U.S. DEPARTMENT OF COMMERCE National Oceanic and Atmospheric Administration National Ocean Service Datums Page Page 1 of 5 Station ID: 8724094 PUBLICATION DATE: 12/12/2003 Name: EAST BAHIA HONDA KEY FL NOAA Chart: 11449 Latitude: 24° 46.5' N ( 24.77500) USGS Quad: EAST BAHIA HONDA KEY Longitude: 81° 13.6' W ( -81.22670) To reach the tidal bench marks from the west end of Seven Mile Bridge on Little Duck Key, proceed by boat 11.1 km (6.0 nm) north to the SE end of East Bahia Honda Key. The bench marks are located along the mangrove shoreline. The tide gage and staff were located on a small temporary offshore platform. T I D A L B E N C H M A R K S PRIMARY BENCH MARK STAMPING: TRADE 1935 DESIGNATION: 872 4094 TRADE MONUMENTATION: Triangulation Station disk VM#: 6332 AGENCY: US Coast and Geodetic Survey (USC&GS) IDB PID#: AA1453 SETTING CLASSIFICATION: Concrete monument OPUS PID: LATITUDE: 24° 46.5' N ( 24.77500) LONGITUDE: 81° 13.7' W ( -81.22830) The primary bench mark is a disk set in the top of a concrete monument located on the SE end of East Bahia Honda Key, 90 m (295 ft) from the extreme southern tip, 18 m (59 ft) from the south shore, on a narrow sand ridge behind a fringe of mangrove in a small open area, and 0.06 m (0.2 ft) above ground level. BENCH MARK STAMPING: TRADE NO 1 1935 DESIGNATION: 872 4094 TRADE 1 MONUMENTATION: Reference Mark disk VM#: 6333 AGENCY: US Coast and Geodetic Survey (USC&GS) IDB PID#: SETTING CLASSIFICATION: Concrete monument OPUS PID: LATITUDE: 24° 46.5' N ( 24.77500) LONGITUDE: 81° 13.6' W ( -81.22670) The bench mark is a disk set in the top of a concrete monument, 13.96 m (45.8 ft) NW of triangulation station TRADE 1935, 0.3 m (1 ft) SE of a witness post, and 0.09 m (0.3 ft) above ground level.
U.S. DEPARTMENT OF COMMERCE National Oceanic and Atmospheric Administration National Ocean Service Page 2 of 5 Station ID: 8724094 PUBLICATION DATE: 12/12/2003 Name: EAST BAHIA HONDA KEY FL NOAA Chart: 11449 Latitude: 24° 46.5' N ( 24.77500) USGS Quad: EAST BAHIA HONDA KEY Longitude: 81° 13.6' W ( -81.22670) T I D A L B E N C H M A R K S BENCH MARK STAMPING: TRADE NO 2 1935 DESIGNATION: 872 4094 TRADE 2 MONUMENTATION: Reference Mark disk VM#: 6334 AGENCY: US Coast and Geodetic Survey (USC&GS) IDB PID#: SETTING CLASSIFICATION: Concrete monument OPUS PID: LATITUDE: 24° 46.5' N ( 24.77500) LONGITUDE: 81° 13.6' W ( -81.22670) The bench mark is a disk set in the top of a concrete monument, 11.16 m (36.6 ft) SE of triangulation station TRADE 1935 on the same ridge, 0.12 m (0.4 ft) SE of a witness post, and 0.06 m (0.2 ft) above ground level. BENCH MARK STAMPING: DON 1974 DESIGNATION: 872 4094 DON MONUMENTATION: Tidal Station disk VM#: 6335 AGENCY: National Ocean Survey (NOS) IDB PID#: SETTING CLASSIFICATION: Copper-clad steel rod OPUS PID: LATITUDE: 24° 46.5' N ( 24.77500) LONGITUDE: 81° 13.6' W ( -81.22670) The bench mark is a disk located on a narrow sand berm on the south side of the key, 26.00 m (85.3 ft) SE of bench mark CAL 1974, 3.35 m (11.0 ft) south of the north side of the sand berm, and 0.24 m (0.8 ft) NW of a witness post. The bench mark is set 3 cm (0.1 ft) above the ground, crimped to a copper-clad steel rod driven to refusal and encased in concrete.
U.S. DEPARTMENT OF COMMERCE National Oceanic and Atmospheric Administration National Ocean Service Page 3 of 5 Station ID: 8724094 PUBLICATION DATE: 12/12/2003 Name: EAST BAHIA HONDA KEY FL NOAA Chart: 11449 Latitude: 24° 46.5' N ( 24.77500) USGS Quad: EAST BAHIA HONDA KEY Longitude: 81° 13.6' W ( -81.22670) T I D A L B E N C H M A R K S BENCH MARK STAMPING: CAL 1974 DESIGNATION: 872 4094 CAL MONUMENTATION: Tidal Station disk VM#: 6336 AGENCY: National Ocean Survey (NOS) IDB PID#: SETTING CLASSIFICATION: Copper-clad steel rod OPUS PID: LATITUDE: 24° 46.5' N ( 24.77500) LONGITUDE: 81° 13.6' W ( -81.22670) The bench mark is a disk located on a narrow sand berm behind a fringe of mangrove trees, 26.00 m (85.3 ft) NW of bench mark DON 1974, 17.71 m (58.1 ft) east of reference mark TRADE NO 2 1935, and 0.21 m (0.7 ft) west of a witness post. The bench mark is set 6 cm (0.2 ft) above ground, crimped to a copper-clad steel rod driven to refusal and encased in concrete.
U.S. DEPARTMENT OF COMMERCE National Oceanic and Atmospheric Administration National Ocean Service Page 4 of 5 Station ID: 8724094 PUBLICATION DATE: 12/12/2003 Name: EAST BAHIA HONDA KEY FL NOAA Chart: 11449 Latitude: 24° 46.5' N ( 24.77500) USGS Quad: EAST BAHIA HONDA KEY Longitude: 81° 13.6' W ( -81.22670) T I D A L D A T U M S Tidal datums at EAST BAHIA HONDA KEY based on: LENGTH OF SERIES: 1 MONTH TIME PERIOD: June 1974 - June 1974 TIDAL EPOCH: 1983-2001 CONTROL TIDE STATION: 8724211 BIG PINE KEY VIADUCT Elevations of tidal datums referred to Mean Lower Low Water (MLLW), in METERS: MEAN HIGHER HIGH WATER MHHW = 0.422 MEAN HIGH WATER MHW = 0.362 MEAN TIDE LEVEL MTL = 0.227 MEAN SEA LEVEL MSL = 0.208 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 TRADE 1935 0.649 0.287 TRADE NO 1 1935 0.640 0.278 TRADE NO 2 1935 0.636 0.274 DON 1974 0.635 0.273 CAL 1974 0.711 0.349
U.S. DEPARTMENT OF COMMERCE National Oceanic and Atmospheric Administration National Ocean Service Page 5 of 5 Station ID: 8724094 PUBLICATION DATE: 12/12/2003 Name: EAST BAHIA HONDA KEY FL NOAA Chart: 11449 Latitude: 24° 46.5' N ( 24.77500) USGS Quad: EAST BAHIA HONDA KEY Longitude: 81° 13.6' W ( -81.22670) 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.