U.S. DEPARTMENT OF COMMERCE National Oceanic and Atmospheric Administration National Ocean Service Datums Page Page 1 of 5 Station ID: 8723851 PUBLICATION DATE: 05/15/2003 Name: LOWER MATECUMBE KEY HAWK CHANNEL FL NOAA Chart: 11449 Latitude: 24° 52.1' N ( 24.86830) USGS Quad: LOWER MATECUMBE KEY Longitude: 80° 42.2' W ( -80.70330) To reach the tidal bench marks from the post office in Islamorada, proceed 10.6 km (6.6 mi) SW on U.S. Highway 1, then continue 0.24 km (0.15 mi) SE along a private drive to the private residence of Robert Jones on the west shore of a canal. The bench marks are located along the private drive. The tide gage and staff were located on the concrete bulkhead behind the Jones residence. T I D A L B E N C H M A R K S PRIMARY BENCH MARK STAMPING: E 329 1970 DESIGNATION: 872 3851 E 329 MONUMENTATION: Tidal Station disk VM#: 6240 AGENCY: US Coast and Geodetic Survey (USC&GS) IDB PID#: AA0408 SETTING CLASSIFICATION: Boulder OPUS PID: LATITUDE: 24° 52.2' N ( 24.87000) LONGITUDE: 80° 42.2' W ( -80.70330) The primary bench mark is a disk set atop a small embedded boulder, 26.97 m (88.5 ft) SW of the SW corner of the Jones residence, 22.65 m (74.3 ft) south of bench mark C 329 1970, 16 m (51 ft) SSE of bench mark B 329 1970, 2 m (6 ft) SE of the centerline of the private drive, and 0.06 m (0.2 ft) above ground level.
U.S. DEPARTMENT OF COMMERCE National Oceanic and Atmospheric Administration National Ocean Service Page 2 of 5 Station ID: 8723851 PUBLICATION DATE: 05/15/2003 Name: LOWER MATECUMBE KEY HAWK CHANNEL FL NOAA Chart: 11449 Latitude: 24° 52.1' N ( 24.86830) USGS Quad: LOWER MATECUMBE KEY Longitude: 80° 42.2' W ( -80.70330) T I D A L B E N C H M A R K S BENCH MARK STAMPING: B 329 1970 DESIGNATION: 872 3851 B 329 MONUMENTATION: Tidal Station disk VM#: 6237 AGENCY: US Coast and Geodetic Survey (USC&GS) IDB PID#: AA0407 SETTING CLASSIFICATION: Concrete monument OPUS PID: LATITUDE: 24° 52.2' N ( 24.87000) LONGITUDE: 80° 42.2' W ( -80.70330) The bench mark is a disk set flush in a concrete monument, 11.43 m (37.5 ft) south of the SW corner of the Jones residence, 5.94 m (19.5 ft) SE of a utility pole, 3.35 m (11.0 ft) NE of the centerline of the drive, 0.46 m (1.5 ft) NE of a utility pole guy wire, and at ground level. BENCH MARK STAMPING: C 329 1970 DESIGNATION: 872 3851 C 329 MONUMENTATION: Tidal Station disk VM#: 6238 AGENCY: US Coast and Geodetic Survey (USC&GS) IDB PID#: AA0409 SETTING CLASSIFICATION: Concrete monument OPUS PID: LATITUDE: 24° 52.2' N ( 24.87000) LONGITUDE: 80° 42.2' W ( -80.70330) The bench mark is a disk set flush in a concrete monument, 20.18 m (66.2 ft) east of the SW corner of the Jones residence, 19.29 m (63.3 ft) east of bench mark B 329 1970, 18 m (60 ft) NE of the centerline of the drive, 17.01 m (55.8 ft) SE of the SE corner of the Jones residence, 2.29 m (7.5 ft) south of a 0.24 m (0.8 ft) diameter pine tree, and at ground level.
