U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Datums Page Page 1 of 7
PUBLICATION DATE: 10/11/1988
Station ID: 9444900 SUPERCEDED DATE: 04/21/2003
Name: PORT TOWNSEND, ADMIRALTY INLET
WASHINGTON
NOAA Chart: 18464 Latitude: 48° 6.9' N
USGS Quad: PORT TOWNSEND SOUTH Longitude: 122° 45.0' W
To reach the tidal bench marks from the west side of the Hodo Canal Bridge,
travel west on Route 104 to the Port Townsend/Chimacum turn-off onto County Road
12, then 14 miles (23 km) to Route 20, turn north and proceed along Route 20 for
4 miles (6 km) into Port Townsend, continue on Water Street (Route 20) to the
end of the town and turn east into the Texaco Oil yard. The bench marks are
generally located along Water Street (Route 20) towards Point Hudson. The tide
station is located in a 10 x 13-foot (3 x 4 m) wooden house on the unused Texaco
Oil pier at Point Hudson.
T I D A L B E N C H M A R K S
PRIMARY BENCH MARK STAMPING:
MONUMENTATION: VM#: 3145
AGENCY: PID:
SETTING CLASSIFICATION:
BENCH MARK STAMPING: NO 9 1952
MONUMENTATION: Survey Disk VM#: 1122
AGENCY: PID:
SETTING CLASSIFICATION: Concrete Foundation
The bench mark is set in the foundation of the concrete wall surrounding the
storage tanks at the Texaco Oil yard, 0.7 foot (0.2 m) SW of the SW wall corner,
0.7 foot (0.2 m) west of the west side of the foundation, and 0.3 foot (0.1 m)
above ground level.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 2 of 7
PUBLICATION DATE: 10/11/1988
Station ID: 9444900 SUPERCEDED DATE: 04/21/2003
Name: PORT TOWNSEND, ADMIRALTY INLET
WASHINGTON
NOAA Chart: 18464 Latitude: 48° 6.9' N
USGS Quad: PORT TOWNSEND SOUTH Longitude: 122° 45.0' W
T I D A L B E N C H M A R K S
BENCH MARK STAMPING: R 257 1944
MONUMENTATION: Survey Disk VM#: 1123
AGENCY: PID#: TR0559
SETTING CLASSIFICATION: Brick Wall
The bench mark is set vertically in the south brick wall of the city hall at the
Water/Madison Street intersection, 1 foot (0.3 m) NE of the SW wall corner, and
5 feet (2 m) above the sidewalk.
BENCH MARK STAMPING: NO 10 1952
MONUMENTATION: Survey Disk VM#: 1124
AGENCY: PID:
SETTING CLASSIFICATION: Concrete Wall
The bench mark is set in the top of the NW corner of the concrete wall around
the storage tanks at the Texaco Oil yard, 1 foot (0.3 m) east of the west side
of the wall, 0.2 foot (0.1 m) south of the north side of the wall, and 3.5 feet
(1.1 m) above ground level.
BENCH MARK STAMPING: TIDAL 13 1972
MONUMENTATION: Survey Disk VM#: 1125
AGENCY: PID:
SETTING CLASSIFICATION: Concrete Pad
The bench mark is set in the south corner of the lower section of a 4 x 8 foot
(1 x 2 m) concrete sewer pumping station at the SW corner of the Monroe and
Water Streets intersection, 38 feet (12 m) south of the intersection centerline,
2.5 feet (0.8 m) SW of an iron sewer manhole cover, and 0.2 foot (0.1 m) above
ground level.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 3 of 7
PUBLICATION DATE: 10/11/1988
Station ID: 9444900 SUPERCEDED DATE: 04/21/2003
Name: PORT TOWNSEND, ADMIRALTY INLET
WASHINGTON
NOAA Chart: 18464 Latitude: 48° 6.9' N
USGS Quad: PORT TOWNSEND SOUTH Longitude: 122° 45.0' W
T I D A L B E N C H M A R K S
BENCH MARK STAMPING: NO. 14 1974
MONUMENTATION: Survey Disk VM#: 1126
AGENCY: PID:
SETTING CLASSIFICATION: Brick Wall
The bench mark is set vertically in the SE brick wall of the Seattle First
National Bank on the north corner of the Water and Adams Streets intersection,
98.5 feet (30.0 m) NE of the Adams Street centerline, 39.5 feet (12.0 m) NW of
the Water Street centerline, and 1.0 foot (0.3 m) above ground level.
BENCH MARK STAMPING: TIDAL BM 16 1975
MONUMENTATION: Survey Disk VM#: 1127
AGENCY: PID:
SETTING CLASSIFICATION: Concrete Wall
The bench mark is set vertically in the SE concrete wall of the Jefferson County
Memorial Athletic field at the Washington and Madison Streets intersection, 9
feet (3 m) NE of the main entrance, and 4 feet (1 m) above ground level.
