U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Datums Page Page 1 of 5
PUBLICATION DATE: 02/02/1984
Station ID: 8726468 SUPERCEDED DATE: 04/21/2003
Name: SHELL POINT, LITTLE MANATEE RIVER
FLORIDA
NOAA Chart: 11414 Latitude: 27° 43.1' N
USGS Quad: RUSKIN Longitude: 82° 28.8' W
To reach the tidal bench marks from the intersection of Shell Point Road and
U.S. Highway 41 in Ruskin south of Tampa, turn right to go west on Shell Point
Road, the marked paved road to the Shell Point Fishing Camp. The gage and staff
were on a fishing pier in the fishing camp, and the bench marks are scattered
around the grounds of the fishing camp.
T I D A L B E N C H M A R K S
PRIMARY BENCH MARK STAMPING: NO 1 1957
MONUMENTATION: Survey Disk VM#: 6512
AGENCY: PID#: AG6207
SETTING CLASSIFICATION: Banister
The bench mark is set in the top of the banister 6 feet (1.8 m) above the ground
level at the west end of the steps, leading to the swimming pool from the
roadway at the fishing camp 2 feet (0.6 m) south of the south edge of the
concrete sidewalk around the pool.
BENCH MARK STAMPING: NO 2 1957
MONUMENTATION: Survey Disk VM#: 6513
AGENCY: PID#: AG6208
SETTING CLASSIFICATION: Concrete Base
The bench mark is set in the NE corner of the concrete base for the bait shed
about level with the ground, and 44.4 feet (13.5 m) north of the east-west sea
wall.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 2 of 5
PUBLICATION DATE: 02/02/1984
Station ID: 8726468 SUPERCEDED DATE: 04/21/2003
Name: SHELL POINT, LITTLE MANATEE RIVER
FLORIDA
NOAA Chart: 11414 Latitude: 27° 43.1' N
USGS Quad: RUSKIN Longitude: 82° 28.8' W
T I D A L B E N C H M A R K S
BENCH MARK STAMPING: NO 3 1957
MONUMENTATION: Survey Disk VM#: 6514
AGENCY: PID#: AG6206
SETTING CLASSIFICATION: Concrete Base
The bench mark is set level with the ground in the NE corner of the concrete
base for the shed at the south end of the tomato garden just east of the
swimming pool, 24.5 feet (7.5 m) east of the SE corner of the steel fence around
the swimming pool, and 1.7 (0.5 m) feet north of the NE corner of the floor.
BENCH MARK STAMPING: 6468 A 1977
MONUMENTATION: Survey Disk VM#: 6515
AGENCY: PID#: AG7518
SETTING CLASSIFICATION: Concrete Seawall
The bench mark is set flush in the sea wall 200.0 feet (61.0 m) ESE of Bench
Mark NO 1 1957, 32.3 feet (9.8 m) WSW of the NW corner of a small house
overhanging the water, and 1.3 feet (0.4 m) west of the SE corner of the sea
wall.
BENCH MARK STAMPING: 6468 B 1977
MONUMENTATION: Survey Disk VM#: 6516
AGENCY: PID#: AG7517
SETTING CLASSIFICATION: Concrete Seawall
The bench mark is set flush in the top of the seawall, 340.0 feet (103.6 m) west
of Bench Mark 6468 A 1977, 81.0 feet (24.7 m) west of the NW end of the wooden
pier, 16.4 feet (5.0 m) SW corner of a covered table area used for cleaning
fish, and 12.0 feet (3.7 m) east of the SW corner of the sea wall.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 3 of 5
PUBLICATION DATE: 02/02/1984
Station ID: 8726468 SUPERCEDED DATE: 04/21/2003
Name: SHELL POINT, LITTLE MANATEE RIVER
FLORIDA
NOAA Chart: 11414 Latitude: 27° 43.1' N
USGS Quad: RUSKIN Longitude: 82° 28.8' W
T I D A L B E N C H M A R K S
BENCH MARK STAMPING: A 262 1966
MONUMENTATION: Survey Disk VM#: 6517
AGENCY: PID#: AG6209
SETTING CLASSIFICATION: Concrete Wall
The bench mark is set in a corner wall about level with the ground along the
north side of the boat ramp, 75.0 feet (22.9 m) north of Bench Mark 6468 B 1977,
6.5 feet (2.0 m) west of the east end of the wall, and 6.4 feet (2.0 m) east of
the west face of the sea wall.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 4 of 5
PUBLICATION DATE: 02/02/1984
Station ID: 8726468 SUPERCEDED DATE: 04/21/2003
Name: SHELL POINT, LITTLE MANATEE RIVER
FLORIDA
NOAA Chart: 11414 Latitude: 27° 43.1' N
USGS Quad: RUSKIN Longitude: 82° 28.8' W
T I D A L D A T U M S
Tidal datums at SHELL POINT, LITTLE MANATEE RIVER based on:
LENGTH OF SERIES: 3 MONTHS
TIME PERIOD: FEBRUARY-APRIL 1977
TIDAL EPOCH: 1960-1978
CONTROL TIDE STATION: 8726468 PORT MANATEE
Elevations of tidal datums referred to Mean Lower Low Water (MLLW), in FEET:
HIGHEST OBSERVED WATER LEVEL (04/05/1977) = 2.95
MEAN HIGHER HIGH WATER MHHW = 2.25
MEAN HIGH WATER MHW = 1.97
MEAN TIDE LEVEL MTL = 1.18
* NATIONAL GEODETIC VERTICAL DATUM NGVD29 = 0.81
MEAN LOW WATER MLW = 0.38
MEAN LOWER LOW WATER MLLW = 0.00
LOWEST OBSERVED WATER LEVEL (03/01/1977) = -1.23
* NGVD reference based on adjustment of 1966 and NOS levels of 1977.
North American Vertical Datum (NAVD88)
Bench Mark Elevation Information In FEET above:
Stamping or Designation MLLW MHW
NO 1 1957 11.38 9.41
NO 2 1957 4.80 2.83
NO 3 1957 6.58 4.61
6468 A 1977 4.27 2.30
6468 B 1977 3.94 1.97
A 262 1966 4.61 2.64
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 5 of 5
PUBLICATION DATE: 02/02/1984
Station ID: 8726468 SUPERCEDED DATE: 04/21/2003
Name: SHELL POINT, LITTLE MANATEE RIVER
FLORIDA
NOAA Chart: 11414 Latitude: 27° 43.1' N
USGS Quad: RUSKIN Longitude: 82° 28.8' 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.