U.S. DEPARTMENT OF COMMERCE
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National Ocean Service
Datums Page Page 1 of 7
Station ID: 9443361 PUBLICATION DATE: 07/15/2004
Name: SEKIU, CLALLAM BAY
WA
NOAA Chart: 18460 Latitude: 48° 15.8' N ( 48.26330)
USGS Quad: CLALLAM BAY Longitude: 124° 17.8' W (-124.29700)
To reach the tidal bench marks from Port Angeles, proceed west on U.S. Highway
101 for 8 km (5 mi) to the intersection with State Highway 112, then bear right
onto State Highway 112 and proceed NW for about 74 km (46 mi) to the town of
Sekiu. The bench marks are located along State Highway 112 and in the town.
The tide gage and staff were located east of the town in a small harbor at the
Coho Resort motel.
T I D A L B E N C H M A R K S
PRIMARY BENCH MARK STAMPING: 3 1931
DESIGNATION: 944 3361 TIDAL 3
MONUMENTATION: Bench Mark disk VM#: 9013
AGENCY: US Coast & Geodetic Survey
(USC&GS) IDB PID#: TS0098
SETTING CLASSIFICATION: Concrete step OPUS PID:
LATITUDE: 48° 15.8' N ( 48.26330) LONGITUDE: 124° 18.1' W (-124.30200)
The primary bench mark is a disk set in the south end of the bottom concrete
step to the front entrance of the Sekiu Community Center, 73 m (240 ft) west of
the shore line.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 2 of 7
Station ID: 9443361 PUBLICATION DATE: 07/15/2004
Name: SEKIU, CLALLAM BAY
WA
NOAA Chart: 18460 Latitude: 48° 15.8' N ( 48.26330)
USGS Quad: CLALLAM BAY Longitude: 124° 17.8' W (-124.29700)
T I D A L B E N C H M A R K S
BENCH MARK STAMPING: M 242 RESET 1969
DESIGNATION: M 242 RESET 1969
MONUMENTATION: Bench Mark disk VM#: 9014
AGENCY: US Coast & Geodetic Survey
(USC&GS) IDB PID#: TS0103
SETTING CLASSIFICATION: Concrete monument OPUS PID:
LATITUDE: 48° 15.6' N ( 48.26000) LONGITUDE: 124° 18.3' W (-124.30500)
The bench mark is a disk located along State Highway 112, 453 m (1485 ft) west
of the centerline of the eastern to Sekiu, 168 m (550 ft) east of the centerline
of Ballard Glen Road leading to the Sekiu airport, 22 m (72 ft) east of power
pole #V166 602, and 14 m (45 ft) north of the centerline of the highway.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 3 of 7
Station ID: 9443361 PUBLICATION DATE: 07/15/2004
Name: SEKIU, CLALLAM BAY
WA
NOAA Chart: 18460 Latitude: 48° 15.8' N ( 48.26330)
USGS Quad: CLALLAM BAY Longitude: 124° 17.8' W (-124.29700)
T I D A L B E N C H M A R K S
BENCH MARK STAMPING: NO 6 1973
DESIGNATION: TIDAL 6
MONUMENTATION: Bench Mark disk VM#: 9015
AGENCY: National Geodetic Survey (NGS) IDB PID#: TS0101
SETTING CLASSIFICATION: Retaining wall OPUS PID:
LATITUDE: 48° 15.8' N ( 48.26330) LONGITUDE: 124° 18.1' W (-124.30200)
The bench mark is a disk set flush in the top of a concrete retaining wall
located at the SE corner of The Cove parking lot, 0.24 km (0.15 mi) north of the
Sekiu Post Office, 5 m (15 ft) west of the centerline of the main road leading
through Sekiu, 0.82 m (2.7 ft) north of the south edge of the retaining wall,
and 1 m (2 ft) above the road level.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 4 of 7
Station ID: 9443361 PUBLICATION DATE: 07/15/2004
