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Bench Mark Sheet for 8724307, CONTENT KEY,GULF OF MEXICO 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Superseded Epoch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Small blue map location marker Unpublished bench mark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: 8724307                         PUBLICATION DATE:  05/12/2004
Name:       CONTENT KEY,GULF OF MEXICO                        
            FL
NOAA Chart: 11448                           Latitude:   24° 47.4' N (  24.79000)
USGS Quad:  CONTENT KEYS                    Longitude:  81° 29.0' W ( -81.48330)


To reach the tidal bench marks from the west end of the U.S. Highway 1 bridge
over Niles Channel on the east side of Summerland Key, proceed by boat north and
then NW on Niles Channel for 8.9 km (5.5 mi) to Channel Marker #64, then head
north across the shallows for 7.2 km (4.5 mi) to the NE tip of the easternmost
key on the west side of Content Passage.  The bench marks are located on the NE
tip of the key.  The tide gage and staff were located on a platform offshore.


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


                 PRIMARY BENCH MARK STAMPING:  NO 2 1970
                         DESIGNATION:          872 4307 TIDAL 2

MONUMENTATION:           Tidal Station disk                    VM#:        11328
AGENCY:                  National Geodetic Survey (NGS)        IDB PID#:  AA0338
SETTING CLASSIFICATION:  Shallow-set pipe                      OPUS PID:        
LATITUDE:   24° 47.4' N (  24.79000)          LONGITUDE:  81° 29.0' W ( -81.48330)


The primary bench mark is a disk set in a small clearing near the east shoreline
of the key, 5 m (16 ft) west of the east shoreline, and 0.27 m (0.9 ft) NE of a
witness post.  The bench mark is set 0.37 m (1.2 ft) above ground level, on top
of a 3-inch pipe driven 3 m (10 ft) to refusal.

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

                                                                                
Station ID: 8724307                         PUBLICATION DATE:  05/12/2004
Name:       CONTENT KEY,GULF OF MEXICO                        
            FL
NOAA Chart: 11448                           Latitude:   24° 47.4' N (  24.79000)
USGS Quad:  CONTENT KEYS                    Longitude:  81° 29.0' W ( -81.48330)


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


                         BENCH MARK STAMPING:  NO 3 1970
                         DESIGNATION:          872 4307 TIDAL 3

MONUMENTATION:           Tidal Station disk                    VM#:        11329
AGENCY:                  National Geodetic Survey (NGS)        IDB PID#:  AA0339
SETTING CLASSIFICATION:  Shallow-set pipe                      OPUS PID:        
LATITUDE:   24° 47.4' N (  24.79000)          LONGITUDE:  81° 29.0' W ( -81.48330)


The bench mark is a disk set in a small clearing near the east shoreline of the
key, 19.66 m (64.5 ft) NNW of bench mark NO 1A 1973, 15.24 m (50.0 ft) west of
the east shoreline, 11.98 m (39.3 ft) WNW of bench mark NO 2 1970, and 0.24 m
(0.8 ft) ENE of a witness post.  The bench mark is set 0.18 m (0.6 ft) above
ground level, on top of a 3-inch pipe driven 3 m (10 ft) to refusal.



                         BENCH MARK STAMPING:  NO 5 1970
                         DESIGNATION:          872 4307 TIDAL 5

MONUMENTATION:           Tidal Station disk                    VM#:        11330
AGENCY:                  National Geodetic Survey (NGS)        IDB PID#:  AA0341
SETTING CLASSIFICATION:  Shallow-set pipe                      OPUS PID:        
LATITUDE:   24° 47.4' N (  24.79000)          LONGITUDE:  81° 29.0' W ( -81.48330)


The bench mark is a disk set in a small clearing near the east shoreline of the
key, 10.12 m (33.2 ft) NE of bench mark NO 4A 1973, 2 m (8 ft) west of the
shoreline, and 0.3 m (1 ft) NE of a witness post.  The bench mark is set 0.98 m
(3.2 ft) above ground level, on top of a 3-inch pipe driven 3 m (10 ft) to
refusal.

