U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Datums Page Page 1 of 5
Station ID: 9452749 PUBLICATION DATE: 06/21/2018
Name: TARR INLET
AK
NOAA Chart: 17318 Latitude: 58° 57.9' N ( 58.96478)
USGS Quad: MT FAIRWEATHER (D-2) Longitude: 136° 52.7' W (-136.87758)
To reach Tarr Inlet tidal benchmarks by boat from Point Gustavus, proceed NNW
for 16.7 km (10.4 miles) through the Glacier Bay National Park waters; at
Strawberry Island, proceed north for 31.5 km (19.6 miles), passing Willoughby
Island, Drake Island, and Lone Island, continue NW 42.6 km (26.5 miles) and
proceed north after Russell Island, into Tarr Inlet. The benchmarks are on the
right on a prominent rock outcrop on the east side of the Inlet; on sloping
granite bedrock granite and boulders at the mouth of Tarr Inlet NW of Russell
Island.
T I D A L B E N C H M A R K S
PRIMARY BENCH MARK STAMPING: 945-2749 A 2009
DESIGNATION: 945 2749 A
MONUMENTATION: Tidal Station disk VM#: 19527
AGENCY: National Ocean Service (NOS) IDB PID#:
SETTING CLASSIFICATION: Rock outcrop OPUS PID:
LATITUDE: 58° 57.9' N ( 58.96450) LONGITUDE: 136° 52.7' W (-136.87817)
The primary bench mark is set in prominent granite out crop on the shore of Tarr
Inlet facing the west located on a rock ledge 1 m (3.2 ft) east of the
intertidal zone with a rock beach to the south at low tide.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 2 of 5
Station ID: 9452749 PUBLICATION DATE: 06/21/2018
Name: TARR INLET
AK
NOAA Chart: 17318 Latitude: 58° 57.9' N ( 58.96478)
USGS Quad: MT FAIRWEATHER (D-2) Longitude: 136° 52.7' W (-136.87758)
T I D A L B E N C H M A R K S
BENCH MARK STAMPING: 9452749 B 2009
DESIGNATION: 945 2749 B
MONUMENTATION: Tidal Station disk VM#: 19528
AGENCY: National Ocean Service (NOS) IDB PID#:
SETTING CLASSIFICATION: Rock outcrop OPUS PID#: BBBN62
LATITUDE: 58° 57.9' N ( 58.96464) LONGITUDE: 136° 52.7' W (-136.87831)
The bench mark is set in granite bedrock located 5.6 m (18.5 ft) north of
benchmark 945 2749 A; climb up a 20 degree incline of boulders 2.3 m (7.5 ft)
above bench mark 945 2749 A.
BENCH MARK STAMPING: 945 2749 C 2009
DESIGNATION: 945 2749 C
MONUMENTATION: Tidal Station disk VM#: 19529
AGENCY: National Ocean Service (NOS) IDB PID#:
SETTING CLASSIFICATION: Rock outcrop OPUS PID:
LATITUDE: 58° 57.9' N ( 58.96467) LONGITUDE: 136° 52.7' W (-136.87833)
The bench mark is set in granite bedrock located 45 m (150 ft) NW of benchmark
945 2749 B; climb a 10 degree incline of boulders 1 m (3.2 ft) above bench mark
945 2749 B.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 3 of 5
Station ID: 9452749 PUBLICATION DATE: 06/21/2018
Name: TARR INLET
AK
NOAA Chart: 17318 Latitude: 58° 57.9' N ( 58.96478)
USGS Quad: MT FAIRWEATHER (D-2) Longitude: 136° 52.7' W (-136.87758)
T I D A L B E N C H M A R K S
BENCH MARK STAMPING: 945-2749 D 2009
DESIGNATION: 945 2749 D
MONUMENTATION: Tidal Station disk VM#: 19530
AGENCY: National Ocean Service (NOS) IDB PID#:
SETTING CLASSIFICATION: Rock outcrop OPUS PID:
LATITUDE: 58° 57.9' N ( 58.96483) LONGITUDE: 136° 52.7' W (-136.87850)
The bench mark is set in granite bedrock located 30 m (100 ft) NW of benchmark
945 2749 C, cross a stream cut in the boulders and walk slightly to the west.
BENCH MARK STAMPING: 9452749 E 2009
DESIGNATION: 945 2749 TIDAL E
MONUMENTATION: Survey disk VM#: 19531
AGENCY: National Ocean Service (NOS) IDB PID#:
SETTING CLASSIFICATION: rock outcrop OPUS PID:
LATITUDE: 58° 57.9' N ( 58.96467) LONGITUDE: 136° 52.7' W (-136.87833)
The bench mark is set in granite bedrock located on top of a flat, large ledge
overlooking bench marks 945 2749 A, 945 2749 B, 945 2749 C, and 945 2749 D, 4.50
m (16 ft) east up a steep 30 degree incline from bench mark 945 2749 C and 2.50
m ( 8.2 ft) above bench mark 945 2749 C.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 4 of 5
Station ID: 9452749 PUBLICATION DATE: 06/21/2018
Name: TARR INLET
AK
NOAA Chart: 17318 Latitude: 58° 57.9' N ( 58.96478)
USGS Quad: MT FAIRWEATHER (D-2) Longitude: 136° 52.7' W (-136.87758)
T I D A L D A T U M S
Tidal datums at TARR INLET based on:
LENGTH OF SERIES: 30 DAYS
TIME PERIOD: Oct 9 2009 - Nov 7 2009
TIDAL EPOCH: 2012-2016
CONTROL TIDE STATION: 9452210 JUNEAU, GASTINEAU CHANNEL, STEPHENS PASS
Elevations of tidal datums referred to Mean Lower Low Water (MLLW), in METERS:
MEAN HIGHER HIGH WATER MHHW = 5.108
MEAN HIGH WATER MHW = 4.824
MEAN TIDE LEVEL MTL = 2.676
MEAN SEA LEVEL MSL = 2.676
MEAN LOW WATER MLW = 0.528
MEAN LOWER LOW WATER MLLW = 0.000
North American Vertical Datum (NAVD88)
Bench Mark Elevation Information In METERS above:
Stamping or Designation MLLW MHW
945-2749 A 2009 5.331 0.507
9452749 B 2009 7.592 2.769
945 2749 C 2009 8.702 3.879
945-2749 D 2009 9.929 5.105
9452749 E 2009 11.208 6.384
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 5 of 5
Station ID: 9452749 PUBLICATION DATE: 06/21/2018
Name: TARR INLET
AK
NOAA Chart: 17318 Latitude: 58° 57.9' N ( 58.96478)
USGS Quad: MT FAIRWEATHER (D-2) Longitude: 136° 52.7' W (-136.87758)
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.