U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Datums Page Page 1 of 7
Station ID: 8724919 PUBLICATION DATE: 05/15/2003
Name: CHOKOLOSKEE
FL
NOAA Chart: 11429 Latitude: 25° 48.8' N ( 25.81330)
USGS Quad: CHOKOLOSKEE Longitude: 81° 21.8' W ( -81.36330)
To reach the tidal bench marks from Everglades City, proceed south on State
Highway 29 to Chokoloskee Island, west on Domere Lane, south on Mamie Street,
and west on Hamilton Lane to Chokoloskee Island Park. The bench marks are near
Hamiltons Stone Crabs and along State Highway 29 north of Domere Lane. The tide
gage and staff were located at Hamiltons Stone Crabs pier.
T I D A L B E N C H M A R K S
PRIMARY BENCH MARK STAMPING: NO 1 1973
DESIGNATION: 872 4919 TIDAL 1
MONUMENTATION: Tidal Station disk VM#: 9695
AGENCY: National Ocean Survey (NOS) IDB PID#: AC3179
SETTING CLASSIFICATION: Concrete bulkhead OPUS PID:
LATITUDE: 25° 48.9' N ( 25.81500) LONGITUDE: 81° 21.8' W ( -81.36330)
The primary bench mark is a disk set flush in the center of the bulkhead inside
the boat basin at Hamiltons Stone Crabs, in the NE corner, 10 m (34 ft) NW of
bench mark NO 2 1973, 5.33 m (17.5 ft) north of the NW corner of the crabhouse,
0.30 m (1.0 ft) west of the east end of a 0.46 m (1.5 ft) wide concrete
bulkhead, and 1 m (3 ft) below the level of the bulkhead.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 2 of 7
Station ID: 8724919 PUBLICATION DATE: 05/15/2003
Name: CHOKOLOSKEE
FL
NOAA Chart: 11429 Latitude: 25° 48.8' N ( 25.81330)
USGS Quad: CHOKOLOSKEE Longitude: 81° 21.8' W ( -81.36330)
T I D A L B E N C H M A R K S
BENCH MARK STAMPING: NO 2 1973
DESIGNATION: 872 4919 TIDAL 2
MONUMENTATION: Tidal Station disk VM#: 9696
AGENCY: National Ocean Survey (NOS) IDB PID#: AC3180
SETTING CLASSIFICATION: Concrete platform OPUS PID:
LATITUDE: 25° 48.9' N ( 25.81500) LONGITUDE: 81° 21.8' W ( -81.36330)
The bench mark is a disk set flush in the concrete shipping platform at the east
corner of the northernmost part of the crabhouse at Hamiltons Stone Crabs, 0.15
m (0.5 ft) east of the crabhouse, 0.15 m (0.5 ft) south of the north end of the
platform, and 0.61 m (2.0 ft) above ground level.
BENCH MARK STAMPING: 4919 F 1984
DESIGNATION: 872 4919 F TIDAL
MONUMENTATION: Tidal Station disk VM#: 9698
AGENCY: National Ocean Service (NOS) IDB PID#: AC3374
SETTING CLASSIFICATION: Concrete porch OPUS PID:
LATITUDE: 25° 48.9' N ( 25.81500) LONGITUDE: 81° 21.6' W ( -81.36000)
The bench mark is a disk set in the concrete porch of the Chokoloskee Post
Office, 17.43 m (57.2 ft) west of the centerline of State Road 29, 8.63 m (28.3
ft) south of the NE corner of the porch, 2.44 m (8.0 ft) north of the centerline
of a breezeway, 0.3 m (1 ft) north of the northernmost roof support, and 0.61 m
(2.0 ft) above road level.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 3 of 7
Station ID: 8724919 PUBLICATION DATE: 05/15/2003
Name: CHOKOLOSKEE
FL
NOAA Chart: 11429 Latitude: 25° 48.8' N ( 25.81330)
USGS Quad: CHOKOLOSKEE Longitude: 81° 21.8' W ( -81.36330)
T I D A L B E N C H M A R K S
BENCH MARK STAMPING: 4919 G 1984
DESIGNATION: 872 4919 G TIDAL
MONUMENTATION: Tidal Station disk VM#: 9699
AGENCY: National Ocean Service (NOS) IDB PID#: AC3373
SETTING CLASSIFICATION: Concrete base OPUS PID:
LATITUDE: 25° 49.1' N ( 25.81830) LONGITUDE: 81° 21.5' W ( -81.35830)
The bench mark is a disk set in the concrete base for a bait tank at Outdoors
Resort Marina, 43.65 m (143.2 ft) east of the centerline of State Road 29, 5.49
m (18.0 ft) north of the boat basin, 0.85 m (2.8 ft) WSW of the SW corner of the
bait tank pumphouse, 0.46 m (1.5 ft) north of a powerline pole with a
transformer, and 0.3 m (1 ft) above road level.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 4 of 7
Station ID: 8724919 PUBLICATION DATE: 05/15/2003
Name: CHOKOLOSKEE
FL
NOAA Chart: 11429 Latitude: 25° 48.8' N ( 25.81330)
USGS Quad: CHOKOLOSKEE Longitude: 81° 21.8' W ( -81.36330)
T I D A L B E N C H M A R K S
BENCH MARK STAMPING: R.M.
