U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Datums Page Page 1 of 4
Station ID: 9465056 PUBLICATION DATE: 12/13/2012
Name: PROTECTION POINT, NUSHAGAK BAY
AK
NOAA Chart: 16322 Latitude: 58° 30.0' N ( 58.50000)
USGS Quad: NUSHAGAK BAY B-3 Longitude: 158° 42.7' W (-158.71200)
T I D A L B E N C H M A R K S
PRIMARY BENCH MARK STAMPING: NO 3 1949
DESIGNATION: 946 5056 TIDAL 3
MONUMENTATION: Tidal Station disk VM#: 20570
AGENCY: US Coast and Geodectic Survey
(USC&GS) IDB PID#:
SETTING CLASSIFICATION: Metal pipe OPUS PID:
LATITUDE: 58° 29.8' N ( 58.49647) LONGITUDE: 158° 42.9' W (-158.71447)
The primary bench mark is a disk set in a 2 1/2-inch brass pipe filled with
concrete on the third ridge inland from the shore, 124.0 m (406.8 ft) WNW of
bench mark 946 5056 TIDAL 4, 66.76 m (219.0 ft) SSW of high water line, 57.79 m
(189.6 ft) WNW of bench mark 946 5056 A and 0.13 cm (0.4 ft) above grade.
BENCH MARK STAMPING: 5056 A 2012
DESIGNATION: 946 5056 A
MONUMENTATION: Flange-encased Rod VM#: 20571
AGENCY: National Ocean Service (NOS) IDB PID#:
SETTING CLASSIFICATION: Stainless steel rod in sleeve OPUS PID#: BBCT76
LATITUDE: 58° 29.8' N ( 58.49631) LONGITUDE: 158° 42.8' W (-158.71356)
The bench mark is a stainless steel rod set on the third ridge inland from
shore, 67.22 m (220.5 ft) WNW of bench mark 946 5056 TIDAL 4, 57.79 m (189.6 ft)
ESE of bench mark 946 5056 TIDAL 3 1949, and 27.28 m (89.5 ft) SSE of the
highest point of nearest prominent ridge. The datum point is set 7 cm (0.2 ft)
below grade, being the top of a stainless steel rod driven 15.0 m (49 ft) to
refusal, and encased in a 5-inch NOS logo cover.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 2 of 4
Station ID: 9465056 PUBLICATION DATE: 12/13/2012
Name: PROTECTION POINT, NUSHAGAK BAY
AK
NOAA Chart: 16322 Latitude: 58° 30.0' N ( 58.50000)
USGS Quad: NUSHAGAK BAY B-3 Longitude: 158° 42.7' W (-158.71200)
T I D A L B E N C H M A R K S
BENCH MARK STAMPING: 5056 B 2012
DESIGNATION: 946 5056 B
MONUMENTATION: Flange-encased Rod VM#: 20572
AGENCY: National Ocean Service (NOS) IDB PID#:
SETTING CLASSIFICATION: Stainless steel rod in sleeve OPUS PID:
LATITUDE: 58° 29.7' N ( 58.49578) LONGITUDE: 158° 42.7' W (-158.71131)
The bench mark is a stainless steel rod set on the third ridge inland from
shore, 72.82 m (238.9 ft) ESE of bench mark 946 5056 TIDAL 4, 68.72 m (225.5 ft)
WNW of bench mark 946 5056 C, and 35.48 m (116.4 ft) SSW of the highest point of
nearest prominent ridge. The datum point is 8 cm (0.3 ft) below grade, being
the top of a stainless steel rod driven 15.5 m (51 ft) to refusal, and encased
in a 5-inch NOS logo cover.
BENCH MARK STAMPING: 5056 C 2012
DESIGNATION: 946 5056 C
MONUMENTATION: Flange-encased Rod VM#: 20573
AGENCY: National Ocean Service (NOS) IDB PID#:
SETTING CLASSIFICATION: Stainless steel rod in sleeve OPUS PID:
LATITUDE: 58° 29.7' N ( 58.49556) LONGITUDE: 158° 42.6' W (-158.71019)
The bench mark is a stainless steel rod set on the third ridge inland from
shore, 145.5 m (477.4 ft) ESE of bench mark 946 5056 TIDAL 4, 68.72 m (225.5 ft)
ESE of bench mark 946 5056 B, 38.89 m (127.6 ft) SSW of the highest point of
nearest prominent ridge. The datum point is 9 cm (0.3 ft) below grade, being
the top of a stainless steel rod driven 15.3 m (50 ft) to refusal, and encased
in a 5-inch NOS logo cover.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 3 of 4
Station ID: 9465056 PUBLICATION DATE: 12/13/2012
Name: PROTECTION POINT, NUSHAGAK BAY
AK
NOAA Chart: 16322 Latitude: 58° 30.0' N ( 58.50000)
USGS Quad: NUSHAGAK BAY B-3 Longitude: 158° 42.7' W (-158.71200)
T I D A L D A T U M S
Tidal datums at PROTECTION POINT, 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 = 5.404
MEAN HIGH WATER MHW = 4.857
MEAN SEA LEVEL MSL = 2.865
MEAN TIDE LEVEL MTL = 2.854
MEAN LOW WATER MLW = 0.850
MEAN LOWER LOW WATER MLLW = 0.000
North American Vertical Datum (NAVD88)
Bench Mark Elevation Information In METERS above:
Stamping or Designation MLLW MHW
NO 3 1949 6.616 1.759
5056 A 2012 6.422 1.565
5056 B 2012 6.380 1.523
5056 C 2012 6.367 1.510
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 4 of 4
Station ID: 9465056 PUBLICATION DATE: 12/13/2012
Name: PROTECTION POINT, NUSHAGAK BAY
AK
NOAA Chart: 16322 Latitude: 58° 30.0' N ( 58.50000)
USGS Quad: NUSHAGAK BAY B-3 Longitude: 158° 42.7' W (-158.71200)
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.