Bench Mark Sheet for 8724273, WATER KEYS SOUTH END 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Superseded Epoch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Small blue map location marker Unpublished bench mark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: 8724273                         PUBLICATION DATE:  03/22/2005
Name:       WATER KEYS SOUTH END                              
            FL
NOAA Chart: 11448                           Latitude:   24° 44.8' N (  24.74670)
USGS Quad:  SUMMERLAND KEY                  Longitude:  81° 27.0' W ( -81.45000)


To reach the tidal bench marks from the highway bridge over Bogie Channel
between Big Pine Key and No Name Key, proceed by boat NW on Bogie Channel and
the marked channel around the north side of Howe Key for 14 km (10 nm) to the SE
end of the largest island of the Water Keys group.  The bench marks are located
on the SE end of the island.  The tide gage and staff were located offshore near
Daymarker 50.


                         T I D A L   B E N C H   M A R K S
                          U.S. DEPARTMENT OF COMMERCE
                National Oceanic and Atmospheric Administration
                            National Ocean Service
                                                                   Page  2 of  5

                                                                                
Station ID: 8724273                         PUBLICATION DATE:  03/22/2005
Name:       WATER KEYS SOUTH END                              
            FL
NOAA Chart: 11448                           Latitude:   24° 44.8' N (  24.74670)
USGS Quad:  SUMMERLAND KEY                  Longitude:  81° 27.0' W ( -81.45000)


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


                 PRIMARY BENCH MARK STAMPING:  WATER KEY RM 1 1934-35
                         DESIGNATION:          WATER KEY RM 1
                         ALIAS:                1

MONUMENTATION:           Reference Mark disk                   VM#:         6888
AGENCY:                  US Coast and Geodetic Survey
                         (USC&GS)                              IDB PID#:  AE4411
SETTING CLASSIFICATION:  Concrete monument                     OPUS PID:        
LATITUDE:   24° 44.8' N (  24.74670)          LONGITUDE:  81° 27.0' W ( -81.45000)


The primary bench mark is a disk set in a 0.21 m (0.7 ft) square concrete
monument, 31.61 m (103.7 ft) SE of bench mark 4273 D 1984, 23 m (75 ft) west of
bench mark WATER KEY 1934-35, 1 m (2 ft) SE of a witness post, and 0.21 m (0.7
ft) above ground level.



                         BENCH MARK STAMPING:  WATER KEY 1934-35
                         DESIGNATION:           WATER KEY
                         ALIAS:                3

MONUMENTATION:           Triangulation Station disk            VM#:         6887
AGENCY:                  US Coast and Geodetic Survey
                         (USC&GS)                              IDB PID#:  AA1581
SETTING CLASSIFICATION:  Concrete monument                     OPUS PID:        
LATITUDE:   24° 45.0' N (  24.75000)          LONGITUDE:  81° 26.8' W ( -81.44670)


The bench mark is a disk set in a 0.21 m (0.7 ft) square concrete monument
located in a high grassy clearing at the SE end of the island, 120 m (394 ft)
NNW of the outer mangroves SSE of the station, 69 m (226 ft) west of the outer
mangroves to the east, 38 m (125 ft) west of the inner edge of the mangroves to
the east, 0.49 m (1.6 ft) west of a witness post, and 0.21 m (0.7 ft) above
ground level.



                         BENCH MARK STAMPING:  WATER KEY RM 2 1934-35
                         DESIGNATION:           WATER KEY RM 2
                         ALIAS:                2

MONUMENTATION:           Reference Mark disk                   VM#:         6889
AGENCY:                  US Coast and Geodetic Survey
                         (USC&GS)                              IDB PID#:  AE4412
SETTING CLASSIFICATION:  Concrete monument                     OPUS PID:        
LATITUDE:   24° 44.8' N (  24.74670)          LONGITUDE:  81° 27.0' W ( -81.45000)


The bench mark is a disk set in a 0.21 m (0.7 ft) square concrete monument,
29.93 m (98.2 ft) west of bench mark 4273 F 1984, 25 m (83 ft) WNW of bench mark
WATER KEY 1934-35, 0.46 m (1.5 ft) SW of a witness post, and 0.15 m (0.5 ft)
above ground level.

