U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Datums Page Page 1 of 6
Station ID: 8720219 PUBLICATION DATE: 10/06/2020
Name: DAMES POINT, ST. JOHNS RIVER
FL
NOAA Chart: 11488 Latitude: 30° 23.2' N ( 30.38670)
USGS Quad: EASTPORT Longitude: 81° 33.5' W ( -81.55830)
To reach the tide gauge from the overpass of Interstate 295 (State Highway 9A)
and State Highway 105 (Heckscher Drive), travel east on Heckscher Drive (Florida
State Highway 105) for approximately 6.1 km (3.8 mi) to the public boat ramp at
Palms Fish Camp, 6359 Heckscher Dr. From the boat ramp, proceed west up the St.
Johns River approximately 6 km (3.8 mi) to the southern tip of Dames Point and
the Dames Point Bridge. The tide gauge is located offshore of the southern tip
of Dames Point and west of the Dames Point Bridge. The tide gauge is mounted on
an offshore four pile structure located about 135 m (443 ft) west of the Dames
Point Park fishing pier and about 15 m (50 ft) offshore.
T I D A L B E N C H M A R K S
PRIMARY BENCH MARK STAMPING: 0219 A 1995
DESIGNATION: 872 0219 A TIDAL
MONUMENTATION: Flange-encased Rod VM#: 13517
AGENCY: National Ocean Service (NOS) IDB PID#: DI0931
SETTING CLASSIFICATION: Stainless steel rod OPUS PID:
LATITUDE: 30° 23.2' N ( 30.38722) LONGITUDE: 81° 33.5' W ( -81.55889)
The primary bench mark is a flange-encased stainless steel rod, located 79.9 m
(262.0 ft) west of the Dames Point Park, 43.3 m (142.0 ft) WSW of the SW corner
of the park restroom, 30.6 m (100.4 ft) west of the east end of the guardrail,
22.6 m (74.0 ft) east of the west end of the guardrail, and 0.3 m (1.0 ft) west
of the guardrail. The datum point is recessed 0.2 m (0.6 ft) below the level of
the NOS logo cap, being the top of a stainless steel rod, driven to refusal at a
depth of 16.2 m (53.2 ft), and encased in a 5-inch NOS logo cap.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 2 of 6
Station ID: 8720219 PUBLICATION DATE: 10/06/2020
Name: DAMES POINT, ST. JOHNS RIVER
FL
NOAA Chart: 11488 Latitude: 30° 23.2' N ( 30.38670)
USGS Quad: EASTPORT Longitude: 81° 33.5' W ( -81.55830)
T I D A L B E N C H M A R K S
BENCH MARK STAMPING: 0219 B 1995
DESIGNATION: 872 0219 B TIDAL
MONUMENTATION: Survey disk VM#: 13518
AGENCY: National Ocean Service (NOS) IDB PID#: DI0930
SETTING CLASSIFICATION: Concrete monument OPUS PID:
LATITUDE: 30° 23.3' N ( 30.38861) LONGITUDE: 81° 33.5' W ( -81.55883)
The bench mark is a disk set on top of a round concrete monument flush with the
ground and about level with Dames Point Park Road, 9.3 m (30.5 ft) west of the
approximate centerline of Dames Point Road, 6.1 m (20.0 ft) east of a 1.8 m (6.0
ft) tall chainlink fence, 2.4 m (7.8 ft) south of the entrance fence, 0.4 m (1.3
ft) west of a 1.8 m x 3.0 m (6.0 ft x 10.0 ft) bridge column, and 0.4 m (1.2 ft)
west of a carsonite witness post.
BENCH MARK STAMPING: 0219 L 2002
DESIGNATION: 872 0219 L TIDAL
MONUMENTATION: Survey disk VM#: 17779
AGENCY: FL Department of Environmental
Protection (FLDEP) IDB PID#: DI0942
SETTING CLASSIFICATION: Concrete monument OPUS PID:
LATITUDE: 30° 23.4' N ( 30.39000) LONGITUDE: 81° 33.6' W ( -81.55922)
The bench mark is a disk set in the top of a round concrete monument recessed
0.1 m (0.2 ft) below the level of the ground and about level with dames point
park road, 6.2 m (20.5 ft) east of the approximate centerline of the park road,
0.5 m (1.6 ft) north of the northwest corner of the bridge column, and 0.4 m
(1.2 ft) north of a carsonite witness post.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 3 of 6
Station ID: 8720219 PUBLICATION DATE: 10/06/2020
Name: DAMES POINT, ST. JOHNS RIVER
FL
NOAA Chart: 11488 Latitude: 30° 23.2' N ( 30.38670)
USGS Quad: EASTPORT Longitude: 81° 33.5' W ( -81.55830)
T I D A L B E N C H M A R K S
BENCH MARK STAMPING: 0219 M 2002
DESIGNATION: 872 0219 M TIDAL
MONUMENTATION: Survey disk VM#: 19145
AGENCY: FLDEP IDB PID#: DI0932
SETTING CLASSIFICATION: OPUS PID:
LATITUDE: 30° 23.5' N ( 30.39111) LONGITUDE: 81° 33.6' W ( -81.55967)
The bench mark is located 6.25 M (20.5 ft) east of the approximate centerline of
the paved road, 0.49 M (1.6 ft) north of the northwest corner of the bridge
column and 0.37 M (1.2 ft) north of a carsonite witness post.
