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Bench Mark Sheet for 8724138, BAHIA HONDA KEY FL

Superseded Epoch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Small blue map location marker Unpublished bench mark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: 8724138                         PUBLICATION DATE:  05/09/2003
Name:       BAHIA HONDA KEY                                   
            FL
NOAA Chart: 11449                           Latitude:   24° 39.3' N (  24.65500)
USGS Quad:  BIG PINE KEY                    Longitude:  81° 16.9' W ( -81.28170)


To reach the tidal bench marks from the Post Office at Marathon, proceed 21.6 km
(13.4 mi) SW on U.S Highway 1 to the east end of the Bahia Honda Bridge over Big
Spanish Channel, 0.3 km (0.2 mi) south of the new bridge.  The bench marks are
located on the old highway bridge which is above an abandoned railroad bridge at
the state recreation area, and near the tackle shop.  The tide gage and staff
were located on the NE concrete wingwall of the railroad bridge.


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


                 PRIMARY BENCH MARK STAMPING:  W BAHIA RM 2 1935
                         DESIGNATION:          872 4138 W BAHIA RM 2

MONUMENTATION:           Tidal Station disk                    VM#:         6369
AGENCY:                  US Coast and Geodetic Survey
                         (USC&GS)                              IDB PID#:  AA0269
SETTING CLASSIFICATION:  Concrete wing wall                    OPUS PID:        
LATITUDE:   24° 39.2' N (  24.65330)          LONGITUDE:  81° 16.9' W ( -81.28170)


The primary bench mark is a disk set in the top of the south concrete wingwall
of the old bridge, 96 m (315 ft) west of the east end of the bridge, 10 m (33
ft) south of the centerline of the highway, 5.24 m (17.2 ft) SE of bench mark NO
4 1936, and 11 m (35 ft) below highway level.

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

                                                                                
Station ID: 8724138                         PUBLICATION DATE:  05/09/2003
Name:       BAHIA HONDA KEY                                   
            FL
NOAA Chart: 11449                           Latitude:   24° 39.3' N (  24.65500)
USGS Quad:  BIG PINE KEY                    Longitude:  81° 16.9' W ( -81.28170)


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


                         BENCH MARK STAMPING:  4138 F 1982
                         DESIGNATION:          872 4138 F

MONUMENTATION:           Tidal Station disk                    VM#:         6365
AGENCY:                  National Ocean Survey (NOS)           IDB PID#:  AA0898
SETTING CLASSIFICATION:  Concrete walkway                      OPUS PID:        
LATITUDE:   24° 39.3' N (  24.65500)          LONGITUDE:  81° 16.9' W ( -81.28170)


The bench mark is a disk set in a concrete walkway, near the tackle shop, 10.79
m (35.4 ft) NW of the south corner of the dive shop, 5.03 m (16.5 ft) east of
the NE edge of the parking lot, 1.34 m (4.4 ft) SSW of the west corner of the
tackle shop, and 0.15 m (0.5 ft) SW of the stairs behind the tackle shop.



                         BENCH MARK STAMPING:  D 70 RESET 1936 TIDAL NO 2
                         DESIGNATION:          872 4138 D 70 RESET

MONUMENTATION:           Tidal Station disk                    VM#:         6366
AGENCY:                  US Coast and Geodetic Survey
                         (USC&GS)                              IDB PID#:  AA0267
SETTING CLASSIFICATION:  Concrete wing wall                    OPUS PID:        
LATITUDE:   24° 39.3' N (  24.65500)          LONGITUDE:  81° 16.9' W ( -81.28170)


The bench mark is a disk set in the top of the north concrete wingwall of the
old bridge, 96 m (315 ft) west of the east end of the bridge, 5 m (16 ft) north
of the centerline of the highway, and 9 m (30 ft) below highway level.

