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Datums Page Page 1 of 5
Station ID: 8727246 PUBLICATION DATE: 01/06/2004
Name: CHASSAHOWITZKA RIVER
FL
NOAA Chart: 11409 Latitude: 28° 42.9' N ( 28.71500)
USGS Quad: CHASSAHOWITZKA Longitude: 82° 34.6' W ( -82.57670)
To reach the tidal bench marks from the First Baptist Church in Chassahowitzka,
proceed west on County Road C-480 for 0.8 km (0.5 mi) to South McClung Loop,
then west on South McClung Loop for 0.2 km (0.1 mi) to the river. The bench
marks are located in the area and along County Road 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
DESIGNATION: 872 7246 A TIDAL
MONUMENTATION: Tidal Station disk VM#: 7755
AGENCY: National Ocean Survey (NOS) IDB PID#: AL7704
SETTING CLASSIFICATION: Stainless steel rod OPUS PID:
LATITUDE: 28° 42.8' N ( 28.71330) LONGITUDE: 82° 34.5' W ( -82.57500)
The primary bench mark is a disk located 0.8 km (0.5 mi) west of the First
Baptist Church, 111 m (365 ft) north of bench mark 7246 C 1978, 19 m (61 ft) NW
of the centerline of County Road C-480, 14.97 m (49.1 ft) SSW of a buff-colored
cinder block house, and 1.04 m (3.4 ft) east of a powerline pole with a witness
sign attached. The bench mark is set 5 cm (0.2 ft) above ground level, crimped
to the top of a stainless steel rod driven 14.6 m (48 ft) to refusal, and
encased in PVC pipe with a concrete kickblock.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 2 of 5
Station ID: 8727246 PUBLICATION DATE: 01/06/2004
Name: CHASSAHOWITZKA RIVER
FL
NOAA Chart: 11409 Latitude: 28° 42.9' N ( 28.71500)
USGS Quad: CHASSAHOWITZKA Longitude: 82° 34.6' W ( -82.57670)
T I D A L B E N C H M A R K S
BENCH MARK STAMPING: 7246 B 1978
DESIGNATION: 872 7246 B TIDAL
MONUMENTATION: Tidal Station disk VM#: 7756
AGENCY: National Ocean Survey (NOS) IDB PID#: AL7706
SETTING CLASSIFICATION: Concrete monument OPUS PID:
LATITUDE: 28° 42.8' N ( 28.71330) LONGITUDE: 82° 34.6' W ( -82.57670)
The bench mark is a disk set in the top of a concrete monument, 26.61 m (87.3
ft) ESE of the SE corner of a board and batten house, 15.24 m (50.0 ft) south of
the centerline of South McClung Loop, 12.74 m (41.8 ft) east of the center hole
for a recreational vehicle dumping station at Lykes Chassahowitzka Campground, 1
m (3 ft) SW of power pole #37 with a witness sign attached, and 0.06 m (0.2 ft)
below ground level.
