U.S. DEPARTMENT OF COMMERCE
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National Ocean Service
Datums Page Page 1 of 9
Station ID: 9418767 PUBLICATION DATE: 10/06/2011
Name: NORTH SPIT, HUMBOLDT BAY
CA
NOAA Chart: 18622 Latitude: 40° 46.0' N ( 40.76670)
USGS Quad: EUREKA Longitude: 124° 13.0' W (-124.21700)
To reach the tidal bench marks from the U.S. Highway 101 in North Eureka, take
Samoa exit from State Highway 255, and proceed NW on State Highway 255 for 2.9
km (1.8 mi) to a T intersection, then turn south onto the Navy Base road and
continue for about 6 km (4 mi) to Humboldt Bay Coast Guard Station. The bench
marks are on the Coast Guard Base property. The tide gauge is at the east end
of the southern pier of two finger piers directly east of the 3-story Coast
Guard station building.
T I D A L B E N C H M A R K S
PRIMARY BENCH MARK STAMPING: NO 9 1937
DESIGNATION: 941 8767 TIDAL 9
MONUMENTATION: Tidal Station disk VM#: 1717
AGENCY: US Coast and Geodetic Survey
(USC&GS) IDB PID#: LV0361
SETTING CLASSIFICATION: Concrete ramp OPUS PID:
LATITUDE: 40° 46.0' N ( 40.76667) LONGITUDE: 124° 13.1' W (-124.21803)
The primary bench mark is a disk set in the SW corner of the concrete ramp at
Humboldt Bay Coast Guard Station boat house, at the south end of the east doors
of the boat house at the west end of the marine railway, 12.95 m (42.5 ft) NW of
the SE edge of concrete apron, 1.45 m (4.8 ft) SW of southern-most rail, and
0.15 m (0.5 ft) SE of the cornerstone of the building which is inscribed "A.D.
1936".
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 2 of 9
Station ID: 9418767 PUBLICATION DATE: 10/06/2011
Name: NORTH SPIT, HUMBOLDT BAY
CA
NOAA Chart: 18622 Latitude: 40° 46.0' N ( 40.76670)
USGS Quad: EUREKA Longitude: 124° 13.0' W (-124.21700)
T I D A L B E N C H M A R K S
BENCH MARK STAMPING: NO 11 1940
DESIGNATION: 941 8767 TIDAL 11
MONUMENTATION: Tidal Station disk VM#: 1718
AGENCY: US Coast and Geodetic Survey
(USC&GS) IDB PID#: LV0359
SETTING CLASSIFICATION: Sea wall OPUS PID#: LV0359
LATITUDE: 40° 46.0' N ( 40.76694) LONGITUDE: 124° 13.1' W (-124.21908)
The bench mark is a disk set in top of the sea wall at Humboldt Bay Coast Guard
Station, 27.74 m (91.0 ft) NE of the center of the north entrance steps to
station, 21.03 m (69.0 ft) south of the north end of the sea wall, 12.50 m (41.0
ft) north of bench mark 12 1962, and 4.14 m (13.6 ft) south of the south side of
the walkway to the boat house.
