U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Datums Page Page 1 of 5
Station ID: 8727293 PUBLICATION DATE: 05/20/2004
Name: HALLS RIVER BRIDGE, HALLS RIVER
FL
NOAA Chart: 11409 Latitude: 28° 48.0' N ( 28.80000)
USGS Quad: HOMOSASSA Longitude: 82° 36.2' W ( -82.60330)
To reach the tidal bench marks from the intersection of U.S. Highway 19/98 and
West Halls River Road (County Road C-490A) in Homosassa Springs, proceed west on
West Halls River Road for 2.66 km (1.65 mi) to the bridge over Halls Creek. The
bench marks are located along West Halls River Road. The tide gage and staff
were located on center of the bridge.
T I D A L B E N C H M A R K S
PRIMARY BENCH MARK STAMPING: 7293 E 1978
DESIGNATION: 872 7293 E TIDAL
MONUMENTATION: Survey disk VM#: 7774
AGENCY: Florida Department of Transportation
(FLDT) IDB PID#: AL7708
SETTING CLASSIFICATION: Bridge abutment OPUS PID:
LATITUDE: 28° 48.1' N ( 28.80170) LONGITUDE: 82° 36.2' W ( -82.60330)
The primary bench mark is a disk set in the SE end of the SW abutment wing wall
of the bridge over Halls River, 67.06 m (220.0 ft) SW of bench mark 7293 D 1978,
17 m (56 ft) NE of the SW end of the metal guardrail on the SE side of West
Halls River Road, 4.85 m (15.9 ft) SE of the centerline of the road, and 0.21 m
(0.7 ft) NW of the SE end of the wing wall.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 2 of 5
Station ID: 8727293 PUBLICATION DATE: 05/20/2004
Name: HALLS RIVER BRIDGE, HALLS RIVER
FL
NOAA Chart: 11409 Latitude: 28° 48.0' N ( 28.80000)
USGS Quad: HOMOSASSA Longitude: 82° 36.2' W ( -82.60330)
T I D A L B E N C H M A R K S
BENCH MARK STAMPING: 7293 A 1978
DESIGNATION: 872 7293 A TIDAL
MONUMENTATION: Tidal Station disk VM#: 7770
AGENCY: National Ocean Survey (NOS) IDB PID#: AL7710
SETTING CLASSIFICATION: Concrete monument OPUS PID:
LATITUDE: 28° 48.0' N ( 28.80000) LONGITUDE: 82° 36.2' W ( -82.60330)
The bench mark is a disk set in the top of a concrete monument neear the
intersection of West Halls River Road and West Hadley Court, 88.91 m (291.7 ft)
SW of bench mark 7293 B 1978, 13.41 m (44.0 ft) SE of the centerline of West
Halls River Road, 3 m (10 ft) south of the centerline of West Hadley Court, 0.52
m (1.7 ft) NE of powerline pole #421325 with a witness sign, and 0.03 m (0.1 ft)
below ground level.
