BENCH MARK STAMPING: 4958 G 2009
DESIGNATION: 941 4958 G
MONUMENTATION: Tidal Station disk VM#: 19226
AGENCY: National Ocean Survey (NOS) IDB PID#:
SETTING CLASSIFICATION: Sea wall OPUS PID#: BBDZ03
LATITUDE: 37° 54.5' N ( 37.90814) LONGITUDE: 122° 40.7' W (-122.67853)
The bench mark is a disk set in centerline on top of a concrete seawall along
the lagoon basin a top of sheet-pile, 24.50 m (80.4 ft) NW of a flag pole
located on the east side of the Seadrift Association bath house, 14.20 m (46.6
ft) north of the NW corner of a of the Seadrift Association bath house, and 5.66
m (18.6 ft) NE of the west corner end of the seawall.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 4 of 7
Station ID: 9414958 PUBLICATION DATE: 09/07/2018
Name: BOLINAS, BOLINAS LAGOON
CA
NOAA Chart: 18649 Latitude: 37° 54.5' N ( 37.90778)
USGS Quad: BOLINAS Longitude: 122° 40.7' W (-122.67861)
T I D A L B E N C H M A R K S
BENCH MARK STAMPING: 4958 H 2009
DESIGNATION: 941 4958 H
MONUMENTATION: Tidal Station disk VM#: 19227
AGENCY: National Ocean Survey (NOS) IDB PID#:
SETTING CLASSIFICATION: Sea wall OPUS PID:
LATITUDE: 37° 54.5' N ( 37.90800) LONGITUDE: 122° 40.7' W (-122.67803)
The bench mark is set in centerline on top of a concrete seawall along the
lagoon basin a top of sheet-pile, 30.45 m (99.9 ft) NE of a flagpole located on
the east side of the Seadrift Association bath house, 14.29 m (32.8 ft) west of
the inside corner of a bend in the concrete cap, and 3.3 m (10.8 ft) north of
the NE corner of a 10 ft by 8 ft concrete slab located south of cap .
BENCH MARK STAMPING: 4958 J 2009
DESIGNATION: 941 4958 J
MONUMENTATION: Tidal Station disk VM#: 19228
AGENCY: National Ocean Service (NOS) IDB PID#:
SETTING CLASSIFICATION: Concrete sea wall OPUS PID:
LATITUDE: 37° 54.5' N ( 37.90786) LONGITUDE: 122° 40.6' W (-122.67750)
The bench mark is a disk set in centerline on top of a concrete seawall along
the lagoon basin a top of sheet-pile, 12.8 m west of the property line between
345 Seadrift and 347 (vacant lot) Seadrift Avenue, 10.00 m (32.8 ft) east of the
property line between 345 Seadrift and 347 (vacant lot) Seadrift Avenue, and
0.52 m (1.7 ft) south of north edge of a concrete cap of the seawall of the
lagoon,.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 5 of 7
Station ID: 9414958 PUBLICATION DATE: 09/07/2018
Name: BOLINAS, BOLINAS LAGOON
CA
NOAA Chart: 18649 Latitude: 37° 54.5' N ( 37.90778)
USGS Quad: BOLINAS Longitude: 122° 40.7' W (-122.67861)
T I D A L B E N C H M A R K S
BENCH MARK STAMPING: 4958 K 2013
DESIGNATION: 941 4958 K
MONUMENTATION: Tidal Station disk VM#: 20643
AGENCY: National Ocean Service (NOS) IDB PID#:
SETTING CLASSIFICATION: Concrete foundation OPUS PID:
LATITUDE: 37° 54.4' N ( 37.90742) LONGITUDE: 122° 40.7' W (-122.67811)
The bench mark is a disk set in top of a concrete foundation for the fence
around the tennis court at Seadrift community beach, located at base of fourth
fence post north of SE corner of court, 26.73 m (87.7 ft) WNW of a yellow fire
hydrant at entrance to parking area, 24.33 m (79.8 ft) south of the NE corner of
tennis court, 12.40 m (40.7 ft) north of the SE corner of court, 0.20 m (0.7 ft)
east of east edge of court.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 6 of 7
Station ID: 9414958 PUBLICATION DATE: 09/07/2018
Name: BOLINAS, BOLINAS LAGOON
CA
NOAA Chart: 18649 Latitude: 37° 54.5' N ( 37.90778)
USGS Quad: BOLINAS Longitude: 122° 40.7' W (-122.67861)
T I D A L D A T U M S
Tidal datums at BOLINAS, BOLINAS LAGOON based on:
LENGTH OF SERIES: 7 years
TIME PERIOD: Jul 2009 - Jun 2011, Dec 2012 - Nov 2017
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:
HIGHEST OBSERVED WATER LEVEL (03/20/2011) = 2.105
MEAN HIGHER HIGH WATER MHHW = 1.303
MEAN HIGH WATER MHW = 1.117
MEAN SEA LEVEL MSL = 0.681
MEAN TIDE LEVEL MTL = 0.672
MEAN LOW WATER MLW = 0.228
MEAN LOWER LOW WATER MLLW = 0.000
North American Vertical Datum NAVD88 = -0.341
LOWEST OBSERVED WATER LEVEL (06/07/2012) = -0.361
North American Vertical Datum (NAVD88)
Bench Mark Elevation Information In METERS above:
Stamping or Designation MLLW MHW
4958 F 2009 4.114 2.997
4958 B 1979 3.650 2.533
4958 C 1979 4.381 3.264
BOLINAS TIDAL 2 2.956 1.839
4958 G 2009 2.749 1.632
4958 H 2009 2.740 1.623
4958 J 2009 2.715 1.598
4958 K 2013 3.186 2.069
Foot Notes:
Bench mark BOLINAS TIDAL 2 is based on one differential leveling connection and
does not meet the quality control standards of the NOS. Therefore, caution
should be used when deriving elevations for this mark.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 7 of 7
Station ID: 9414958 PUBLICATION DATE: 09/07/2018
Name: BOLINAS, BOLINAS LAGOON
CA
NOAA Chart: 18649 Latitude: 37° 54.5' N ( 37.90778)
USGS Quad: BOLINAS Longitude: 122° 40.7' W (-122.67861)
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.