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

                                                   PUBLICATION DATE:  01/28/1983
Station ID: 8746724                                SUPERCEDED DATE:   04/21/2003
Name:       JOHNSON BAYOU                                     
            MISSISSIPPI
NOAA Chart: 11371                                  Latitude:         30° 20.2' N
USGS Quad:  PASSCHRISTIAN                          Longitude:        89° 13.5' W


To reach the tidal bench marks from the intersection of Menge Avenue and U.S.
Highway 90, proceed north on Menge Avenue for 1.0 mile (1.6 km) to Jones Avenue,
which is the first paved street to the left after crossing the bridge, then
continue west on Jones Avenue for 0.4 mile (0.6 km) to its intersection with
Morrow Drive, then 0.1 mile (0.2 km) south on Morrow Drive to the last house on
the right.  The tide gage and staff were located SW of the house (Borodenko
residence) on a small platform just offshore of the bulkhead.


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


                 PRIMARY BENCH MARK STAMPING:  6724 B 1978

MONUMENTATION:           Survey Disk                               VM#:    10396
AGENCY:                                                            PID:         
SETTING CLASSIFICATION:  Stainless Steel Rod


The bench mark is at the SE corner of the Borodenko property, 147.0 feet (44.8
m) east of Bench Mark 6724 A 1978, 113.6 feet (34.6 m) ESE of the SE corner of
the Borodenko house, 43.7 feet (13.3 m) SSE of power pole #IPCD-665-GP-40-LR-FT,
and 7.2 feet (2.2 m) north of a wooden bulkhead on Johnson Bayou.  The bench
mark is 0.3 foot (0.1 m) below ground level, crimped to a stainless steel rod
driven 54 feet (16 m) to refusal, and encased in a 4-inch PVC pipe and concrete
kickblock.



                         BENCH MARK STAMPING:  6724 A 1978

MONUMENTATION:           Survey Disk                               VM#:    10395
AGENCY:                                                            PID:         
SETTING CLASSIFICATION:  Concrete Slab


The bench mark is in the SW quadrant of the Borodenko property, 32.9 feet (10.0
m) north of a wooden bulkhead at the edge of Johnson Bayou, 28.7 feet (8.7 m)
south of the SW corner of the Borodenko residence.  The bench mark is set flush
on the SE corner of a concrete slab.

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

                                                   PUBLICATION DATE:  01/28/1983
Station ID: 8746724                                SUPERCEDED DATE:   04/21/2003
Name:       JOHNSON BAYOU                                     
            MISSISSIPPI
NOAA Chart: 11371                                  Latitude:         30° 20.2' N
USGS Quad:  PASSCHRISTIAN                          Longitude:        89° 13.5' W


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


                         BENCH MARK STAMPING:  6724 C 1978

MONUMENTATION:           Survey Disk                               VM#:    10397
AGENCY:                                                            PID:         
SETTING CLASSIFICATION:  Stainless Steel Rod


The bench mark is 239 feet (73 m) east of the centerline intersection of Jones
Avenue and Morrow Street, 32.6 feet (9.9 m) west of the centerline of a dirt
road leading north from Jones Avenue, 24.2 feet (7.4 m) north of the centerline
of Jones Avenue, and 7.6 feet (2.3 m) NW of power pole #MRGO-666-GP-40-LP-FT-
540.  The bench mark is 0.5 foot (0.2 m) below ground level, crimped to a
stainless steel rod driven 60 feet (18 m) to refusal, and encased in a 4-inch
PVC pipe and concrete kickblock.



                         BENCH MARK STAMPING:  6724 D 1978

MONUMENTATION:           Survey Disk                               VM#:    10398
AGENCY:                                                            PID:         
SETTING CLASSIFICATION:  Stainless Steel Rod


The bench mark is 270 feet (82 m) north of Bench Mark 6724 B 1978, 33.0 feet
(10.1 m) west of the NW corner of a concrete block house, 20.0 feet (6.1 m) east
of the centerline of Morrow Street, and 1.5 feet (0.5 m) east of power pole
#7-55-GP-40-LR-FT-140.  The bench mark is 0.3 foot (0.1 m) below ground level,
crimped to a stainless steel rod driven 60 feet (18 m) to refusal, and encased
in a 4-inch PVC pipe and concrete kickblock.

