U.S. DEPARTMENT OF COMMERCE
                National Oceanic and Atmospheric Administration
                            National Ocean Service
Datums Page                                                        Page  1 of  7

                                                                                
Station ID: 8725837                         PUBLICATION DATE:  06/02/2011
Name:       MYAKKA RIVER, US 41                               
            FL
NOAA Chart: 11426                           Latitude:   27°  2.7' N (  27.04500)
USGS Quad:  MYAKKA RIVER                    Longitude:  82° 17.6' W ( -82.29330)


To reach the tidal bench marks from the intersection of Venice Avenue and US
Highway 41 in Venice, proceed 19 km (12 mi) SE along US Highway 41 to the bridge
over the Myakka River.  The bench marks are located around the Plamore Resort. 
The tide gage and staff were located on a small concrete pier behind the bar
building of the resort.


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


                 PRIMARY BENCH MARK STAMPING:  5837 A 1977
                         DESIGNATION:          872 5837 A

MONUMENTATION:           Tidal Station disk                    VM#:         6089
AGENCY:                  National Ocean Survey (NOS)           IDB PID#:  AG7854
SETTING CLASSIFICATION:  Concrete walkway                      OPUS PID:        
LATITUDE:   27°  2.7' N (  27.04500)          LONGITUDE:  82° 17.6' W ( -82.29330)


The primary bench mark is a disk set flush in the top of a concrete sidewalk
level with the restaurant parking lot, 17.07 m (56.0 ft) WSW of the NW corner of
the boat dock, 11.58 m (38.0 ft) SSE of bench mark 5837 B 1977, 11.58 m (38.0
ft) NE of the centerline of the road to the Myakka River Inn, and 1.28 m (4.2
ft) SW of the SW corner of the restuarant building.

                          U.S. DEPARTMENT OF COMMERCE
                National Oceanic and Atmospheric Administration
                            National Ocean Service
                                                                   Page  2 of  7

                                                                                
Station ID: 8725837                         PUBLICATION DATE:  06/02/2011
Name:       MYAKKA RIVER, US 41                               
            FL
NOAA Chart: 11426                           Latitude:   27°  2.7' N (  27.04500)
USGS Quad:  MYAKKA RIVER                    Longitude:  82° 17.6' W ( -82.29330)


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


                         BENCH MARK STAMPING:  U 255 RESET 1975
                         DESIGNATION:          U 255 RESET

MONUMENTATION:           Bench Mark disk                       VM#:         6088
AGENCY:                  National Geodetic Survey (NGS)        IDB PID#:  AG0915
SETTING CLASSIFICATION:  Concrete sidewalk                     OPUS PID:        
LATITUDE:   27°  2.7' N (  27.04500)          LONGITUDE:  82° 17.6' W ( -82.29330)


The bench mark is a disk set flush in the top of a concrete sidewalk level with
the restaurant parking lot, located along the north side of apartment #2 at the
Myakka River Inn, 35.81 m (117.5 ft) SSE of bench mark BM 2 RESET 1975, 11.28 m
(37.0 ft) WSW of the NW corner of the bar building, 2.13 m (7.0 ft) south of the
NW corner of the sidewalk, 0.30 m (1.0 ft) west of the NW corner of apartment #2
and 0.21 m (0.7 ft) south of a brick flower box.



                         BENCH MARK STAMPING:  BM 3
                         DESIGNATION:          872 5836 TIDAL 3

MONUMENTATION:           Tidal Station disk                    VM#:         6091
AGENCY:                  US Coast and Geodetic Survey
                         (USC&GS)                              IDB PID#:  AG1863
SETTING CLASSIFICATION:  Concrete sidewalk                     OPUS PID:        
LATITUDE:   27°  2.6' N (  27.04330)          LONGITUDE:  82° 17.6' W ( -82.29330)


The bench mark is a disk set flush in the sidewalk located at the SE corner of
the apartment building, 17.07 m (56.0 ft) west of the water's edge of the river,
14 m (46 ft) east of bench mark U 255 RESET 1975, 0.09 m (0.3 ft) east of the NE
corner of the apartment building and 0.09 m (0.3 ft) east of a brick flower box.

