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Bench Mark Sheet for 8723752, EAST KEY, FLORIDA BAY 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Superseded Epoch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Small blue map location marker Unpublished bench mark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  7

                                                                                
Station ID: 8723752                         PUBLICATION DATE:  05/12/2004
Name:       EAST KEY, FLORIDA BAY                             
            FL
NOAA Chart: 11463                           Latitude:   24° 59.8' N (  24.99670)
USGS Quad:  PLANTATION KEY                  Longitude:  80° 36.6' W ( -80.61000)


To reach the tidal bench marks from the Islamorada Coast Guard Station at Snake
Creek on Plantation Key, proceed by boat NNW for 5.8 km (3.6 statute mi) to the
SE side of East Key.  The bench marks are located on the SE side of East Key. 
The tide gage and staff were located off the SE shore of East Key on a light
structure.


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


                 PRIMARY BENCH MARK STAMPING:  NO 1 1975
                         DESIGNATION:          CRANE KEY NO 1

MONUMENTATION:           Bench Mark disk                       VM#:         6021
AGENCY:                  National Ocean Survey (NOS)           IDB PID#:  AC4848
SETTING CLASSIFICATION:  Copper-clad steel rod                 OPUS PID:        
LATITUDE:   25°  0.2' N (  25.00330)          LONGITUDE:  80° 37.1' W ( -80.61830)


The primary bench mark is a disk located 24 m (80 ft) NW of the shoreline, 1.98
m (6.5 ft) NW of a witness sign nailed to a buttonwood tree, and 0.34 m (1.1 ft)
NW of a witness post, and 9 cm (0.3 ft) above the ground.  The bench mark is set
in concrete atop a copper-clad rod driven an unspecified depth to refusal.

                          U.S. DEPARTMENT OF COMMERCE
                National Oceanic and Atmospheric Administration
                            National Ocean Service
                                                                   Page  2 of  7

                                                                                
Station ID: 8723752                         PUBLICATION DATE:  05/12/2004
Name:       EAST KEY, FLORIDA BAY                             
            FL
NOAA Chart: 11463                           Latitude:   24° 59.8' N (  24.99670)
USGS Quad:  PLANTATION KEY                  Longitude:  80° 36.6' W ( -80.61000)


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


                         BENCH MARK STAMPING:  EAST 1859 NO 1 1934
                         DESIGNATION:          EAST RM 1

MONUMENTATION:           Reference Mark disk                   VM#:         6019
AGENCY:                  US Coast and Geodetic Survey
                         (USC&GS)                              IDB PID#:  AE9201
SETTING CLASSIFICATION:  Concrete in pipe                      OPUS PID:        
LATITUDE:   24° 59.8' N (  24.99670)          LONGITUDE:  80° 36.6' W ( -80.61000)


The bench mark is a disk set in a 6-inch diameter tile sewer pipe, 33.83 m
(111.0 ft) ENE of reference mark EAST 1859 NO 2 1934, 21.55 m (70.7 ft) NE of
bench mark EAST, and 0.24 m (0.8 ft) west of a witness post.

                          U.S. DEPARTMENT OF COMMERCE
                National Oceanic and Atmospheric Administration
                            National Ocean Service
                                                                   Page  3 of  7

                                                                                
Station ID: 8723752                         PUBLICATION DATE:  05/12/2004
Name:       EAST KEY, FLORIDA BAY                             
            FL
NOAA Chart: 11463                           Latitude:   24° 59.8' N (  24.99670)
USGS Quad:  PLANTATION KEY                  Longitude:  80° 36.6' W ( -80.61000)


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


                         BENCH MARK STAMPING:  EAST 1859 NO 2 1934
                         DESIGNATION:          EAST RM 2

MONUMENTATION:           Reference Mark disk                   VM#:         6020
AGENCY:                  US Coast and Geodetic Survey
                         (USC&GS)                              IDB PID#:  AE9202
SETTING CLASSIFICATION:  Concrete in pipe                      OPUS PID:        
LATITUDE:   24° 59.8' N (  24.99670)          LONGITUDE:  80° 36.6' W ( -80.61000)


The bench mark is a disk set in concrete in a 6-inch diameter tile sewer pipe,
21.66 m (71.1 ft) NW of bench mark EAST, 0.24 m (0.8 ft) east of a witness post,
and 6 cm (0.2 ft) above the ground.



                         BENCH MARK STAMPING:  NO 2 1975
                         DESIGNATION:          872 3752 TIDAL 2

MONUMENTATION:           Tidal Station disk                    VM#:         6022
AGENCY:                  National Ocean Survey (NOS)           IDB PID#:        
SETTING CLASSIFICATION:  Copper-clad steel rod                 OPUS PID:        
LATITUDE:   24° 59.8' N (  24.99670)          LONGITUDE:  80° 36.6' W ( -80.61000)


The bench mark is a disk located 20.63 m (67.7 ft) NNW of bench mark NO 1 1975,
20 m (65 ft) SE of bench mark East 1859 NO 2 1934, 4 m (12 ft) NW of a witness
sign on a buttonwood tree, and 0.24 m (0.8 ft) NW of a witness post. The bench
mark is set 15 cm (0.5 ft) above ground level, crimped to a copper-clad rod
driven an unspecified depth to refusal.

