U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Datums Page Page 1 of 5
Station ID: 9465374 PUBLICATION DATE: 04/29/2013
Name: SNAG POINT, DILLINGHAM, NUSHAGAK BAY
AK
NOAA Chart: 16323 Latitude: 59° 2.4' N ( 59.04000)
USGS Quad: DILLINGHAM (A-7) Longitude: 158° 26.8' W (-158.44700)
From the post office, proceed SW 0.05 km (0.03 mi) along D Street to the
intersection with 2nd Avenue West, turn left and proceed south 0.15 km (0.09 mi)
to the intersection with Main Street East, turn left and proceed 0.15 km (0.09
mi) ENE to the intersection with 1st Avenue West, turn right and proceed south
0.22 km (0.14 mi) to a steep left turn leading down to the seawall, turn left
and proceed east 0.26 km (0.16 mi) on foot along the seawall to the location of
the tide gauge. The orifice was located approximately 50 m offshore of the
seawall. The bench marks are located along Main Street East, 1st Avenue West
and behind the seawall.
T I D A L B E N C H M A R K S
PRIMARY BENCH MARK STAMPING: 5374 B 2007
DESIGNATION: 946 5374 B
MONUMENTATION: Metal Rod VM#: 18352
AGENCY: National Ocean Sevice (NOS) IDB PID#:
SETTING CLASSIFICATION: Stainless steel rod OPUS PID#: BBBF17
LATITUDE: 59° 2.3' N ( 59.03792) LONGITUDE: 158° 27.6' W (-158.46081)
The primary bench mark is set behind the seawall east of the City Dock, 31.17 m
(102.3 ft) ENE of the western end of the seawall, 9.0 m (30 ft) SE of the base
of a mud bluff, and 4.80 m (15.7 ft) NE of a 15 degree bend in the seawall. The
bench mark is set 1.10 m (3.6 ft) below the top of the seawall, and 0.33 m (1.1
ft) below grade, being the top of a stainless steel rod driven 7 m (23 ft) to
refusal and encased in a 6-inch PVC pipe with NOS logo cap.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 2 of 5
Station ID: 9465374 PUBLICATION DATE: 04/29/2013
Name: SNAG POINT, DILLINGHAM, NUSHAGAK BAY
AK
NOAA Chart: 16323 Latitude: 59° 2.4' N ( 59.04000)
USGS Quad: DILLINGHAM (A-7) Longitude: 158° 26.8' W (-158.44700)
T I D A L B E N C H M A R K S
BENCH MARK STAMPING: 5374 A 2007
DESIGNATION: 946 5374 A
MONUMENTATION: Metal Rod VM#: 18351
AGENCY: National Ocean Sevice (NOS) IDB PID#:
SETTING CLASSIFICATION: Stainless steel rod OPUS PID:
LATITUDE: 59° 2.3' N ( 59.03803) LONGITUDE: 158° 27.6' W (-158.45936)
The bench mark is set behind the seawall east of the City Dock, 45.10 m (148.0
ft) WSW of a 15 degree bend in the seawall, 21.82 m (71.6 ft) ENE of a 15 degree
bend in the seawall, 16.85 m (55.3 ft) ENE of a ladder on the seawall used to
access the beach below, 11 m (36 ft) SE of the base of a grassy bluff, and 0.44
m (1.4 ft) NNW of the seawall. The bench mark is set 0.88 m (2.8 ft) below the
top of the seawall, and 0.12 m (0.4 ft) below grade, being the top of a
stainless steel rod driven 7 m (23 ft) to refusal and encased in a 6-inch PVC
pipe with NOS logo cap.
