U.S. DEPARTMENT OF COMMERCE
                National Oceanic and Atmospheric Administration
                            National Ocean Service
Datums Page                                                        Page  1 of  7

                                                                                
Station ID: 8725667                         PUBLICATION DATE:  04/27/2012
Name:       PLACIDA, GASPARILLA SOUND                         
            FL
NOAA Chart: 11426                           Latitude:   26° 50.0' N (  26.83330)
USGS Quad:  PLACIDA                         Longitude:  82° 15.9' W ( -82.26500)


To reach the tidal bench marks proceed on County Road 771 to the Coral Creek
Bridge over Coral Creek in Placida.  The bench marks are located along the sides
of the road.  The tide gage and staff were located on the dock at the SW corner
of the bridge.


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


                 PRIMARY BENCH MARK STAMPING:  5667 B 1977
                         DESIGNATION:          872 5667 B TIDAL

MONUMENTATION:           Tidal Station disk                    VM#:         7379
AGENCY:                  National Ocean Survey (NOS)           IDB PID#:  AG7783
SETTING CLASSIFICATION:  Concrete abutment                     OPUS PID:        
LATITUDE:   26° 50.0' N (  26.83330)          LONGITUDE:  82° 15.8' W ( -82.26330)


The primary bench mark is a disk set flush in the SW abutment of the County Road
771 bridge over Coral Creek, 130 m (425 ft) north of the Placida Post Office,
5.64 m (18.5 ft) NW of the centerline of the highway, and 0.46 m (1.5 ft) NW of
the west corner of the bridge.



                         BENCH MARK STAMPING:  5667 A RESET 1982
                         DESIGNATION:          872 5667 A TIDAL RESET

MONUMENTATION:           Tidal Station disk                    VM#:         7380
AGENCY:                  National Ocean Survey (NOS)           IDB PID#:  AG7785
SETTING CLASSIFICATION:  Concrete step                         OPUS PID:        
LATITUDE:   26° 50.0' N (  26.83330)          LONGITUDE:  82° 15.8' W ( -82.26330)


The bench mark is a disk in the second set of steps leading to the front
entrance of the Placida Post Office, 15.06 m (49.4 ft) west of the centerline of
the road, 14.20 m (46.6 ft) north of the NE corner of the Gasparilla Fishery
building, 0.67 m (2.2 ft) east of the SE corner of the post office building, and
0.61 m (2.0 ft) above ground level.

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

                                                                                
Station ID: 8725667                         PUBLICATION DATE:  04/27/2012
Name:       PLACIDA, GASPARILLA SOUND                         
            FL
NOAA Chart: 11426                           Latitude:   26° 50.0' N (  26.83330)
USGS Quad:  PLACIDA                         Longitude:  82° 15.9' W ( -82.26500)


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


                         BENCH MARK STAMPING:  5667 C RESET 1982
                         DESIGNATION:          872 5667 C TIDAL RESET

MONUMENTATION:           Tidal Station disk                    VM#:         7381
AGENCY:                  National Ocean Survey (NOS)           IDB PID#:  AG7782
SETTING CLASSIFICATION:  Concrete sidewalk                     OPUS PID:        
LATITUDE:   26° 50.0' N (  26.83330)          LONGITUDE:  82° 15.8' W ( -82.26330)


The bench mark is a disk set in the concrete sidewalk of the County Road 771
bridge over Coral Creek, 31.85 m (104.5 ft) SW of the north corner of the
bridge, 4.27 m (14.0 ft) NW of the centerline of the highway and 0.37 m (1.2 ft)
SE of the NW bridge rail.



                         BENCH MARK STAMPING:  5667 D
                         DESIGNATION:          872 5667 D TIDAL

MONUMENTATION:           Survey disk                           VM#:        17159
AGENCY:                  Florida Department of Transportation
                         (FLDT)                                IDB PID#:  AG7784
SETTING CLASSIFICATION:  Bridge Abutment                       OPUS PID:        
LATITUDE:   26° 50.0' N (  26.83330)          LONGITUDE:  82° 15.8' W ( -82.26330)


The bench mark is a disk set in the SW abutment located 5.64 m (18.5 ft) SW of
the approximate centerline of County Road 771,  2.20 m (6.9 ft) NW of a wooden
guard rail, and 0.67 m (2.2 ft) SE of a metal guard rail.

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

                                                                                
Station ID: 8725667                         PUBLICATION DATE:  04/27/2012
Name:       PLACIDA, GASPARILLA SOUND                         
            FL
NOAA Chart: 11426                           Latitude:   26° 50.0' N (  26.83330)
USGS Quad:  PLACIDA                         Longitude:  82° 15.9' W ( -82.26500)


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


                         BENCH MARK STAMPING:  5667 E
                         DESIGNATION:          872 5667 E TIDAL

MONUMENTATION:           Survey disk                           VM#:        17160
AGENCY:                  Florida Department of Transportation
                         (FLDT)                                IDB PID#:  AG7781
SETTING CLASSIFICATION:  Concrete bridge abutment              OPUS PID:        
LATITUDE:   27° 28.0' N (  27.46592)          LONGITUDE:  82° 41.2' W ( -82.68717)


The bench mark is a disk set in the bridge abutment located 5.48 m (18.0 ft) NW
of the approximate centerline of County Road 771, 0.67 m (2.2 ft) NW of a metal
guard rail, and 0.06 m (0.2 ft) NW of the north end of a concrete guard rail.

