U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Datums Page Page 1 of 5
PUBLICATION DATE: 10/19/1984
Station ID: 8727151 SUPERCEDED DATE: 04/21/2003
Name: BAYPORT, GULF OF MEXICO
FLORIDA
NOAA Chart: 11409 Latitude: 28° 32.0' N
USGS Quad: BAYPORT Longitude: 82° 39.0' W
To reach the tidal bench marks from the intersection of U.S. Highway 19 and
County Road 50 at Weeki Wachee Springs, Florida, proceed west on County Road 50
5.7 miles (9.2 km) to the entrance to the County Park at Bayport, continue
through the Park 0.95 miles (1.5 km) to the end of the road. The bench marks
are located in area around park and the tide gage and staff were located on the
fishing pier.
T I D A L B E N C H M A R K S
PRIMARY BENCH MARK STAMPING: 7151 D 1978
MONUMENTATION: Survey Disk VM#: 7743
AGENCY: PID#: AL7725
SETTING CLASSIFICATION: Stainless Steel Rod
The bench mark is 240.5 feet (73.3 m) north of Bench Mark TT50 ERS, 1952, 48.7
feet (14.8 m) north of the NW corner of a picnic table platform, 38.5 feet (11.7
m) west of the road, 6.8 feet (2.1 m) south of a concrete retaining wall, 6.5
feet (2.0 m) east of a concrete retaining wall, and 1.0 feet (0.3 m) east of a
witness post. The bench mark is crimped to a stainless steel rod driven 11 feet
(3 m) to refusal and encased in PVC pipe and a concrete kickblock.
BENCH MARK STAMPING: 7151 A 1978
MONUMENTATION: Survey Disk VM#: 7740
AGENCY: PID#: AL7724
SETTING CLASSIFICATION: Concrete Post
The bench mark is 100.0 feet (30 m) north of a concrete bulkhead for a canal,
55.4 feet (16.9 m) west of the SW corner of a covered picnic shelter, 15.0 feet
(4.6 m) east of the centerline of the paved entrance road, 1.5 feet (0.4 m)
north of a witness post, and 0.1 foot (0.03 m) below ground level, set in a
concrete post.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 2 of 5
PUBLICATION DATE: 10/19/1984
Station ID: 8727151 SUPERCEDED DATE: 04/21/2003
Name: BAYPORT, GULF OF MEXICO
FLORIDA
NOAA Chart: 11409 Latitude: 28° 32.0' N
USGS Quad: BAYPORT Longitude: 82° 39.0' W
T I D A L B E N C H M A R K S
BENCH MARK STAMPING: 7151 B 1978
MONUMENTATION: Survey Disk VM#: 7741
AGENCY: PID#: AL7722
SETTING CLASSIFICATION: Concrete Post
The bench mark is within the perimeter of the County Park in a triangular grass,
median strip on the south side of the park entrance road, 323 feet (98 m) NE of
Bench Mark 7151 A 1978, 74.4 feet (22.7 m) NNE of the NW corner of the restroom
building, 16.3 feet (5.0 m) south of the centerline of the entrance road, 13.8
feet (4.2 m) west of a palm tree, 9.8 feet (3.0 m) east of a pine tree, 1.5 feet
(0.5 m) south of a witness post, and 0.1 foot (0.3 m) below ground level, set in
a concrete post.
BENCH MARK STAMPING: 7151 C 1978
MONUMENTATION: Survey Disk VM#: 7742
AGENCY: PID#: AL7723
SETTING CLASSIFICATION: Concrete Post
The bench mark is 180.5 feet (55 m) SSW of Bench Mark 7151 C 1978, 134.6 feet
east of the SE corner of the westernmost of two boat launching ramps, 87.1 feet
(26.5 m) south of the SE corner of the restroom buildings, 8.8 feet (2.7 m)
north of a concrete bulkhead for the canal, 4.1 feet (1.2 m) west of a power
pole, and 0.1 feet (0.03 m) below ground level, set in a concrete post.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 3 of 5
PUBLICATION DATE: 10/19/1984
Station ID: 8727151 SUPERCEDED DATE: 04/21/2003
Name: BAYPORT, GULF OF MEXICO
FLORIDA
NOAA Chart: 11409 Latitude: 28° 32.0' N
USGS Quad: BAYPORT Longitude: 82° 39.0' W
T I D A L B E N C H M A R K S
BENCH MARK STAMPING: 50 ERS TT 1952 3.9 FEET
MONUMENTATION: Survey Disk VM#: 7744
AGENCY: PID#: AL7726
SETTING CLASSIFICATION: Concrete Seawall
The bench mark is set in the seawall on the west end of the paved parking area,
92.0 feet (28 m) north of the tide gage, 25.4 feet (7.7 m) south of the paved
parking area, 20.0 feet (6.1 m) SE of the SE corner of a concrete pad supporting
a picnic table, 19.0 feet (5.8 m) west of the NW end of the fishing pier and 1.4
feet (0.4 m) north of the south edge of the concrete bulkhead.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 4 of 5
PUBLICATION DATE: 10/19/1984
Station ID: 8727151 SUPERCEDED DATE: 04/21/2003
Name: BAYPORT, GULF OF MEXICO
FLORIDA
NOAA Chart: 11409 Latitude: 28° 32.0' N
USGS Quad: BAYPORT Longitude: 82° 39.0' W
T I D A L D A T U M S
Tidal datums at BAYPORT, GULF OF MEXICO based on:
LENGTH OF SERIES: 5 MONTHS
TIME PERIOD: JULY 1978 - MARCH 1979
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 (01/21/1979) = 5.73
MEAN HIGHER HIGH WATER MHHW = 3.28
MEAN HIGH WATER MHW = 2.85
MEAN TIDE LEVEL MTL = 1.67
MEAN LOW WATER MLW = 0.49
MEAN LOWER LOW WATER MLLW = 0.00
LOWEST OBSERVED WATER LEVEL (02/10/1979) = -0.96
North American Vertical Datum (NAVD88)
Bench Mark Elevation Information In FEET above:
Stamping or Designation MLLW MHW
7151 D 1978 5.40 2.55
7151 A 1978 7.15 4.30
7151 B 1978 7.01 4.16
7151 C 1978 5.52 2.67
50 ERS TT 1952 3.9 FEET 5.10 2.25
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 5 of 5
PUBLICATION DATE: 10/19/1984
Station ID: 8727151 SUPERCEDED DATE: 04/21/2003
Name: BAYPORT, GULF OF MEXICO
FLORIDA
NOAA Chart: 11409 Latitude: 28° 32.0' N
USGS Quad: BAYPORT Longitude: 82° 39.0' 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.