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

                                                   PUBLICATION DATE:  07/19/1985
Station ID: 8720296                                SUPERCEDED DATE:   04/21/2003
Name:       ORTEGA RIVER ENTRANCE                             
            FLORIDA
NOAA Chart: 11492                                  Latitude:         30° 16.7' N
USGS Quad:  JACKSONVILLE                           Longitude:        81° 42.3' W


To reach the tidal bench marks from the intersection of Interstate Highway I-295
and U.S. Highway 17, proceed 4.3 miles (6.9 km) north of U.S. Highway 17 to its
intersection with State Highway C-211 (Ortega River Boulevard and Grand Avenue),
then 1.9 miles (3.1 km) NW on Highway C-211 to the dirt drive leading to the
residence of the Van Dorens.  The bench marks are along Highway C-211 (Grand
Avenue).  The tide gage and staff were located on a pier owned by the Van
Dorens.


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


                 PRIMARY BENCH MARK STAMPING:  NO 1 1939

MONUMENTATION:           Survey Disk                               VM#:     5167
AGENCY:                                                            PID#:  BC2456
SETTING CLASSIFICATION:  Concrete Bulkhead


The bench mark is set in the top of a concrete bulkhead on the south shore of
the Ortega River along State Highway C-211, 340 feet (104 m) SE of the SE end of
the highway bridge over the Ortega River, and 40.4 feet (12.3 m) SW of the
centerline of the highway.



                         BENCH MARK STAMPING:  NO 2 1939

MONUMENTATION:           Survey Disk                               VM#:     5168
AGENCY:                                                            PID#:  BC2455
SETTING CLASSIFICATION:  Concrete Bulkhead


The bench mark is set in the top of a concrete bulkhead on the south shore of
the Ortega River along State Highway C-211, 205 feet (62 m) SE of the SE end of
the highway bridge, and 135 feet (41 m) NW of Bench Mark NO 1 1939.

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

                                                   PUBLICATION DATE:  07/19/1985
Station ID: 8720296                                SUPERCEDED DATE:   04/21/2003
Name:       ORTEGA RIVER ENTRANCE                             
            FLORIDA
NOAA Chart: 11492                                  Latitude:         30° 16.7' N
USGS Quad:  JACKSONVILLE                           Longitude:        81° 42.3' W


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


                         BENCH MARK STAMPING:  0296 A 1978

MONUMENTATION:           Survey Disk                               VM#:     5169
AGENCY:                                                            PID#:  BC2457
SETTING CLASSIFICATION:  Copper-clad Steel Rod


The bench mark is in the traffic island across from the dirt drive leading to
the Van Doren residence at 2711 Grand Avenue, 210 feet (64 m) SSE of the north
end of the first traffic island south of the bridge over Ortega River, 21.0 feet
(6.4 m) SSW of the centerline of the northbound lane of Grand Avenue, and 20.5
feet (6.2 m) NNE of the centerline of the southbound lane of Grand Avenue.  The
bench mark is at ground level, crimped to the top of a copper-clad steel rod
driven 40 feet (12 m) to refusal, and encased in a PVC pipe and concrete
kickblock.



                         BENCH MARK STAMPING:  0296 B 1978

MONUMENTATION:           Survey Disk                               VM#:     5170
AGENCY:                                                            PID#:  BC2458
SETTING CLASSIFICATION:  Copper-clad Steel Rod


The bench mark is 84 feet (26 m) SE of the intersection of Grand Avenue and
McGirts Boulevard, 54 feet (16 m) SE of the intersection of Grand Avenue and El
Dorado Avenue, and 51 feet (16 m) SE of the north end of the second traffic
island of Grand Avenue south of the bridge.  The bench mark is 0.5 foot (0.2 m)
below ground level, crimped to a copper-clad steel rod riven 42 feet (13 m) 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

                                                   PUBLICATION DATE:  07/19/1985
Station ID: 8720296                                SUPERCEDED DATE:   04/21/2003
Name:       ORTEGA RIVER ENTRANCE                             
            FLORIDA
NOAA Chart: 11492                                  Latitude:         30° 16.7' N
USGS Quad:  JACKSONVILLE                           Longitude:        81° 42.3' W


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


                         BENCH MARK STAMPING:  0296 C RESET 3 1978 RLB GWH

MONUMENTATION:           Survey Disk                               VM#:     5171
AGENCY:                                                            PID#:  BC2454
SETTING CLASSIFICATION:  Concrete Post


The bench mark is set flush in the top of a concrete post, 43.0 feet (13.1 m) SE
of the SE corner of the Ortega River bridge, 31.5 feet (9.6 m) SW of the
centerline of Ortega Boulevard, 10.5 feet (3.2 m) NW of a concrete seawall, and
at ground level.

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

                                                   PUBLICATION DATE:  07/19/1985
Station ID: 8720296                                SUPERCEDED DATE:   04/21/2003
Name:       ORTEGA RIVER ENTRANCE                             
            FLORIDA
NOAA Chart: 11492                                  Latitude:         30° 16.7' N
USGS Quad:  JACKSONVILLE                           Longitude:        81° 42.3' W


                            T I D A L   D A T U M S 


Tidal datums at ORTEGA RIVER ENTRANCE based on:

     LENGTH OF SERIES:      6 MONTHS
     TIME PERIOD:           AUGUST 1978 - JANUARY 1979
     TIDAL EPOCH:           1960-1978
     CONTROL TIDE STATION:  8720220  


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

     HIGHEST OBSERVED WATER LEVEL (11/04/1978)         =   2.33
     MEAN HIGHER HIGH WATER                     MHHW   =   1.26
     MEAN HIGH WATER                            MHW    =   1.18
     MEAN TIDE LEVEL                            MTL    =   0.63
     MEAN LOW WATER                             MLW    =   0.07
     MEAN LOWER LOW WATER                       MLLW   =   0.00
     LOWEST  OBSERVED WATER LEVEL (01/26/1979)         =  -1.42

North American Vertical Datum (NAVD88)

Bench Mark Elevation Information                In FEET above:

     Stamping or Designation                    MLLW        MHW

     NO 1 1939                                   7.14      5.96
     NO 2 1939                                   7.04      5.86
     0296 A 1978                                11.90     10.72
     0296 B 1978                                17.62     16.44
     0296 C RESET 3 1978 RLB GWH                 7.52      6.34


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

                                                   PUBLICATION DATE:  07/19/1985
Station ID: 8720296                                SUPERCEDED DATE:   04/21/2003
Name:       ORTEGA RIVER ENTRANCE                             
            FLORIDA
NOAA Chart: 11492                                  Latitude:         30° 16.7' N
USGS Quad:  JACKSONVILLE                           Longitude:        81° 42.3' 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.