BENCH MARK STAMPING: 5374 C 2007
DESIGNATION: 946 5374 C
MONUMENTATION: Tidal Station disk VM#: 18353
AGENCY: National Ocean Sevice (NOS) IDB PID#:
SETTING CLASSIFICATION: Doorway OPUS PID:
LATITUDE: 59° 2.3' N ( 59.03831) LONGITUDE: 158° 27.7' W (-158.46178)
The bench mark is a disk set flush in the garage doorway of the Icicle Seafoods
building, 17.82 m (58.5 ft) ENE of the NW corner of the building, 12.74 m (41.8
ft) WSW of the NE building corner, 4.50 m (14.8 ft) ENE of the east edge of the
man door, 4.20 m (13.8 ft) ENE of the west end of the garage door, and 0.06 m
(0.2 ft) WSW from the east edge of the garage door.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 3 of 5
Station ID: 9465374 PUBLICATION DATE: 04/29/2013
Name: SNAG POINT, DILLINGHAM, NUSHAGAK BAY
AK
NOAA Chart: 16323 Latitude: 59° 2.4' N ( 59.04000)
USGS Quad: DILLINGHAM (A-7) Longitude: 158° 26.8' W (-158.44700)
T I D A L B E N C H M A R K S
BENCH MARK STAMPING: 5374 D 2007
DESIGNATION: 946 5374 D
MONUMENTATION: Tidal Station disk VM#: 18354
AGENCY: National Ocean Sevice (NOS) IDB PID#:
SETTING CLASSIFICATION: Concrete patio OPUS PID:
LATITUDE: 59° 2.4' N ( 59.03931) LONGITUDE: 158° 27.8' W (-158.46283)
The bench mark is a disk set flush in a concrete patio between the north side of
the City office building and a preschool, 8.85 m (29.0 ft) SE of the Main Street
curb, 7.20 m (23.6 ft) NE of center of the eastern entrance to the City Hall
building, 3.87 m (12.7 ft) south of the wooden stairs to the preschool, 1.27 m
(4.2 ft) NW of the flag pole, and 0.74 m (2.4 ft) NW of the edge of the concrete
patio.
BENCH MARK STAMPING: 5374 E 2007
DESIGNATION: 946 5374 E
MONUMENTATION: Tidal Station disk VM#: 18355
AGENCY: National Ocean Sevice (NOS) IDB PID#:
SETTING CLASSIFICATION: Concrete apron OPUS PID:
LATITUDE: 59° 2.4' N ( 59.03944) LONGITUDE: 158° 28.0' W (-158.46708)
The bench mark is a disk set in a concrete apron in front of the Alaska
Commercial Store, 6.90 m (22.6 ft) west of the base of a handicap accessible
ramp, 6.30 m (20.7 ft) NNE of the edge of the sidewalk, 1.94 m (6.4 ft) ESE of
the entrance to the store, 1.20 m (3.9 ft) NNW of the base of the stairs, 0.33 m
(1.1 ft) north of the edge of the concrete and 0.73 m (2.4 ft) below the wooden
deck.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 4 of 5
Station ID: 9465374 PUBLICATION DATE: 04/29/2013
Name: SNAG POINT, DILLINGHAM, NUSHAGAK BAY
AK
NOAA Chart: 16323 Latitude: 59° 2.4' N ( 59.04000)
USGS Quad: DILLINGHAM (A-7) Longitude: 158° 26.8' W (-158.44700)
T I D A L D A T U M S
Tidal datums at SNAG POINT, DILLINGHAM, NUSHAGAK BAY based on:
LENGTH OF SERIES: 2 MONTHS
TIME PERIOD: June 2012 - July 2012
TIDAL EPOCH: 1983-2001
CONTROL TIDE STATION:
Elevations of tidal datums referred to Mean Lower Low Water (MLLW), in METERS:
MEAN HIGHER HIGH WATER MHHW = 6.291
MEAN HIGH WATER MHW = 5.757
MEAN SEA LEVEL MSL = 3.303
MEAN TIDE LEVEL MTL = 3.232
MEAN LOW WATER MLW = 0.705
MEAN LOWER LOW WATER MLLW = 0.000
North American Vertical Datum (NAVD88)
Bench Mark Elevation Information In METERS above:
Stamping or Designation MLLW MHW
5374 B 2007 7.581 1.824
5374 A 2007 7.808 2.051
5374 C 2007 16.060 10.303
5374 D 2007 18.426 12.669
5374 E 2007 13.347 7.590
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 5 of 5
Station ID: 9465374 PUBLICATION DATE: 04/29/2013
Name: SNAG POINT, DILLINGHAM, NUSHAGAK BAY
AK
NOAA Chart: 16323 Latitude: 59° 2.4' N ( 59.04000)
USGS Quad: DILLINGHAM (A-7) Longitude: 158° 26.8' W (-158.44700)
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.