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

                                                                                
Station ID: 8725667                         PUBLICATION DATE:  04/27/2012
Name:       PLACIDA, GASPARILLA SOUND                         
            FL
NOAA Chart: 11426                           Latitude:   26° 50.0' N (  26.83330)
USGS Quad:  PLACIDA                         Longitude:  82° 15.9' W ( -82.26500)


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


                         BENCH MARK STAMPING:  CHA 15 1983 BSM
                         DESIGNATION:          CHA 15

MONUMENTATION:           Survey disk                           VM#:        19971
AGENCY:                  Florida Dept. of Environmental
                         Protection (FLDEP)                    IDB PID#:  AG7780
SETTING CLASSIFICATION:  Concrete culvert headwall             OPUS PID:        
LATITUDE:   26° 50.6' N (  26.84389)          LONGITUDE:  82° 15.4' W ( -82.25611)


The bench mark is a disk set 0.30 m (1 ft) below the centerline of highway,
bearing 14.05 m (46.1 ft) NW of the centerline of the road, 4.72 m (15.5 ft) SW
of the NE end of the headwall, 36.21 m (118.8 ft) NNW and across the highway
from a power pole, and 2.13 m (7.0 ft) NE of a witness post.

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

                                                                                
Station ID: 8725667                         PUBLICATION DATE:  04/27/2012
Name:       PLACIDA, GASPARILLA SOUND                         
            FL
NOAA Chart: 11426                           Latitude:   26° 50.0' N (  26.83330)
USGS Quad:  PLACIDA                         Longitude:  82° 15.9' W ( -82.26500)


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


                         BENCH MARK STAMPING:  CHA 16 1983 BSM
                         DESIGNATION:          CHA 16

MONUMENTATION:           Survey disk                           VM#:        19972
AGENCY:                  Florida Dept. of Environmental
                         Protection (FLDEP)                    IDB PID#:  AG7779
SETTING CLASSIFICATION:  Concrete culvert headwall             OPUS PID:        
LATITUDE:   26° 51.1' N (  26.85250)          LONGITUDE:  82° 15.0' W ( -82.24917)


The bench mark is a disk set above the level of the centerline of the highway,
bearing 12.2 m (40.1 ft) SE of the centerline of the highway, 1.5 m (5 ft) SW of
the NE end of the headwall, 13.41 m (44 ft) SW of a power pole, and 2.34 m (7.7
ft) NE of a witness post.

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

                                                                                
Station ID: 8725667                         PUBLICATION DATE:  04/27/2012
Name:       PLACIDA, GASPARILLA SOUND                         
            FL
NOAA Chart: 11426                           Latitude:   26° 50.0' N (  26.83330)
USGS Quad:  PLACIDA                         Longitude:  82° 15.9' W ( -82.26500)


                            T I D A L   D A T U M S 


Tidal datums at PLACIDA, GASPARILLA SOUND based on:

     LENGTH OF SERIES:      5 MONTHS
     TIME PERIOD:           August 1977 - December 1977
     TIDAL EPOCH:           1983-2001
     CONTROL TIDE STATION:  8725744 PUNTA GORDA


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

     MEAN HIGHER HIGH WATER                     MHHW   =  0.429
     North American Vertical Datum              NAVD88 =  0.389
     MEAN HIGH WATER                            MHW    =  0.358
     MEAN SEA LEVEL                             MSL    =  0.239
     MEAN TIDE LEVEL                            MTL    =  0.234
     MEAN LOW WATER                             MLW    =  0.109
     MEAN LOWER LOW WATER                       MLLW   =  0.000

North American Vertical Datum (NAVD88)

Bench Mark Elevation Information                In METERS above:

     Stamping or Designation                    MLLW        MHW

     5667 B 1977                                 2.735    2.377
     5667 A RESET 1982                           1.813    1.455
     5667 C RESET 1982                           3.344    2.986
     5667 D                                      3.004    2.646
     5667 E                                      3.155    2.797
     CHA 15 1983 BSM                             1.641    1.283
     CHA 16 1983 BSM                             1.785    1.427


Foot Notes:

Geodetic heights of the bench marks meet all NOAA/NOS/NGS quality control
standards for Second Order, Class 1 leveling.  It is advised that a confirmation
set of levels be established for bench marks CHA 15 1983 BSM and CHA 16 1983 BSM
to verify height differences before using tidal bench mark elevation
information.

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

                                                                                
Station ID: 8725667                         PUBLICATION DATE:  04/27/2012
Name:       PLACIDA, GASPARILLA SOUND                         
            FL
NOAA Chart: 11426                           Latitude:   26° 50.0' N (  26.83330)
USGS Quad:  PLACIDA                         Longitude:  82° 15.9' W ( -82.26500)


                             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.