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Bench Mark Sheet for 9450495, Saltery Cove AK

Superseded Epoch

Large map location marker Station Location
Small red map location marker Published bench mark
Small blue map location marker Unpublished bench mark

Bench mark positions only appear on the map if their coordinates in the CO-OPS database are at the precision of degrees/minutes/seconds/and tenths of seconds. If the coordinates are less precise, the mark will not appear.

Printable version

                          U.S. DEPARTMENT OF COMMERCE
                National Oceanic and Atmospheric Administration
                            National Ocean Service
Datums Page                                                        Page  1 of  5

                                                                                
Station ID: 9450495                         PUBLICATION DATE:  06/28/2004
Name:       SALTERY COVE, SKOWL ARM                           
            AK
NOAA Chart: 17426                           Latitude:   55° 24.1' N (  55.40170)
USGS Quad:  CRAIG (B-1)                     Longitude: 132° 19.7' W (-132.32800)


To reach the tidal bench marks from Ketchikan, Alaska, proceed 43.5 km (23.5 nm)
WNW by a float plane or boat to the confluence of Skowl Arm and McKenzie Inlet
on Prince of Wales Island and Saltery Cove is located nearby.  The tidal bench
marks are on the beach at the head of Saltery Cove.  The tide gauge was located
on the beach.


                         T I D A L   B E N C H   M A R K S


                 PRIMARY BENCH MARK STAMPING:  NO 5 1958
                         DESIGNATION:          945 0495 TIDAL 5

MONUMENTATION:           Tidal Station disk                    VM#:        17416
AGENCY:                  US Coast and Geodetic Survey
                         (USC&GS)                              IDB PID#:        
SETTING CLASSIFICATION:  Rock outcrop                          OPUS PID:        
LATITUDE:   55° 24.1' N (  55.40170)          LONGITUDE: 132° 19.7' W (-132.32800)


The primary bench mark is a disk set in top of a flat rock outcrop on a rocky
point, 114 m (372 ft) SE of bench mark NO 2 1921, 5 m (15 ft) east of old engine
parts, under the NE corner of the main ruins of cannery on the west shore of
Saltery Cove, and just below the apparent high water line.

                          U.S. DEPARTMENT OF COMMERCE
                National Oceanic and Atmospheric Administration
                            National Ocean Service
                                                                   Page  2 of  5

                                                                                
Station ID: 9450495                         PUBLICATION DATE:  06/28/2004
Name:       SALTERY COVE, SKOWL ARM                           
            AK
NOAA Chart: 17426                           Latitude:   55° 24.1' N (  55.40170)
USGS Quad:  CRAIG (B-1)                     Longitude: 132° 19.7' W (-132.32800)


                         T I D A L   B E N C H   M A R K S


                         BENCH MARK STAMPING:  NO 2 1921
                         DESIGNATION:          945 0495 TIDAL 2

MONUMENTATION:           Tidal Station disk                    VM#:        17413
AGENCY:                  US Coast and Geodetic Survey
                         (USC&GS)                              IDB PID#:        
SETTING CLASSIFICATION:  Rocky ledge                           OPUS PID:        
LATITUDE:   55° 24.1' N (  55.40170)          LONGITUDE: 132° 19.7' W (-132.32800)


The bench mark is a disk set in a flat spot on a rocky ledge, 114 m (372 ft) NW
of bench mark NO 5 1958, slightly above apparent high water line, and below the
bluff on which the ruins of two cottages are located.



                         BENCH MARK STAMPING:  NO 3 1921
                         DESIGNATION:          945 0495 TIDAL 3

MONUMENTATION:           Tidal Station disk                    VM#:        17414
AGENCY:                  US Coast and Geodetic Survey
                         (USC&GS)                              IDB PID#:        
SETTING CLASSIFICATION:  Rock outcrop                          OPUS PID:        
LATITUDE:   55° 24.1' N (  55.40170)          LONGITUDE: 132° 19.7' W (-132.32800)


The bench mark is a disk set in a rock outcrop, 80 m (262 ft) NW of bench mark
NO 6 1959, 30 m (100 ft) north of another clump of rocks, SE across the head of
Saltery Cove from bench mark NO 5 1958, in the NW section of a clump of rocks on
low point, and at the apparent high water line.