BENCH MARK STAMPING: TIDAL BM 17 1975
MONUMENTATION: Survey Disk VM#: 1128
AGENCY: PID:
SETTING CLASSIFICATION: Concrete Sill
The bench mark is set in a concrete sill along the SW side of the Victorian
Square building at the north corner of the Water and Tyler Streets intersection,
67 feet (20 m) NW of the Water Street centerline, 37 feet (11 m) NE of the Tyler
Street centerline, and 0.2 foot (0.1 m) above ground level.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 4 of 7
PUBLICATION DATE: 10/11/1988
Station ID: 9444900 SUPERCEDED DATE: 04/21/2003
Name: PORT TOWNSEND, ADMIRALTY INLET
WASHINGTON
NOAA Chart: 18464 Latitude: 48° 6.9' N
USGS Quad: PORT TOWNSEND SOUTH Longitude: 122° 45.0' W
T I D A L B E N C H M A R K S
BENCH MARK STAMPING: 4900 A 1978 TIDAL
MONUMENTATION: Survey Disk VM#: 1129
AGENCY: PID:
SETTING CLASSIFICATION: Copper-clad Steel Rod
The bench mark is set at the west corner of the Monroe and Washington Streets
intersection, 259 feet (79 m) ENE of Bench Mark Tidal BM 16 1975, 47.5 feet
(14.5 m) NW of the Monroe Street centerline, 19.5 feet (5.9 m) north of a fire
hydrant, and 2.5 feet (0.8 m) east of a witness post. The bench mark is set at
ground level, crimped to a copper-clad steel rod driven 47.5 feet (14.5 m), and
encased in a 4-inch PVC pipe and concrete kickblock.
BENCH MARK STAMPING: 4900 B 1981
MONUMENTATION: Survey Disk VM#: 1130
AGENCY: PID:
SETTING CLASSIFICATION: Copper-clad Steel Rod
The bench mark is located in the John B. Pope Marine Park on the SE side of
Water Street, 164.7 feet (50.2 m) east of Bench Mark R 257 1944, 96.3 feet (29.4
m) SE of the Water Street centerline, 3.0 feet (0.9 m) NE of a 50-foot high
wooden flagpole, and 2.0 feet (0.6 m) NE of the NE edge of the concrete flagpole
foundation. The bench mark is set 0.2 foot (0.1 m) below ground level, crimped
to a copper-clad steel rod driven 55 feet (17 m), and encased in a 4-inch PVC
pipe and concrete kickblock.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 5 of 7
PUBLICATION DATE: 10/11/1988
Station ID: 9444900 SUPERCEDED DATE: 04/21/2003
Name: PORT TOWNSEND, ADMIRALTY INLET
WASHINGTON
NOAA Chart: 18464 Latitude: 48° 6.9' N
USGS Quad: PORT TOWNSEND SOUTH Longitude: 122° 45.0' W
T I D A L B E N C H M A R K S
BENCH MARK STAMPING: 4900 C 1982
MONUMENTATION: Survey Disk VM#: 1131
AGENCY: PID:
SETTING CLASSIFICATION: Galvanized Steel Rod
The bench mark is set at the south corner of the Quincy and Washington Streets
intersection, 131 feet (40 m) SW of Bench Mark Tidal BM 16 1975, 68.8 feet (21.0
m) ESE of the telephone pole #641367, 67 feet (20 m) NW of the NW corner of the
green building with the sign FOE 182, 2.3 feet (0.7 m) NW of the sidewalks NW
edge, 1.2 feet (0.4 m) south of the south corner of the Jefferson County
Memorial Athletic field, and 0.4 foot (0.1 m) SE of an orange fiberglass witness
post. The bench mark is set at ground level, crimped to a galvanized steel rod
driven 40 feet (12 m) to refusal, and encased in a 4-inch PVC pipe and concrete
kickblock.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 6 of 7
PUBLICATION DATE: 10/11/1988
Station ID: 9444900 SUPERCEDED DATE: 04/21/2003
Name: PORT TOWNSEND, ADMIRALTY INLET
WASHINGTON
NOAA Chart: 18464 Latitude: 48° 6.9' N
USGS Quad: PORT TOWNSEND SOUTH Longitude: 122° 45.0' W
T I D A L D A T U M S
Tidal datums at PORT TOWNSEND, ADMIRALTY INLET based on:
LENGTH OF SERIES: 12 YEARS
TIME PERIOD: 1972-1983
TIDAL EPOCH: 1960-1978
CONTROL TIDE STATION: 9447130 SEATTLE
Elevations of tidal datums referred to Mean Lower Low Water (MLLW), in FEET:
HIGHEST OBSERVED WATER LEVEL (12/16/1982) = 11.77
MEAN HIGHER HIGH WATER MHHW = 8.45
MEAN HIGH WATER MHW = 7.74
MEAN TIDE LEVEL MTL = 5.15
MEAN LOW WATER MLW = 2.55
MEAN LOWER LOW WATER MLLW = 0.00
LOWEST OBSERVED WATER LEVEL (06/02/1973) = -3.96
North American Vertical Datum (NAVD88)
Bench Mark Elevation Information In FEET above:
Stamping or Designation MLLW MHW
0 0.00 0.00
NO 9 1952 11.71 3.97
R 257 1944 20.47 12.73
NO 10 1952 17.26 9.52
TIDAL 13 1972 14.33 6.59
NO. 14 1974 16.37 8.63
TIDAL BM 16 1975 20.95 13.21
TIDAL BM 17 1975 15.98 8.24
4900 A 1978 TIDAL 16.27 8.53
4900 B 1981 11.71 3.97
4900 C 1982 16.49 8.75
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 7 of 7
PUBLICATION DATE: 10/11/1988
Station ID: 9444900 SUPERCEDED DATE: 04/21/2003
Name: PORT TOWNSEND, ADMIRALTY INLET
WASHINGTON
NOAA Chart: 18464 Latitude: 48° 6.9' N
USGS Quad: PORT TOWNSEND SOUTH Longitude: 122° 45.0' 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 (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 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.