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

                                                                                
Station ID: 8729909                         PUBLICATION DATE:  06/16/2004
Name:       BIG LAGOON                                        
            FL
NOAA Chart: 11382                           Latitude:   30° 19.6' N (  30.32670)
USGS Quad:  FORT BARRANCAS                  Longitude:  87° 21.4' W ( -87.35670)


To reach the tidal bench marks from the intersection of State Road 292 and
County Road 292-A (Gulf Beach Highway) in the community of Perdido Bay, proceed
east on County Road 292-A for 5.23 km (3.25 mi) to the Grand Lagoon Yacht Club
on the south side of the highway.  The bench marks are along County Road 292-A
and at the yacht club.  The tide gage and staff were located on the Grand Lagoon
Yacht Club pier.


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


                 PRIMARY BENCH MARK STAMPING:  9909 C 1977
                         DESIGNATION:          872 9909 C TIDAL

MONUMENTATION:           Tidal Station disk                    VM#:        10308
AGENCY:                  National Ocean Survey (NOS)           IDB PID#:  BG3624
SETTING CLASSIFICATION:  Copper-clad steel rod                 OPUS PID#: BG3624
LATITUDE:   30° 19.6' N (  30.32670)          LONGITUDE:  87° 22.1' W ( -87.36830)


The primary bench mark is a disk located 13.20 m (43.3 ft) west of the
centerline of the entrance drive to the Grand Lagoon Yacht Club, 10.27 m (33.7
ft) south of the centerline of County Road 292-A (Gulf Beach Highway), 2.13 m
(7.0 ft) east of the yacht club sign, 1.34 m (4.4 ft) north of a 1 m (2 ft)
square piece of concrete, and 0.30 m (1 ft) north of a witness post.  The bench
mark is set 0.09 m (0.3 ft) below ground level, crimped to the top of a
copper-clad steel rod driven an unspecified depth to refusal, and encased in a
PVC pipe and concrete kickblock.

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

                                                                                
Station ID: 8729909                         PUBLICATION DATE:  06/16/2004
Name:       BIG LAGOON                                        
            FL
NOAA Chart: 11382                           Latitude:   30° 19.6' N (  30.32670)
USGS Quad:  FORT BARRANCAS                  Longitude:  87° 21.4' W ( -87.35670)


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


                         BENCH MARK STAMPING:  9909 D 1977
                         DESIGNATION:          872 9909 D TIDAL

MONUMENTATION:           Tidal Station disk                    VM#:        10309
AGENCY:                  National Ocean Survey (NOS)           IDB PID#:  BG3623
SETTING CLASSIFICATION:  Copper-clad steel rod                 OPUS PID:        
LATITUDE:   30° 19.7' N (  30.32830)          LONGITUDE:  87° 22.1' W ( -87.36830)


The bench mark is a disk located 103 m (337 ft) west of bench mark 9909 E 1977,
32 m (105 ft) west of a private driveway, 9.14 m (30.0 ft) east of the east
entrance to the parking lot for a Catholic Church, 8.75 m (28.7 ft) north of the
centerline of State Road 292-A (Gulf Beach Highway), 2.07 m (6.8 ft) SW of
powerline pole #0952349408, and 9 cm (0.3 ft) south of a witness post.  The
bench mark is set 9 cm (0.3 ft) below ground level, crimped to the top of a
copper-clad steel rod driven an unspecified depth to refusal, and encased in a
PVC pipe and concrete kickblock.



                         BENCH MARK STAMPING:  9909 E 1977
                         DESIGNATION:          872 9909 E TIDAL

MONUMENTATION:           Tidal Station disk                    VM#:        10310
AGENCY:                  National Ocean Survey (NOS)           IDB PID#:  BG3622
SETTING CLASSIFICATION:  Copper-clad steel rod                 OPUS PID:        
LATITUDE:   30° 19.7' N (  30.32830)          LONGITUDE:  87° 22.0' W ( -87.36670)


The bench mark is a disk located 9.81 m (32.2 ft) east of the centerline of a
dirt driveway, 9.60 m (31.5 ft) north of the centerline of State Road 292-A
(Gulf Beach Highway), and 2.68 m (8.8 ft) SSE of school bus shelter across
street from residence #10611.  The bench mark is set 9 cm (0.3 ft) below ground
level, crimped to the top of a copper-clad steel rod driven an unspecified depth
to refusal, and encased in a PVC pipe and concrete kickblock.

