U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Datums Page Page 1 of 7
Station ID: 8723519 PUBLICATION DATE: 02/05/2004
Name: OCEAN REEF HARBOR, KEY LARGO
FL
NOAA Chart: 11462 Latitude: 25° 18.5' N ( 25.30830)
USGS Quad: CARD SOUND Longitude: 80° 16.6' W ( -80.27670)
To reach the tidal bench marks from Ocean Reef, proceed to the Dock Masters
building. The bench marks are in the vicinity of the building and bulkhead.
The tide gage and staff were located near the west end of an east-west bulkhead.
T I D A L B E N C H M A R K S
PRIMARY BENCH MARK STAMPING: K 327 1970
DESIGNATION: K 327
MONUMENTATION: Bench Mark disk VM#: 5903
AGENCY: National Geodetic Survey (NGS) IDB PID#: AC1059
SETTING CLASSIFICATION: Concrete bulkhead OPUS PID:
LATITUDE: 25° 18.6' N ( 25.31000) LONGITUDE: 80° 16.6' W ( -80.27670)
The primary bench mark is a disk set flush in the top of a concrete bulkhead at
a right angle turn, 46.63 m (153.0 ft) east of bench mark H 327 1970, 38.89 m
(127.6 ft) west of bench mark L 327 1970, and 25.76 m (84.5 ft) SE of the SE
side of the Dock Masters building.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 2 of 7
Station ID: 8723519 PUBLICATION DATE: 02/05/2004
Name: OCEAN REEF HARBOR, KEY LARGO
FL
NOAA Chart: 11462 Latitude: 25° 18.5' N ( 25.30830)
USGS Quad: CARD SOUND Longitude: 80° 16.6' W ( -80.27670)
T I D A L B E N C H M A R K S
BENCH MARK STAMPING: L 327 1970
DESIGNATION: L 327
MONUMENTATION: Bench Mark disk VM#: 5904
AGENCY: National Geodetic Survey (NGS) IDB PID#: AC1062
SETTING CLASSIFICATION: Concrete bulkhead OPUS PID:
LATITUDE: 25° 18.7' N ( 25.31170) LONGITUDE: 80° 16.6' W ( -80.27670)
The bench mark is a disk set flush in the top of a concrete bulkhead, 65 m (212
ft) east of the east side of the Dock Masters building, 38.89 m (127.6 ft) east
of bench mark K 327 1970, 4 m (13 ft) west of the west face of the concrete base
for an electrical outlet, and 0.46 m (1.5 ft) north of the north face of the
bulkhead.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 3 of 7
Station ID: 8723519 PUBLICATION DATE: 02/05/2004
Name: OCEAN REEF HARBOR, KEY LARGO
FL
NOAA Chart: 11462 Latitude: 25° 18.5' N ( 25.30830)
USGS Quad: CARD SOUND Longitude: 80° 16.6' W ( -80.27670)
T I D A L B E N C H M A R K S
BENCH MARK STAMPING: G 327 1970
DESIGNATION: G 327
MONUMENTATION: Bench Mark disk VM#: 7484
AGENCY: National Geodetic Survey (NGS) IDB PID#: AC1063
SETTING CLASSIFICATION: Concrete bulkhead OPUS PID:
LATITUDE: 25° 18.7' N ( 25.31170) LONGITUDE: 80° 16.6' W ( -80.27670)
The bench mark is a disk set flush in the top of a concrete bulkhead, 38.04 m
(124.8 ft) north of bench mark H 327 1970, 17.77 m (58.3 ft) NW of the NW corner
of the Dock Masters building, 1.13 m (3.7 ft) north of the centerline of a
concrete dock, and 0.43 m (1.4 ft) SE of the NE corner of the dock.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 4 of 7
Station ID: 8723519 PUBLICATION DATE: 02/05/2004
Name: OCEAN REEF HARBOR, KEY LARGO
FL
NOAA Chart: 11462 Latitude: 25° 18.5' N ( 25.30830)