                          U.S. DEPARTMENT OF COMMERCE
                National Oceanic and Atmospheric Administration
                            National Ocean Service
                                                                   Page  3 of  5

                                                                                
Station ID: 9450495                         PUBLICATION DATE:  06/28/2004
Name:       SALTERY COVE, SKOWL ARM                           
            AK
NOAA Chart: 17426                           Latitude:   55° 24.1' N (  55.40170)
USGS Quad:  CRAIG (B-1)                     Longitude: 132° 19.7' W (-132.32800)


                         T I D A L   B E N C H   M A R K S


                         BENCH MARK STAMPING:  NO 4 1958
                         DESIGNATION:          945 0495 TIDAL 4

MONUMENTATION:           Tidal Station disk                    VM#:        17415
AGENCY:                  US Coast and Geodetic Survey
                         (USC&GS)                              IDB PID#:        
SETTING CLASSIFICATION:  Top of a rock                         OPUS PID:        
LATITUDE:   55° 24.1' N (  55.40170)          LONGITUDE: 132° 19.7' W (-132.32800)


The bench mark is a disk set in top of a rock, 130 m (426 ft) SW of bench mark
NO 6 1959, 122 m (400 ft) SW of a clump of rocks with a 6 m (20 ft) tall cedar
tree and 5 m (15 ft) tall spruce tree, 46 m (150 ft) north of the tree line at
the head of Saltery Cove, and 6 m (20 ft) east of a small stream at the low
water.



                         BENCH MARK STAMPING:  NO 6 1959
                         DESIGNATION:          945 0495 TIDAL 6

MONUMENTATION:           Tidal Station disk                    VM#:        17417
AGENCY:                  US Coast and Geodetic Survey
                         (USC&GS)                              IDB PID#:        
SETTING CLASSIFICATION:  Rock outcrop                          OPUS PID:        
LATITUDE:   55° 24.1' N (  55.40170)          LONGITUDE: 132° 19.7' W (-132.32800)


The bench mark is a disk set in top of a rock outcrop, 130 m (426 ft) NE of
bench mark NO 4 1958, 80 m (262 ft) SE of bench mark NO 3 1921, 21 m (70 ft) SSE
of a 6 m (20 ft) tall cedar tree and a 5 m (15 ft) tall spruce tree, on the
clump of rocks at the head of Saltery Cove, and just below the highest point of
the highest rock in the outcrop.

                          U.S. DEPARTMENT OF COMMERCE
                National Oceanic and Atmospheric Administration
                            National Ocean Service
                                                                   Page  4 of  5

                                                                                
Station ID: 9450495                         PUBLICATION DATE:  06/28/2004
Name:       SALTERY COVE, SKOWL ARM                           
            AK
NOAA Chart: 17426                           Latitude:   55° 24.1' N (  55.40170)
USGS Quad:  CRAIG (B-1)                     Longitude: 132° 19.7' W (-132.32800)


                            T I D A L   D A T U M S 


Tidal datums at SALTERY COVE, SKOWL ARM based on:

     LENGTH OF SERIES:      1 MONTH
     TIME PERIOD:           August 2003 - August 2003
     TIDAL EPOCH:           1983-2001
     CONTROL TIDE STATION:  9450460 KETCHIKAN, TONGASS NARROWS


Elevations of tidal datums referred to Mean Lower Low Water (MLLW), in METERS:

     MEAN HIGHER HIGH WATER                     MHHW   =  4.746
     MEAN HIGH WATER                            MHW    =  4.469
     MEAN TIDE LEVEL                            MTL    =  2.477
     MEAN SEA LEVEL                             MSL    =  2.473
     MEAN LOW WATER                             MLW    =  0.485
     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 5 1958                                   4.530    0.061
     NO 2 1921                                   5.434    0.965
     NO 3 1921                                   4.640    0.171
     NO 4 1958                                   3.812   -0.657
     NO 6 1959                                   5.631    1.162


                          U.S. DEPARTMENT OF COMMERCE
                National Oceanic and Atmospheric Administration
                            National Ocean Service
                                                                   Page  5 of  5

                                                                                
Station ID: 9450495                         PUBLICATION DATE:  06/28/2004
Name:       SALTERY COVE, SKOWL ARM                           
            AK
NOAA Chart: 17426                           Latitude:   55° 24.1' N (  55.40170)
USGS Quad:  CRAIG (B-1)                     Longitude: 132° 19.7' W (-132.32800)


                             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.

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Revised: 08/08/2018
NOAA / National Ocean Service
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