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Bench Mark Sheet for 9452634, Elfin 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Superseded Epoch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Small blue map location marker Unpublished bench mark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  9

                                                                                
Station ID: 9452634                         PUBLICATION DATE:  12/20/2012
Name:       ELFIN COVE, PORT ALTHORP                          
            AK
NOAA Chart: 17302                           Latitude:   58° 11.7' N (  58.19472)
USGS Quad:  MT. FAIRWEATHER (A-1)           Longitude: 136° 20.8' W (-136.34694)


To reach the tidal bench marks from the seaplane base at Juneau, Alaska, proceed
110 km (59 nm) west to the community of Elfin Cove.  From the seaplane float
located in the outer cove, proceed 250 m (820 ft) SE along the community board
walk to the north shore of the inner cove.  The bench marks are located along
the NE shoreline of the inner cove.


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


                 PRIMARY BENCH MARK STAMPING:  4 1959
                         DESIGNATION:          945 2634 TIDAL 4

MONUMENTATION:           Tidal Station disk                    VM#:        14511
AGENCY:                  US Coast and Geodetic Survey
                         (USC&GS)                              IDB PID#:        
SETTING CLASSIFICATION:  Boulder                               OPUS PID:        
LATITUDE:   58° 11.6' N (  58.19403)          LONGITUDE: 136° 20.7' W (-136.34458)


The primary bench mark is a disk set in top of a 1 m (3 ft) high boulder located
on the north side of the walk, 21.92 m (71.9 ft) NW of the center root on the
large tree north of the boardwalk used as a brace for the stairway up the hill,
8.41 m (27.6 ft) NW of the NE corner of the yellow building on the south side
(shore side) of the boardwalk, 2.00 m (6.6 ft) east of the large yellow shingled
house called "Patti's FP Smokers" just east of Elfin Cove School/Community
Building, 1.58 m (5.2 ft) north of the north edge of the boardwalk, and 0.70 m
(2.3 ft) east of the yellow shed attached to the east side of the yellow
shingled house.

                          U.S. DEPARTMENT OF COMMERCE
                National Oceanic and Atmospheric Administration
                            National Ocean Service
                                                                   Page  2 of  9

                                                                                
Station ID: 9452634                         PUBLICATION DATE:  12/20/2012
Name:       ELFIN COVE, PORT ALTHORP                          
            AK
NOAA Chart: 17302                           Latitude:   58° 11.7' N (  58.19472)
USGS Quad:  MT. FAIRWEATHER (A-1)           Longitude: 136° 20.8' W (-136.34694)


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


                         BENCH MARK STAMPING:  1952
                         DESIGNATION:          945 2634 TIDAL 5

MONUMENTATION:           Tidal Station disk                    VM#:        14512
AGENCY:                  US Coast and Geodetic Survey
                         (USC&GS)                              IDB PID#:        
SETTING CLASSIFICATION:  Steel pipe                            OPUS PID:        
LATITUDE:   58° 11.6' N (  58.19353)          LONGITUDE: 136° 20.6' W (-136.34392)


The bench mark is a disk set flush with natural grade in the top of a 2-1/2-inch
steel pipe projecting from a cairn of rocks just east of a small creek, 91.44 m
(300.0 ft) east along the walk from the Elfin Cove School/Community Building,
12.20 m (40.0 ft) ESE of bench mark 2634 B 1991, 4.51 m (14.8 ft) ESE of the
center of a stream, 3.41 m (11.2 ft) NNW of the NW center of a wooden shed, and
0.79 m (2.6 ft) north of the boardwalk. 



                         BENCH MARK STAMPING:  2634 A 1991
                         DESIGNATION:          945 2634 A TIDAL

MONUMENTATION:           Tidal Station disk                    VM#:        14513
AGENCY:                  National Ocean Service (NOS)          IDB PID#:        
SETTING CLASSIFICATION:  Rock outcrop                          OPUS PID:        
LATITUDE:   58° 11.6' N (  58.19392)          LONGITUDE: 136° 20.6' W (-136.34406)


The bench mark is a disk set flush in a rock outcropping on the water side of
the boardwalk betwen the large yellow shingled house called The Gift and Gab
Shop and the gray shed next to the small creek running under the boardwalk,
32.31 m (106.0 ft) south of bench mark 4 1959, 12.50 m (41.0 ft) ESE of the
center of a roof on the large tree north of the boardwalk used as brace for
stairway up the hill, 9.39 m (30.8 ft) WSW of bench mark 2634 B 1991, 1.0 m (3.3
ft) south of the boardwalk, and 0.91 m (3.0 ft) below the boardwalk.

