U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Datums Page Page 1 of 5
Station ID: 9455146 PUBLICATION DATE: 04/21/2003
Name: AIALIK SILL
AK
NOAA Chart: 16682 Latitude: 59° 53.1' N ( 59.88500)
USGS Quad: BLYING SOUND (D-8) Longitude: 149° 43.1' W (-149.71800)
To reach the tidal benchmarks from Seward via boat, proceed 15 km (8 nm) SSE
along Resurrection Bay to Calisto Head, then 32.5 km (17.6 nm) south along
Resurrection Bay to Aialik Cape, then 10.8 km (5.8 nm) WNW along Aialik Bay to
the center of Aialik Bay, then 15.2 km (8.2 nm) north along Aialik Bay to the
north side of Aialik Sill, then 2.1 km (1.1 nm) WNW to the tide station. The
benchmarks are located along the northern shoreline of Aialik Sill and west
shore of Aialik Bay north of the sill. The tide station was located on Aialik
Sill near benchmark 5146 E 2000.
T I D A L B E N C H M A R K S
PRIMARY BENCH MARK STAMPING: 9455146 A 2000
DESIGNATION: 945 5146 A
MONUMENTATION: Tidal Station disk VM#: 16392
AGENCY: National Ocean Service (NOS) IDB PID#:
SETTING CLASSIFICATION: Rock outrop OPUS PID:
LATITUDE: 59° 53.1' N ( 59.88500) LONGITUDE: 149° 43.1' W (-149.71800)
The primary benchmark is a disk set in a rock outcrop, 334 m (1096 ft) NW of
benchmark 9455146 D 2000, 99 m (325 ft) north of benchmark 9455146 B 2000, 3 m
(10 ft) west of the seaward extent of the rock outcropping, 2 m (6 ft) above the
rock beach, and 2 m (5 ft) below the vegetation line.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 2 of 5
Station ID: 9455146 PUBLICATION DATE: 04/21/2003
Name: AIALIK SILL
AK
NOAA Chart: 16682 Latitude: 59° 53.1' N ( 59.88500)
USGS Quad: BLYING SOUND (D-8) Longitude: 149° 43.1' W (-149.71800)
T I D A L B E N C H M A R K S
BENCH MARK STAMPING: 9455146 B 2000
DESIGNATION: 945 5146 B
MONUMENTATION: Tidal Station disk VM#: 16393
AGENCY: National Ocean Service (NOS) IDB PID#:
SETTING CLASSIFICATION: Rock outcrop OPUS PID:
LATITUDE: 59° 53.4' N ( 59.89000) LONGITUDE: 149° 43.7' W (-149.72800)
The benchmark is a disk set flush on the north side of a rock outcropping in a
small shoulder, 660 m (2165 ft) WNW from benchmark 9455146 E 2000, 285 m (935
ft) west of benchmark 9455146 D 2000, 99 m (325 ft) south of benchmark 9455146 A
2000, 15 m (49 ft) SW of the vegetation line at the west end of a black sand
beach on the north side of the glacial sill, and 1 m (4 ft) above the ground.
