U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Datums Page Page 1 of 8
PUBLICATION DATE: 10/30/1984
Station ID: 9450460 SUPERCEDED DATE: 04/21/2003
Name: KETCHIKAN, TONGASS NARROWS
ALASKA
NOAA Chart: 17430 Latitude: 55° 20.0' N
USGS Quad: KETCHIKAN B-5 Longitude: 131° 37.5' W
To reach the tidal bench marks from the Ketchikan, Alaska State Ferry Termi-
nal, exit south onto Tongass Avenue, proceed SE 2.0 miles (3.2 km) around the
tunnel downtown, bear right onto Front Street for 0.1 mile (0.2 km), then bear
left onto Mill Street (at the Federal Building) for 0.1 mile (0.2 km), bear
right onto Stedman Street for 0.6 mile (1.0 km) to the Coast Guard Base, proceed
SW for 0.1 mile (0.2 km) to the Coast Guard Machine Shop Building, turn north
and follow the pier to the south for 0.1 mile (0.2km). The bench marks are
located in the general vicinity of the U.S. Coast Guard Station in Ketchikan
Harbor. The tide station is a 6-foot (2 m) by 8-foot (2 m) white plywood shed on
the landward side of the pier behind the Sewage Plant.
T I D A L B E N C H M A R K S
PRIMARY BENCH MARK STAMPING: NO 24 1921
MONUMENTATION: Survey Disk VM#: 1165
AGENCY: PID:
SETTING CLASSIFICATION: Concrete Foundation
The bench mark is set vertically in the SW side of the west corner of the U.S.
Coast Guard Repair Base (lighthouse depot) Administration Building, and 1 foot
(0.3 m) from the west corner. The bench mark is set 1 foot (0.3 m) above ground
level.
BENCH MARK STAMPING: NO 30 1922
MONUMENTATION: Survey Disk VM#: 1167
AGENCY: PID:
SETTING CLASSIFICATION: Concrete Foundation
The bench mark is set vertically in the NE concrete wall of the Old Heckman
Store Building which borders an alley SE of 314 Dock Street between Tongass
Housewares Shop and Tongass Trading Company Building, 10 feet (3 m) SW of the
buildings west corner. The bench mark is set 2.5 feet (0.8 m) above ground
level.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 2 of 8
PUBLICATION DATE: 10/30/1984
Station ID: 9450460 SUPERCEDED DATE: 04/21/2003
Name: KETCHIKAN, TONGASS NARROWS
ALASKA
NOAA Chart: 17430 Latitude: 55° 20.0' N
USGS Quad: KETCHIKAN B-5 Longitude: 131° 37.5' W
T I D A L B E N C H M A R K S
BENCH MARK STAMPING: NO 32 1922
MONUMENTATION: Survey Disk VM#: 1168
AGENCY: PID:
SETTING CLASSIFICATION: Concrete Foundation
The bench mark is set in the north edge of the circular concrete foundation of
the most southerly Standard Oil Company Oil Tank, 410 feet (125 m) NW of the
junction of the Coast Guard Base entrance with the Shore Highway, 73.5 feet
(22.4 m) SE of the concrete highway centerline, 20 feet (6 m) east of a ladder
leading down the south side of the oil tank, and 8.5 feet (2.6 m) north of the
northerly adjacent oil tank.
BENCH MARK STAMPING: BM NO 34 1944
MONUMENTATION: Survey Disk VM#: 1169
AGENCY: PID:
SETTING CLASSIFICATION: Concrete Wall
The bench mark is set in the top SW corner of a concrete retaining wall on the
NE side of the Entrance Road to the Coast Guard Administration Building, 172
feet (52 m) NE of the large north door in the NE face of the Administration
Building, and 78 feet (24 m) south of the east gage post of the Base Entrance.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 3 of 8
PUBLICATION DATE: 10/30/1984
Station ID: 9450460 SUPERCEDED DATE: 04/21/2003
Name: KETCHIKAN, TONGASS NARROWS
ALASKA
NOAA Chart: 17430 Latitude: 55° 20.0' N
USGS Quad: KETCHIKAN B-5 Longitude: 131° 37.5' W
T I D A L B E N C H M A R K S
BENCH MARK STAMPING: NO 37 1956
MONUMENTATION: Survey Disk VM#: 1170
AGENCY: PID#: AI4914
SETTING CLASSIFICATION: Concrete Wall
The bench mark is set in a concrete retaining wall that extends from the NE
corner of the Administration Building and parallels the Entrance Road, 71 feet
(22 m) SSE of the gas pump at the SW corner of the firehouse, 67 feet (20 m)
north of the NE corner of the Battery Shop, and 10.5 feet (3.2 m) west of the
Entrance Road centerline. The bench mark is set 1 foot (0.3 m) above the
pavement.
