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Bench Mark Sheet for 8724205, MAYO 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Superseded Epoch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Small blue map location marker Unpublished bench mark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: 8724205                         PUBLICATION DATE:  05/12/2004
Name:       MAYO KEY                                          
            FL
NOAA Chart: 11445                           Latitude:   24° 44.0' N (  24.73330)
USGS Quad:  BIG PINE KEY                    Longitude:  81° 21.7' W ( -81.36170)


To reach the tidal bench marks from the Bogie Channel Bridge linking Big Pine
Key and No Name Key, proceed NW by boat 4.0 km (2.5 statute mi) to the midpoint
of the eastern shore of Mayo Key.  The bench marks are located midway along the
eastern shore, west of mangroves.  The tide gage and staff were located
offshore, west of the marks and the eastern shoreline.


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


                 PRIMARY BENCH MARK STAMPING:  NO 1 1974
                         DESIGNATION:          872 4205 TIDAL 1

MONUMENTATION:           Tidal Station disk                    VM#:         6436
AGENCY:                  National Ocean Survey (NOS)           IDB PID#:        
SETTING CLASSIFICATION:  Copper-clad steel rod                 OPUS PID:        
LATITUDE:   24° 44.0' N (  24.73330)          LONGITUDE:  81° 21.7' W ( -81.36170)


The primary bench mark is a disk located about 485 m (1590 ft) NW of the SE tip
of the key, 43 m (140 ft) west of the outer edge of the mangroves along the
eastern shore, 38 m (126 ft) WSW of a wooden witness post located 4 m (14 ft)
WSW of the outer edge of the mangroves, 23 m (76 ft) east of bench mark NO 3
1974, 5 m (17 ft) WSW of the inner fringe of mangroves, and 0.24 m (0.8 ft) east
of a witness post.  The bench mark is set 12 cm (0.4 ft) above ground level, set
flush in concrete atop a copper-clad rod, and driven to refusal.

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

                                                                                
Station ID: 8724205                         PUBLICATION DATE:  05/12/2004
Name:       MAYO KEY                                          
            FL
NOAA Chart: 11445                           Latitude:   24° 44.0' N (  24.73330)
USGS Quad:  BIG PINE KEY                    Longitude:  81° 21.7' W ( -81.36170)


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


                         BENCH MARK STAMPING:  NO 2 1974
                         DESIGNATION:          872 4205 TIDAL 2

MONUMENTATION:           Tidal Station disk                    VM#:         6437
AGENCY:                  National Ocean Survey (NOS)           IDB PID#:        
SETTING CLASSIFICATION:  Copper-clad steel rod                 OPUS PID:        
LATITUDE:   24° 44.0' N (  24.73330)          LONGITUDE:  81° 21.7' W ( -81.36170)


The bench mark is a disk located 49 m (160 ft) west of the outer edge of the
mangroves on the eastern shore, 13.72 m (45.0 ft) NW of bench mark NO 1 1974,
7.25 m (23.8 ft) ESE of a witness sign nailed to a tree, and 0.24 m (0.8 ft)
east of a witness post.  The bench mark is set 6 cm (0.2 ft)  above ground
level, set flush in concrete atop a copper-clad rod, and driven to refusal.



                         BENCH MARK STAMPING:  NO 3 1974
                         DESIGNATION:          872 4205 TIDAL 3

MONUMENTATION:           Tidal Station disk                    VM#:         6438
AGENCY:                  National Ocean Survey (NOS)           IDB PID#:        
SETTING CLASSIFICATION:  Copper-clad steel rod                 OPUS PID:        
LATITUDE:   24° 44.0' N (  24.73330)          LONGITUDE:  81° 21.7' W ( -81.36170)


The bench mark is a disk located 64 m (210 ft) west of the outer edge of the
mangroves on the eastern shore, 15.94 m (52.3 ft) ENE of bench mark NO 5 1974,
15.06 m (49.4 ft) WSW of bench mark NO 2 1974, and 0.30 m (1.0 ft) east of a
witness post. The bench mark is set 6 cm (0.2 ft) above ground level, set flush
in concrete atop a copper-clad rod, and driven to refusal.

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

                                                                                
Station ID: 8724205                         PUBLICATION DATE:  05/12/2004
Name:       MAYO KEY                                          
            FL
NOAA Chart: 11445                           Latitude:   24° 44.0' N (  24.73330)
USGS Quad:  BIG PINE KEY                    Longitude:  81° 21.7' W ( -81.36170)


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


                         BENCH MARK STAMPING:  NO 5 1974
                         DESIGNATION:          872 4205 TIDAL 5

MONUMENTATION:           Tidal Station disk                    VM#:         6440
AGENCY:                  National Ocean Survey (NOS)           IDB PID#:        
SETTING CLASSIFICATION:  Copper-clad steel rod                 OPUS PID:        
LATITUDE:   24° 44.0' N (  24.73330)          LONGITUDE:  81° 21.7' W ( -81.36170)


The bench mark is a disk located 79 m (260 ft) west of the outer edge of
mangroves on the eastern shore, 19.35 m (63.5 ft) SSW of bench mark NO 4 1974,
4.79 m (15.7 ft) east of a witness sign nailed to a tree, and 0.30 m (1.0 ft)
east of a witness post. The bench mark is set 9 cm (0.3 ft) above ground level,
set flush in concrete atop a copper-clad rod, and driven to refusal.

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

                                                                                
Station ID: 8724205                         PUBLICATION DATE:  05/12/2004
Name:       MAYO KEY                                          
            FL
NOAA Chart: 11445                           Latitude:   24° 44.0' N (  24.73330)
USGS Quad:  BIG PINE KEY                    Longitude:  81° 21.7' W ( -81.36170)


                            T I D A L   D A T U M S 


Tidal datums at MAYO KEY based on:

     LENGTH OF SERIES:      1 MONTH
     TIME PERIOD:           August 1974 - August 1974
     TIDAL EPOCH:           1983-2001
     CONTROL TIDE STATION:  8724580 KEY WEST


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

     MEAN HIGHER HIGH WATER                     MHHW   =  0.496
     MEAN HIGH WATER                            MHW    =  0.428
     MEAN TIDE LEVEL                            MTL    =  0.253
     MEAN SEA LEVEL                             MSL    =  0.240
     MEAN LOW WATER                             MLW    =  0.078
     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 1974                                   0.710    0.282
     NO 2 1974                                   0.549    0.121
     NO 3 1974                                   0.563    0.135
     NO 5 1974                                   0.742    0.314


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

                                                                                
Station ID: 8724205                         PUBLICATION DATE:  05/12/2004
Name:       MAYO KEY                                          
            FL
NOAA Chart: 11445                           Latitude:   24° 44.0' N (  24.73330)
USGS Quad:  BIG PINE KEY                    Longitude:  81° 21.7' W ( -81.36170)


                             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 8724205 MAYO KEY, FL

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