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

                                                   PUBLICATION DATE:  01/28/1983
Station ID: 8746724                                SUPERCEDED DATE:   04/21/2003
Name:       JOHNSON BAYOU                                     
            MISSISSIPPI
NOAA Chart: 11371                                  Latitude:         30° 20.2' N
USGS Quad:  PASSCHRISTIAN                          Longitude:        89° 13.5' W


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


                         BENCH MARK STAMPING:  6724 E 1978

MONUMENTATION:           Survey Disk                               VM#:    10399
AGENCY:                                                            PID:         
SETTING CLASSIFICATION:  Stainless Steel Rod


The bench mark is on the SW corner of the property of Hartwig and Mildice, 253
feet (77 m) north of Bench Mark 6724 D 1978, 167 feet (51 m) south of the
centerline intersection of Jones Avenue and Morrow Street, 46.0 feet (14.0 m) SW
of the SW corner of the house on the property of Hartwig and Mildice, and 18.2
feet (5.5 m) east of the centerline of Morrow Street.  The bench mark is 0.4
foot (0.1 m) below ground level, crimped to a stainless steel rod driven 60 feet
(18 m) to refusal, and encased in a 4-inch PVC pipe and concrete kickblock.



                         BENCH MARK STAMPING:  X 134 1943

MONUMENTATION:           Survey Disk                               VM#:    10400
AGENCY:                                                            PID#:  BH0913
SETTING CLASSIFICATION:  Concrete Monument


The bench mark is 1.55 miles (2.5 km) east along the Louisville and Nashville
railroad from the station at Pass Christian, then 1.3 miles (2.1 km) north along
Menge Avenue to the intersection of the avenue and a black top road leading
west, 19.5 feet (5.9 m) south of the centerline of the west road, 8 feet (2.4 m)
NE of an 18-inch pipe culvert under the west road, 3.6 feet (1. 1 m) SW of power
and telephone pole #1101-S 102-11, and 1.5 feet (0.5 m) east of a wooden witness
post.  The bench mark is set in the top of a concrete post 0.25 foot (0.08 m)
below ground.  NOTE:  The bench mark is also 0.95 mile (1.5 km) south of the
school at Cuevas.

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

                                                   PUBLICATION DATE:  01/28/1983
Station ID: 8746724                                SUPERCEDED DATE:   04/21/2003
Name:       JOHNSON BAYOU                                     
            MISSISSIPPI
NOAA Chart: 11371                                  Latitude:         30° 20.2' N
USGS Quad:  PASSCHRISTIAN                          Longitude:        89° 13.5' W


                            T I D A L   D A T U M S 


Tidal datums at JOHNSON BAYOU based on:

     LENGTH OF SERIES:      3 MONTHS
     TIME PERIOD:           NOVEMBER 1978-JANUARY1979
     TIDAL EPOCH:           1960-1978
     CONTROL TIDE STATION:  8747038 HENDERSON AVENUEBRIDGE, WOLF RIVER


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

     HIGHEST OBSERVED WATER LEVEL (01/01/1979)         =   2.90
     MEAN HIGHER HIGH WATER                     MHHW   =   1.88
     MEAN HIGH WATER                            MHW    =   1.70
     MEAN TIDE LEVEL                            MTL    =   0.96
     MEAN LOW WATER                             MLW    =   0.22
     MEAN LOWER LOW WATER                       MLLW   =   0.00
     LOWEST  OBSERVED WATER LEVEL (01/02/1979)         =  -1.80

North American Vertical Datum (NAVD88)

Bench Mark Elevation Information                In FEET above:

     Stamping or Designation                    MLLW        MHW

     6724 B 1978                                 3.86      2.16
     6724 A 1978                                 5.23      3.53
     6724 C 1978                                 9.65      7.95
     6724 D 1978                                 7.52      5.82
     6724 E 1978                                 7.36      5.66
     X 134 1943                                 25.95     24.25


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

                                                   PUBLICATION DATE:  01/28/1983
Station ID: 8746724                                SUPERCEDED DATE:   04/21/2003
Name:       JOHNSON BAYOU                                     
            MISSISSIPPI
NOAA Chart: 11371                                  Latitude:         30° 20.2' N
USGS Quad:  PASSCHRISTIAN                          Longitude:        89° 13.5' W


                             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 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.