USGS Quad: CARD SOUND Longitude: 80° 16.6' W ( -80.27670)
T I D A L B E N C H M A R K S
BENCH MARK STAMPING: H 327 1970
DESIGNATION: H 327
MONUMENTATION: Bench Mark disk VM#: 7485
AGENCY: National Geodetic Survey (NGS) IDB PID#: AC1060
SETTING CLASSIFICATION: Concrete bulkhead OPUS PID:
LATITUDE: 25° 18.6' N ( 25.31000) LONGITUDE: 80° 16.6' W ( -80.27670)
The bench mark is a disk set flush in the top of a concrete bulkhead, 46.63 m
(153.0 ft) west of bench mark K 327 1970, 38.04 m (124.8 ft) south of bench mark
G 327 1970, 10.76 m (35.3 ft) SW of the SW corner of the Dock Masters building,
and 0.40 m (1.3 ft) NE of the SW corner of the bulkhead.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 5 of 7
Station ID: 8723519 PUBLICATION DATE: 02/05/2004
Name: OCEAN REEF HARBOR, KEY LARGO
FL
NOAA Chart: 11462 Latitude: 25° 18.5' N ( 25.30830)
USGS Quad: CARD SOUND Longitude: 80° 16.6' W ( -80.27670)
T I D A L B E N C H M A R K S
BENCH MARK STAMPING: J 327 1970
DESIGNATION: J 327
MONUMENTATION: Bench Mark disk VM#: 7486
AGENCY: National Geodetic Survey (NGS) IDB PID#: AC1061
SETTING CLASSIFICATION: Concrete wall OPUS PID:
LATITUDE: 25° 18.7' N ( 25.31170) LONGITUDE: 80° 16.6' W ( -80.27670)
The bench mark is a disk set in the top of a 0.09 m (0.3 ft) wide concrete
planter box wall along the east side of the Dock Masters building, 36 m (118 ft)
NW of bench mark K 327 1970, 3.81 m (12.5 ft) south of the NE corner of the Dock
Masters building, 0.09 m (0.3 ft) east of the east face of the Dock Masters
building, and 0.61 m (2.0 ft) above the ground.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 6 of 7
Station ID: 8723519 PUBLICATION DATE: 02/05/2004
Name: OCEAN REEF HARBOR, KEY LARGO
FL
NOAA Chart: 11462 Latitude: 25° 18.5' N ( 25.30830)
USGS Quad: CARD SOUND Longitude: 80° 16.6' W ( -80.27670)
T I D A L D A T U M S
Tidal datums at OCEAN REEF HARBOR, KEY LARGO based on:
LENGTH OF SERIES: 1 YEAR
TIME PERIOD: February 1971 - January 1972
TIDAL EPOCH: 1983-2001
CONTROL TIDE STATION: 8723170 MIAMI BEACH (CITY PIER)
Elevations of tidal datums referred to Mean Lower Low Water (MLLW), in METERS:
HIGHEST OBSERVED WATER LEVEL (11/02/1971) = 1.069
MEAN HIGHER HIGH WATER MHHW = 0.772
MEAN HIGH WATER MHW = 0.763
North American Vertical Datum NAVD88 = 0.688
MEAN SEA LEVEL MSL = 0.422
MEAN TIDE LEVEL MTL = 0.413
MEAN LOW WATER MLW = 0.064
MEAN LOWER LOW WATER MLLW = 0.000
LOWEST OBSERVED WATER LEVEL (04/15/1972) = -0.406
North American Vertical Datum (NAVD88)
Bench Mark Elevation Information In METERS above:
Stamping or Designation MLLW MHW
K 327 1970 1.322 0.559
L 327 1970 1.341 0.578
G 327 1970 1.396 0.633
H 327 1970 1.399 0.636
J 327 1970 2.312 1.549
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 7 of 7
Station ID: 8723519 PUBLICATION DATE: 02/05/2004
Name: OCEAN REEF HARBOR, KEY LARGO
FL
NOAA Chart: 11462 Latitude: 25° 18.5' N ( 25.30830)
USGS Quad: CARD SOUND Longitude: 80° 16.6' W ( -80.27670)
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.