U.S. DEPARTMENT OF COMMERCE
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National Ocean Service
Datums Page Page 1 of 6
Station ID: 9416841 PUBLICATION DATE: 04/21/2003
Name: ARENA COVE, PACIFIC OCEAN
CALIFORNIA
NOAA Chart: 18640 Latitude: 38° 54.8' N
USGS Quad: POINT ARENA Longitude: 123° 42.5' W
To reach the tidal bench marks from Highway 1, turn west on Iversen Ave. and
continue 1.8 km (1.1 mi) to the waterfront. The bench marks are located along
Port Road and Point Arena Creek in the vicinity. The tide house is located at
the end of the Arena Cove Pier.
T I D A L B E N C H M A R K S
PRIMARY BENCH MARK STAMPING: 6 1945
DESIGNATION: 941 6841 TIDAL 6
MONUMENTATION: Tidal Station disk VM#: 1005
AGENCY: US Coast and Geodetic Survey (USC&GS) PID#: JT9392
SETTING CLASSIFICATION: Rock outcrop
The primary bench mark is a disk set in the top of a long narrow rock
outcropping 152 m (500 ft) south of Arena Cove Pier along shoreline, 76 m (250
ft) south of a small stream emptying into the ocean, and 9 m (29 ft) west of the
base of a high cliff.
BENCH MARK STAMPING: 5 1945
DESIGNATION: 941 6841 TIDAL 5
MONUMENTATION: Tidal Station disk VM#: 1006
AGENCY: US Coast and Geodetic Survey (USC&GS) PID#: JT9391
SETTING CLASSIFICATION: Retaining wall
The bench mark is a disk set in the top of a retaining wall east of boat house
at Arena Cove Ocean Fresh Building, just west of the curve in the wall, 3.05 m
(10.0 ft) east from east face of the boat house, and 0.55 m (1.8 ft) north of
the south edge of the wall.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 2 of 6
Station ID: 9416841 PUBLICATION DATE: 04/21/2003
Name: ARENA COVE, PACIFIC OCEAN
CALIFORNIA
NOAA Chart: 18640 Latitude: 38° 54.8' N
USGS Quad: POINT ARENA Longitude: 123° 42.5' W
T I D A L B E N C H M A R K S
BENCH MARK STAMPING: 6841 D 1977
DESIGNATION: 941 6841 D TIDAL
MONUMENTATION: Tidal Station disk VM#: 1007
AGENCY: National Ocean Survey (NOS) PID#: JT9390
SETTING CLASSIFICATION: Concrete step
The bench mark is a disk set in the second lowest concrete step in the stairway
leading to the former Coast Guard Quarters, 0.24 km (0.15 mi) east of the
inshore end of the Arena Cove Pier, 30 m (100 ft) NNE of the centerline of Port
Street which leads to the Arena Cove Pier, 1.83 m (6.0 ft) west of the west
corner of a double doored wooden Arena Cove Lift Boat station, and 0.12 m (0.4
ft) west of the eastern corner of the second step.
BENCH MARK STAMPING: 6841 F 1978
DESIGNATION: 941 6841 F TIDAL
MONUMENTATION: Tidal Station disk VM#: 1009
AGENCY: National Ocean Survey (NOS) PID#: JT9393
SETTING CLASSIFICATION: Rock outcrop
The bench mark is a disk set at the center of a 5 m x 3 m x 2 m (15 ft x 10 ft x
5 ft) high rock outcrop, 198 m (650 ft) south the Arena Cove Pier along
shoreline, 18 m (60 ft) south of a 3 m (10 ft) high rock pinnacle, 47 m (154 ft)
south of bench mark 6 1945, 9 m (30 ft) west of the base of high cliff.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 3 of 6
Station ID: 9416841 PUBLICATION DATE: 04/21/2003
Name: ARENA COVE, PACIFIC OCEAN
CALIFORNIA
NOAA Chart: 18640 Latitude: 38° 54.8' N
USGS Quad: POINT ARENA Longitude: 123° 42.5' W
T I D A L B E N C H M A R K S
BENCH MARK STAMPING: 6841 H 1979
DESIGNATION: 941 6841 H TIDAL
MONUMENTATION: Tidal Station disk VM#: 1011
AGENCY: National Ocean Survey (NOS) PID#: JT9388
SETTING CLASSIFICATION: Copper-clad steel rod
The bench mark is a disk set in the center of a niche at the bottom of a hill,
0.53 km (0.33 mi) east of the inshore end of the Arena Cove Pier, 92 m (302 ft)
east of a 3 m (10 ft) metal water line cover, 67 m (219 ft) west of a 3 m (10
ft) metal water line cover, 18 m (60 ft) SE of the most easterly of four large
Eucalyptus trees, 9 m (30 ft) north of the centerline of Port Road, and 0.46 m
(1.5 ft) north of a 0.10 m x 0.10 m x 1.22 m (0.3 ft x 0.3 ft x 4 ft) high white
redwood witness post. The bench mark is set 6 cm (0.2 ft) below the ground,
crimped to the top of a 5/8-inch copper-clad steel rod driven 2.4 m (8 ft) to
refusal, and encased in a 4-inch PVC pipe.
