U.S. DEPARTMENT OF COMMERCE
                National Oceanic and Atmospheric Administration
                            National Ocean Service
Datums Page                                                        Page  1 of  5

                                                                                
Station ID: 8723467                         PUBLICATION DATE:  12/12/2003
Name:       TOTTEN KEY, BISCAYNE BAY                          
            FL
NOAA Chart: 11463                           Latitude:   25° 22.7' N (  25.37830)
USGS Quad:  ARSENICKER KEYS                 Longitude:  80° 15.4' W ( -80.25670)


To reach the tidal bench marks by boat from the marina just north of Wednesday
Point, Card Sound, on Key Largo, proceed north for 8.4 km (5.2 statute mi)
through Card Sound and into Biscayne Bay to the mouth of a small creek on the SW
shore of Totten Key.  The bench marks are located north of the creek.  The tide
gage and staff were located offshore near the mouth of the creek.


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


                 PRIMARY BENCH MARK STAMPING:  NO 1 1974
                         DESIGNATION:          872 3467 TIDAL 1

MONUMENTATION:           Tidal Station disk                    VM#:         5874
AGENCY:                  National Ocean Survey (NOS)           IDB PID#:        
SETTING CLASSIFICATION:  Concrete filled PVC pipe              OPUS PID:        
LATITUDE:   25° 22.7' N (  25.37830)          LONGITUDE:  80° 15.4' W ( -80.25670)


The primary bench mark is a disk set in a concrete filled PVC pipe atop a steel
rod located on a mangrove point just north of a creek, 6 m (20 ft) ESE of the
point, 5 m (15 ft) north of the creek side of the point, 0.55 m (1.8 ft) SSW of
an old witness post, 0.24 m (0.8 ft) NW of a new witness post, and 0.46 m (1.5
ft) above the mud.

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

                                                                                
Station ID: 8723467                         PUBLICATION DATE:  12/12/2003
Name:       TOTTEN KEY, BISCAYNE BAY                          
            FL
NOAA Chart: 11463                           Latitude:   25° 22.7' N (  25.37830)
USGS Quad:  ARSENICKER KEYS                 Longitude:  80° 15.4' W ( -80.25670)


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


                         BENCH MARK STAMPING:  NO 2 1974
                         DESIGNATION:          872 3467 TIDAL 2

MONUMENTATION:           Tidal Station disk                    VM#:         5875
AGENCY:                  National Ocean Survey (NOS)           IDB PID#:        
SETTING CLASSIFICATION:  Concrete filled PVC pipe              OPUS PID:        
LATITUDE:   25° 22.7' N (  25.37830)          LONGITUDE:  80° 15.4' W ( -80.25670)


The bench mark is a disk set in a concrete filled PVC pipe atop a steel rod, 8 m
(25 ft) north of the creek side of the point, 5 m (15 ft) NE of bench mark NO 1
1974, 2 m (6 ft) SE of the NW side of the key, 1.01 m (3.3 ft) NW of a witness
sign nailed to a tree, 0.24 m (0.8 ft) WNW of a witness post, and 0.30 m (1.0
ft) above the mud.



                         BENCH MARK STAMPING:  NO 3 1974
                         DESIGNATION:          872 3467 TIDAL 3

MONUMENTATION:           Tidal Station disk                    VM#:         5876
AGENCY:                  National Ocean Survey (NOS)           IDB PID#:        
SETTING CLASSIFICATION:  Concrete filled PVC pipe              OPUS PID:        
LATITUDE:   25° 22.7' N (  25.37830)          LONGITUDE:  80° 15.4' W ( -80.25670)


The bench mark is a disk set in a concrete filled PVC pipe atop a steel rod, 6 m
(20 ft) north of the creek side of the point, 5 m (18 ft) east of bench mark NO
1 1974, 4 m (12 ft) SE of bench mark NO 2 1974, 0.24 m (0.8 ft) WNW of a witness
post, and 0.30 m (1.0 ft) above the mud.

