U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Datums Page Page 1 of 4
PUBLICATION DATE: 07/13/1989
Station ID: 8726706 SUPERCEDED DATE: 04/21/2003
Name: CLEARWATER, CLEARWATER HARBOR
FLORIDA
NOAA Chart: 11410 Latitude: 27° 57.3' N
USGS Quad: CLEARWATER Longitude: 82° 48.4' W
To reach the tidal bench marks from the intersection of alternate U.S. Route 19
(Fort Harrison Avenue) and Magnolia Road, travel west on Magnolia Road to the
pier. The bench marks are along Magnolia Road and U.S. Highway 19, and the tide
gage and staff were located on the pier at the end of Magnolia Road.
T I D A L B E N C H M A R K S
PRIMARY BENCH MARK STAMPING: TBM NO 1 1949
MONUMENTATION: Survey Disk VM#: 6786
AGENCY: PID#: AG0992
SETTING CLASSIFICATION: Concrete Sea Wall
The bench mark is set on a concrete sea wall at the foot of the west end of
Magnolia Road, 22.9 feet (7.0 m) south of the south hand rail of the walkway to
the Harbor Oaks Pier, and 1.6 feet (0.5 m) north of the concrete wall.
BENCH MARK STAMPING: TBM NO 2 1949
MONUMENTATION: Survey Disk VM#: 6787
AGENCY: PID#: AG0998
SETTING CLASSIFICATION: Curbing
The bench mark is at the west end of Magnolia Road on the north curbing, 21.5
feet (6.6 m) east of the edge of the sea wall, and 11.7 feet (3.6 m) west of the
centerline of the driveway.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 2 of 4
PUBLICATION DATE: 07/13/1989
Station ID: 8726706 SUPERCEDED DATE: 04/21/2003
Name: CLEARWATER, CLEARWATER HARBOR
FLORIDA
NOAA Chart: 11410 Latitude: 27° 57.3' N
USGS Quad: CLEARWATER Longitude: 82° 48.4' W
T I D A L B E N C H M A R K S
BENCH MARK STAMPING: NO 5 1975
MONUMENTATION: Survey Disk VM#: 6788
AGENCY: PID#: AG1003
SETTING CLASSIFICATION: Curbing
The bench mark is in the curb at the SE corner of the intersection of Magnolia
Road and Druid Road, 33 feet (10.1 m) east of the centerline of Druid Road, and
10 feet (3.0 m) south of the centerline of Magnolia Road.
BENCH MARK STAMPING: HARRIS 0
MONUMENTATION: Survey Disk VM#: 6789
AGENCY: PID#: AG0586
SETTING CLASSIFICATION: Concrete Post
The bench mark is 1 block south of Bench Mark No 5 1975, 34 feet (10.4 m) south
of the centerline of Lotus Path, 13.9 feet (4.2 m) west of the centerline of
Druid Road, and 2.6 feet (0.8 m) WSW of a witness post.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 3 of 4
PUBLICATION DATE: 07/13/1989
Station ID: 8726706 SUPERCEDED DATE: 04/21/2003
Name: CLEARWATER, CLEARWATER HARBOR
FLORIDA
NOAA Chart: 11410 Latitude: 27° 57.3' N
USGS Quad: CLEARWATER Longitude: 82° 48.4' W
T I D A L D A T U M S
Tidal datums at CLEARWATER, CLEARWATER HARBOR based on:
LENGTH OF SERIES: 8 MONTHS
TIME PERIOD: NOVEMBER 1975-SEPTEMBER 1976
TIDAL EPOCH: 1960-1978
CONTROL TIDE STATION: 8726724 CLEARWATER BEACH
Elevations of tidal datums referred to Mean Lower Low Water (MLLW), in FEET:
HIGHEST OBSERVED WATER LEVEL (12/20/1976) = 4.04
MEAN HIGHER HIGH WATER MHHW = 2.74
MEAN HIGH WATER MHW = 2.40
MEAN TIDE LEVEL MTL = 1.46
* NATIONAL GEODETIC VERTICAL DATUM NGVD29 = 1.04
MEAN LOW WATER MLW = 0.51
MEAN LOWER LOW WATER MLLW = 0.00
LOWEST OBSERVED WATER LEVEL (01/05/1976) = -1.03
* NGVD reference based on elevations published in Quad HGZ L247, 1982, and
NOS leveling of 1982.
North American Vertical Datum (NAVD88)
Bench Mark Elevation Information In FEET above:
Stamping or Designation MLLW MHW
TBM NO 1 1949 4.63 2.23
TBM NO 2 1949 5.10 2.70
NO 5 1975 28.97 26.57
HARRIS 0 25.65 23.25
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 4 of 4
PUBLICATION DATE: 07/13/1989
Station ID: 8726706 SUPERCEDED DATE: 04/21/2003
Name: CLEARWATER, CLEARWATER HARBOR
FLORIDA
NOAA Chart: 11410 Latitude: 27° 57.3' N
USGS Quad: CLEARWATER Longitude: 82° 48.4' 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.