BENCH MARK STAMPING: 7293 B 1978
DESIGNATION: 872 7293 B TIDAL
MONUMENTATION: Tidal Station disk VM#: 7771
AGENCY: National Ocean Survey (NOS) IDB PID#: AL7709
SETTING CLASSIFICATION: Galvanized steel rod OPUS PID:
LATITUDE: 28° 48.0' N ( 28.80000) LONGITUDE: 82° 36.2' W ( -82.60330)
The bench mark is a disk located 103.33 m (339.0 ft) SW of bench mark 7293 D
1978, 12.50 m (41.0 ft) SE of the centerline of West Halls River Road, 6.52 m
(21.4 ft) NE of the centerline of the drive leading to Aqua Marine Services, and
1.83 m (6.0 ft) SW of powerline pole #421323 with a witness sign. The bench
mark is crimped to the top of a galvanized steel rod driven 3.0 m (10 ft) to
refusal, and encased in a PVC pipe and concrete kickblock. NOTE: Mark recovered
in poor condition by US Power Squadron in 1993.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 3 of 5
Station ID: 8727293 PUBLICATION DATE: 05/20/2004
Name: HALLS RIVER BRIDGE, HALLS RIVER
FL
NOAA Chart: 11409 Latitude: 28° 48.0' N ( 28.80000)
USGS Quad: HOMOSASSA Longitude: 82° 36.2' W ( -82.60330)
T I D A L B E N C H M A R K S
BENCH MARK STAMPING: 7293 C 1978
DESIGNATION: 872 7293 C TIDAL
MONUMENTATION: Tidal Station disk VM#: 7772
AGENCY: National Ocean Survey (NOS) IDB PID#: AL7711
SETTING CLASSIFICATION: Galvanized steel rod OPUS PID:
LATITUDE: 28° 48.0' N ( 28.80000) LONGITUDE: 82° 36.3' W ( -82.60500)
The bench mark is a disk located near the intersection of West Halls River Road
and West Grotto Court, 85 m (280 ft) SW of bench mark 7293 A 1978, 13.32 m (43.7
ft) east of the centerline of West Halls River Road, 6.40 m (21.0 ft) south of
the centerline of West Grotto Court, 0.73 m (2.4 ft) SW of powerline pole #11770
with a witness sign. The bench mark is crimped to the top of a galvanized steel
rod driven 2.7 m (9 ft) to refusal, and encased in a PVC pipe and concrete
kickblock.
BENCH MARK STAMPING: 7293 D 1978
DESIGNATION: 872 7293 D TIDAL
MONUMENTATION: Survey disk VM#: 7773
AGENCY: Florida Department of Transportation
(FLDT) IDB PID#: AL7707
SETTING CLASSIFICATION: Bridge abutment OPUS PID:
LATITUDE: 28° 48.1' N ( 28.80170) LONGITUDE: 82° 36.1' W ( -82.60170)
The bench mark is a disk set in the NW end of the NE abutment wing wall for the
bridge, 17.04 m (55.9 ft) west of the east end of a metal guardrail on the north
side of West Halls River Road, 4.79 m (15.7 ft) NW of the centerline of the
road, and 3.72 m (12.2 ft) NE of the bridge bulkhead.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 4 of 5
Station ID: 8727293 PUBLICATION DATE: 05/20/2004
Name: HALLS RIVER BRIDGE, HALLS RIVER
FL
NOAA Chart: 11409 Latitude: 28° 48.0' N ( 28.80000)
USGS Quad: HOMOSASSA Longitude: 82° 36.2' W ( -82.60330)
T I D A L D A T U M S
Tidal datums at HALLS RIVER BRIDGE, HALLS RIVER based on:
LENGTH OF SERIES: 3 MONTHS
TIME PERIOD: September 1978 - November 1978
TIDAL EPOCH: 1983-2001
CONTROL TIDE STATION: 8726724 CLEARWATER BEACH, GULF OF MEXICO
Elevations of tidal datums referred to Mean Lower Low Water (MLLW), in METERS:
MEAN HIGHER HIGH WATER MHHW = 0.208
MEAN HIGH WATER MHW = 0.161
North American Vertical Datum NAVD88 = 0.143
MEAN SEA LEVEL MSL = 0.101
MEAN TIDE LEVEL MTL = 0.093
MEAN LOW WATER MLW = 0.024
MEAN LOWER LOW WATER MLLW = 0.000
North American Vertical Datum (NAVD88)
Bench Mark Elevation Information In METERS above:
Stamping or Designation MLLW MHW
7293 E 1978 2.868 2.707
7293 A 1978 0.909 0.748
7293 B 1978 0.995 0.834
7293 C 1978 1.102 0.941
7293 D 1978 2.860 2.699
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 5 of 5
Station ID: 8727293 PUBLICATION DATE: 05/20/2004
Name: HALLS RIVER BRIDGE, HALLS RIVER
FL
NOAA Chart: 11409 Latitude: 28° 48.0' N ( 28.80000)
USGS Quad: HOMOSASSA Longitude: 82° 36.2' W ( -82.60330)
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.