U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Datums Page Page 1 of 4
PUBLICATION DATE: 05/31/1988
Station ID: 8723862 SUPERCEDED DATE: 04/21/2003
Name: MATECUMBE HARBOR, LOWER MATECUMBE KEY
FLORIDA
NOAA Chart: 11449 Latitude: 24° 51.1' N
USGS Quad: LOWER MATECUMBEKEY Longitude: 80° 44.4' W
To reach the tidal bench marks from the Post Office in Islamorada, proceed SW on
U.S. Highway 1 for 9.1 miles (14.6 km) to the Boy Scouts of America Seabase on
the SW end of Lower Matecumbe Key. The bench marks are located on the grounds
of the Boy Scouts Seabase. The tide gage and staff were located at the NW
corner of the main wooden pier.
T I D A L B E N C H M A R K S
PRIMARY BENCH MARK STAMPING: NO 1 1975
MONUMENTATION: Survey Disk VM#: 6242
AGENCY: PID#: AA0810
SETTING CLASSIFICATION: Concrete Sea Wall
The bench mark is set flush in the top of the concrete sea wall north of the NE
corner of the main wooden pier, 21 feet (6 m) north of the north corner of the
southernmost building, and about level with the ground.
BENCH MARK STAMPING: NO 2 1975
MONUMENTATION: Survey Disk VM#: 6243
AGENCY: PID#: AA0812
SETTING CLASSIFICATION: Concrete Sea Wall
The bench mark is set flush in the top of the concrete sea wall about midway
between the main wooden pier and where the sea wall turns west towards the
harbor, 101 feet (31 m) NNE of Bench Mark NO 1 1975, and about level with the
ground.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 2 of 4
PUBLICATION DATE: 05/31/1988
Station ID: 8723862 SUPERCEDED DATE: 04/21/2003
Name: MATECUMBE HARBOR, LOWER MATECUMBE KEY
FLORIDA
NOAA Chart: 11449 Latitude: 24° 51.1' N
USGS Quad: LOWER MATECUMBEKEY Longitude: 80° 44.4' W
T I D A L B E N C H M A R K S
BENCH MARK STAMPING: NO 3 1975
MONUMENTATION: Survey Disk VM#: 6244
AGENCY: PID#: AA0813
SETTING CLASSIFICATION: Concrete Sea Wall
The bench mark is set flush in the top of the concrete sea wall at the bend
where the sea wall turns west towards the harbor, 148 feet (45 m) NNW of Bench
Mark NO 2 1975, and about level with the ground.
BENCH MARK STAMPING: NO 4 1975
MONUMENTATION: Survey Disk VM#: 6245
AGENCY: PID#: AA0811
SETTING CLASSIFICATION: Concrete Foundation
The bench mark is set in the NW concrete footing of the Seabase Office building,
9 feet (3 m) SW of the north corner of the building, and about level with the
ground.
BENCH MARK STAMPING: NO 5 1975
MONUMENTATION: Survey Disk VM#: 6246
AGENCY: PID#: AA0814
SETTING CLASSIFICATION: Concrete Sidewalk
The bench mark is set flush in the concrete sidewalk at the SW corner of the
single multi-unit apartment building north of the Seabase Office building, 93.5
feet (28.5 m) NE of Bench Mark NO 4 1975, 79 feet (24 m) east of Bench Mark NO 2
1975, and about level with the ground.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 3 of 4
PUBLICATION DATE: 05/31/1988
Station ID: 8723862 SUPERCEDED DATE: 04/21/2003
Name: MATECUMBE HARBOR, LOWER MATECUMBE KEY
FLORIDA
NOAA Chart: 11449 Latitude: 24° 51.1' N
USGS Quad: LOWER MATECUMBEKEY Longitude: 80° 44.4' W
T I D A L D A T U M S
Tidal datums at MATECUMBE HARBOR, LOWER MATECUMBE KEY based on:
LENGTH OF SERIES: 1 MONTH
TIME PERIOD: MAY 9 - JUNE 11, 1975
TIDAL EPOCH: 1960-1978
CONTROL TIDE STATION: 8723852 LOWER MATECUMBE
Elevations of tidal datums referred to Mean Lower Low Water (MLLW), in FEET:
HIGHEST OBSERVED WATER LEVEL (05/14/1975) = 1.58
MEAN HIGHER HIGH WATER MHHW = 1.05
MEAN HIGH WATER MHW = 0.91
MEAN TIDE LEVEL MTL = 0.50
MEAN LOW WATER MLW = 0.08
MEAN LOWER LOW WATER MLLW = 0.00
North American Vertical Datum (NAVD88)
Bench Mark Elevation Information In FEET above:
Stamping or Designation MLLW MHW
NO 1 1975 3.56 2.65
NO 2 1975 3.58 2.67
NO 3 1975 3.51 2.60
NO 4 1975 3.99 3.08
NO 5 1975 3.74 2.83
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 4 of 4
PUBLICATION DATE: 05/31/1988
Station ID: 8723862 SUPERCEDED DATE: 04/21/2003
Name: MATECUMBE HARBOR, LOWER MATECUMBE KEY
FLORIDA
NOAA Chart: 11449 Latitude: 24° 51.1' N
USGS Quad: LOWER MATECUMBEKEY Longitude: 80° 44.4' 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.