BENCH MARK STAMPING: NO 12 1962
DESIGNATION: 941 8767 TIDAL 12
MONUMENTATION: Tidal Station disk VM#: 1719
AGENCY: US Coast and Geodetic Survey
(USC&GS) IDB PID#: LV0360
SETTING CLASSIFICATION: Sea wall OPUS PID:
LATITUDE: 40° 46.0' N ( 40.76678) LONGITUDE: 124° 13.1' W (-124.21772)
The bench mark is a disk set in the sea wall at Humboldt Bay Coast Guard
Station, about 40 m (130 ft) north of the marine railway at station, 25 m (83
ft) ENE of NE corner of steps to north entrance of station, 12 m (41 ft) south
of bench mark NO 11 1940, 6 m (20 ft) south of an expansion joint in the sea
wall, and 0.30 m (1 ft) south of bend in sea wall.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 3 of 9
Station ID: 9418767 PUBLICATION DATE: 10/06/2011
Name: NORTH SPIT, HUMBOLDT BAY
CA
NOAA Chart: 18622 Latitude: 40° 46.0' N ( 40.76670)
USGS Quad: EUREKA Longitude: 124° 13.0' W (-124.21700)
T I D A L B E N C H M A R K S
BENCH MARK STAMPING: 8767 A 1981
DESIGNATION: 941 8767 A TIDAL
MONUMENTATION: Tidal Station disk VM#: 1720
AGENCY: National Ocean Survey (NOS) IDB PID#: LV0634
SETTING CLASSIFICATION: Concrete foundation OPUS PID:
LATITUDE: 40° 46.0' N ( 40.76672) LONGITUDE: 124° 13.1' W (-124.21831)
The bench mark is a disk set in a concrete base of a flag pole for the U.S.
Coast Guard Station at Humboldt Bay, 30.78 m (101.0 ft) NW of the sea wall at
Coast Guard Station, 10.82 m (35.5 ft) west of the SW corner of the U.S. Coast
Guard Station, 6.95 m (22.8 ft) north of a water main valve, 1.52 m (5.0 ft)
east of the west edge of the concrete flag pole base, and 0.27 m (0.9 ft) SW of
the flagpole.
BENCH MARK STAMPING: 8767 B 1981
DESIGNATION: 941 8767 B TIDAL
MONUMENTATION: Tidal Station disk VM#: 1721
AGENCY: National Ocean Survey (NOS) IDB PID#: LV0632
SETTING CLASSIFICATION: Stainless steel rod OPUS PID#: LV0632
LATITUDE: 40° 46.1' N ( 40.76789) LONGITUDE: 124° 13.0' W (-124.21725)
The bench mark is a disk located 74.10 m (243.1 ft) North of NW corner of ramp
leading to a small boat pier, 52 m (171 ft) NE of NE corner of a parking lot, 16
m (52 ft) SW of the NW corner of the concrete mat along the water. The bench
mark is set 9 cm (0.3 ft) below ground level, crimped to a stainless steel rod
driven 14.6 m (48 ft), and encased in a 4-inch PVC plastic pipe with cover.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 4 of 9
Station ID: 9418767 PUBLICATION DATE: 10/06/2011
Name: NORTH SPIT, HUMBOLDT BAY
CA
NOAA Chart: 18622 Latitude: 40° 46.0' N ( 40.76670)
USGS Quad: EUREKA Longitude: 124° 13.0' W (-124.21700)
T I D A L B E N C H M A R K S
BENCH MARK STAMPING: 8767 C 1981
DESIGNATION: 941 8767 C TIDAL
MONUMENTATION: Tidal Station disk VM#: 1722
AGENCY: National Ocean Survey (NOS) IDB PID#: LV0630
SETTING CLASSIFICATION: Stainless steel rod OPUS PID:
LATITUDE: 40° 46.1' N ( 40.76769) LONGITUDE: 124° 13.1' W (-124.21867)
The bench mark is a disk located 78 m (257 ft) SW of bench mark 8767 D 1981, 37
m (122 ft) west of the NW corner of a white picket fence surrounding the Coast
Guard Station, 23 m (77 ft) SW of a power pole along the entrance road, and 0.91
m (3.0 ft) south of a NOS orange colored fiberglass witness post. The bench
mark is set 9 cm (0.3 ft) below ground level, crimped to a stainless steel rod
driven 12.2 m (40 ft), and encased in a 4-inch PVC plastic pipe with cover.