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

                                                                                
Station ID: 8724307                         PUBLICATION DATE:  05/12/2004
Name:       CONTENT KEY,GULF OF MEXICO                        
            FL
NOAA Chart: 11448                           Latitude:   24° 47.4' N (  24.79000)
USGS Quad:  CONTENT KEYS                    Longitude:  81° 29.0' W ( -81.48330)


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


                         BENCH MARK STAMPING:  NO 1A 1973
                         DESIGNATION:          872 4307 TIDAL 1 A

MONUMENTATION:           Tidal Station disk                    VM#:        11331
AGENCY:                  National Ocean Survey (NOS)           IDB PID#:  AA1632
SETTING CLASSIFICATION:  Shallow-set pipe                      OPUS PID:        
LATITUDE:   24° 47.4' N (  24.79000)          LONGITUDE:  81° 29.0' W ( -81.48330)


The bench mark is a disk set in concrete inside a 4-inch metal pipe, in a small
clearing near the east shoreline of the key, 15.06 m (49.4 ft) SSW of bench mark
NO 2 1970, 6 m (20 ft) west of the shoreline, 0.21 m (0.7 ft) east of a witness
post, and 0.06 m (0.2 ft) above ground level.



                         BENCH MARK STAMPING:  NO 4A 1973
                         DESIGNATION:          872 4307 TIDAL 4 A

MONUMENTATION:           Tidal Station disk                    VM#:        11332
AGENCY:                  National Ocean Survey (NOS)           IDB PID#:  AA1631
SETTING CLASSIFICATION:  Shallow-set pipe                      OPUS PID:        
LATITUDE:   24° 47.4' N (  24.79000)          LONGITUDE:  81° 29.0' W ( -81.48330)


The bench mark is a disk set in a small clearing on the east shoreline of the
key, 19.05 m (62.5 ft) NNW of bench mark NO 2 1970, 11 m (36 ft) north of bench
mark NO 3 1970, 9 m (28 ft) SW of the shoreline, and 0.55 m (1.8 ft) NE of a
witness post.  The bench mark is set 0.3 m (1 ft) above ground level, set in
concrete on top of a 3-inch pipe driven 3 m (10 ft) to refusal.

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

                                                                                
Station ID: 8724307                         PUBLICATION DATE:  05/12/2004
Name:       CONTENT KEY,GULF OF MEXICO                        
            FL
NOAA Chart: 11448                           Latitude:   24° 47.4' N (  24.79000)
USGS Quad:  CONTENT KEYS                    Longitude:  81° 29.0' W ( -81.48330)


                            T I D A L   D A T U M S 


Tidal datums at CONTENT KEY,GULF OF MEXICO based on:

     LENGTH OF SERIES:      1 YEAR
     TIME PERIOD:           March 1974 - February 1975
     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 (11/04/1971)         =  1.408
     MEAN HIGHER HIGH WATER                     MHHW   =  1.059
     MEAN HIGH WATER                            MHW    =  0.986
     North American Vertical Datum              NAVD88 =  0.850
     MEAN SEA LEVEL                             MSL    =  0.564
     MEAN TIDE LEVEL                            MTL    =  0.560
     MEAN LOW WATER                             MLW    =  0.135
     MEAN LOWER LOW WATER                       MLLW   =  0.000
     LOWEST  OBSERVED WATER LEVEL (02/05/1974)         = -0.338

North American Vertical Datum (NAVD88)

Bench Mark Elevation Information                In METERS above:

     Stamping or Designation                    MLLW        MHW

     NO 2 1970                                   1.762    0.776
     NO 3 1970                                   1.702    0.716
     NO 5 1970                                   1.855    0.869
     NO 1A 1973                                  1.384    0.398
     NO 4A 1973                                  1.837    0.851


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

                                                                                
Station ID: 8724307                         PUBLICATION DATE:  05/12/2004
Name:       CONTENT KEY,GULF OF MEXICO                        
            FL
NOAA Chart: 11448                           Latitude:   24° 47.4' N (  24.79000)
USGS Quad:  CONTENT KEYS                    Longitude:  81° 29.0' W ( -81.48330)


                             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 8724307 CONTENT KEY,GULF OF MEXICO, FL

Revised: 10/15/2013
NOAA / National Ocean Service
Web site owner: Center for Operational Oceanographic Products and Services