NOAA Web Site Link Tides and Currents Home Page Transparent placeholder image

Bench Mark Sheet for 8729753, BLACKWATER RIVER FL

Superseded Epoch

Large map location marker Station Location
Small red map location marker Published bench mark
Small blue map location marker Unpublished bench mark

Bench mark positions only appear on the map if their coordinates in the CO-OPS database are at the precision of degrees/minutes/seconds/and tenths of seconds. If the coordinates are less precise, the mark will not appear.

Printable version

                          U.S. DEPARTMENT OF COMMERCE
                National Oceanic and Atmospheric Administration
                            National Ocean Service
Datums Page                                                        Page  1 of  4

                                                                                
Station ID: 8729753                         PUBLICATION DATE:  04/29/2004
Name:       BLACKWATER RIVER                                  
            FL
NOAA Chart: 11382                           Latitude:   30° 38.2' N (  30.63670)
USGS Quad:  MILTON NORTH                    Longitude:  87°  1.7' W ( -87.02830)


To reach the tidal bench marks from the intersection of Willing Street and U.S.
Highway 90 in Milton, at the west end of the U.S. Highway bridge over the
Blackwater River, proceed NW on Willing Street for 0.2 km (0.1 mi) to Country
Road C-191, then proceed north and east on County Road C-191 for 2.4 km (1.5 mi)
to the driveway to the Hawkins property, then SE along the drive to the
Blackwater River.  The bench marks are along the Hawkins property and along
County Road C-191.  The tide gage and staff were located on a small dock near a
picnic shelter at the Hawkins' residence.


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


                 PRIMARY BENCH MARK STAMPING:  9753 A 1976
                         DESIGNATION:          872 9753 A TIDAL

MONUMENTATION:           Tidal Station disk                    VM#:        10225
AGENCY:                  National Ocean Survey (NOS)           IDB PID#:  BG4552
SETTING CLASSIFICATION:  Concrete porch                        OPUS PID:        
LATITUDE:   30° 38.3' N (  30.63830)          LONGITUDE:  87°  1.5' W ( -87.02500)


The primary bench mark is a disk set flush in the south corner of the concrete
porch on the SW side of the Hawkins' house, 74 m (244 ft) east of bench mark
9753 C 1976, 6.95 m (22.8 ft) west of the south corner of the house, and 2.29 m
(7.5 ft) SW of the SW side of the house.

                          U.S. DEPARTMENT OF COMMERCE
                National Oceanic and Atmospheric Administration
                            National Ocean Service
                                                                   Page  2 of  4

                                                                                
Station ID: 8729753                         PUBLICATION DATE:  04/29/2004
Name:       BLACKWATER RIVER                                  
            FL
NOAA Chart: 11382                           Latitude:   30° 38.2' N (  30.63670)
USGS Quad:  MILTON NORTH                    Longitude:  87°  1.7' W ( -87.02830)


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


                         BENCH MARK STAMPING:  9753 C 1976
                         DESIGNATION:          872 9753 C TIDAL

MONUMENTATION:           Tidal Station disk                    VM#:        10226
AGENCY:                  National Ocean Survey (NOS)           IDB PID#:  BG4551
SETTING CLASSIFICATION:  Copper-clad steel rod                 OPUS PID:        
LATITUDE:   30° 38.3' N (  30.63830)          LONGITUDE:  87°  1.5' W ( -87.02500)


The bench mark is a disk located 74 m (244 ft) west of bench mark 9753 A 1976,
70 m (230 ft) SE of bench mark 9753 D 1976, 55 m (180 ft) SE of the centerline
of County Road C-191, 0.76 m (2.5 ft) east of a powerline pole with witness
sign, and 12.95 m (42.5 ft) SW of the centerline of the driveway to the Hawkins'
house.  The bench mark is set 15 cm (0.5 ft) below ground level, crimped to the
top of a copper-clad steel rod driven 7.6 m (25 ft) to refusal, and encased in a
PVC pipe and concrete kickblock.



                         BENCH MARK STAMPING:  9753 E 1976
                         DESIGNATION:          872 9753 E TIDAL

MONUMENTATION:           Tidal Station disk                    VM#:        16540
AGENCY:                  National Ocean Survey (NOS)           IDB PID#:  BG4549
SETTING CLASSIFICATION:  Concrete culvert head wall            OPUS PID:        
LATITUDE:   30° 38.3' N (  30.63830)          LONGITUDE:  87°  1.6' W ( -87.02670)


The bench mark is a disk set in the top of the SW end of a concrete culvert head
wall, 0.2 km (0.1 mi) SW of bench mark 9753 D 1976, 7.22 m (23.7 ft) NW of the
centerline of County Road C-191, and 1 m (2 ft) below the level of the road.

                          U.S. DEPARTMENT OF COMMERCE
                National Oceanic and Atmospheric Administration
                            National Ocean Service
                                                                   Page  3 of  4

                                                                                
Station ID: 8729753                         PUBLICATION DATE:  04/29/2004
Name:       BLACKWATER RIVER                                  
            FL
NOAA Chart: 11382                           Latitude:   30° 38.2' N (  30.63670)
USGS Quad:  MILTON NORTH                    Longitude:  87°  1.7' W ( -87.02830)


                            T I D A L   D A T U M S 


Tidal datums at BLACKWATER RIVER based on:

     LENGTH OF SERIES:      10 MONTHS
     TIME PERIOD:           January 1993 - October 1993
     TIDAL EPOCH:           1983-2001
     CONTROL TIDE STATION:  8729747 SHIELD POINT, BLACKWATER RIVER


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

     MEAN HIGHER HIGH WATER                     MHHW   =  0.505
     MEAN HIGH WATER                            MHW    =  0.467
     MEAN SEA LEVEL                             MSL    =  0.253
     MEAN TIDE LEVEL                            MTL    =  0.252
     North American Vertical Datum              NAVD88 =  0.144
     MEAN LOW WATER                             MLW    =  0.037
     MEAN LOWER LOW WATER                       MLLW   =  0.000

North American Vertical Datum (NAVD88)

Bench Mark Elevation Information                In METERS above:

     Stamping or Designation                    MLLW        MHW

     9753 A 1976                                 2.680    2.213
     9753 C 1976                                 1.509    1.042
     9753 E 1976                                 1.765    1.298


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

                                                                                
Station ID: 8729753                         PUBLICATION DATE:  04/29/2004
Name:       BLACKWATER RIVER                                  
            FL
NOAA Chart: 11382                           Latitude:   30° 38.2' N (  30.63670)
USGS Quad:  MILTON NORTH                    Longitude:  87°  1.7' W ( -87.02830)


                             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.

Return to Top
Products available at 8729753 BLACKWATER RIVER, FL

Revised: 10/15/2013
NOAA / National Ocean Service
Web site owner: Center for Operational Oceanographic Products and Services