BENCH MARK STAMPING: 8767 D 1981
DESIGNATION: 941 8767 D TIDAL
MONUMENTATION: Tidal Station disk VM#: 1723
AGENCY: National Ocean Survey (NOS) IDB PID#: LV0631
SETTING CLASSIFICATION: Stainless steel rod OPUS PID:
LATITUDE: 40° 46.1' N ( 40.76825) LONGITUDE: 124° 13.1' W (-124.21803)
The bench mark is a disk located 77.4 m (253.9 ft) west of bench mark 8767 B
1981, 27.13 m (89.0 ft) SE of the SE corner of U.S.C.G. Building No. 10, 8.84 m
(29.0 ft) east of the centerline of the entrance road to the U.S. Coast Guard
Humboldt Bay, and 3.81 m (12.5 ft) NE of a brown street light base. The bench
mark is set 9 cm (0.3 ft) below ground level, crimped to a stainless steel rod
driven 14.6 m (48 ft), and encased in a 4-inch PVC plastic pipe with cover.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 5 of 9
Station ID: 9418767 PUBLICATION DATE: 10/06/2011
Name: NORTH SPIT, HUMBOLDT BAY
CA
NOAA Chart: 18622 Latitude: 40° 46.0' N ( 40.76670)
USGS Quad: EUREKA Longitude: 124° 13.0' W (-124.21700)
T I D A L B E N C H M A R K S
BENCH MARK STAMPING: 8767 F 1983
DESIGNATION: 941 8767 F TIDAL
MONUMENTATION: Tidal Station disk VM#: 1725
AGENCY: National Ocean Service (NOS) IDB PID#: LV0636
SETTING CLASSIFICATION: Concrete sea wall OPUS PID:
LATITUDE: 40° 46.0' N ( 40.76631) LONGITUDE: 124° 13.1' W (-124.21872)
The bench mark is a disk set in the top of south end of a sea wall at the
Humboldt Bay U.S. Coast Guard station, 51.21 m (168.0 ft) south of bench mark
941 8767 A, 32.61 m (107.0 ft) east of a building marked "Flammable Storage",
10.18 m (33.4 ft) NE from the SE corner of a green chain link fence that
surrounds the U.S. Coast Guard base, and 0.24 m (0.8 ft) west from the east edge
of the sea wall.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 6 of 9
Station ID: 9418767 PUBLICATION DATE: 10/06/2011
Name: NORTH SPIT, HUMBOLDT BAY
CA
NOAA Chart: 18622 Latitude: 40° 46.0' N ( 40.76670)
USGS Quad: EUREKA Longitude: 124° 13.0' W (-124.21700)
T I D A L B E N C H M A R K S
BENCH MARK STAMPING: V 1403 1988
DESIGNATION: V 1403
MONUMENTATION: Metal Rod VM#: 1727
AGENCY: US Coast and Geodetic Survey
(USC&GS) IDB PID#: LV0637
SETTING CLASSIFICATION: Stainless steel rod in sleeve OPUS PID#: LV0637
LATITUDE: 40° 46.0' N ( 40.76675) LONGITUDE: 124° 13.1' W (-124.21789)
The bench mark is located 12.31 m (40.4 ft) NNW of the north corner of a wooden
dock, 10.21 m (33.5 ft) SE of the east corner of the U.S. Coast Guard Station,
6.71 m (22.0 ft) NW of the SE edge of a sea wall, and 0.8 m (2.6 ft) SE of the
SE edge of an asphalt walkway. The bench mark is set level with the walkway,
being the top of a stainless steel rod in sleeve, driven to a depth of 19.5 m
(64 ft), and encased in a 5-inch pipe flush with the ground.