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

                                                                                
Station ID: 8729909                         PUBLICATION DATE:  06/16/2004
Name:       BIG LAGOON                                        
            FL
NOAA Chart: 11382                           Latitude:   30° 19.6' N (  30.32670)
USGS Quad:  FORT BARRANCAS                  Longitude:  87° 21.4' W ( -87.35670)


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


                         BENCH MARK STAMPING:  9909 F 1984
                         DESIGNATION:          872 9909 F TIDAL

MONUMENTATION:           Tidal Station disk                    VM#:        10311
AGENCY:                  National Ocean Service (NOS)          IDB PID#:  BG3625
SETTING CLASSIFICATION:  Concrete steps                        OPUS PID:        
LATITUDE:   30° 19.6' N (  30.32670)          LONGITUDE:  87° 22.1' W ( -87.36830)


The bench mark is a disk set in top of the first concrete step for the stairway
on the east side of the clubhouse, 15.45 m (50.7 ft) north of the SW corner of
the clubhouse, 7.44 m (24.4 ft) south of the NW corner of the clubhouse, and
4.42 m (14.5 ft) east of the centerline of the drive to the boat basin.



                         BENCH MARK STAMPING:  9909 A 1977
                         DESIGNATION:          872 9909 A TIDAL

MONUMENTATION:           Tidal Station disk                    VM#:        16554
AGENCY:                  National Ocean Survey (NOS)           IDB PID#:  BG3626
SETTING CLASSIFICATION:  Concrete base for flagpole            OPUS PID:        
LATITUDE:   30° 19.6' N (  30.32670)          LONGITUDE:  87° 22.1' W ( -87.36830)


The bench mark is a disk set in the top of the concrete base for the flagpole at
the Grand Lagoon Yacht Club, 53 m (175 ft) SSW of the SW corner of the
clubhouse, 6 m (21 ft) east of a boat ramp, and 0.4 m (1.4 ft) north of the
flagpole.

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

                                                                                
Station ID: 8729909                         PUBLICATION DATE:  06/16/2004
Name:       BIG LAGOON                                        
            FL
NOAA Chart: 11382                           Latitude:   30° 19.6' N (  30.32670)
USGS Quad:  FORT BARRANCAS                  Longitude:  87° 21.4' W ( -87.35670)


                            T I D A L   D A T U M S 


Tidal datums at BIG LAGOON based on:

     LENGTH OF SERIES:      2 MONTHS
     TIME PERIOD:           January 1994 - February 1994
     TIDAL EPOCH:           1983-2001
     CONTROL TIDE STATION:  8729840 PENSACOLA, PENSACOLA BAY


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

     MEAN HIGHER HIGH WATER                     MHHW   =  0.322
     MEAN HIGH WATER                            MHW    =  0.313
     MEAN TIDE LEVEL                            MTL    =  0.163
     MEAN SEA LEVEL                             MSL    =  0.153
     North American Vertical Datum              NAVD88 =  0.052
     MEAN LOW WATER                             MLW    =  0.013
     MEAN LOWER LOW WATER                       MLLW   =  0.000

North American Vertical Datum (NAVD88)

Bench Mark Elevation Information                In METERS above:

     Stamping or Designation                    MLLW        MHW

     9909 C 1977                                 4.147    3.834
     9909 D 1977                                 4.389    4.076
     9909 E 1977                                 4.007    3.694
     9909 F 1984                                 2.374    2.061
     9909 A 1977                                 1.072    0.759


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

                                                                                
Station ID: 8729909                         PUBLICATION DATE:  06/16/2004
Name:       BIG LAGOON                                        
            FL
NOAA Chart: 11382                           Latitude:   30° 19.6' N (  30.32670)
USGS Quad:  FORT BARRANCAS                  Longitude:  87° 21.4' W ( -87.35670)


                             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.