                          U.S. DEPARTMENT OF COMMERCE
                National Oceanic and Atmospheric Administration
                            National Ocean Service
                                                                   Page  3 of  7

                                                                                
Station ID: 8725837                         PUBLICATION DATE:  06/02/2011
Name:       MYAKKA RIVER, US 41                               
            FL
NOAA Chart: 11426                           Latitude:   27°  2.7' N (  27.04500)
USGS Quad:  MYAKKA RIVER                    Longitude:  82° 17.6' W ( -82.29330)


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


                         BENCH MARK STAMPING:  5837 C
                         DESIGNATION:          872 5837 C

MONUMENTATION:           Survey disk                           VM#:        19920
AGENCY:                  Florida Department of Transportation
                         (FLDT)                                IDB PID#:  DL9715
SETTING CLASSIFICATION:  Concrete bridge rail                  OPUS PID:        
LATITUDE:   27°  2.7' N (  27.04583)          LONGITUDE:  82° 17.5' W ( -82.29142)


The bench mark is a disk set flush in the top of the SW concrete bridge
guardrail and about 0.9 m (3.0 ft) above the level of U.S.  Highway 41
Southbound, 6.9 m (22.8 ft) SE of the approximate centerline of U.S. Highway 41
southbound lanes, 2.5 m (8.1 ft) NE of the SW end of a concrete guardrail, and
1.7 m (5.7 ft) NE of a metal guardrail.



                         BENCH MARK STAMPING:  5837 D
                         DESIGNATION:          872 5837 D

MONUMENTATION:           Survey disk                           VM#:        19921
AGENCY:                  Florida Department of Transportation
                         (FLDT)                                IDB PID#:  DL9714
SETTING CLASSIFICATION:  Concrete bridge rail                  OPUS PID:        
LATITUDE:   27°  2.8' N (  27.04611)          LONGITUDE:  82° 17.5' W ( -82.29097)


The bench mark is a disk set flush in the top of the SE concrete bridge
guardrail and about 0.9 m (3.0 ft) above the level of U.S.  Highway 41
southbound, 10.5 m (34.4 ft) west of a metal light pole numbered 45bc-07, 6.9 m
(22.8 ft) SE of the approximate centerline of U.S. Highway 41 south-bound lanes,
and 2.4 m (8.0 ft) SW of the NE end of a concrete guardrail.

                          U.S. DEPARTMENT OF COMMERCE
                National Oceanic and Atmospheric Administration
                            National Ocean Service
                                                                   Page  4 of  7

                                                                                
Station ID: 8725837                         PUBLICATION DATE:  06/02/2011
Name:       MYAKKA RIVER, US 41                               
            FL
NOAA Chart: 11426                           Latitude:   27°  2.7' N (  27.04500)
USGS Quad:  MYAKKA RIVER                    Longitude:  82° 17.6' W ( -82.29330)


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


                         BENCH MARK STAMPING:  HAVOLINE 2 1974
                         DESIGNATION:          HAVOLINE 2

MONUMENTATION:           Horizontal Station disk               VM#:        19922
AGENCY:                  National Geodetic Survey (NGS)        IDB PID#:  AG1868
SETTING CLASSIFICATION:  Concrete monument                     OPUS PID:        
LATITUDE:   27°  2.8' N (  27.04675)          LONGITUDE:  82° 15.4' W ( -82.25617)


The bench mark is disk set in the top of a concrete monument recessed 0.15 m
(0.5 ft) inches below the level of the ground and about 0.15 m (0.5) ft below
the level of U.S.  Highway 41.

