U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Datums Page Page 1 of 5
Station ID: 8724229 PUBLICATION DATE: 03/09/2004
Name: ANNETTE KEY
FL
NOAA Chart: 11448 Latitude: 24° 45.5' N ( 24.75830)
USGS Quad: CONTENT KEYS Longitude: 81° 23.4' W ( -81.39000)
To reach the tidal bench marks from the bridge between Big Pine Key and No Name
Key, proceed by boat north for 3.7 km (2.0 nm) and then NW for 3.6 km (1.9 nm)
to the northern tip of Annette Key. The bench marks are located at the northern
tip of the Key. The tide gage and staff were located just east of the northern
tip.
T I D A L B E N C H M A R K S
PRIMARY BENCH MARK STAMPING: RM 1 1935
DESIGNATION: 872 4229 ANN RM 1
MONUMENTATION: Reference Mark disk VM#: 6827
AGENCY: US Coast and Geodetic Survey
(USC&GS) IDB PID#:
SETTING CLASSIFICATION: Concrete monument OPUS PID:
LATITUDE: 24° 45.5' N ( 24.75830) LONGITUDE: 81° 23.4' W ( -81.39000)
The bench mark is a disk set in concrete monument located in the northern tip of
the key, 26.73 m (87.7 ft) NNE of bench mark ANN 1935, 12.50 m (41.0 ft) west of
bench mark NO 3 1935, 0.24 m (0.8 ft) east of a witness post, and 0.30 m (1 ft)
above the level of the ground.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 2 of 5
Station ID: 8724229 PUBLICATION DATE: 03/09/2004
Name: ANNETTE KEY
FL
NOAA Chart: 11448 Latitude: 24° 45.5' N ( 24.75830)
USGS Quad: CONTENT KEYS Longitude: 81° 23.4' W ( -81.39000)
T I D A L B E N C H M A R K S
BENCH MARK STAMPING: ANN 1935
DESIGNATION: ANN 1935
MONUMENTATION: Triangulation Station disk VM#: 6826
AGENCY: US Coast and Geodetic Survey
(USC&GS) IDB PID#: AA1574
SETTING CLASSIFICATION: Concrete monument OPUS PID:
LATITUDE: 24° 45.5' N ( 24.75830) LONGITUDE: 81° 23.4' W ( -81.39000)
The bench mark is a disk set in a concrete monument at the northern tip of the
Key, about 54 m (177 ft) SSW of the approximate high water line at the north end
of the Key, 1.34 m (4.4 ft) north of a witness sign nailed to a tree, 0.24 m
(0.8 ft) east of a witness post, and 0.30 m (1.0 ft) above the ground.
BENCH MARK STAMPING: RM 2 1935
DESIGNATION: 872 4229 ANN RM 2
MONUMENTATION: Reference Mark disk VM#: 6828
AGENCY: US Coast and Geodetic Survey
(USC&GS) IDB PID#:
SETTING CLASSIFICATION: Concrete monument OPUS PID:
LATITUDE: 24° 45.5' N ( 24.75830) LONGITUDE: 81° 23.4' W ( -81.39000)
The bench mark is a disk set in a concrete monument located at the northern tip
of the Key, 25.01 m 82.0 ft) east of bench mark ANN 1935, 0.21 m (0.7 ft) east
of a witness post, and 0.30 m (1.0 ft) above the ground.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 3 of 5
Station ID: 8724229 PUBLICATION DATE: 03/09/2004
Name: ANNETTE KEY
FL
NOAA Chart: 11448 Latitude: 24° 45.5' N ( 24.75830)
USGS Quad: CONTENT KEYS Longitude: 81° 23.4' W ( -81.39000)
T I D A L B E N C H M A R K S
BENCH MARK STAMPING: NO 3 1974
DESIGNATION: 872 4229 TIDAL 3
MONUMENTATION: Tidal Station disk VM#: 6830
AGENCY: National Ocean Survey (NOS) IDB PID#:
SETTING CLASSIFICATION: Unspecified deep rod OPUS PID:
LATITUDE: 24° 45.5' N ( 24.75830) LONGITUDE: 81° 23.4' W ( -81.39000)
The bench mark is a disk located in a grassy clearing, 23 m (75 ft) SSW of the
approximate high water line at the NE shore of the Key, 15 m (48 ft) west of the
inner mangrove edge of the east shore, and 0.24 m (0.8 ft) east of a witness
post. The bench mark is crimped to an unspecifed deep rod driven to refusal.
BENCH MARK STAMPING: NO 4 1974
DESIGNATION: 872 4229 TIDAL 4
MONUMENTATION: Tidal Station disk VM#: 9125
AGENCY: National Ocean Survey (NOS) IDB PID#:
SETTING CLASSIFICATION: Unspecified deep rod OPUS PID:
LATITUDE: 24° 45.5' N ( 24.75830) LONGITUDE: 81° 23.4' W ( -81.39000)
The bench mark is a disk located at the NE point of the key at the edge of the
Inner Mangrove fringe, 13.41 m (44.0 ft) east of Bench Mark NO 3 1974, 9.75 m
(32.0 ft) east of the edge of a clearing, 1.16 m (3.8 ft) WSW of a witness sign
nailed to a tree, and 0.24 m (0.8 ft) east of a witness post. The bench mark is
crimped to an unspecifed deep rod driven to refusal.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 4 of 5
Station ID: 8724229 PUBLICATION DATE: 03/09/2004
Name: ANNETTE KEY
FL
NOAA Chart: 11448 Latitude: 24° 45.5' N ( 24.75830)
USGS Quad: CONTENT KEYS Longitude: 81° 23.4' W ( -81.39000)
T I D A L D A T U M S
Tidal datums at ANNETTE 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 = 0.734
MEAN HIGH WATER MHW = 0.664
MEAN TIDE LEVEL MTL = 0.378
MEAN SEA LEVEL MSL = 0.346
MEAN LOW WATER MLW = 0.092
MEAN LOWER LOW WATER MLLW = 0.000
North American Vertical Datum (NAVD88)
Bench Mark Elevation Information In METERS above:
Stamping or Designation MLLW MHW
RM 1 1935 0.967 0.303
ANN 1935 0.997 0.333
RM 2 1935 0.946 0.282
NO 3 1974 0.764 0.100
NO 4 1974 0.735 0.071
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 5 of 5
Station ID: 8724229 PUBLICATION DATE: 03/09/2004
Name: ANNETTE KEY
FL
NOAA Chart: 11448 Latitude: 24° 45.5' N ( 24.75830)
USGS Quad: CONTENT KEYS Longitude: 81° 23.4' W ( -81.39000)
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.