U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Datums Page Page 1 of 5
Station ID: 8728151 PUBLICATION DATE: 05/12/2004
Name: ST. MARKS CITY
FL
NOAA Chart: 11405 Latitude: 30° 9.3' N ( 30.15500)
USGS Quad: ST. MARKS Longitude: 84° 12.2' W ( -84.20330)
To reach the tidal bench marks from the intersection of U.S. Highway 98 and
State Highway 363, proceed south on State Highway 363 to the Sam O. Purdom Power
Plant in St. Marks, then continue south on State Highway 363 for 1.05 km (0.65
mi) to the end of the highway, then turn left and proceed east on Riverside
Drive for 0.2 km (0.1 mi) to Shields Marina, on the north side of the St. Marks
River. The tide gage and staff were on a piling on the south side of the main
boat house at the marina. The bench marks are on the Tenneco Corporation
property, along State Highway 363, and along Riverside Drive.
T I D A L B E N C H M A R K S
PRIMARY BENCH MARK STAMPING: 8151 B 1977
DESIGNATION: 872 8151 B TIDAL FLDNR
MONUMENTATION: Tidal Station disk VM#: 8287
AGENCY: Florida Department of Natural Resources
(FLDNR) IDB PID#: BE2427
SETTING CLASSIFICATION: Copper-clad steel rod OPUS PID:
LATITUDE: 30° 9.3' N ( 30.15500) LONGITUDE: 84° 12.2' W ( -84.20330)
The primary bench mark is a disk located at the junction of State Highway 363
and Riverside Drive, 14.63 m (48.0 ft) WSW of the centerline of State Highway
363, 11.43 m (37.5 ft) NNW of the centerline of Riverside Drive, 5.67 m (18.6
ft) WSW of an iron grating over a drainage box, 1.77 m (5.8 ft) WSW of the Port
Leon Historical Marker sign, and 0.06 m (0.2 ft) ESE of a metal witness post.
The bench mark is set 0.03 m (0.1 ft) above ground level, crimped to the top of
a copper-clad steel rod driven 4.0 m (13 ft) to refusal, and encased in a PVC
pipe and concrete kickblock. NOTE: Mark not found in 1999 by US Power Squadron.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 2 of 5
Station ID: 8728151 PUBLICATION DATE: 05/12/2004
Name: ST. MARKS CITY
FL
NOAA Chart: 11405 Latitude: 30° 9.3' N ( 30.15500)
USGS Quad: ST. MARKS Longitude: 84° 12.2' W ( -84.20330)
T I D A L B E N C H M A R K S
BENCH MARK STAMPING: 8151 C 1977
DESIGNATION: 872 8151 C TIDAL FLDNR
MONUMENTATION: Tidal Station disk VM#: 8288
AGENCY: Florida Department of Natural Resources
(FLDNR) IDB PID#: BE2426
SETTING CLASSIFICATION: Copper-clad steel rod OPUS PID:
LATITUDE: 30° 9.4' N ( 30.15670) LONGITUDE: 84° 12.3' W ( -84.20500)
The bench mark is a disk located on the east side of State Highway 363, 29.26 m
(96.0 ft) NE of the NE corner of Bo Lynn Grocery and Meat Market, 9.30 m (30.5
ft) ENE of the centerline of State Highway 363, 3 m (10 ft) SE of the north end
of a concrete pipe in the drainage ditch, and 0.06 m (0.2 ft) WSW of a metal
witness post. The bench mark is set 0.06 m (0.2 ft) above ground level, crimped
to the top of a copper-clad steel rod driven 4.3 m (14 ft) to refusal, and
encased in a PVC pipe and concrete kickblock.
BENCH MARK STAMPING: NO 6 1958
DESIGNATION: 872 8151 TIDAL 6
MONUMENTATION: Tidal Station disk VM#: 8289
AGENCY: US Coast and Geodetic Survey
(USC&GS) IDB PID#: BE1143
SETTING CLASSIFICATION: Building foundation OPUS PID:
LATITUDE: 30° 9.4' N ( 30.15670) LONGITUDE: 84° 12.2' W ( -84.20330)
The bench mark is a disk set flush in the foundation for the Tenneco Petroleum
Corporation Office on the east side of State Highway 363, in the SE corner of
the building, 1.52 m (5.0 ft) SE of the SE corner of the building, 0.15 m (0.5
ft) north of the south face, 0.15 m (0.5 ft) west of the east face, and 0.61 m
(2.0 ft) above ground level.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 3 of 5
Station ID: 8728151 PUBLICATION DATE: 05/12/2004
Name: ST. MARKS CITY
FL
NOAA Chart: 11405 Latitude: 30° 9.3' N ( 30.15500)
USGS Quad: ST. MARKS Longitude: 84° 12.2' W ( -84.20330)
T I D A L B E N C H M A R K S
BENCH MARK STAMPING: NO 7 1958
DESIGNATION: 872 8151 TIDAL 7
MONUMENTATION: Tidal Station disk VM#: 8290
AGENCY: US Coast and Geodetic Survey
(USC&GS) IDB PID#: BE1144
SETTING CLASSIFICATION: Loading platform OPUS PID:
LATITUDE: 30° 9.4' N ( 30.15670) LONGITUDE: 84° 12.3' W ( -84.20500)
The bench mark is a disk set flush in the top of the loading platform of the
Tenneco Petroleum Corporation Warehouse and Canning Plant on the west side of
State Highway 363, 0.30 m (1.0 ft) north of the south face of the foundation,
0.15 m (0.5 ft) west of the east face, and 0.76 m (2.5 ft) above ground level.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 4 of 5
Station ID: 8728151 PUBLICATION DATE: 05/12/2004
Name: ST. MARKS CITY
FL
NOAA Chart: 11405 Latitude: 30° 9.3' N ( 30.15500)
USGS Quad: ST. MARKS Longitude: 84° 12.2' W ( -84.20330)
T I D A L D A T U M S
Tidal datums at ST. MARKS CITY based on:
LENGTH OF SERIES: 1 MONTH
TIME PERIOD: June 1977 - June 1977
TIDAL EPOCH: 1983-2001
CONTROL TIDE STATION: 8728229 SHELL POINT, WALKER CREEK
Elevations of tidal datums referred to Mean Lower Low Water (MLLW), in METERS:
MEAN HIGHER HIGH WATER MHHW = 1.120
MEAN HIGH WATER MHW = 1.042
MEAN TIDE LEVEL MTL = 0.621
MEAN SEA LEVEL MSL = 0.613
North American Vertical Datum NAVD88 = 0.563
MEAN LOW WATER MLW = 0.200
MEAN LOWER LOW WATER MLLW = 0.000
North American Vertical Datum (NAVD88)
Bench Mark Elevation Information In METERS above:
Stamping or Designation MLLW MHW
8151 B 1977 1.668 0.626
8151 C 1977 1.657 0.615
NO 6 1958 2.378 1.336
NO 7 1958 2.647 1.605
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 5 of 5
Station ID: 8728151 PUBLICATION DATE: 05/12/2004
Name: ST. MARKS CITY
FL
NOAA Chart: 11405 Latitude: 30° 9.3' N ( 30.15500)
USGS Quad: ST. MARKS Longitude: 84° 12.2' W ( -84.20330)
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.