BENCH MARK STAMPING: 0219 N 2002
DESIGNATION: 872 0219 N TIDAL
MONUMENTATION: Survey disk VM#: 19146
AGENCY: FL Department of Environmental
Protection (FLDEP) IDB PID#: DI0945
SETTING CLASSIFICATION: Bridge column OPUS PID:
LATITUDE: 30° 23.5' N ( 30.39233) LONGITUDE: 81° 33.6' W ( -81.56044)
The bench mark is a disk set vertically in the west face of the west bridge
column, 1.3 m (4.2 ft) above the level of the ground and above the level of the
road, 15.9 m (52.2 ft) south of the centerline of Dames Point Road, and 9.0 m
(29.5 ft) west of the approximate centerline of the paved road leading to Dames
Point park.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 4 of 6
Station ID: 8720219 PUBLICATION DATE: 10/06/2020
Name: DAMES POINT, ST. JOHNS RIVER
FL
NOAA Chart: 11488 Latitude: 30° 23.2' N ( 30.38670)
USGS Quad: EASTPORT Longitude: 81° 33.5' W ( -81.55830)
T I D A L B E N C H M A R K S
BENCH MARK STAMPING: 0219 P 2013
DESIGNATION: 872 0219 P
MONUMENTATION: Survey disk VM#: 20942
AGENCY: National Ocean Service IDB PID:
SETTING CLASSIFICATION: Retaining wall OPUS PID#: BBDJ07
LATITUDE: 30° 23.3' N ( 30.38769) LONGITUDE: 81° 33.6' W ( -81.55933)
The bench mark is a disk set in the top of a concrete retaining wall along the
southwestern edge of the Martin Marietta Aggregates Facility Pond, located 51.3
m (168.3 ft) NW of the center of the NW piling of the four pile offshore
structure for the dames point tidal station, 24.8 m (81.3 ft) W of the eastern
edge of the easternmost retaining wall, and 7.5 m (24.1 ft) NE of the interface
between rip rap and the western edge of the retaining wall foundation.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 5 of 6
Station ID: 8720219 PUBLICATION DATE: 10/06/2020
Name: DAMES POINT, ST. JOHNS RIVER
FL
NOAA Chart: 11488 Latitude: 30° 23.2' N ( 30.38670)
USGS Quad: EASTPORT Longitude: 81° 33.5' W ( -81.55830)
T I D A L D A T U M S
Tidal datums at DAMES POINT, ST. JOHNS RIVER based on:
LENGTH OF SERIES: 3 YEARS
TIME PERIOD: 01/2014-12/2014, 01/2016-12/2017
TIDAL EPOCH: 1983-2001
CONTROL TIDE STATION: 8720218 BAR PILOTS DOCK, ST JOHNS RIVER
Elevations of tidal datums referred to Mean Lower Low Water (MLLW), in METERS:
HIGHEST OBSERVED WATER LEVEL (09/11/2017) = 2.233
MEAN HIGHER HIGH WATER MHHW = 1.114
MEAN HIGH WATER MHW = 1.065
North American Vertical Datum NAVD88 = 0.683
MEAN SEA LEVEL MSL = 0.567
MEAN TIDE LEVEL MTL = 0.549
MEAN LOW WATER MLW = 0.033
MEAN LOWER LOW WATER MLLW = 0.000
LOWEST OBSERVED WATER LEVEL (01/08/2002) = -0.480
North American Vertical Datum (NAVD88)
Bench Mark Elevation Information In METERS above:
Stamping or Designation MLLW MHW
0219 A 1995 2.661 1.596
0219 B 1995 3.547 2.482
0219 L 2002 3.934 2.869
0219 M 2002 4.579 3.514
0219 N 2002 5.814 4.749
0219 P 2013 2.632 1.567
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 6 of 6
Station ID: 8720219 PUBLICATION DATE: 10/06/2020
Name: DAMES POINT, ST. JOHNS RIVER
FL
NOAA Chart: 11488 Latitude: 30° 23.2' N ( 30.38670)
USGS Quad: EASTPORT Longitude: 81° 33.5' W ( -81.55830)
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.