BENCH MARK STAMPING: TIDAL BM 38 1974
MONUMENTATION: Survey Disk VM#: 1171
AGENCY: PID:
SETTING CLASSIFICATION: Concrete Wall
The bench mark is set in a concrete wall at the Anderes Mobil Oil Company,
Ketchikan Bulk Plant, 81 feet (25 m) SW of the centerline of Stedman Road, 30.6
feet (9.3 m) SW of the north corner of the wall, 27.2 feet (8.3 m) SE of Mobil
office building, and 4.4 feet (1.3 m) NW of the northern most Mobile Oil Tank.
The bench mark is set 1 foot (0.3 m) above ground level inside the chain link
fence.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 4 of 8
PUBLICATION DATE: 10/30/1984
Station ID: 9450460 SUPERCEDED DATE: 04/21/2003
Name: KETCHIKAN, TONGASS NARROWS
ALASKA
NOAA Chart: 17430 Latitude: 55° 20.0' N
USGS Quad: KETCHIKAN B-5 Longitude: 131° 37.5' W
T I D A L B E N C H M A R K S
BENCH MARK STAMPING: TIDAL BM 39 1974
MONUMENTATION: Survey Disk VM#: 1172
AGENCY: PID:
SETTING CLASSIFICATION: Concrete Foundation
The bench mark is set vertically in the SE foundation of the Ketchikan Commu-
nity College A1 Robertson Building at the intersection of Stedman and Deermount
Streets, 46.3 feet (14.1 m) SW of the Stedman Street centerline, 36 feet (11 m)
NW of the extended Deermount Street centerline, and 4 feet (1 m) SW of the east
corner of the building. The bench mark is set 2.5 feet (0.8 m) above ground
level.
BENCH MARK STAMPING: 0460 A 1979
MONUMENTATION: Survey Disk VM#: 1173
AGENCY: PID:
SETTING CLASSIFICATION: Bedrock
The bench mark is set in a bedrock out crop in the Standard Oil Tank Farm, 65
feet (20 m) SW of the Stedman Road centerline, 44.9 feet (13.7 m) south of a
utility pole, 19 feet (6 m) slope distance NW of Tank No. 19, and 2.5 feet (0.8
m) SW of where a 2-feet (0.6 m) high concrete wall terminates onto the outcrop.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 5 of 8
PUBLICATION DATE: 10/30/1984
Station ID: 9450460 SUPERCEDED DATE: 04/21/2003
Name: KETCHIKAN, TONGASS NARROWS
ALASKA
NOAA Chart: 17430 Latitude: 55° 20.0' N
USGS Quad: KETCHIKAN B-5 Longitude: 131° 37.5' W
T I D A L B E N C H M A R K S
BENCH MARK STAMPING: 0460 B 1982
MONUMENTATION: Survey Disk VM#: 1174
AGENCY: PID:
SETTING CLASSIFICATION: Bedrock
The bench mark is set in a bedrock outcrop in the SE corner of the Standard Oil
Tank Farm, 136 feet (41 m) SW of the centerline of Stedman Street, 39 feet (12
m) north of the NW corner of the Coast Guard gymnasium, 24.5 feet (7.5 m) NW of
the SW corner of the upper Coast Guard parking lot near the Base Entrance, and
15.2 feet (4.6 m) south of the easternmost fuel tank. The bench mark is set 2.0
feet (0.6 m) above ground level.
