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

                                                                                
Station ID: 8726217                         PUBLICATION DATE:  05/12/2011
Name:       CORTEZ, SARASOTA BAY                              
            FL
NOAA Chart: 11424                           Latitude:   27° 28.0' N (  27.46670)
USGS Quad:  BRADENTON BEACH                 Longitude:  82° 41.2' W ( -82.68670)


To reach the tidal bench marks from the Cortez Post Office, proceed west on
State Road 684 (Cortez Road West) for 0.6 km (0.4 mi) to Cortez Fishing Center
on the left. The bench marks are north and south sides of State Road 684 at the
bridge over Anna Maria Sound, and at the US Coast Guard Station. The tide gage
and staff were located off the dock of Cortez Marina.


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


                 PRIMARY BENCH MARK STAMPING:  NO 1 1953
                         DESIGNATION:          872 6217 TIDAL 1

MONUMENTATION:           Tidal Station disk                    VM#:         6139
AGENCY:                  US Coast and Geodetic Survey
                         (USC&GS)                              IDB PID#:  AG2000
SETTING CLASSIFICATION:  Concrete sea wall                     OPUS PID#: AG2000
LATITUDE:   27° 28.0' N (  27.46670)          LONGITUDE:  82° 41.3' W ( -82.68830)


The primary bench mark is a disk set in the top of a concrete sea wall located
behind the U.S. Coast Guard Station in Cortez, 24.84 m (81.5 ft) SW of the SW
corner of the station, 19.51 m (64.0 ft) ESE of the flagpole, 7.92 m (26.0 ft)
west of the centerline of the black-topped walk leading to the north end of the
fishing pier. NOTE: Mark is painted yellow.

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

                                                                                
Station ID: 8726217                         PUBLICATION DATE:  05/12/2011
Name:       CORTEZ, SARASOTA BAY                              
            FL
NOAA Chart: 11424                           Latitude:   27° 28.0' N (  27.46670)
USGS Quad:  BRADENTON BEACH                 Longitude:  82° 41.2' W ( -82.68670)


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


                         BENCH MARK STAMPING:  NO 2 1953
                         DESIGNATION:          872 6217 TIDAL 2

MONUMENTATION:           Tidal Station disk                    VM#:         6144
AGENCY:                  US Coast and Geodetic Survey
                         (USC&GS)                              IDB PID#:  AG1999
SETTING CLASSIFICATION:  Concrete sea wall                     OPUS PID#: AG1999
LATITUDE:   27° 28.0' N (  27.46670)          LONGITUDE:  82° 41.2' W ( -82.68670)


The bench mark is a disk set flush in the top of a concrete seawall behind the
U.S. Coast Guard Station, 21.3 m (69.8 ft) WNW of bench mark NO 1 1953, 13.3 m
(43.5 ft) west of the west edge of a concrete slab for a diesel tank, 3.0 m (9.8
ft) SSW of the south end of an 2.4 m (8.0 ft) chain link fence, and 0.8 m (2.5
ft) north of where the seawall makes a right angle turn.



                         BENCH MARK STAMPING:  NO 3 1953
                         DESIGNATION:          872 6217 TIDAL 3

MONUMENTATION:           Tidal Station disk                    VM#:         6145
AGENCY:                  US Coast and Geodetic Survey
                         (USC&GS)                              IDB PID#:  AG1998
SETTING CLASSIFICATION:  Concrete slab                         OPUS PID:        
LATITUDE:   27° 28.0' N (  27.46670)          LONGITUDE:  82° 41.2' W ( -82.68670)


The bench mark is a disk set flush in the top of a concrete slab near the SW
corner of the house about 0.3 m (1.0 ft) above the level of Bayview Avenue, 23.2
m (76.0 ft) east of the centerline of 124th Street Court West, and 14.2 m (46.5
ft) north of the centerline of Bay View Avenue.

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

                                                                                
Station ID: 8726217                         PUBLICATION DATE:  05/12/2011
Name:       CORTEZ, SARASOTA BAY                              
            FL
NOAA Chart: 11424                           Latitude:   27° 28.0' N (  27.46670)
USGS Quad:  BRADENTON BEACH                 Longitude:  82° 41.2' W ( -82.68670)


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


                         BENCH MARK STAMPING:  K 254 1965
                         DESIGNATION:          K 254

MONUMENTATION:           Bench Mark disk                       VM#:         6146
AGENCY:                  US Coast and Geodetic Survey
                         (USC&GS)                              IDB PID#:  AG1995
SETTING CLASSIFICATION:  Concrete bridge abutment              OPUS PID:        
LATITUDE:   27° 28.1' N (  27.46830)          LONGITUDE:  82° 41.3' W ( -82.68830)


The bench mark is a disk set in the top of the south end of the east concrete
abutment of the bridge, 6.25 m (20.5 ft) south of the  center line of the
highway, and about level with the highway.