U.S. DEPARTMENT OF COMMERCE National Oceanic and Atmospheric Administration National Ocean Service Page 3 of 5 Station ID: 8723851 PUBLICATION DATE: 05/15/2003 Name: LOWER MATECUMBE KEY HAWK CHANNEL FL NOAA Chart: 11449 Latitude: 24° 52.1' N ( 24.86830) USGS Quad: LOWER MATECUMBE KEY Longitude: 80° 42.2' W ( -80.70330) T I D A L B E N C H M A R K S BENCH MARK STAMPING: D 329 1970 DESIGNATION: 872 3851 D 329 MONUMENTATION: Tidal Station disk VM#: 6239 AGENCY: US Coast and Geodetic Survey (USC&GS) IDB PID#: AA0412 SETTING CLASSIFICATION: Concrete step OPUS PID: LATITUDE: 24° 52.2' N ( 24.87000) LONGITUDE: 80° 42.2' W ( -80.70330) The bench mark is a disk set in the bottom concrete step of a landing platform to the SW end of the Jones boat dock, 2.74 m (9.0 ft) NW of the NE corner of the Jones residence, 0.55 m (1.8 ft) NE of the NE end of the step, and 1 m (2 ft) below the base of the residence. BENCH MARK STAMPING: F 329 1970 DESIGNATION: 872 3851 F 329 MONUMENTATION: Tidal Station disk VM#: 6241 AGENCY: US Coast and Geodetic Survey (USC&GS) IDB PID#: AA0411 SETTING CLASSIFICATION: Concrete monument OPUS PID: LATITUDE: 24° 52.3' N ( 24.87170) LONGITUDE: 80° 42.2' W ( -80.70330) The bench mark is a disk set flush in a concrete monument, 0.08 km (0.05 mi) NW of the Jones residence, 6 m (19 ft) NE of and across the private drive from a lone 0.24 m (0.8 ft) diameter pine tree, 3 m (10 ft) NW of a utility pole, 1 m (2 ft) SE of a metal witness post, 0.43 m (1.4 ft) south a utility pole guy wire, and at ground level.
U.S. DEPARTMENT OF COMMERCE National Oceanic and Atmospheric Administration National Ocean Service Page 4 of 5 Station ID: 8723851 PUBLICATION DATE: 05/15/2003 Name: LOWER MATECUMBE KEY HAWK CHANNEL FL NOAA Chart: 11449 Latitude: 24° 52.1' N ( 24.86830) USGS Quad: LOWER MATECUMBE KEY Longitude: 80° 42.2' W ( -80.70330) T I D A L D A T U M S Tidal datums at LOWER MATECUMBE KEY HAWK CHANNEL based on: LENGTH OF SERIES: 12 MONTHS TIME PERIOD: May 1971 - April 1972 TIDAL EPOCH: 1983-2001 CONTROL TIDE STATION: 8723170 MIAMI BEACH (CITY PIER) Elevations of tidal datums referred to Mean Lower Low Water (MLLW), in METERS: HIGHEST OBSERVED WATER LEVEL (11/02/1971) = 0.961 MEAN HIGHER HIGH WATER MHHW = 0.683 MEAN HIGH WATER MHW = 0.639 North American Vertical Datum NAVD88 = 0.635 MEAN SEA LEVEL MSL = 0.359 MEAN TIDE LEVEL MTL = 0.352 MEAN LOW WATER MLW = 0.065 MEAN LOWER LOW WATER MLLW = 0.000 LOWEST OBSERVED WATER LEVEL (02/10/1971) = -0.359 North American Vertical Datum (NAVD88) Bench Mark Elevation Information In METERS above: Stamping or Designation MLLW MHW E 329 1970 1.715 1.076 B 329 1970 1.780 1.141 C 329 1970 1.622 0.983 D 329 1970 1.188 0.549 F 329 1970 1.771 1.132 Foot Notes:
U.S. DEPARTMENT OF COMMERCE National Oceanic and Atmospheric Administration National Ocean Service Page 5 of 5 Station ID: 8723851 PUBLICATION DATE: 05/15/2003 Name: LOWER MATECUMBE KEY HAWK CHANNEL FL NOAA Chart: 11449 Latitude: 24° 52.1' N ( 24.86830) USGS Quad: LOWER MATECUMBE KEY Longitude: 80° 42.2' W ( -80.70330) 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.