BENCH MARK STAMPING: 6841 J 1979
DESIGNATION: 941 6841 J TIDAL
MONUMENTATION: Tidal Station disk VM#: 1012
AGENCY: National Ocean Survey (NOS) PID#: JT9387
SETTING CLASSIFICATION: Copper-clad steel rod
The bench mark is a disk located in a planter triangle formed by a split
driveway and Port Road at 240 Port Road, about 0.8 km (0.5 mi) east of the
inshore end of the Arena Cove pier, 11.83 m (38.8 ft) SW of a wood fence corner,
10 m (33 ft) north of the centerline of Port Road, 5 m (16 ft) south of the "Y"
in the driveway, and 1 m (2 ft) west of a 0.10 m x 0.10 m x 1.22 m (0.3 ft x 0.3
ft x 4 ft) high white painted redwood witness post. The bench mark is set 0.46
m (1.5 ft) below ground level, crimped to the top of a 5/8-inch copper-clad
steel rod driven 1.2 m (4 ft) to refusal, and encased in a 4-inch PVC pipe.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 4 of 6
Station ID: 9416841 PUBLICATION DATE: 04/21/2003
Name: ARENA COVE, PACIFIC OCEAN
CALIFORNIA
NOAA Chart: 18640 Latitude: 38° 54.8' N
USGS Quad: POINT ARENA Longitude: 123° 42.5' W
T I D A L B E N C H M A R K S
BENCH MARK STAMPING: 6841 N 1990
DESIGNATION: 941 6841 N
MONUMENTATION: Tidal Station disk VM#: 1015
AGENCY: National Ocean Service (NOS) PID:
SETTING CLASSIFICATION: Concrete bull rail
The bench mark is a disk set in the south concrete bullrail of the Point Arena
Pier, 16 m (53 ft) east of the west end of the pier, 2 m (7 ft) west of the base
of a crane on the south side of the pier, and 0.15 m (0.5 ft) north of the south
face of the pier.
BENCH MARK STAMPING: 6841 Q 1991
DESIGNATION: 941 6841 Q
MONUMENTATION: Tidal Station disk VM#: 3124
AGENCY: National Ocean Service (NOS) PID:
SETTING CLASSIFICATION: Concrete slab
The bench mark is a disk set in the NW corner of a 1.68 m x 1.37 m (5.5 ft x 4.5
ft) concrete service access panel, 3 m (9 ft) south of street lamp pole No. 32,
2.26 m (7.4 ft) east of a 2 m (7 ft) diameter circular sewer access with a
4-inch goose neck vent pipe.
BENCH MARK STAMPING: 6841 R 1991
DESIGNATION: 941 6841 R
MONUMENTATION: Tidal Station disk VM#: 3125
AGENCY: National Ocean Service (NOS) PID:
SETTING CLASSIFICATION: Rock outcrop
The bench mark is a disk set in a 4 m x 3 m x 1 m (12 ft x 8 ft x 3 ft) bedrock
outcrop mid-way along the rock cliff, 244 m (800 ft) south of Arena Cove Pier,
53 m (174 ft) south of bench mark 6841 F 1978, 18 m (60 ft) inshore of three
kelp covered rocks awash, and 7 m (23 ft) west of the rock cliff.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 5 of 6
Station ID: 9416841 PUBLICATION DATE: 04/21/2003
Name: ARENA COVE, PACIFIC OCEAN
CALIFORNIA
NOAA Chart: 18640 Latitude: 38° 54.8' N
USGS Quad: POINT ARENA Longitude: 123° 42.5' W
T I D A L D A T U M S
Tidal datums at ARENA COVE, PACIFIC OCEAN based on:
LENGTH OF SERIES: 12 Years
TIME PERIOD: January 1991 - December 2002
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:
HIGHEST OBSERVED WATER LEVEL (02/06/1998) = 2.635
MEAN HIGHER HIGH WATER (MHHW) = 1.792
MEAN HIGH WATER (MHW) = 1.587
MEAN TIDE LEVEL (MTL) = 0.971
MEAN SEA LEVEL (MSL) = 0.960
MEAN LOW WATER (MLW) = 0.354
NORTH AMERICAN VERTICAL DATUM-1988 (NAVD) = 0.037
MEAN LOWER LOW WATER (MLLW) = 0.000
LOWEST OBSERVED WATER LEVEL (12/03/1990) = -0.776
National Geodetic Vertical Datum (NGVD 29)
Bench Mark Elevation Information In METERS above:
Stamping or Designation MLLW MHW
6 1945 2.778 1.191
5 1945 6.234 4.647
6841 D 1977 7.450 5.863
6841 F 1978 2.987 1.400
6841 H 1979 7.718 6.131
6841 J 1979 13.955 12.368
6841 N 1990 8.697 7.110
6841 Q 1991 5.085 3.498
6841 R 1991 2.758 1.171
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 6 of 6
Station ID: 9416841 PUBLICATION DATE: 04/21/2003
Name: ARENA COVE, PACIFIC OCEAN
CALIFORNIA
NOAA Chart: 18640 Latitude: 38° 54.8' N
USGS Quad: POINT ARENA Longitude: 123° 42.5' 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.