                          U.S. DEPARTMENT OF COMMERCE
                National Oceanic and Atmospheric Administration
                            National Ocean Service
                                                                   Page  5 of  7

                                                                                
Station ID: 8725837                         PUBLICATION DATE:  06/02/2011
Name:       MYAKKA RIVER, US 41                               
            FL
NOAA Chart: 11426                           Latitude:   27°  2.7' N (  27.04500)
USGS Quad:  MYAKKA RIVER                    Longitude:  82° 17.6' W ( -82.29330)


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


                         BENCH MARK STAMPING:  V 634 2005
                         DESIGNATION:          V 634

MONUMENTATION:           Flange-encased Rod                    VM#:        19923
AGENCY:                  National Geodetic Survey (NGS)        IDB PID#:  DJ3119
SETTING CLASSIFICATION:  Stainless steel rod                   OPUS PID:        
LATITUDE:   27°  2.9' N (  27.04789)          LONGITUDE:  82° 16.5' W ( -82.27564)


The bench mark is a stainless steel rod located 10.15 m (33.3 ft) south of the
approximate centerline of U.S. Highway 41 northbound, 31.8 ft north of the
approximate centerline of U.S. Highway 41 southbound, 3.81 m (12.5 ft) north of
a metal guardrail and 0.30 m (1.0 ft) west of a carsonite witness post.  The
bench mark is a stainless steel rod driven to refusal at a depth of 4.87 m (16.0
ft) with an NGS logo cap recessed 1 inch below the level of the ground and level
with U.S.  Highway 41, the datum point being recessed 4 inches below the level
of the NGS logo cap.

                          U.S. DEPARTMENT OF COMMERCE
                National Oceanic and Atmospheric Administration
                            National Ocean Service
                                                                   Page  6 of  7

                                                                                
Station ID: 8725837                         PUBLICATION DATE:  06/02/2011
Name:       MYAKKA RIVER, US 41                               
            FL
NOAA Chart: 11426                           Latitude:   27°  2.7' N (  27.04500)
USGS Quad:  MYAKKA RIVER                    Longitude:  82° 17.6' W ( -82.29330)


                            T I D A L   D A T U M S 


Tidal datums at MYAKKA RIVER, US 41 based on:

     LENGTH OF SERIES:      3 MONTHS
     TIME PERIOD:           October 1977 - December 1977
     TIDAL EPOCH:           1983-2001
     CONTROL TIDE STATION:  8725744 PUNTA GORDA


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

     MEAN HIGHER HIGH WATER                     MHHW   =  0.580
     MEAN HIGH WATER                            MHW    =  0.499
     North American Vertical Datum              NAVD88 =  0.441
     MEAN SEA LEVEL                             MSL    =  0.312
     MEAN TIDE LEVEL                            MTL    =  0.306
     MEAN LOW WATER                             MLW    =  0.112
     MEAN LOWER LOW WATER                       MLLW   =  0.000

North American Vertical Datum (NAVD88)

Bench Mark Elevation Information                In METERS above:

     Stamping or Designation                    MLLW        MHW

     5837 A 1977                                 1.656    1.157
     U 255 RESET 1975                            1.581    1.082
     BM 3                                        1.583    1.084
     5837 C                                      5.871    5.372
     5837 D                                      5.363    4.864
     HAVOLINE 2 1974                             2.434    1.935
     V 634 2005                                  3.767    3.268


Foot Notes:

Geodetic heights of the bench marks meet all NOAA/NOS/NGS quality control
standards for Second Order, Class 1 leveling.  It is advised that a confirmation
set of levels be established for bench marks 5837 C, 5837 D, HAVOLINE 2 1974,and
V 634 2005 to verify height differences before using tidal bench mark elevation
information.

                          U.S. DEPARTMENT OF COMMERCE
                National Oceanic and Atmospheric Administration
                            National Ocean Service
                                                                   Page  7 of  7

                                                                                
Station ID: 8725837                         PUBLICATION DATE:  06/02/2011
Name:       MYAKKA RIVER, US 41                               
            FL
NOAA Chart: 11426                           Latitude:   27°  2.7' N (  27.04500)
USGS Quad:  MYAKKA RIVER                    Longitude:  82° 17.6' W ( -82.29330)


                             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.