BENCH MARK STAMPING: 9455146 C 2000
DESIGNATION: 945 5146 C
MONUMENTATION: Tidal Station disk VM#: 16394
AGENCY: National Ocean Service (NOS) IDB PID#:
SETTING CLASSIFICATION: Rock outcrop OPUS PID:
LATITUDE: 59° 53.3' N ( 59.88830) LONGITUDE: 149° 43.7' W (-149.72800)
The benchmark is a disk set on the eastern face of a rock outcropping, 37 m
(121) feet SW of the vegetation line at a black sand beach on the north side of
the glacial sill, 5 m (15 ft) below the vegetation line, and 1 m (3 ft) above
the ground.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 3 of 5
Station ID: 9455146 PUBLICATION DATE: 04/21/2003
Name: AIALIK SILL
AK
NOAA Chart: 16682 Latitude: 59° 53.1' N ( 59.88500)
USGS Quad: BLYING SOUND (D-8) Longitude: 149° 43.1' W (-149.71800)
T I D A L B E N C H M A R K S
BENCH MARK STAMPING: 9455146 D 2000
DESIGNATION: 945 5146 D
MONUMENTATION: Tidal Station disk VM#: 16395
AGENCY: National Ocean Service (NOS) IDB PID#:
SETTING CLASSIFICATION: Stainless steel rod OPUS PID:
LATITUDE: 59° 53.3' N ( 59.88830) LONGITUDE: 149° 43.7' W (-149.72800)
The benchmark is a stainless steel rod located 375 m (1230 ft) NW of benchmark
9455146 E 2000, 334 m (1096 ft) SE of benchmark 9455146 A 2000, 285 m (935 ft)
ESE of benchmark 9455146 B 2000, 7 m (23 ft) south of the vegetation line along
a black sand beach, and 3 m (10 ft) south of a 4 inch x 4 inch wooden witness
post. The datum point is set 3 cm (0.1 ft) below ground, being the top of a 9/16
inch stainless steel rod driven 6 m (20 ft) to refusal, and encased in a 6.5
inch PVC pipe with 7.25 inch NOS logo cover set 0.06 m (0.2 ft) above ground.
BENCH MARK STAMPING: 9455146 E 2000
DESIGNATION: 945 5146 E
MONUMENTATION: Tidal Station disk VM#: 16396
AGENCY: National Ocean Service (NOS) IDB PID#:
SETTING CLASSIFICATION: Stainless steel rod OPUS PID:
LATITUDE: 59° 53.1' N ( 59.88500) LONGITUDE: 149° 43.1' W (-149.71800)
The benchmark is a stainless steel rod located 660 m (2165 ft) ESE of benchmark
9455146 B 2000, 375 m (1230 ft) SE of benchmark 9455146 D 2000, 16 m (53 ft)
south of the vegetation line along a black sand beach, and 3 m (10 ft) south of
a of a 4 inch x 4 inch wooden witness post set 0.6 m (2 ft) in the ground. The
datum point is set 3 cm (0.1 ft) below ground, being the top of a 9/16 inch
stainless steel rod driven 6 m (20 ft) to refusal, and encased in a 6.5 inch PVC
pipe with 7.25 inch NOS logo cover set 0.03 m (0.01 ft) above ground.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 4 of 5
Station ID: 9455146 PUBLICATION DATE: 04/21/2003
Name: AIALIK SILL
AK
NOAA Chart: 16682 Latitude: 59° 53.1' N ( 59.88500)
USGS Quad: BLYING SOUND (D-8) Longitude: 149° 43.1' W (-149.71800)
T I D A L D A T U M S
Tidal datums at AIALIK SILL based on:
LENGTH OF SERIES: 4 Months
TIME PERIOD: July 2000 - October 2000
TIDAL EPOCH: 1983-2001
CONTROL TIDE STATION: 9455090 SEWARD, RESURRECTION BAY
Elevations of tidal datums referred to Mean Lower Low Water (MLLW), in METERS:
MEAN HIGHER HIGH WATER MHHW = 3.246
MEAN HIGH WATER MHW = 2.968
MEAN SEA LEVEL MSL = 1.694
MEAN TIDE LEVEL MTL = 1.691
MEAN LOW WATER MLW = 0.414
MEAN LOWER LOW WATER MLLW = 0.000
North American Vertical Datum (NAVD88)
Bench Mark Elevation Information In METERS above:
Stamping or Designation MLLW MHW
9455146 A 2000 3.169 0.201
9455146 B 2000 6.106 3.138
9455146 C 2000 5.747 2.779
9455146 D 2000 4.821 1.853
9455146 E 2000 5.863 2.895
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 5 of 5
Station ID: 9455146 PUBLICATION DATE: 04/21/2003
Name: AIALIK SILL
AK
NOAA Chart: 16682 Latitude: 59° 53.1' N ( 59.88500)
USGS Quad: BLYING SOUND (D-8) Longitude: 149° 43.1' W (-149.71800)
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.