U.S. DEPARTMENT OF COMMERCE
                National Oceanic and Atmospheric Administration
                            National Ocean Service
Datums Page                                                        Page  1 of  6

                                                                                
Station ID: 8726685                         PUBLICATION DATE:  04/01/2004
Name:       TWENTY-SECOND ST. CAUSEWAY                        
            FL
NOAA Chart: 11413                           Latitude:   27° 56.3' N (  27.93830)
USGS Quad:  TAMPA                           Longitude:  82° 25.9' W ( -82.43170)


To reach the tidal bench marks from the intersection of U.S. Highway 41 Business
and State Highway 60 in Tampa, proceed south on U.S. Highway 41 Business for 2.4
km (1.5 mi) to the 22nd Street Causeway Bridge over McKay Bay.  The bench marks
are on and in the vicinity of the north end of the 22nd Street Causeway.  The
tide gage and staff were located on a small offshore structure in McKay Bay,
just east of bench mark 6685 A 1977.


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


                 PRIMARY BENCH MARK STAMPING:  6685 A 1977
                         DESIGNATION:          872 6685 A TIDAL

MONUMENTATION:           Tidal Station disk                    VM#:         7493
AGENCY:                  National Ocean Survey (NOS)           IDB PID#:  AG7499
SETTING CLASSIFICATION:  Concrete bridge sea wall              OPUS PID:        
LATITUDE:   27° 56.1' N (  27.93500)          LONGITUDE:  82° 26.0' W ( -82.43330)


The primary bench mark is a disk set in the bridge sea wall, 18 m (58 ft) NE of
the north corner of the northbound bridge, 0.40 m (1.3 ft) NW of the SE corner
of the NE sea wall, and is 5 m (15 ft) below road level.



                         BENCH MARK STAMPING:  6685 B 1977
                         DESIGNATION:          872 6685 B TIDAL

MONUMENTATION:           Tidal Station disk                    VM#:         7494
AGENCY:                  National Ocean Survey (NOS)           IDB PID#:  AG7498
SETTING CLASSIFICATION:  Concrete bridge sea wall              OPUS PID:        
LATITUDE:   27° 56.1' N (  27.93500)          LONGITUDE:  82° 26.0' W ( -82.43330)


The bench mark is a disk set in the top of the bridge sea wall located on the NE
side of the road, 23 m (77 ft) NE of the centerline of the northbound lane, 0.27
m (0.9 ft) SE of the NW end of the sea wall, and 1 m (4 ft) below road level.

                          U.S. DEPARTMENT OF COMMERCE
                National Oceanic and Atmospheric Administration
                            National Ocean Service
                                                                   Page  2 of  6

                                                                                
Station ID: 8726685                         PUBLICATION DATE:  04/01/2004
Name:       TWENTY-SECOND ST. CAUSEWAY                        
            FL
NOAA Chart: 11413                           Latitude:   27° 56.3' N (  27.93830)
USGS Quad:  TAMPA                           Longitude:  82° 25.9' W ( -82.43170)


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


                         BENCH MARK STAMPING:  6685 C 1977
                         DESIGNATION:          872 6685 C TIDAL

MONUMENTATION:           Tidal Station disk                    VM#:         7495
AGENCY:                  National Ocean Survey (NOS)           IDB PID#:  AG7497
SETTING CLASSIFICATION:  Concrete culvert head wall            OPUS PID:        
LATITUDE:   27° 56.2' N (  27.93670)          LONGITUDE:  82° 26.0' W ( -82.43330)


The bench mark is a disk set flush in a concrete culvert head wall, 0.2 km (0.1
mi) north of the bridge, 11 m (36 ft) NE of the centerline of the northbound
lane, 2 m (7 ft) NW of the SE end of the culvert head wall, 2 m (7 ft) SE of the
NW end of the head wall, and is 1 m (2 ft) below road level.



                         BENCH MARK STAMPING:  6685 D
                         DESIGNATION:          872 6685 D TIDAL FLDT

MONUMENTATION:           Bench Mark disk                       VM#:         7496
AGENCY:                  Florida Department of Transportation
                         (FLDOT)                               IDB PID#:  AG7501
SETTING CLASSIFICATION:  Concrete railing                      OPUS PID#: AG7501
LATITUDE:   27° 56.1' N (  27.93500)          LONGITUDE:  82° 26.0' W ( -82.43330)


The bench mark is a disk set in the concrete bridge railing located on the NE
corner of the northbound bridge, 6.86 m (22.5 ft) NE of the centerline of the
northbound lane, 1.68 m (5.5 ft) SE of the NW end of the bridge rail, and 1 m (3
ft) above road level.