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

                                                                                
Station ID: 8724273                         PUBLICATION DATE:  03/22/2005
Name:       WATER KEYS SOUTH END                              
            FL
NOAA Chart: 11448                           Latitude:   24° 44.8' N (  24.74670)
USGS Quad:  SUMMERLAND KEY                  Longitude:  81° 27.0' W ( -81.45000)


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


                         BENCH MARK STAMPING:  4273 D 1984
                         DESIGNATION:          872 4273 D

MONUMENTATION:           Tidal Station disk                    VM#:         6890
AGENCY:                  National Ocean Service (NOS)          IDB PID#:        
SETTING CLASSIFICATION:  Rock outcrop                          OPUS PID:        
LATITUDE:   24° 44.8' N (  24.74670)          LONGITUDE:  81° 27.0' W ( -81.45000)


The bench mark is a disk set in a rock outcrop located in a clearing on the SW
side of the SE end of the island, 36 m (119 ft) WNW of bench mark WATER KEY
1934-35, 31.61 m (103.7 ft) NW of bench mark WATER KEY RM 1 1934-35, 15 m (50
ft) SW of bench mark WATER KEY RM 2 1934-35, 0.76 m (2.5 ft) east of a witness
post, and 0.06 m (0.2 ft) above ground level.



                         BENCH MARK STAMPING:  4273 F 1984
                         DESIGNATION:          872 4273 F

MONUMENTATION:           Tidal Station disk                    VM#:         6891
AGENCY:                  National Ocean Service (NOS)          IDB PID#:        
SETTING CLASSIFICATION:  Stainless steel rod                   OPUS PID:        
LATITUDE:   24° 44.8' N (  24.74670)          LONGITUDE:  81° 27.0' W ( -81.45000)


The bench mark is a disk located on the SE end of the island, 47.03 m (154.3 ft)
ENE of bench mark 4273 D 1984, 29.93 m (98.2 ft) east of bench mark WATER KEY RM
2 1934-35, 19 m (61 ft) NNE of bench mark WATER KEY 1934-35, and 0.49 m (1.6 ft)
SW of a witness post.  The bench mark is set 0.15 m (0.5 ft) below ground level,
crimped to the top of a stainless steel rod driven 3.7 m (12 ft), and encased in
a PVC pipe which projects 0.49 m (1.6 ft) above ground level.

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

                                                                                
Station ID: 8724273                         PUBLICATION DATE:  03/22/2005
Name:       WATER KEYS SOUTH END                              
            FL
NOAA Chart: 11448                           Latitude:   24° 44.8' N (  24.74670)
USGS Quad:  SUMMERLAND KEY                  Longitude:  81° 27.0' W ( -81.45000)


                            T I D A L   D A T U M S 


Tidal datums at WATER KEYS SOUTH END based on:

     LENGTH OF SERIES:      4 MONTHS
     TIME PERIOD:           November 1973 - February 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   =  0.781
     MEAN HIGH WATER                            MHW    =  0.701
     MEAN TIDE LEVEL                            MTL    =  0.387
     MEAN SEA LEVEL                             MSL    =  0.362
     MEAN LOW WATER                             MLW    =  0.072
     MEAN LOWER LOW WATER                       MLLW   =  0.000

North American Vertical Datum (NAVD88)

Bench Mark Elevation Information                In METERS above:

     Stamping or Designation                    MLLW        MHW

     WATER KEY RM 1 1934-35                      0.968    0.267
     WATER KEY 1934-35                           1.065    0.364
     WATER KEY RM 2 1934-35                      1.136    0.435
     4273 D 1984                                 0.814    0.113
     4273 F 1984                                 0.801    0.100


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

                                                                                
Station ID: 8724273                         PUBLICATION DATE:  03/22/2005
Name:       WATER KEYS SOUTH END                              
            FL
NOAA Chart: 11448                           Latitude:   24° 44.8' N (  24.74670)
USGS Quad:  SUMMERLAND KEY                  Longitude:  81° 27.0' W ( -81.45000)


                             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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