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

                                                                                
Station ID: 8724138                         PUBLICATION DATE:  05/09/2003
Name:       BAHIA HONDA KEY                                   
            FL
NOAA Chart: 11449                           Latitude:   24° 39.3' N (  24.65500)
USGS Quad:  BIG PINE KEY                    Longitude:  81° 16.9' W ( -81.28170)


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


                         BENCH MARK STAMPING:  G 329 1970
                         DESIGNATION:          872 4138 G 329

MONUMENTATION:           Tidal Station disk                    VM#:         6367
AGENCY:                  National Ocean Survey (NOS)           IDB PID#:  AA0271
SETTING CLASSIFICATION:  Concrete wing wall                    OPUS PID:        
LATITUDE:   24° 39.3' N (  24.65500)          LONGITUDE:  81° 16.8' W ( -81.28000)


The bench mark is a disk set in the top of the NW corner of the 6th concrete
step from the bottom of the landing near the old bridge, 46 m (150 ft) north of
the north edge of the bridge, 43.31 m (142.1 ft) east of the east face of the
concrete wingwall of the railroad bridge and the NE corner of the highway
bridge, 18 m (58 ft) south of the shoreline, and 3 m (10 ft) above the apparent
high water level.



                         BENCH MARK STAMPING:  NO 4 1936
                         DESIGNATION:          872 4138 TIDAL 4

MONUMENTATION:           Tidal Station disk                    VM#:         6368
AGENCY:                  US Coast and Geodetic Survey
                         (USC&GS)                              IDB PID#:  AA0268
SETTING CLASSIFICATION:  Concrete wing wall                    OPUS PID:        
LATITUDE:   24° 39.3' N (  24.65500)          LONGITUDE:  81° 16.9' W ( -81.28170)


The bench mark is a disk set in the top of the south concrete wingwall of the
old bridge, 96 m (315 ft) west of the east end of the bridge, 5 m (16 ft) south
of the centerline of the highway, and 9 m (30 ft) below highway level.

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

                                                                                
Station ID: 8724138                         PUBLICATION DATE:  05/09/2003
Name:       BAHIA HONDA KEY                                   
            FL
NOAA Chart: 11449                           Latitude:   24° 39.3' N (  24.65500)
USGS Quad:  BIG PINE KEY                    Longitude:  81° 16.9' W ( -81.28170)


                            T I D A L   D A T U M S 


Tidal datums at BAHIA HONDA KEY based on:

     LENGTH OF SERIES:      12 MONTHS
     TIME PERIOD:           February 1971 - January 1972
     TIDAL EPOCH:           1983-2001
     CONTROL TIDE STATION:  8724580 KEY WEST


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

     HIGHEST OBSERVED WATER LEVEL (11/05/1971)         =  0.772
     North American Vertical Datum              NAVD88 =  0.512
     MEAN HIGHER HIGH WATER                     MHHW   =  0.470
     MEAN HIGH WATER                            MHW    =  0.398
     MEAN SEA LEVEL                             MSL    =  0.228
     MEAN TIDE LEVEL                            MTL    =  0.222
     MEAN LOW WATER                             MLW    =  0.046
     MEAN LOWER LOW WATER                       MLLW   =  0.000
     LOWEST  OBSERVED WATER LEVEL (04/26/1971)         = -0.298

North American Vertical Datum (NAVD88)

Bench Mark Elevation Information                In METERS above:

     Stamping or Designation                    MLLW        MHW

     W BAHIA RM 2 1935                           6.905    6.507
     4138 F 1982                                 1.671    1.273
     D 70 RESET 1936 TIDAL NO 2                  7.804    7.406
     G 329 1970                                  3.879    3.481
     NO 4 1936                                   7.861    7.463


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

                                                                                
Station ID: 8724138                         PUBLICATION DATE:  05/09/2003
Name:       BAHIA HONDA KEY                                   
            FL
NOAA Chart: 11449                           Latitude:   24° 39.3' N (  24.65500)
USGS Quad:  BIG PINE KEY                    Longitude:  81° 16.9' W ( -81.28170)


                             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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Products available at 8724138 BAHIA HONDA KEY, FL

Revised: 10/15/2013
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