BENCH MARK STAMPING: 0460 C 1982
MONUMENTATION: Survey Disk VM#: 1175
AGENCY: PID:
SETTING CLASSIFICATION: Bedrock
The bench mark is set in a bedrock outcrop next to the Coast Guard Railway, 147
feet (45 m) NE of the NE corner of the Receiving Warehouse Building, 52.4 feet
(16.0 m) SE of the SE corner of the drydock covering the railway, 28.0 feet (8.5
m) south of the south rail of the railway, 9.2 feet (2.8 m) east of a lone pine
tree, and 5.7 feet (1.7 m) east of a galvanized eye bolt embedded in the
outcrop.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 6 of 8
PUBLICATION DATE: 10/30/1984
Station ID: 9450460 SUPERCEDED DATE: 04/21/2003
Name: KETCHIKAN, TONGASS NARROWS
ALASKA
NOAA Chart: 17430 Latitude: 55° 20.0' N
USGS Quad: KETCHIKAN B-5 Longitude: 131° 37.5' W
T I D A L B E N C H M A R K S
BENCH MARK STAMPING: B M 1
MONUMENTATION: Survey Marker VM#: 1176
AGENCY: PID:
SETTING CLASSIFICATION: Concrete Curb
The bench mark is set in the NE end of the concrete curb surrounding the sewage
treatment plant, 38.6 feet (11.8 m) NW of the Receiving Warehouse Building, 2.3
feet (0.7 m) NE of the NE end of a wooden guard rail, 1.3 feet (0.4 m) SW of a
gray door marker Leave Compression On, and 1.0 foot (0.3 m) west of the NE end
of the curb. The bench mark is set 0.9 foot (0.3 m) above ground level.
BENCH MARK STAMPING: NO STAMPING 1
MONUMENTATION: Steel Guard VM#: 1177
AGENCY: PID:
SETTING CLASSIFICATION: Not Applicable
The bench mark is the top of a projective-shaped steel guard painted yellow. By
the SE corner of the Administration Building. The steel guard top is 2.5 feet
(0.8 m) above ground level. (Note: Bench mark historically referred to as
No.36, 1944)
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 7 of 8
PUBLICATION DATE: 10/30/1984
Station ID: 9450460 SUPERCEDED DATE: 04/21/2003
Name: KETCHIKAN, TONGASS NARROWS
ALASKA
NOAA Chart: 17430 Latitude: 55° 20.0' N
USGS Quad: KETCHIKAN B-5 Longitude: 131° 37.5' W
T I D A L D A T U M S
Tidal datums at KETCHIKAN, TONGASS NARROWS based on:
LENGTH OF SERIES: 19 YEARS
TIME PERIOD: 1960-1978
TIDAL EPOCH: 1960-1978
CONTROL TIDE STATION:
Elevations of tidal datums referred to Mean Lower Low Water (MLLW), in FEET:
HIGHEST OBSERVED WATER LEVEL (12/02/1967) = 21.27
MEAN HIGHER HIGH WATER MHHW = 15.38
MEAN HIGH WATER MHW = 14.50
MEAN TIDE LEVEL MTL = 8.03
MEAN LOW WATER MLW = 1.55
MEAN LOWER LOW WATER MLLW = 0.00
LOWEST OBSERVED WATER LEVEL (12/30/1959) = -5.13
North American Vertical Datum (NAVD88)
Bench Mark Elevation Information In FEET above:
Stamping or Designation MLLW MHW
NO 24 1921 23.12 8.62
NO 30 1922 26.53 12.03
NO 32 1922 54.08 39.58
BM NO 34 1944 49.32 34.82
NO 37 1956 35.09 20.59
TIDAL BM 38 1974 30.60 16.10
TIDAL BM 39 1974 32.46 17.96
0460 A 1979 49.78 35.28
0460 B 1982 61.77 47.27
0460 C 1982 17.86 3.36
B M 1 23.16 8.66
NO STAMPING 1 24.20 9.70
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 8 of 8
PUBLICATION DATE: 10/30/1984
Station ID: 9450460 SUPERCEDED DATE: 04/21/2003
Name: KETCHIKAN, TONGASS NARROWS
ALASKA
NOAA Chart: 17430 Latitude: 55° 20.0' N
USGS Quad: KETCHIKAN B-5 Longitude: 131° 37.5' 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 (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.