BENCH MARK STAMPING: 7246 C 1978
DESIGNATION: 872 7246 C TIDAL
MONUMENTATION: Tidal Station disk VM#: 7757
AGENCY: National Ocean Survey (NOS) IDB PID#: AL7705
SETTING CLASSIFICATION: Stainless steel rod OPUS PID:
LATITUDE: 28° 42.8' N ( 28.71330) LONGITUDE: 82° 34.5' W ( -82.57500)
The bench mark is a disk located 134 m (440 ft) east of bench mark 7246 B 1978,
19.23 m (63.1 ft) NNE of the NE corner of a green stucco house, 7.35 m (24.1 ft)
west of the centerline of a paved road leading to Chassahowitzka Village, 5.09 m
(16.7 ft) south of the centerline of South McClung Loop, 0.82 m (2.7 ft) WNW of
a witness post, and 0.58 m (1.9 ft) SW of a powerline pole. The bench mark is
crimped to the top of a stainless steel rod driven 9.8 m (32 ft) to refusal, and
encased in a PVC pipe with concrete kickblock.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 3 of 5
Station ID: 8727246 PUBLICATION DATE: 01/06/2004
Name: CHASSAHOWITZKA RIVER
FL
NOAA Chart: 11409 Latitude: 28° 42.9' N ( 28.71500)
USGS Quad: CHASSAHOWITZKA Longitude: 82° 34.6' W ( -82.57670)
T I D A L B E N C H M A R K S
BENCH MARK STAMPING: 7246 D 1978
DESIGNATION: 872 7246 D TIDAL
MONUMENTATION: Tidal Station disk VM#: 7758
AGENCY: National Ocean Survey (NOS) IDB PID#: AL7703
SETTING CLASSIFICATION: Concrete monument OPUS PID#: AL7703
LATITUDE: 28° 42.8' N ( 28.71330) LONGITUDE: 82° 34.4' W ( -82.57330)
The bench mark is a disk set in the top of a concrete monument, 147 m (483 ft)
east of bench mark 7246 A 1978, 13.47 m (44.2 ft) north of the centerline of
County Road C-480, 11.46 m (37.6 ft) east of the SE corner of the Chassahowitzka
Lodge, 0.85 m (2.8 ft) west of a telephone booth, 0.82 m (2.7 ft) south of a
metal witness post, and 0.06 m (0.2 ft) below ground level. NOTE: Mark not
found in 1994 by US Power Squadron.
BENCH MARK STAMPING: 7246 E E 1978
DESIGNATION: 872 7246 E TIDAL
MONUMENTATION: Tidal Station disk VM#: 7759
AGENCY: National Ocean Survey (NOS) IDB PID#: AL7702
SETTING CLASSIFICATION: Concrete monument OPUS PID:
LATITUDE: 28° 42.9' N ( 28.71500) LONGITUDE: 82° 34.1' W ( -82.56830)
The bench mark is a disk set in the top of a concrete monument, 0.6 km (0.4 mi)
east of bench mark 7246 D 1978, 10.82 m (35.5 ft) north of the centerline of
County Road C-480, 10 m (32 ft) west of the centerline of Riviera Drive, 8.81 m
(28.9 ft) SE of the SE corner of the First Baptist Church, 0.85 m (2.8 ft) north
of a powerline pole with a witness sign attached.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 4 of 5
Station ID: 8727246 PUBLICATION DATE: 01/06/2004
Name: CHASSAHOWITZKA RIVER
FL
NOAA Chart: 11409 Latitude: 28° 42.9' N ( 28.71500)
USGS Quad: CHASSAHOWITZKA Longitude: 82° 34.6' W ( -82.57670)
T I D A L D A T U M S
Tidal datums at CHASSAHOWITZKA RIVER based on:
LENGTH OF SERIES: 5 MONTHS
TIME PERIOD: June 1978 - October 1978
TIDAL EPOCH: 1983-2001
CONTROL TIDE STATION: 8727520 CEDAR KEY, GULF OF MEXICO
Elevations of tidal datums referred to Mean Lower Low Water (MLLW), in METERS:
MEAN HIGHER HIGH WATER MHHW = 0.177
MEAN HIGH WATER MHW = 0.143
MEAN TIDE LEVEL MTL = 0.087
MEAN SEA LEVEL MSL = 0.080
MEAN LOW WATER MLW = 0.031
MEAN LOWER LOW WATER MLLW = 0.000
North American Vertical Datum NAVD88 = -0.088
North American Vertical Datum (NAVD88)
Bench Mark Elevation Information In METERS above:
Stamping or Designation MLLW MHW
7246 A 1978 2.425 2.282
7246 B 1978 1.606 1.463
7246 C 1978 2.216 2.073
7246 D 1978 2.859 2.716
7246 E E 1978 2.161 2.018
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 5 of 5
Station ID: 8727246 PUBLICATION DATE: 01/06/2004
Name: CHASSAHOWITZKA RIVER
FL
NOAA Chart: 11409 Latitude: 28° 42.9' N ( 28.71500)
USGS Quad: CHASSAHOWITZKA Longitude: 82° 34.6' W ( -82.57670)
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.
Station Location
Published bench mark
Unpublished bench mark