                         BENCH MARK STAMPING:  6217 B 1977
                         DESIGNATION:          872 6217 B TIDAL

MONUMENTATION:           Tidal Station disk                    VM#:         6148
AGENCY:                  National Ocean Survey (NOS)           IDB PID#:  AG7727
SETTING CLASSIFICATION:  Concrete sea wall                     OPUS PID:        
LATITUDE:   27° 28.1' N (  27.46830)          LONGITUDE:  82° 41.5' W ( -82.69170)


The bench mark is a disk set in the bulkhead on the south side of the bridge,
0.40 m (1.3 ft) west of the SE end of the bulkhead, 8.32 m (27.3 ft) SW of power
pole 12707, 13 m (43 ft) south of the SE corner of the bridge, and 3 m (10 ft)
below road.

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

                                                                                
Station ID: 8726217                         PUBLICATION DATE:  05/12/2011
Name:       CORTEZ, SARASOTA BAY                              
            FL
NOAA Chart: 11424                           Latitude:   27° 28.0' N (  27.46670)
USGS Quad:  BRADENTON BEACH                 Longitude:  82° 41.2' W ( -82.68670)


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


                         BENCH MARK STAMPING:  6217 C 1977
                         DESIGNATION:          872 6217 C TIDAL

MONUMENTATION:           Tidal Station disk                    VM#:         6149
AGENCY:                  National Ocean Survey (NOS)           IDB PID#:  AG7728
SETTING CLASSIFICATION:  Concrete sea wall                     OPUS PID:        
LATITUDE:   27° 28.1' N (  27.46830)          LONGITUDE:  82° 41.5' W ( -82.69170)


The bench mark is a disk set in the south seawall of a boat basin on the north
side of the bridge, 3.54 m (11.6 ft) west of the east end of the seawall, 16.76
m (55 ft) WNW of power transformer 13R363223, 19.51 m (64.0 ft) north of the
centerline of State Road 684, and 2.44 m (8 ft) below road.

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

                                                                                
Station ID: 8726217                         PUBLICATION DATE:  05/12/2011
Name:       CORTEZ, SARASOTA BAY                              
            FL
NOAA Chart: 11424                           Latitude:   27° 28.0' N (  27.46670)
USGS Quad:  BRADENTON BEACH                 Longitude:  82° 41.2' W ( -82.68670)


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


                         BENCH MARK STAMPING:  J 254 1965
                         DESIGNATION:          J 254

MONUMENTATION:           Bench Mark disk                       VM#:        19865
AGENCY:                  US Coast and Geodetic Survey
                         (USC&GS)                              IDB PID#:  AG1981
SETTING CLASSIFICATION:  Concrete bridge abutment              OPUS PID:        
LATITUDE:   27° 28.1' N (  27.46811)          LONGITUDE:  82° 41.9' W ( -82.69789)


The bench mark is a disk set in the west bridge abutment on the north side of
the road, 6.10 m (20 ft) north of the center of Cortez road, and 0.43 m (1.4 ft)
south of the north edge of the abutment.

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

                                                                                
Station ID: 8726217                         PUBLICATION DATE:  05/12/2011
Name:       CORTEZ, SARASOTA BAY                              
            FL
NOAA Chart: 11424                           Latitude:   27° 28.0' N (  27.46670)
USGS Quad:  BRADENTON BEACH                 Longitude:  82° 41.2' W ( -82.68670)


                            T I D A L   D A T U M S 


Tidal datums at CORTEZ, SARASOTA BAY based on:

     LENGTH OF SERIES:      5 MONTHS
     TIME PERIOD:           June 1990 - October 1990
     TIDAL EPOCH:           1983-2001
     CONTROL TIDE STATION:  8726520 ST. PETERSBURG, TAMPA BAY


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

     MEAN HIGHER HIGH WATER                     MHHW   =  0.637
     MEAN HIGH WATER                            MHW    =  0.548
     North American Vertical Datum              NAVD88 =  0.473
     MEAN SEA LEVEL                             MSL    =  0.333
     MEAN TIDE LEVEL                            MTL    =  0.326
     MEAN LOW WATER                             MLW    =  0.104
     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 1953                                   1.445    0.897
     NO 2 1953                                   1.459    0.911
     NO 3 1953                                   1.775    1.227
     K 254 1965                                  4.707    4.159
     6217 B 1977                                 1.568    1.020
     6217 C 1977                                 1.572    1.024
     J 254 1965                                  4.579    4.031


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 mark J 254 1965 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: 8726217                         PUBLICATION DATE:  05/12/2011
Name:       CORTEZ, SARASOTA BAY                              
            FL
NOAA Chart: 11424                           Latitude:   27° 28.0' N (  27.46670)
USGS Quad:  BRADENTON BEACH                 Longitude:  82° 41.2' W ( -82.68670)


                             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.