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Datums Page Page 1 of 5
Station ID: 8723851 PUBLICATION DATE: 05/15/2003
Name: LOWER MATECUMBE KEY HAWK CHANNEL
FL
NOAA Chart: 11449 Latitude: 24° 52.1' N ( 24.86830)
USGS Quad: LOWER MATECUMBE KEY Longitude: 80° 42.2' W ( -80.70330)
To reach the tidal bench marks from the post office in Islamorada, proceed 10.6
km (6.6 mi) SW on U.S. Highway 1, then continue 0.24 km (0.15 mi) SE along a
private drive to the private residence of Robert Jones on the west shore of a
canal. The bench marks are located along the private drive. The tide gage and
staff were located on the concrete bulkhead behind the Jones residence.
T I D A L B E N C H M A R K S
PRIMARY BENCH MARK STAMPING: E 329 1970
DESIGNATION: 872 3851 E 329
MONUMENTATION: Tidal Station disk VM#: 6240
AGENCY: US Coast and Geodetic Survey
(USC&GS) IDB PID#: AA0408
SETTING CLASSIFICATION: Boulder OPUS PID:
LATITUDE: 24° 52.2' N ( 24.87000) LONGITUDE: 80° 42.2' W ( -80.70330)
The primary bench mark is a disk set atop a small embedded boulder, 26.97 m
(88.5 ft) SW of the SW corner of the Jones residence, 22.65 m (74.3 ft) south of
bench mark C 329 1970, 16 m (51 ft) SSE of bench mark B 329 1970, 2 m (6 ft) SE
of the centerline of the private drive, and 0.06 m (0.2 ft) above ground level.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 2 of 5
Station ID: 8723851 PUBLICATION DATE: 05/15/2003
Name: LOWER MATECUMBE KEY HAWK CHANNEL
FL
NOAA Chart: 11449 Latitude: 24° 52.1' N ( 24.86830)
USGS Quad: LOWER MATECUMBE KEY Longitude: 80° 42.2' W ( -80.70330)
T I D A L B E N C H M A R K S
BENCH MARK STAMPING: B 329 1970
DESIGNATION: 872 3851 B 329
MONUMENTATION: Tidal Station disk VM#: 6237
AGENCY: US Coast and Geodetic Survey
(USC&GS) IDB PID#: AA0407
SETTING CLASSIFICATION: Concrete monument OPUS PID:
LATITUDE: 24° 52.2' N ( 24.87000) LONGITUDE: 80° 42.2' W ( -80.70330)
The bench mark is a disk set flush in a concrete monument, 11.43 m (37.5 ft)
south of the SW corner of the Jones residence, 5.94 m (19.5 ft) SE of a utility
pole, 3.35 m (11.0 ft) NE of the centerline of the drive, 0.46 m (1.5 ft) NE of
a utility pole guy wire, and at ground level.
BENCH MARK STAMPING: C 329 1970
DESIGNATION: 872 3851 C 329
MONUMENTATION: Tidal Station disk VM#: 6238
AGENCY: US Coast and Geodetic Survey
(USC&GS) IDB PID#: AA0409
SETTING CLASSIFICATION: Concrete monument OPUS PID:
LATITUDE: 24° 52.2' N ( 24.87000) LONGITUDE: 80° 42.2' W ( -80.70330)
The bench mark is a disk set flush in a concrete monument, 20.18 m (66.2 ft)
east of the SW corner of the Jones residence, 19.29 m (63.3 ft) east of bench
mark B 329 1970, 18 m (60 ft) NE of the centerline of the drive, 17.01 m (55.8
ft) SE of the SE corner of the Jones residence, 2.29 m (7.5 ft) south of a 0.24
m (0.8 ft) diameter pine tree, and at ground level.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 3 of 5
Station ID: 8723851 PUBLICATION DATE: 05/15/2003
Name: LOWER MATECUMBE KEY HAWK CHANNEL
FL
NOAA Chart: 11449 Latitude: 24° 52.1' N ( 24.86830)
USGS Quad: LOWER MATECUMBE KEY Longitude: 80° 42.2' W ( -80.70330)
T I D A L B E N C H M A R K S
BENCH MARK STAMPING: D 329 1970
DESIGNATION: 872 3851 D 329
MONUMENTATION: Tidal Station disk VM#: 6239
AGENCY: US Coast and Geodetic Survey
(USC&GS) IDB PID#: AA0412
SETTING CLASSIFICATION: Concrete step OPUS PID:
LATITUDE: 24° 52.2' N ( 24.87000) LONGITUDE: 80° 42.2' W ( -80.70330)
The bench mark is a disk set in the bottom concrete step of a landing platform
to the SW end of the Jones boat dock, 2.74 m (9.0 ft) NW of the NE corner of the
Jones residence, 0.55 m (1.8 ft) NE of the NE end of the step, and 1 m (2 ft)
below the base of the residence.
BENCH MARK STAMPING: F 329 1970
DESIGNATION: 872 3851 F 329
MONUMENTATION: Tidal Station disk VM#: 6241
AGENCY: US Coast and Geodetic Survey
(USC&GS) IDB PID#: AA0411
SETTING CLASSIFICATION: Concrete monument OPUS PID:
LATITUDE: 24° 52.3' N ( 24.87170) LONGITUDE: 80° 42.2' W ( -80.70330)
The bench mark is a disk set flush in a concrete monument, 0.08 km (0.05 mi) NW
of the Jones residence, 6 m (19 ft) NE of and across the private drive from a
lone 0.24 m (0.8 ft) diameter pine tree, 3 m (10 ft) NW of a utility pole, 1 m
(2 ft) SE of a metal witness post, 0.43 m (1.4 ft) south a utility pole guy
wire, and at ground level.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 4 of 5
Station ID: 8723851 PUBLICATION DATE: 05/15/2003
Name: LOWER MATECUMBE KEY HAWK CHANNEL
FL
NOAA Chart: 11449 Latitude: 24° 52.1' N ( 24.86830)
USGS Quad: LOWER MATECUMBE KEY Longitude: 80° 42.2' W ( -80.70330)
T I D A L D A T U M S
Tidal datums at LOWER MATECUMBE KEY HAWK CHANNEL based on:
LENGTH OF SERIES: 12 MONTHS
TIME PERIOD: May 1971 - April 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) = 0.961
MEAN HIGHER HIGH WATER MHHW = 0.683
MEAN HIGH WATER MHW = 0.639
North American Vertical Datum NAVD88 = 0.635
MEAN SEA LEVEL MSL = 0.359
MEAN TIDE LEVEL MTL = 0.352
MEAN LOW WATER MLW = 0.065
MEAN LOWER LOW WATER MLLW = 0.000
LOWEST OBSERVED WATER LEVEL (02/10/1971) = -0.359
North American Vertical Datum (NAVD88)
Bench Mark Elevation Information In METERS above:
Stamping or Designation MLLW MHW
E 329 1970 1.715 1.076
B 329 1970 1.780 1.141
C 329 1970 1.622 0.983
D 329 1970 1.188 0.549
F 329 1970 1.771 1.132
Foot Notes:
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 5 of 5
Station ID: 8723851 PUBLICATION DATE: 05/15/2003
Name: LOWER MATECUMBE KEY HAWK CHANNEL
FL
NOAA Chart: 11449 Latitude: 24° 52.1' N ( 24.86830)
USGS Quad: LOWER MATECUMBE KEY Longitude: 80° 42.2' W ( -80.70330)
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.
Station Location
Published bench mark
Unpublished bench mark