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

                                                                                
Station ID: 8723467                         PUBLICATION DATE:  12/12/2003
Name:       TOTTEN KEY, BISCAYNE BAY                          
            FL
NOAA Chart: 11463                           Latitude:   25° 22.7' N (  25.37830)
USGS Quad:  ARSENICKER KEYS                 Longitude:  80° 15.4' W ( -80.25670)


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


                         BENCH MARK STAMPING:  3467 D 1984
                         DESIGNATION:          872 3467 D

MONUMENTATION:           Tidal Station disk                    VM#:         5877
AGENCY:                  National Ocean Survey (NOS)           IDB PID#:        
SETTING CLASSIFICATION:  Stainless steel rod                   OPUS PID:        
LATITUDE:   25° 22.7' N (  25.37830)          LONGITUDE:  80° 15.4' W ( -80.25670)


The bench mark is a disk located on a mangrove point, 6.10 m (20.0 ft) south of
bench mark NO 2 1974, 5.06 m (16.6 ft) SE of bench mark NO 1 1974, 4.57 m (15.0
ft) NNE of the north side of the creek, 3.41 m (11.2 ft) SSW of bench mark NO 3
1974,  and 0.24 m (0.8 ft) NE of a witness post.  The bench mark is set 15 cm
(0.5 ft) above ground level, crimped to the top of a stainless steel rod driven
an unspecified depth to refusal, and encased in a PVC pipe projecting 0.21 m
(0.7 ft) above ground level and concrete kickblock.



                         BENCH MARK STAMPING:  3467 E 1984
                         DESIGNATION:          872 3467 E

MONUMENTATION:           Tidal Station disk                    VM#:         5878
AGENCY:                  National Ocean Survey (NOS)           IDB PID#:        
SETTING CLASSIFICATION:  Stainless steel rod                   OPUS PID:        
LATITUDE:   25° 22.7' N (  25.37830)          LONGITUDE:  80° 15.4' W ( -80.25670)


The bench mark is a disk located on a mangrove point, 7.01 m (23.0 ft) ESE of
bench mark NO 1 1974, 6.01 m (20.0 ft) NNE of the north side of the creek, 2.99
m (9.8 ft) ENE of bench mark 3467 D 1984, 2.32 m (7.6 ft) NW of bench mark NO 3
1974, and 0.24 m (0.8 ft) west of a witness post.  The bench mark is set 15 cm
(0.5 ft) above ground level, crimped to the top of a stainless steel rod driven
an unspecified depth to refusal, and encased in a PVC pipe (projecting 0.21 m
(0.7 ft) above ground level) and concrete kickblock.

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

                                                                                
Station ID: 8723467                         PUBLICATION DATE:  12/12/2003
Name:       TOTTEN KEY, BISCAYNE BAY                          
            FL
NOAA Chart: 11463                           Latitude:   25° 22.7' N (  25.37830)
USGS Quad:  ARSENICKER KEYS                 Longitude:  80° 15.4' W ( -80.25670)


                            T I D A L   D A T U M S 


Tidal datums at TOTTEN KEY, BISCAYNE BAY based on:

     LENGTH OF SERIES:      1 MONTH
     TIME PERIOD:           July 1974 - July 1974
     TIDAL EPOCH:           1983-2001
     CONTROL TIDE STATION:  8723350 RAGGED KEY #3


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

     MEAN HIGHER HIGH WATER                     MHHW   =  0.434
     MEAN HIGH WATER                            MHW    =  0.411
     MEAN TIDE LEVEL                            MTL    =  0.220
     MEAN SEA LEVEL                             MSL    =  0.209
     MEAN LOW WATER                             MLW    =  0.029
     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 1974                                   0.333   -0.078
     NO 2 1974                                   0.258   -0.153
     NO 3 1974                                   0.292   -0.119
     3467 D 1984                                 0.182   -0.229
     3467 E 1984                                 0.141   -0.270


Foot Notes:

Bench marks 3467 D 1984 and 3467 E 1984 are based on one differential leveling
connection and do not meet the quality control standards of the NOS. Therefore,
caution shuold be used when deriving elevations for these marks.

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

                                                                                
Station ID: 8723467                         PUBLICATION DATE:  12/12/2003
Name:       TOTTEN KEY, BISCAYNE BAY                          
            FL
NOAA Chart: 11463                           Latitude:   25° 22.7' N (  25.37830)
USGS Quad:  ARSENICKER KEYS                 Longitude:  80° 15.4' W ( -80.25670)


                             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.