U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Datums Page Page 1 of 4
Station ID: 8726273 PUBLICATION DATE: 09/16/2003
Name: DESOTO POINT
FL
NOAA Chart: 11414 Latitude: 27° 31.4' N ( 27.52330)
USGS Quad: ANNA MARIA Longitude: 82° 39.0' W ( -82.65000)
To reach the tidal bench marks from the Post Office (downtown at state Highway
and 9th street) in Bradenton, proceed 6.1 km (3.8 mi) west on State Highway 64
to 75th Street West, then 2.4 km (1.5 mi) north on 75th Street West to 17th
Avenue N.W., then 0.3 km (0.2 mi) north on 83rd Street N.W. to 21st Avenue N.W.,
then 0.5 km (0.3 mi) west on 21st Avenue N.W. to 88th Court N.W., then 0.3 km
(0.2 mi) north on 88th Court N.W. to Boca Del Rio Marina. The bench marks are
along 21st Avenue N.W. and at Boca Del Rio Marina. The tidal bench marks are in
the vicinity of the Marina. The tide guage and staff were in the most northern
boat slip along the west side of the marina.
T I D A L B E N C H M A R K S
PRIMARY BENCH MARK STAMPING: 6273 B 1977
DESIGNATION: 872 6273 B TIDAL
MONUMENTATION: Tidal Station disk VM#: 6177
AGENCY: National Ocean Survey (NOS) IDB PID#: AG7668
SETTING CLASSIFICATION: Concrete sea wall OPUS PID:
LATITUDE: 27° 31.3' N ( 27.52170) LONGITUDE: 82° 39.0' W ( -82.65000)
The primary bench mark is a disk set in seawall, 12 m (41 ft) east of the east
edge of the westernmost north-south seawall, 1.71 m (5.6 ft) south of the south
edge of an east-west seawall, and 2 m (5 ft) north of the NW corner of a 5 m x 6
m (15 ft x 20 ft) concrete pad.
BENCH MARK STAMPING: 6273 E 1977
DESIGNATION: 872 6273 E TIDAL
MONUMENTATION: Tidal Station disk VM#: 6178
AGENCY: National Ocean Survey (NOS) IDB PID#: AG7665
SETTING CLASSIFICATION: Concrete monument OPUS PID:
LATITUDE: 27° 31.3' N ( 27.52170) LONGITUDE: 82° 39.0' W ( -82.65000)
The bench mark is a disk set in the top of a concrete monument, 75 m (246 ft)
south of bench mark 6273 B 1977, 11.28 m (37.0 ft) north of a power pole, 4.27
m (14.0 ft) west of the center line of a paved road, and 0.40 m (1.3 ft) east of
a witness post.
BENCH MARK STAMPING: 6273 G 1990
DESIGNATION: 872 6273 G TIDAL
MONUMENTATION: Flange-encased Rod VM#: 6180
AGENCY: National Ocean Service (NOS) IDB PID#: AG9414
SETTING CLASSIFICATION: Stainless steel rod OPUS PID:
LATITUDE: 27° 31.3' N ( 27.52170) LONGITUDE: 82° 39.0' W ( -82.65000)
The bench mark is a flange encased rod located 91.84 m (301.3 ft) north of bench
mark 6273 B 1977, 6.80 m (22.3 ft) south of the south edge of the north seawall,
and 0.12 m (0.4 ft) east of a witness post. The bench mark is set level with
the ground, being the top of a stainless steel rod driven 14.6 m (48 ft) to
refusal, and encased in a stamped NOS logo cap attached to a PVC pipe surrounded
by concrete.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 2 of 4
Station ID: 8726273 PUBLICATION DATE: 09/16/2003
Name: DESOTO POINT
FL
NOAA Chart: 11414 Latitude: 27° 31.4' N ( 27.52330)
USGS Quad: ANNA MARIA Longitude: 82° 39.0' W ( -82.65000)
T I D A L B E N C H M A R K S
BENCH MARK STAMPING: 6273 H 1990
DESIGNATION: 872 6273 H TIDAL
MONUMENTATION: Flange-encased Rod VM#: 6181
AGENCY: National Ocean Service (NOS) IDB PID#: AG9416
SETTING CLASSIFICATION: Stainless steel rod OPUS PID:
LATITUDE: 27° 31.3' N ( 27.52170) LONGITUDE: 82° 39.0' W ( -82.65000)
The bench mark is located 8.99 m (29.5 ft) east of the projected south
centerline of 88th Court N.W., 7.47 m (24.5 ft) south of the centerline of 21st
Avenue N.W., 6.34 m (20.8 ft) SE of a power pole, and 0.37 m (1.2 ft) north of a
witness post. The bench mark set level with the ground, being the top of a
stainless steel rod driven 20.1 m (66 ft) to refusal, and encased in a stamped
NOS logo cap attached to a PVC pipe surrounded by concrete.
BENCH MARK STAMPING: 6273 J 1990
DESIGNATION: 872 6273 J TIDAL
MONUMENTATION: Flange-encased Rod VM#: 6182
AGENCY: National Ocean Service (NOS) IDB PID#: AG9413
SETTING CLASSIFICATION: Stainless steel rod OPUS PID:
LATITUDE: 27° 31.3' N ( 27.52170) LONGITUDE: 82° 39.0' W ( -82.65000)
The bench mark is located 65 m (214 ft) east of bench mark 6273 E 1977, 4.39 m
(14.4 ft) SE of a 0.70 m (2.3 ft) diameter trunk of a mango tree, 3 m (11 ft)
north of the Boca Del Rio Marina entrance, 0.88 m (2.9 ft) west of a chain link
fence, and 0.76 m (2.5 ft) west of a witness post. The bench mark set level with
the ground, being the top of a stainless steel rod driven 20.1 m (66 ft) to
refusal, and encased in a stamped NOS logo cap attached to a PVC pipe surrounded
by concrete.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 3 of 4
Station ID: 8726273 PUBLICATION DATE: 09/16/2003
Name: DESOTO POINT
FL
NOAA Chart: 11414 Latitude: 27° 31.4' N ( 27.52330)
USGS Quad: ANNA MARIA Longitude: 82° 39.0' W ( -82.65000)
T I D A L D A T U M S
Tidal datums at DESOTO POINT based on:
LENGTH OF SERIES: 5 MONTHS
TIME PERIOD: June 1990 - October 1990
TIDAL EPOCH: 1983-2001
CONTROL TIDE STATION: 8726520 ST. PETERSBURG, TAMPA BAY
Elevations of tidal datums referred to Mean Lower Low Water (MLLW), in METERS:
MEAN HIGHER HIGH WATER MHHW = 0.660
MEAN HIGH WATER MHW = 0.575
North American Vertical Datum NAVD88 = 0.493
MEAN SEA LEVEL MSL = 0.349
MEAN TIDE LEVEL MTL = 0.342
MEAN LOW WATER MLW = 0.109
MEAN LOWER LOW WATER MLLW = 0.000
North American Vertical Datum (NAVD88)
Bench Mark Elevation Information In METERS above:
Stamping or Designation MLLW MHW
6273 B 1977 1.252 0.677
6273 E 1977 2.177 1.602
6273 G 1990 1.740 1.165
6273 H 1990 5.356 4.781
6273 J 1990 3.620 3.045
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 4 of 4
Station ID: 8726273 PUBLICATION DATE: 09/16/2003
Name: DESOTO POINT
FL
NOAA Chart: 11414 Latitude: 27° 31.4' N ( 27.52330)
USGS Quad: ANNA MARIA Longitude: 82° 39.0' W ( -82.65000)
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.