                          U.S. DEPARTMENT OF COMMERCE
                National Oceanic and Atmospheric Administration
                            National Ocean Service
                                                                   Page  3 of  9

                                                                                
Station ID: 9452634                         PUBLICATION DATE:  12/20/2012
Name:       ELFIN COVE, PORT ALTHORP                          
            AK
NOAA Chart: 17302                           Latitude:   58° 11.7' N (  58.19472)
USGS Quad:  MT. FAIRWEATHER (A-1)           Longitude: 136° 20.8' W (-136.34694)


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


                         BENCH MARK STAMPING:  2634 B 1991
                         DESIGNATION:          945 2634 B TIDAL

MONUMENTATION:           Tidal Station disk                    VM#:        14514
AGENCY:                  National Ocean Service (NOS)          IDB PID#:        
SETTING CLASSIFICATION:  Rock outcrop                          OPUS PID:        
LATITUDE:   58° 11.6' N (  58.19378)          LONGITUDE: 136° 20.6' W (-136.34389)


The bench mark is a disk set flush in a rock outcropping on the landward side of
the boardwalk between the large yellow shingled house called The Gift and Gab
Shop and the gray shed next to the small creek running under the boardwalk,
14.39 m (47.2 ft) WNW of the NW corner of wooden shed, 12.19 m (40.0 ft) WNW of
bench mark 1952, 9.75 m (32.0 ft) NE of bench mark 2634 A 1991, 7.99 m (26.2 ft)
west of the center of the creek, 0.3 m (1 ft) north of the boardwalk, and 0.61 m
(2.0 ft) above the boardwalk.

                          U.S. DEPARTMENT OF COMMERCE
                National Oceanic and Atmospheric Administration
                            National Ocean Service
                                                                   Page  4 of  9

                                                                                
Station ID: 9452634                         PUBLICATION DATE:  12/20/2012
Name:       ELFIN COVE, PORT ALTHORP                          
            AK
NOAA Chart: 17302                           Latitude:   58° 11.7' N (  58.19472)
USGS Quad:  MT. FAIRWEATHER (A-1)           Longitude: 136° 20.8' W (-136.34694)


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


                         BENCH MARK STAMPING:  2634 G 2005
                         DESIGNATION:          945 2634 G

MONUMENTATION:           Tidal Station disk                    VM#:        17942
AGENCY:                  National Ocean Service (NOS)          IDB PID#:        
SETTING CLASSIFICATION:  In rock outcrop                       OPUS PID:        
LATITUDE:   58° 11.7' N (  58.19422)          LONGITUDE: 136° 20.8' W (-136.34744)


The bench mark is a disk set flush in a large outcropping of rock near the
waters edge south of th fuel dock,  50.90 m (167.0 ft) SSW of the 10th pair of
pilings supporting the boardwalk NW (seaward) of the white shed, 43.89 m (144.0
ft) north of the 1.0 m (3.3 ft) long wooden witness post nailed to a boardwalk
post (below boardwalk) at the north end of the green shed north of store, 24.29
m (79.7 ft) SE of 2.0 m (6.6 ft) high x 1.5 m (4.9 ft) wide x 4.0 m (13.1 ft)
long rock point exposed at mean high water which projects 0.61 m (2.0 ft) above
the barnacle line, sloping north and is the most landward outcrop, and 6.18 m
(53.1 ft) (sloped distance) NW of the post for the sign that says "Elf Inn Way"
at the beginning of the wooden boardwalk between the fuel tank farm and the
General Store.

                          U.S. DEPARTMENT OF COMMERCE
                National Oceanic and Atmospheric Administration
                            National Ocean Service
                                                                   Page  5 of  9

                                                                                
Station ID: 9452634                         PUBLICATION DATE:  12/20/2012
Name:       ELFIN COVE, PORT ALTHORP                          
            AK
NOAA Chart: 17302                           Latitude:   58° 11.7' N (  58.19472)
USGS Quad:  MT. FAIRWEATHER (A-1)           Longitude: 136° 20.8' W (-136.34694)