                          U.S. DEPARTMENT OF COMMERCE
                National Oceanic and Atmospheric Administration
                            National Ocean Service
                                                                   Page  4 of  7

                                                                                
Station ID: 8723752                         PUBLICATION DATE:  05/12/2004
Name:       EAST KEY, FLORIDA BAY                             
            FL
NOAA Chart: 11463                           Latitude:   24° 59.8' N (  24.99670)
USGS Quad:  PLANTATION KEY                  Longitude:  80° 36.6' W ( -80.61000)


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


                         BENCH MARK STAMPING:   
                         DESIGNATION:          EAST
                         ALIAS:                NO STAMPING 1

MONUMENTATION:           Chiseled Cross                        VM#:         6023
AGENCY:                  US Coast and Geodetic Survey
                         (USC&GS)                              IDB PID#:  AA1322
SETTING CLASSIFICATION:  Granite monument                      OPUS PID:        
LATITUDE:   24° 59.9' N (  24.99830)          LONGITUDE:  80° 36.6' W ( -80.61000)


The bench mark is a granite monument with a faint cross cut in the top, on the
SW side of East Key in an open ground inshore from the mangroves that grow close
together along the shore, 21.55 m (70.7 ft) SW of reference mark EAST 1859 NO 1
1934, 17.77 m (58.3 ft) NW of bench mark NO 2 1975,  and 0.18 m (0.6 ft) SE of a
witness post.  

                          U.S. DEPARTMENT OF COMMERCE
                National Oceanic and Atmospheric Administration
                            National Ocean Service
                                                                   Page  5 of  7

                                                                                
Station ID: 8723752                         PUBLICATION DATE:  05/12/2004
Name:       EAST KEY, FLORIDA BAY                             
            FL
NOAA Chart: 11463                           Latitude:   24° 59.8' N (  24.99670)
USGS Quad:  PLANTATION KEY                  Longitude:  80° 36.6' W ( -80.61000)


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


                         BENCH MARK STAMPING:   
                         DESIGNATION:          EAST RP NW
                         ALIAS:                NO STAMPING 2

MONUMENTATION:           Chiseled Cross                        VM#:         6024
AGENCY:                  US Coast and Geodetic Survey
                         (USC&GS)                              IDB PID#:  AE9203
SETTING CLASSIFICATION:  Granite monument                      OPUS PID:        
LATITUDE:   24° 59.8' N (  24.99670)          LONGITUDE:  80° 36.6' W ( -80.61000)


The bench mark is a 9 cm (0.3 ft) square granite monument with a prominent cross
cut in the top (designated as a reference mark for Triangulation Station EAST),
in the middle of the SW side of East Key, and 1.95 m (6.4 ft) NNW of bench mark
EAST, and 6 cm (0.2 ft) above the ground.  NOTE:  This is also referred to as
the north granite monument.

                          U.S. DEPARTMENT OF COMMERCE
                National Oceanic and Atmospheric Administration
                            National Ocean Service
                                                                   Page  6 of  7

                                                                                
Station ID: 8723752                         PUBLICATION DATE:  05/12/2004
Name:       EAST KEY, FLORIDA BAY                             
            FL
NOAA Chart: 11463                           Latitude:   24° 59.8' N (  24.99670)
USGS Quad:  PLANTATION KEY                  Longitude:  80° 36.6' W ( -80.61000)


                            T I D A L   D A T U M S 


Tidal datums at EAST KEY, FLORIDA BAY based on:

     LENGTH OF SERIES:      1 MONTH
     TIME PERIOD:           June 1975 - June 1975
     TIDAL EPOCH:           1983-2001
     CONTROL TIDE STATION:  8723852 LOWER MATECUMBE KEY, FLA. BAY


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

     MEAN HIGHER HIGH WATER                     MHHW   =  0.186
     MEAN HIGH WATER                            MHW    =  0.160
     MEAN TIDE LEVEL                            MTL    =  0.082
     MEAN SEA LEVEL                             MSL    =  0.079
     MEAN LOW WATER                             MLW    =  0.004
     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 1 1975                                   0.306    0.146
     EAST 1859 NO 1 1934                         0.258    0.098
     EAST 1859 NO 2 1934                         0.299    0.139
     NO 2 1975                                   0.349    0.189
     EAST                                        0.315    0.155
     EAST RP NW                                  0.299    0.139


Foot Notes:

Bench mark East RP NW is based on one differential leveling connection and does
not meet the quality control standards of the NOS. Therefore, caution should be
used when deriving an elevation for this mark.

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

                                                                                
Station ID: 8723752                         PUBLICATION DATE:  05/12/2004
Name:       EAST KEY, FLORIDA BAY                             
            FL
NOAA Chart: 11463                           Latitude:   24° 59.8' N (  24.99670)
USGS Quad:  PLANTATION KEY                  Longitude:  80° 36.6' W ( -80.61000)


                             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 8723752 EAST KEY, FLORIDA BAY, FL

Revised: 08/08/2018
NOAA / National Ocean Service
Web site owner: Center for Operational Oceanographic Products and Services