U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Datums Page Page 1 of 5
PUBLICATION DATE: 10/24/1984
Station ID: 8727246 SUPERCEDED DATE: 04/21/2003
Name: CHASSAHOWITZKA, CHASSAHOWITZKA RIVER
FLORIDA
NOAA Chart: 11409 Latitude: 28° 42.9' N
USGS Quad: CHASSAHOWITZKA Longitude: 82° 34.6' W
To reach the tidal bench marks from the intersection of U.S. Highway 19-98 AND
State Highway C-480, proceed west on State Highway C-480 1.8 miles (2.9 km) to
the end of the truck travel. The bench marks are located in area along C-480.
The tide gage and staff were located on a USGS platform in the river.
T I D A L B E N C H M A R K S
PRIMARY BENCH MARK STAMPING: 7246 A 1978
MONUMENTATION: Survey Disk VM#: 7755
AGENCY: PID#: AL7704
SETTING CLASSIFICATION: Stainless Steel Rod
The bench mark is located 365 feet (111 m) north of Bench Mark 7246 C 1978, 61
feet (19 m) NW of the centerline of State Road C-480, 49.1 feet (15 m) SSW of a
yellow block house and 3.4 feet (1.0 m) east of a power pole. The bench mark is
crimped to a stainless steel rod driven 48 feet (15 m) to refusal and encased in
PVC pipe and a concrete kickblock.
BENCH MARK STAMPING: 7246 B 1978
MONUMENTATION: Survey Disk VM#: 7756
AGENCY: PID#: AL7706
SETTING CLASSIFICATION: Concrete Post
The bench mark is set flush in the top of a concrete post, 93 feet (28 m) ESE of
the SE corner of the porch of a white wooden house, 50 feet (15 m) south of the
centerline of State Road C-480 and 3 feet (0.9 m) SW of power pole #37. The
bench mark is level with the ground.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 2 of 5
PUBLICATION DATE: 10/24/1984
Station ID: 8727246 SUPERCEDED DATE: 04/21/2003
Name: CHASSAHOWITZKA, CHASSAHOWITZKA RIVER
FLORIDA
NOAA Chart: 11409 Latitude: 28° 42.9' N
USGS Quad: CHASSAHOWITZKA Longitude: 82° 34.6' W
T I D A L B E N C H M A R K S
BENCH MARK STAMPING: 7246 C 1978
MONUMENTATION: Survey Disk VM#: 7757
AGENCY: PID#: AL7705
SETTING CLASSIFICATION: Stainless Steel Rod
The bench mark is located 440 feet (134.1 m) east of Bench Mark 7246 B 1978
along C-480, 63.1 feet (19.2 m) north of the north corner of a green stucco
house, 24.1 feet (7.3 m) west of the centerline of a gravel road leading to
Chassahowitzka Village, 16.7 feet (5.1 m) south of the centerline of C-480 and
1.9 feet (0.6 m) SW of a power pole. The bench mark is crimped to a stainless
steel rod driven 32 feet (9.7 m) to refusal and encased in PVC pipe and a
concrete kickblock.
BENCH MARK STAMPING: 7246 D 1978
MONUMENTATION: Survey Disk VM#: 7758
AGENCY: PID#: AL7703
SETTING CLASSIFICATION: Concrete Post
The bench mark is set in the top of a concrete post 483 feet (147 m) east of
Bench Mark 7246 A 1978, 44.2 feet (13.5 m) north of the centerline of State Road
C-480, 37.6 feet (11.5 m) east of the SE corner of the Chassahowitzka River
Lodge, 2.8 feet (0.9 m) west of a telephone booth and 2.7 feet (0.8 m) south of
a metal witness post. The bench mark is below ground level.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 3 of 5
PUBLICATION DATE: 10/24/1984
Station ID: 8727246 SUPERCEDED DATE: 04/21/2003
Name: CHASSAHOWITZKA, CHASSAHOWITZKA RIVER
FLORIDA
NOAA Chart: 11409 Latitude: 28° 42.9' N
USGS Quad: CHASSAHOWITZKA Longitude: 82° 34.6' W
T I D A L B E N C H M A R K S
BENCH MARK STAMPING: 7246 E E 1978
MONUMENTATION: Survey Disk VM#: 7759
AGENCY: PID#: AL7702
SETTING CLASSIFICATION: Concrete Post
The bench mark is set flush in the top of a concrete post 0.37 miles (0.6 km)
east of Bench Mark 7246 D 1978, 35.5 feet (10.8 m) north of the centerline of
State Road C-480, 32 feet (10 m) west of a surfaced side road, 28.9 feet (8.8 m)
SE of the SE corner of the First Baptist Church and 2.8 feet (0.9 m) north of a
power pole. The bench mark is level with the ground.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 4 of 5
PUBLICATION DATE: 10/24/1984
Station ID: 8727246 SUPERCEDED DATE: 04/21/2003
Name: CHASSAHOWITZKA, CHASSAHOWITZKA RIVER
FLORIDA
NOAA Chart: 11409 Latitude: 28° 42.9' N
USGS Quad: CHASSAHOWITZKA Longitude: 82° 34.6' W
T I D A L D A T U M S
Tidal datums at CHASSAHOWITZKA, CHASSAHOWITZKA RIVER based on:
LENGTH OF SERIES: 4 MONTHS
TIME PERIOD: JULY - OCTOBER 1978
TIDAL EPOCH: 1960-1978
CONTROL TIDE STATION: 8727520 CEDAR KEY
Elevations of tidal datums referred to Mean Lower Low Water (MLLW), in FEET:
HIGHEST OBSERVED WATER LEVEL (07/28/1978) = 1.49
MEAN HIGHER HIGH WATER MHHW = 0.60
MEAN HIGH WATER MHW = 0.49
MEAN TIDE LEVEL MTL = 0.30
MEAN LOW WATER MLW = 0.10
MEAN LOWER LOW WATER MLLW = 0.00
LOWEST OBSERVED WATER LEVEL (10/18/1978) = 0.11
North American Vertical Datum (NAVD88)
Bench Mark Elevation Information In FEET above:
Stamping or Designation MLLW MHW
7246 A 1978 8.16 7.67
7246 B 1978 5.47 4.98
7246 C 1978 7.48 6.99
7246 D 1978 9.58 9.09
7246 E E 1978 7.29 6.80
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 5 of 5
PUBLICATION DATE: 10/24/1984
Station ID: 8727246 SUPERCEDED DATE: 04/21/2003
Name: CHASSAHOWITZKA, CHASSAHOWITZKA RIVER
FLORIDA
NOAA Chart: 11409 Latitude: 28° 42.9' N
USGS Quad: CHASSAHOWITZKA Longitude: 82° 34.6' 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.