U.S. DEPARTMENT OF COMMERCE
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National Ocean Service
Datums Page Page 1 of 5
Station ID: 9455912 PUBLICATION DATE: 05/21/2004
Name: FIRE ISLAND
AK
NOAA Chart: 16665 Latitude: 61° 10.4' N ( 61.17330)
USGS Quad: TYONEK (A-1) Longitude: 150° 12.8' W (-150.21300)
This tertiary tide station is located on the northwestern shore of Fire Island,
near the confluence of Knik Arm and Turnagain Arm in Cook Inlet. The station is
approx. 7.5 miles west of Anchorage International Airport and 11 miles southwest
of the Port of Anchorage. The station was accessed by helicopter and fixed wing
from Anchorage and Big Lake.
T I D A L B E N C H M A R K S
PRIMARY BENCH MARK STAMPING: RIFE 1960
DESIGNATION: 945 5912 RIFE
MONUMENTATION: Triangulation Station disk VM#: 14788
AGENCY: US Coast and Geodetic Survey
(USC&GS) IDB PID#: UW6154
SETTING CLASSIFICATION: Boulder OPUS PID:
LATITUDE: 61° 10.3' N ( 61.17247) LONGITUDE: 150° 12.3' W (-150.20544)
The bench mark is a disk set in the middle of the north slope of a long
prominent boulder 2 m (6 ft) high, 3 m (10 ft) wide, and 5 m (15 ft) long with
long axis parallel with beach, located on the north shore of Fire Island
directly at the foot of a 30 m (100 ft) bluff, 283 m (930 ft) west (T) of Fire
Island Front Range, 114 m (374 ft) east of bench mark 5912 C 1998, 8 m (25 ft)
north of brush line at high water, 0.76 m (2.5 ft ) south of the north edge of
the boulder, and 0.37 m (1.2 ft) lower than the highest point on the boulder.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 2 of 5
Station ID: 9455912 PUBLICATION DATE: 05/21/2004
Name: FIRE ISLAND
AK
NOAA Chart: 16665 Latitude: 61° 10.4' N ( 61.17330)
USGS Quad: TYONEK (A-1) Longitude: 150° 12.8' W (-150.21300)
T I D A L B E N C H M A R K S
BENCH MARK STAMPING: BM 12 1974
DESIGNATION: 945 5912 BM 12
MONUMENTATION: Tidal Station disk VM#: 14791
AGENCY: National Ocean Survey (NOS) IDB PID#:
SETTING CLASSIFICATION: Large granite boulder OPUS PID:
LATITUDE: 61° 10.4' N ( 61.17261) LONGITUDE: 150° 12.2' W (-150.20322)
The bench mark is a disk set flush in the top of a large granite boulder that is
2 m by 1 m (5 ft by 4 ft), 125 m (409 ft) east of bench mark RIFE 1960, 6 m (19
ft) north of brush line at high water, 1.34 m (4.4 ft) south of the north edge
of the boulder, 0.18 m (0.6 ft) north of the southern tip of the boulder, and
0.40 m (1.3 ft) above beach level, .
BENCH MARK STAMPING: BM 13 1974
DESIGNATION: 945 5912 BM 13
MONUMENTATION: Tidal Station disk VM#: 14792
AGENCY: National Ocean Survey (NOS) IDB PID#:
SETTING CLASSIFICATION: Large granite boulder OPUS PID#: BBDG04
LATITUDE: 61° 10.4' N ( 61.17300) LONGITUDE: 150° 14.0' W (-150.23325)
The bench mark is a disk set flush in a large granite boulder 2 m (7 ft) by 2 m
(8 ft), 283 m (930 ft) east of bench mark RIFE 1960, 178 m (584 ft) east of
bench mark 12 1974, 9.14 m (30.0 ft) from the foot of a 9 m (30 ft) bluff
directly below Fire Island Front Range, 1.22 m (4.0 ft) south of the north edge
of the boulder, 0.98 m (3.2 ft) east of the western edge of the boulder, 0.18 m
(0.6 ft) below the highest point of the boulder, and 1.13 m (3.7 ft) above beach
level.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 3 of 5
Station ID: 9455912 PUBLICATION DATE: 05/21/2004
Name: FIRE ISLAND
AK
NOAA Chart: 16665 Latitude: 61° 10.4' N ( 61.17330)
USGS Quad: TYONEK (A-1) Longitude: 150° 12.8' W (-150.21300)
T I D A L B E N C H M A R K S
BENCH MARK STAMPING: 5912 D 1998
DESIGNATION: 945 5912 D
MONUMENTATION: Tidal Station disk VM#: 16044
AGENCY: LCMF, Inc. IDB PID#:
SETTING CLASSIFICATION: Boulder OPUS PID:
LATITUDE: 61° 10.4' N ( 61.17330) LONGITUDE: 150° 12.0' W (-150.20000)
The bench mark is a disk set in a drill hole in the top of a 5 m (18 ft) by 4 m
(12 ft) by 2 m (8 ft) high boulder with a vertical south face, 61 m (200 ft)
north of toe of 18 m (60 ft) high bluff, 59 m (193 ft) NW of bench mark 5912 C
1998, 2 m (8 ft) north of bench mark 5912 E 1998 (same boulder), and 0.18 m (0.6
ft) below the highest part of the boulder at the southern end.