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


                         BENCH MARK STAMPING:  2634 F 2005
                         DESIGNATION:          945 2634 F TIDAL

MONUMENTATION:           Tidal Station disk                    VM#:        17943
AGENCY:                  National Ocean Service (NOS)          IDB PID#:        
SETTING CLASSIFICATION:  In rock outcrop                       OPUS PID#: BBBB67
LATITUDE:   58° 11.7' N (  58.19472)          LONGITUDE: 136° 20.8' W (-136.34694)


The bench mark is a disk set flush in a rock outcropping north of the dock
leading to the fuel dock, 34.69 m (113.8 ft) SSE of bench mark 2634 E 2005,
29.60 m (97.1 ft) NW of the bottom of the stairs on the north side of the
boardwalk just east of the white metal shed near the tank farm, 11.31 m (37.1
ft) SSW of a white sign that says  This is not a dump no metal glass or food ,
and 5.79 m (19.0 ft) north of Toner & Nordland survey disk.  



                         BENCH MARK STAMPING:  2634 E 2005
                         DESIGNATION:          945 2634 E

MONUMENTATION:           Tidal Station disk                    VM#:        17944
AGENCY:                  National Ocean Service (NOS)          IDB PID#:        
SETTING CLASSIFICATION:  In rock outcrop                       OPUS PID:        
LATITUDE:   58° 11.7' N (  58.19503)          LONGITUDE: 136° 20.8' W (-136.34711)


The bench mark is a disk set flush in a rock outcropping at the waters edge
between the fuel dock and transient dock, 34.69 m (113.8 ft) NNW of bench mark
2634 F 2005, 25.70 m (84.3 ft) NNW of a white  This is not a dump  sign, 4.11 m
(13.5 ft) north of a 0.40 m (1.3 ft) high anchor bolt securing a cable that
supports a dolphin near the fuel dock, and recessed 4 cm (0.1 ft) into outcrop.

                          U.S. DEPARTMENT OF COMMERCE
                National Oceanic and Atmospheric Administration
                            National Ocean Service
                                                                   Page  6 of  9

                                                                                
Station ID: 9452634                         PUBLICATION DATE:  12/20/2012
Name:       ELFIN COVE, PORT ALTHORP                          
            AK
NOAA Chart: 17302                           Latitude:   58° 11.7' N (  58.19472)
USGS Quad:  MT. FAIRWEATHER (A-1)           Longitude: 136° 20.8' W (-136.34694)


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


                         BENCH MARK STAMPING:  2634 D 2005
                         DESIGNATION:          945 2634 D TIDAL

MONUMENTATION:           Tidal Station disk                    VM#:        17945
AGENCY:                  National Ocean Service (NOS)          IDB PID#:        
SETTING CLASSIFICATION:  In rock outcrop                       OPUS PID:        
LATITUDE:   58° 11.7' N (  58.19508)          LONGITUDE: 136° 20.8' W (-136.34589)


The bench mark is a disk set flush in a 6.0 m (19.7 ft) long x 2.5 m (8.2 ft)
wide x 0.9 m (3.0 ft) high rock outcropping in front of the Elfin Cove Lodge,
36.52 m (119.8 ft) ENE of the 8th pair of pilings from the end of the boardwalk
leading to the main boat dock, 19.29 m (63.3 ft) WSW of a 0.1 m (0.3 ft) square
metal post that supports the sign for the Fishmasters Inn set in a 0.79 m (2.6
ft) square concrete foundation straddling the boardwalk to boat dock, and 7.89 m
(25.9 ft) NW of the bottom stair leading from the deck of the Elfin Cove Lodge
to the bench on the shore side of lodge.  

                          U.S. DEPARTMENT OF COMMERCE
                National Oceanic and Atmospheric Administration
                            National Ocean Service
                                                                   Page  7 of  9

                                                                                
Station ID: 9452634                         PUBLICATION DATE:  12/20/2012
Name:       ELFIN COVE, PORT ALTHORP                          
            AK
NOAA Chart: 17302                           Latitude:   58° 11.7' N (  58.19472)
USGS Quad:  MT. FAIRWEATHER (A-1)           Longitude: 136° 20.8' W (-136.34694)


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


                         BENCH MARK STAMPING:  TERRA SURVEYS TIDAL BM YAGER
                                               USACE 2003
                         DESIGNATION:          YAGER

MONUMENTATION:           Tidal Station disk                    VM#:        17947
AGENCY:                  National Ocean Service (NOS)          IDB PID#:        
SETTING CLASSIFICATION:  Retaining walls                       OPUS PID:        
LATITUDE:   58° 11.7' N (  58.19500)          LONGITUDE: 136° 20.8' W (-136.34667)


The bench mark is a disk set vertically in the grey retaining wall of the fuel
tank farm,  7.10 m (23.3 ft) SW from the NW corner of the grey retaining wall,
4.69 m (15.4 ft) ESE from the SE corner of a white utility building, 2.50 m (8.2
ft) NE of the corner of wooden foot bridge, 1.19 m (3.9 ft) ESE from the
centerline of the 1.0 m (3.3 ft) wide trail, and 0.4 m (1.3 ft) above ground.  