                          U.S. DEPARTMENT OF COMMERCE
                National Oceanic and Atmospheric Administration
                            National Ocean Service
                                                                   Page  3 of  6

                                                                                
Station ID: 8726685                         PUBLICATION DATE:  04/01/2004
Name:       TWENTY-SECOND ST. CAUSEWAY                        
            FL
NOAA Chart: 11413                           Latitude:   27° 56.3' N (  27.93830)
USGS Quad:  TAMPA                           Longitude:  82° 25.9' W ( -82.43170)


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


                         BENCH MARK STAMPING:  6685 E
                         DESIGNATION:          872 6685 E TIDAL FLDT

MONUMENTATION:           Bench Mark disk                       VM#:         7497
AGENCY:                  Florida Department of Transportation
                         (FLDOT)                               IDB PID#:  AG7500
SETTING CLASSIFICATION:  Concrete railing                      OPUS PID:        
LATITUDE:   27° 56.1' N (  27.93500)          LONGITUDE:  82° 26.0' W ( -82.43330)


The bench mark is a disk set in the concrete bridge railing located on the NW
corner of the southbound bridge, 6.86 m (22.5 ft) SW of the centerline of the
southbound lane, 1.68 m (5.5 ft) SE of the NW end of the bridge rail, and is 1 m
(3 ft) above road level.

                          U.S. DEPARTMENT OF COMMERCE
                National Oceanic and Atmospheric Administration
                            National Ocean Service
                                                                   Page  4 of  6

                                                                                
Station ID: 8726685                         PUBLICATION DATE:  04/01/2004
Name:       TWENTY-SECOND ST. CAUSEWAY                        
            FL
NOAA Chart: 11413                           Latitude:   27° 56.3' N (  27.93830)
USGS Quad:  TAMPA                           Longitude:  82° 25.9' W ( -82.43170)


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


                         BENCH MARK STAMPING:  MCKAY 1 1981
                         DESIGNATION:          MCKAY 1 USE

MONUMENTATION:           Traverse Station disk                 VM#:         7498
AGENCY:                  US Army Corps of Engineers (USE)      IDB PID#:  AG7502
SETTING CLASSIFICATION:  Concrete sidewalk                     OPUS PID:        
LATITUDE:   27° 56.0' N (  27.93330)          LONGITUDE:  82° 25.9' W ( -82.43170)


The bench mark is a disk set in the concrete sidewalk of the northbound bridge
located near the middle of the bridge, 251 m (823 ft) NW of the SE end of the
bridge, 246 m (807 ft) SE of the NW end of the bridge, 15.45 m (50.7 ft) SE of
the center of a ladder going down, 6.46 m (21.2 ft) SW of the northbound lane,
3.20 m (10.5 ft) NW of the center of the channel underneath the bridge, 0.64 m
(2.1 ft) NE of the side of the concrete rail, and 0.15 m (0.5 ft) above road
level.

                          U.S. DEPARTMENT OF COMMERCE
                National Oceanic and Atmospheric Administration
                            National Ocean Service
                                                                   Page  5 of  6

                                                                                
Station ID: 8726685                         PUBLICATION DATE:  04/01/2004
Name:       TWENTY-SECOND ST. CAUSEWAY                        
            FL
NOAA Chart: 11413                           Latitude:   27° 56.3' N (  27.93830)
USGS Quad:  TAMPA                           Longitude:  82° 25.9' W ( -82.43170)


                            T I D A L   D A T U M S 


Tidal datums at TWENTY-SECOND ST. CAUSEWAY based on:

     LENGTH OF SERIES:      3 MONTHS
     TIME PERIOD:           September 1977 - November 1977
     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   =  0.822
     MEAN HIGH WATER                            MHW    =  0.739
     North American Vertical Datum              NAVD88 =  0.519
     MEAN SEA LEVEL                             MSL    =  0.442
     MEAN TIDE LEVEL                            MTL    =  0.432
     MEAN LOW WATER                             MLW    =  0.126
     MEAN LOWER LOW WATER                       MLLW   =  0.000

North American Vertical Datum (NAVD88)

Bench Mark Elevation Information                In METERS above:

     Stamping or Designation                    MLLW        MHW

     6685 A 1977                                 1.464    0.725
     6685 B 1977                                 1.476    0.737
     6685 C 1977                                 1.546    0.807
     6685 D                                      7.485    6.746
     6685 E                                      7.414    6.675
     MCKAY 1 1981                               14.691   13.952


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

                                                                                
Station ID: 8726685                         PUBLICATION DATE:  04/01/2004
Name:       TWENTY-SECOND ST. CAUSEWAY                        
            FL
NOAA Chart: 11413                           Latitude:   27° 56.3' N (  27.93830)
USGS Quad:  TAMPA                           Longitude:  82° 25.9' W ( -82.43170)


                             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.