BENCH MARK STAMPING: 8767 H 1995
DESIGNATION: 941 8767 H
MONUMENTATION: Tidal Station disk VM#: 12659
AGENCY: National Ocean Service (NOS) IDB PID#:
SETTING CLASSIFICATION: Concrete wall OPUS PID:
LATITUDE: 40° 46.0' N ( 40.76719) LONGITUDE: 124° 13.1' W (-124.21761)
The bench mark is a disk set flush in top of a concrete head wall near the
northern-most dock walkway at the U.S.C.G. Base and adjacent to two white
flammable tanks, 9.80 ,m (32.2 ft) SW of NW corner of northern-most concrete
pier apron, 3.0 m (9.8 ft) west of a 1m (3 ft) tall round metal outdoor light,
0.86 m (2.8 ft) east of NE corner of white 500 gallon waste oil tank, and 0.28 m
(0.9 ft) south of northern 45 degree angle in head wall.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 7 of 9
Station ID: 9418767 PUBLICATION DATE: 10/06/2011
Name: NORTH SPIT, HUMBOLDT BAY
CA
NOAA Chart: 18622 Latitude: 40° 46.0' N ( 40.76670)
USGS Quad: EUREKA Longitude: 124° 13.0' W (-124.21700)
T I D A L B E N C H M A R K S
BENCH MARK STAMPING: 8767 J 1995
DESIGNATION: 941 8767 J
MONUMENTATION: Tidal Station disk VM#: 12660
AGENCY: National Ocean Service (NOS) IDB PID#:
SETTING CLASSIFICATION: Concrete slab OPUS PID:
LATITUDE: 40° 46.0' N ( 40.76694) LONGITUDE: 124° 13.1' W (-124.21908)
The bench mark is a disk set flush in the top of an 2 m x 4 m (8 ft x 14 ft)
concrete slab near the SE corner of the USCG base parking lot, 32.50 m (106.6
ft) east of a meteorological tower, 9.25 m (30.3 ft) west of the NW corner of
the block house containing flammable fluids, and 0.79 m (2.6 ft) north of the NW
corner of the block shed containing HAZMAT drums.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 8 of 9
Station ID: 9418767 PUBLICATION DATE: 10/06/2011
Name: NORTH SPIT, HUMBOLDT BAY
CA
NOAA Chart: 18622 Latitude: 40° 46.0' N ( 40.76670)
USGS Quad: EUREKA Longitude: 124° 13.0' W (-124.21700)
T I D A L D A T U M S
Tidal datums at NORTH SPIT, HUMBOLDT BAY based on:
LENGTH OF SERIES: 19 YEARS
TIME PERIOD: January 1983 - December 2001
TIDAL EPOCH: 1983-2001
CONTROL TIDE STATION:
Elevations of tidal datums referred to Mean Lower Low Water (MLLW), in METERS:
HIGHEST OBSERVED WATER LEVEL (12/31/2005) = 3.013
MEAN HIGHER HIGH WATER MHHW = 2.090
MEAN HIGH WATER MHW = 1.874
MEAN TIDE LEVEL MTL = 1.129
MEAN SEA LEVEL MSL = 1.129
MEAN LOW WATER MLW = 0.384
North American Vertical Datum NAVD88 = 0.103
MEAN LOWER LOW WATER MLLW = 0.000
LOWEST OBSERVED WATER LEVEL (01/20/1988) = -0.883
North American Vertical Datum (NAVD88)
Bench Mark Elevation Information In METERS above:
Stamping or Designation MLLW MHW
NO 9 1937 4.771 2.898
NO 11 1940 4.251 2.378
NO 12 1962 4.233 2.359
8767 A 1981 4.814 2.940
8767 B 1981 3.275 1.401
8767 C 1981 3.335 1.461
8767 D 1981 3.731 1.858
8767 F 1983 4.235 2.362
V 1403 1988 4.503 2.630
8767 H 1995 3.982 2.108
8767 J 1995 3.555 1.681
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 9 of 9
Station ID: 9418767 PUBLICATION DATE: 10/06/2011
Name: NORTH SPIT, HUMBOLDT BAY
CA
NOAA Chart: 18622 Latitude: 40° 46.0' N ( 40.76670)
USGS Quad: EUREKA Longitude: 124° 13.0' W (-124.21700)
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.