Name: SEKIU, CLALLAM BAY
WA
NOAA Chart: 18460 Latitude: 48° 15.8' N ( 48.26330)
USGS Quad: CLALLAM BAY Longitude: 124° 17.8' W (-124.29700)
T I D A L B E N C H M A R K S
BENCH MARK STAMPING: NO 7 1973
DESIGNATION: TIDAL 7
MONUMENTATION: Bench Mark disk VM#: 9016
AGENCY: National Geodetic Survey (NGS) IDB PID#: TS0099
SETTING CLASSIFICATION: Concrete step OPUS PID:
LATITUDE: 48° 15.7' N ( 48.26170) LONGITUDE: 124° 18.1' W (-124.30200)
The bench mark is a disk set flush in the top step of the entrance to the Sekiu
post office, 0.76 m (2.5 ft) ESE of the NE corner of the building, 0.76 m (2.5
ft) east of the north end of the the entrance door, 0.37 m (1.2 ft) SW of the NE
corner of the step, 0.24 m (0.8 ft) south of a flag pole, and 1 m (4 ft) above
ground level.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 5 of 7
Station ID: 9443361 PUBLICATION DATE: 07/15/2004
Name: SEKIU, CLALLAM BAY
WA
NOAA Chart: 18460 Latitude: 48° 15.8' N ( 48.26330)
USGS Quad: CLALLAM BAY Longitude: 124° 17.8' W (-124.29700)
T I D A L B E N C H M A R K S
BENCH MARK STAMPING: K 473 1974
DESIGNATION: K 473
MONUMENTATION: Bench Mark disk VM#: 9017
AGENCY: National Geodetic Survey (NGS) IDB PID#: TS0095
SETTING CLASSIFICATION: Copper clad steel rod OPUS PID:
LATITUDE: 48° 15.6' N ( 48.26000) LONGITUDE: 124° 18.0' W (-124.30000)
The bench mark is a disk located at the junction of State Highway 112 and Front
Street, 26 m (86 ft) NE of the centerline of the highway, 14 m (46 ft) SSW of
the centerline of Front Street, 3 m (9 ft) NW of the first telephone pole NW of
the junction, and 0.52 m (1.7 ft) NW of a metal witness post. The bench mark is
set 6 cm (0.2 ft) below the ground, crimped to a 1.2 m (4 ft) copper-clad steel
rod with base plate and encased in a 4-inch metal pipe and concrete kickblock.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 6 of 7
Station ID: 9443361 PUBLICATION DATE: 07/15/2004
Name: SEKIU, CLALLAM BAY
WA
NOAA Chart: 18460 Latitude: 48° 15.8' N ( 48.26330)
USGS Quad: CLALLAM BAY Longitude: 124° 17.8' W (-124.29700)
T I D A L D A T U M S
Tidal datums at SEKIU, CLALLAM BAY based on:
LENGTH OF SERIES: 8 MONTHS
TIME PERIOD: June 1973 - January 1974
TIDAL EPOCH: 1983-2001
CONTROL TIDE STATION: 9443090 NEAH BAY, STRAIT OF JUAN DE FUCA
Elevations of tidal datums referred to Mean Lower Low Water (MLLW), in METERS:
MEAN HIGHER HIGH WATER MHHW = 2.286
MEAN HIGH WATER MHW = 2.030
MEAN TIDE LEVEL MTL = 1.287
MEAN SEA LEVEL MSL = 1.269
MEAN LOW WATER MLW = 0.545
North American Vertical Datum NAVD88 = 0.176
MEAN LOWER LOW WATER MLLW = 0.000
North American Vertical Datum (NAVD88)
Bench Mark Elevation Information In METERS above:
Stamping or Designation MLLW MHW
3 1931 14.456 12.426
M 242 RESET 1969 59.811 57.781
NO 6 1973 5.424 3.394
NO 7 1973 7.535 5.505
K 473 1974 26.018 23.988
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 7 of 7
Station ID: 9443361 PUBLICATION DATE: 07/15/2004
Name: SEKIU, CLALLAM BAY
WA
NOAA Chart: 18460 Latitude: 48° 15.8' N ( 48.26330)
USGS Quad: CLALLAM BAY Longitude: 124° 17.8' W (-124.29700)
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.