                         BENCH MARK STAMPING:  2634 J 2011
                         DESIGNATION:          945 2634 J

MONUMENTATION:           Tidal Station disk                    VM#:        20193
AGENCY:                  National Ocean Service (NOS)          IDB PID#:        
SETTING CLASSIFICATION:  Concrete foundation                   OPUS PID:        
LATITUDE:   58° 11.6' N (  58.19414)          LONGITUDE: 136° 20.7' W (-136.34550)


The bench mark is a disk set flush in the western edge of the concrete
foundation for an electrical transformer on the west side of the Jim Lewis Elfin
Cove Power Generating Facility on the east side of the boardwalk, 34.20 m (112.2
ft) NW of a white flagpole at the SW corner of the Elfin Cove Post Office, 11.90
m (39.0 ft) SE of the bottom of a ramp leading to the entrance of COHO's Bar and
Grill, 8.50 m (27.9 ft) SSE of the bottom stair of the deck leading to the gift
shop, 0.70 m (2.3 ft) west of a green electrical utility box, and 0.13 m (0.4
ft) above natural grade.

                          U.S. DEPARTMENT OF COMMERCE
                National Oceanic and Atmospheric Administration
                            National Ocean Service
                                                                   Page  8 of  9

                                                                                
Station ID: 9452634                         PUBLICATION DATE:  12/20/2012
Name:       ELFIN COVE, PORT ALTHORP                          
            AK
NOAA Chart: 17302                           Latitude:   58° 11.7' N (  58.19472)
USGS Quad:  MT. FAIRWEATHER (A-1)           Longitude: 136° 20.8' W (-136.34694)


                            T I D A L   D A T U M S 


Tidal datums at ELFIN COVE, PORT ALTHORP based on:

     LENGTH OF SERIES:      6 YEARS
     TIME PERIOD:           May 2006 - April 2012
     TIDAL EPOCH:           1983-2001
     CONTROL TIDE STATION:  9451600 SITKA, BARONOF ISLAND, SITKA SOUND


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

     HIGHEST OBSERVED WATER LEVEL (12/31/2005)         =  4.554
     MEAN HIGHER HIGH WATER                     MHHW   =  3.359
     MEAN HIGH WATER                            MHW    =  3.088
     MEAN TIDE LEVEL                            MTL    =  1.767
     MEAN SEA LEVEL                             MSL    =  1.750
     MEAN LOW WATER                             MLW    =  0.445
     MEAN LOWER LOW WATER                       MLLW   =  0.000
     LOWEST  OBSERVED WATER LEVEL (12/14/2008)         = -1.432

North American Vertical Datum (NAVD88)

Bench Mark Elevation Information                In METERS above:

     Stamping or Designation                    MLLW        MHW

     4 1959                                      6.484    3.396
     1952                                        6.384    3.296
     2634 A 1991                                 4.961    1.873
     2634 B 1991                                 6.584    3.496
     2634 G 2005                                 4.865    1.777
     2634 F 2005                                 5.358    2.270
     2634 E 2005                                 3.619    0.531
     2634 D 2005                                 3.863    0.775
     TERRA SURVEYS TIDAL BM YAGER USACE
     2003                                        6.025    2.937
     2634 J 2011                                 7.376    4.288


                          U.S. DEPARTMENT OF COMMERCE
                National Oceanic and Atmospheric Administration
                            National Ocean Service
                                                                   Page  9 of  9

                                                                                
Station ID: 9452634                         PUBLICATION DATE:  12/20/2012
Name:       ELFIN COVE, PORT ALTHORP                          
            AK
NOAA Chart: 17302                           Latitude:   58° 11.7' N (  58.19472)
USGS Quad:  MT. FAIRWEATHER (A-1)           Longitude: 136° 20.8' W (-136.34694)


                             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
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