BENCH MARK STAMPING: 5912 C 1998
DESIGNATION: 945 5912 C
MONUMENTATION: Tidal Station disk VM#: 16045
AGENCY: LCMF, Inc. IDB PID#:
SETTING CLASSIFICATION: Boulder OPUS PID:
LATITUDE: 61° 10.3' N ( 61.17170) LONGITUDE: 150° 12.0' W (-150.20000)
The bench mark is a disk set in the south ledge of a 2 m by 2 m (7 ft by 7 ft)
boulder, 114 m (374 ft) west of bench mark RIFE 1960, 59 m (193 ft) SE of bench
mark 5912 E 1998, 23 m (75 ft) north of brush line at high water, and 0.61 m
(2.0 ft) above beach level.
BENCH MARK STAMPING: E
DESIGNATION: 945 5912 E
ALIAS: Bolt E
MONUMENTATION: Bolt VM#: 16046
AGENCY: LCMF, Inc. IDB PID#:
SETTING CLASSIFICATION: Boulder OPUS PID:
LATITUDE: 61° 10.4' N ( 61.17331) LONGITUDE: 150° 12.5' W (-150.20831)
The bench mark is a 5/8 inch diameter stainless steel machine bolt with hex head
set horizontal and projecting 1.5 inches from a 5 m (18 ft) by 4 m (12 ft) by 2
m (8 ft) high boulder (same boulder as bench mark 5912 D 1998 is located) with a
vertical south face, 57 m (186 ft) NW of bench mark 5912 C 1998, 2 m (8 ft) SW
of bench mark 5912 D 1998, and 0.7m (2.3 ft) above beach level.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 4 of 5
Station ID: 9455912 PUBLICATION DATE: 05/21/2004
Name: FIRE ISLAND
AK
NOAA Chart: 16665 Latitude: 61° 10.4' N ( 61.17330)
USGS Quad: TYONEK (A-1) Longitude: 150° 12.8' W (-150.21300)
T I D A L D A T U M S
Tidal datums at FIRE ISLAND based on:
LENGTH OF SERIES: 3 MONTHS
TIME PERIOD: June 2001 - August 2001
TIDAL EPOCH: 1983-2001
CONTROL TIDE STATION: 9455920 ANCHORAGE, KNIK ARM, COOK INLET
Elevations of tidal datums referred to Mean Lower Low Water (MLLW), in METERS:
MEAN HIGHER HIGH WATER MHHW = 8.203
MEAN HIGH WATER MHW = 7.986
MEAN SEA LEVEL MSL = 4.537
MEAN TIDE LEVEL MTL = 4.329
MEAN LOW WATER MLW = 0.672
MEAN LOWER LOW WATER MLLW = 0.000
North American Vertical Datum (NAVD88)
Bench Mark Elevation Information In METERS above:
Stamping or Designation MLLW MHW
RIFE 1960 9.142 1.156
BM 12 1974 8.637 0.651
BM 13 1974 8.659 0.673
5912 D 1998 4.814 -3.172
5912 C 1998 6.937 -1.049
E 2.722 -5.264
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 5 of 5
Station ID: 9455912 PUBLICATION DATE: 05/21/2004
Name: FIRE ISLAND
AK
NOAA Chart: 16665 Latitude: 61° 10.4' N ( 61.17330)
USGS Quad: TYONEK (A-1) Longitude: 150° 12.8' W (-150.21300)
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.