DESIGNATION: RM
MONUMENTATION: Survey disk VM#: 12488
AGENCY: Florida Department of Interior (FLDI) IDB PID#: AC3178
SETTING CLASSIFICATION: Concrete monument OPUS PID:
LATITUDE: 25° 49.1' N ( 25.81830) LONGITUDE: 81° 21.6' W ( -81.36000)
The bench mark is a disk set in the top of a 0.1 m (0.3 ft) square concrete
monument across the highway from Outdoors Resort Marina, 30.48 m (100.0 ft) west
of the centerline of the highway, 18.14 m (59.5 ft) west of a utility pole with
a light, 15.24 m (50.0 ft) west of a 0.15 m (0.5 ft) square concrete road
boundary marker projecting 0.61 m (2.0 ft), 0.12 m (0.4 ft) north of a similar
marker, and at highway level.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 5 of 7
Station ID: 8724919 PUBLICATION DATE: 05/15/2003
Name: CHOKOLOSKEE
FL
NOAA Chart: 11429 Latitude: 25° 48.8' N ( 25.81330)
USGS Quad: CHOKOLOSKEE Longitude: 81° 21.8' W ( -81.36330)
T I D A L B E N C H M A R K S
BENCH MARK STAMPING: R. M. 1
DESIGNATION: RM 1 DI
MONUMENTATION: Survey disk VM#: 17083
AGENCY: Florida Department of Interior (FLDI) IDB PID#: AC3181
SETTING CLASSIFICATION: Concrete bulkhead OPUS PID:
LATITUDE: 25° 49.1' N ( 25.81830) LONGITUDE: 81° 21.6' W ( -81.36000)
The bench mark is a disk set flush in concrete bulkhead 20.57 m (67.5 ft) south
of the south side of the crab house, 17 m (55 ft) east of waters edge, 12.04 m
(39.5 ft) north of a power pole, 6 m (20 ft) west of the centerline of a main
unpaved drive.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 6 of 7
Station ID: 8724919 PUBLICATION DATE: 05/15/2003
Name: CHOKOLOSKEE
FL
NOAA Chart: 11429 Latitude: 25° 48.8' N ( 25.81330)
USGS Quad: CHOKOLOSKEE Longitude: 81° 21.8' W ( -81.36330)
T I D A L D A T U M S
Tidal datums at CHOKOLOSKEE based on:
LENGTH OF SERIES: 6 YEARS
TIME PERIOD: August 1973 - July 1979
TIDAL EPOCH: 1983-2001
CONTROL TIDE STATION: 8725110 NAPLES, GULF OF MEXICO
Elevations of tidal datums referred to Mean Lower Low Water (MLLW), in METERS:
HIGHEST OBSERVED WATER LEVEL (06/25/1974) = 1.642
MEAN HIGHER HIGH WATER MHHW = 0.968
MEAN HIGH WATER MHW = 0.884
North American Vertical Datum NAVD88 = 0.678
MEAN TIDE LEVEL MTL = 0.498
MEAN SEA LEVEL MSL = 0.471
MEAN LOW WATER MLW = 0.112
MEAN LOWER LOW WATER MLLW = 0.000
LOWEST OBSERVED WATER LEVEL (12/14/1978) = -0.421
North American Vertical Datum (NAVD88)
Bench Mark Elevation Information In METERS above:
Stamping or Designation MLLW MHW
NO 1 1973 1.667 0.783
NO 2 1973 3.144 2.260
4919 F 1984 2.643 1.759
4919 G 1984 2.033 1.149
R.M. 1.013 0.129
R. M. 1 3.198 2.314
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 7 of 7
Station ID: 8724919 PUBLICATION DATE: 05/15/2003
Name: CHOKOLOSKEE
FL
NOAA Chart: 11429 Latitude: 25° 48.8' N ( 25.81330)
USGS Quad: CHOKOLOSKEE Longitude: 81° 21.8' W ( -81.36330)
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.