U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Datums Page Page 1 of 5
Station ID: 8724205 PUBLICATION DATE: 05/12/2004
Name: MAYO KEY
FL
NOAA Chart: 11445 Latitude: 24° 44.0' N ( 24.73330)
USGS Quad: BIG PINE KEY Longitude: 81° 21.7' W ( -81.36170)
To reach the tidal bench marks from the Bogie Channel Bridge linking Big Pine
Key and No Name Key, proceed NW by boat 4.0 km (2.5 statute mi) to the midpoint
of the eastern shore of Mayo Key. The bench marks are located midway along the
eastern shore, west of mangroves. The tide gage and staff were located
offshore, west of the marks and the eastern shoreline.
T I D A L B E N C H M A R K S
PRIMARY BENCH MARK STAMPING: NO 1 1974
DESIGNATION: 872 4205 TIDAL 1
MONUMENTATION: Tidal Station disk VM#: 6436
AGENCY: National Ocean Survey (NOS) IDB PID#:
SETTING CLASSIFICATION: Copper-clad steel rod OPUS PID:
LATITUDE: 24° 44.0' N ( 24.73330) LONGITUDE: 81° 21.7' W ( -81.36170)
The primary bench mark is a disk located about 485 m (1590 ft) NW of the SE tip
of the key, 43 m (140 ft) west of the outer edge of the mangroves along the
eastern shore, 38 m (126 ft) WSW of a wooden witness post located 4 m (14 ft)
WSW of the outer edge of the mangroves, 23 m (76 ft) east of bench mark NO 3
1974, 5 m (17 ft) WSW of the inner fringe of mangroves, and 0.24 m (0.8 ft) east
of a witness post. The bench mark is set 12 cm (0.4 ft) above ground level, set
flush in concrete atop a copper-clad rod, and driven to refusal.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 2 of 5
Station ID: 8724205 PUBLICATION DATE: 05/12/2004
Name: MAYO KEY
FL
NOAA Chart: 11445 Latitude: 24° 44.0' N ( 24.73330)
USGS Quad: BIG PINE KEY Longitude: 81° 21.7' W ( -81.36170)
T I D A L B E N C H M A R K S
BENCH MARK STAMPING: NO 2 1974
DESIGNATION: 872 4205 TIDAL 2
MONUMENTATION: Tidal Station disk VM#: 6437
AGENCY: National Ocean Survey (NOS) IDB PID#:
SETTING CLASSIFICATION: Copper-clad steel rod OPUS PID:
LATITUDE: 24° 44.0' N ( 24.73330) LONGITUDE: 81° 21.7' W ( -81.36170)
The bench mark is a disk located 49 m (160 ft) west of the outer edge of the
mangroves on the eastern shore, 13.72 m (45.0 ft) NW of bench mark NO 1 1974,
7.25 m (23.8 ft) ESE of a witness sign nailed to a tree, and 0.24 m (0.8 ft)
east of a witness post. The bench mark is set 6 cm (0.2 ft) above ground
level, set flush in concrete atop a copper-clad rod, and driven to refusal.
BENCH MARK STAMPING: NO 3 1974
DESIGNATION: 872 4205 TIDAL 3
MONUMENTATION: Tidal Station disk VM#: 6438
AGENCY: National Ocean Survey (NOS) IDB PID#:
SETTING CLASSIFICATION: Copper-clad steel rod OPUS PID:
LATITUDE: 24° 44.0' N ( 24.73330) LONGITUDE: 81° 21.7' W ( -81.36170)
The bench mark is a disk located 64 m (210 ft) west of the outer edge of the
mangroves on the eastern shore, 15.94 m (52.3 ft) ENE of bench mark NO 5 1974,
15.06 m (49.4 ft) WSW of bench mark NO 2 1974, and 0.30 m (1.0 ft) east of a
witness post. The bench mark is set 6 cm (0.2 ft) above ground level, set flush
in concrete atop a copper-clad rod, and driven to refusal.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 3 of 5
Station ID: 8724205 PUBLICATION DATE: 05/12/2004
Name: MAYO KEY
FL
NOAA Chart: 11445 Latitude: 24° 44.0' N ( 24.73330)
USGS Quad: BIG PINE KEY Longitude: 81° 21.7' W ( -81.36170)
T I D A L B E N C H M A R K S
BENCH MARK STAMPING: NO 5 1974
DESIGNATION: 872 4205 TIDAL 5
MONUMENTATION: Tidal Station disk VM#: 6440
AGENCY: National Ocean Survey (NOS) IDB PID#:
SETTING CLASSIFICATION: Copper-clad steel rod OPUS PID:
LATITUDE: 24° 44.0' N ( 24.73330) LONGITUDE: 81° 21.7' W ( -81.36170)
The bench mark is a disk located 79 m (260 ft) west of the outer edge of
mangroves on the eastern shore, 19.35 m (63.5 ft) SSW of bench mark NO 4 1974,
4.79 m (15.7 ft) east of a witness sign nailed to a tree, and 0.30 m (1.0 ft)
east of a witness post. The bench mark is set 9 cm (0.3 ft) above ground level,
set flush in concrete atop a copper-clad rod, and driven to refusal.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 4 of 5
Station ID: 8724205 PUBLICATION DATE: 05/12/2004
Name: MAYO KEY
FL
NOAA Chart: 11445 Latitude: 24° 44.0' N ( 24.73330)
USGS Quad: BIG PINE KEY Longitude: 81° 21.7' W ( -81.36170)
T I D A L D A T U M S
Tidal datums at MAYO KEY based on:
LENGTH OF SERIES: 1 MONTH
TIME PERIOD: August 1974 - August 1974
TIDAL EPOCH: 1983-2001
CONTROL TIDE STATION: 8724580 KEY WEST
Elevations of tidal datums referred to Mean Lower Low Water (MLLW), in METERS:
MEAN HIGHER HIGH WATER MHHW = 0.496
MEAN HIGH WATER MHW = 0.428
MEAN TIDE LEVEL MTL = 0.253
MEAN SEA LEVEL MSL = 0.240
MEAN LOW WATER MLW = 0.078
MEAN LOWER LOW WATER MLLW = 0.000
North American Vertical Datum (NAVD88)
Bench Mark Elevation Information In METERS above:
Stamping or Designation MLLW MHW
NO 1 1974 0.710 0.282
NO 2 1974 0.549 0.121
NO 3 1974 0.563 0.135
NO 5 1974 0.742 0.314
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 5 of 5
Station ID: 8724205 PUBLICATION DATE: 05/12/2004
Name: MAYO KEY
FL
NOAA Chart: 11445 Latitude: 24° 44.0' N ( 24.73330)
USGS Quad: BIG PINE KEY Longitude: 81° 21.7' W ( -81.36170)
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.