U.S. DEPARTMENT OF COMMERCE National Oceanic and Atmospheric Administration National Ocean Service Datums Page Page 1 of 5 Station ID: 8723691 PUBLICATION DATE: 05/23/2003 Name: PT. CHARLES, GAGE 'C', KEY LARGO FL NOAA Chart: 11462 Latitude: 25° 4.9' N ( 25.08170) USGS Quad: ROCK HARBOR Longitude: 80° 27.0' W ( -80.45000) To reach the tidal bench marks from the post office in Key Largo, proceed south on U.S. Highway 1 for 1.1 km (0.7 mi) to the Key Largo Moose Lodge at the intersection of Griffins Way, then proceed SE on Griffins Way for 0.3 km (0.2 mi) to the end of the road. The bench marks are on a sea wall at a private residence and at the Moose Lodge. The tide gage and staff were attached to the sea wall west of bench mark NO 1 1975. T I D A L B E N C H M A R K S PRIMARY BENCH MARK STAMPING: NO 2 1975 DESIGNATION: 872 3691 TIDAL 2 MONUMENTATION: Tidal Station disk VM#: 5973 AGENCY: National Ocean Survey (NOS) IDB PID#: AC3361 SETTING CLASSIFICATION: Concrete sea wall OPUS PID: LATITUDE: 25° 4.9' N ( 25.08170) LONGITUDE: 80° 27.0' W ( -80.45000) The primary bench mark is a disk set flush in the north end of the concrete sea wall, 23 m (77 ft) north of bench mark NO 1 1975, 1.13 m (3.7 ft) west of the east edge of the sea wall, and 0.24 m (0.8 ft) south of the north end of the sea wall. BENCH MARK STAMPING: NO 1 1975 DESIGNATION: 872 3691 TIDAL 1 MONUMENTATION: Tidal Station disk VM#: 5972 AGENCY: National Ocean Survey (NOS) IDB PID#: AC3362 SETTING CLASSIFICATION: Concrete sea wall OPUS PID: LATITUDE: 25° 4.9' N ( 25.08170) LONGITUDE: 80° 27.0' W ( -80.45000) The bench mark is a disk set flush in the corner of the concrete sea wall near the SE corner of a private residence, 24 m (79 ft) south of the north end of the sea wall, and 11.43 m (37.5 ft) west of the east end of the sea wall.
U.S. DEPARTMENT OF COMMERCE National Oceanic and Atmospheric Administration National Ocean Service Page 2 of 5 Station ID: 8723691 PUBLICATION DATE: 05/23/2003 Name: PT. CHARLES, GAGE 'C', KEY LARGO FL NOAA Chart: 11462 Latitude: 25° 4.9' N ( 25.08170) USGS Quad: ROCK HARBOR Longitude: 80° 27.0' W ( -80.45000) T I D A L B E N C H M A R K S BENCH MARK STAMPING: NO 4 1975 DESIGNATION: 872 3691TIDAL 4 MONUMENTATION: Tidal Station disk VM#: 15844 AGENCY: National Ocean Survey (NOS) IDB PID#: AC3360 SETTING CLASSIFICATION: Rock outcrop OPUS PID: LATITUDE: 25° 4.9' N ( 25.08170) LONGITUDE: 80° 27.0' W ( -80.45000) The bench mark is a disk set in the top of a rock outcropping located NW of the workshop utility building, 35 m (115 ft) SW of the NW corner of the two-story house, 14.63 m (48.0 ft) south of the centerline of the drive, 12.89 m (42.3 ft) north of a fenceline, and 8.38 m (27.5 ft) NW of a workshop utility building. BENCH MARK STAMPING: NO 5 1975 DESIGNATION: 872 3691TIDAL 5 MONUMENTATION: Tidal Station disk VM#: 15845 AGENCY: National Ocean Survey (NOS) IDB PID#: AC3354 SETTING CLASSIFICATION: Concrete storm drain OPUS PID: LATITUDE: 25° 4.9' N ( 25.08170) LONGITUDE: 80° 27.0' W ( -80.45000) The bench mark is a disk set flush in top of a storm drain on the NW side of the northbound lane of U.S. Highway 1, 9.27 m (30.4 ft) NE of a telephone pole, 7 m (22 ft) east of the NE corner of the east wing of the Moose Lodge, 5.18 m (17.0 ft) NE of a sign, and 0.3 m (1 ft) below the level of the highway.
U.S. DEPARTMENT OF COMMERCE National Oceanic and Atmospheric Administration National Ocean Service Page 3 of 5 Station ID: 8723691 PUBLICATION DATE: 05/23/2003 Name: PT. CHARLES, GAGE 'C', KEY LARGO FL NOAA Chart: 11462 Latitude: 25° 4.9' N ( 25.08170) USGS Quad: ROCK HARBOR Longitude: 80° 27.0' W ( -80.45000) T I D A L B E N C H M A R K S BENCH MARK STAMPING: NO 3 1975 DESIGNATION: 872 3691 TIDAL 3 MONUMENTATION: Tidal Station disk VM#: 17065 AGENCY: National Ocean Survey (NOS) IDB PID#: SETTING CLASSIFICATION: Concrete slab OPUS PID: LATITUDE: 25° 4.9' N ( 25.08170) LONGITUDE: 80° 27.0' W ( -80.45000) The bench mark is a disk set flush in a concrete slab on the side of Mr. L.B. Griffin residence, 35 m (114 ft) NW of bench mark NO 1, 25.45 m (83.5 ft) SW of bench mark NO 2, and 6.22 m (20.4 ft) south of NE corner of residence.
U.S. DEPARTMENT OF COMMERCE National Oceanic and Atmospheric Administration National Ocean Service Page 4 of 5 Station ID: 8723691 PUBLICATION DATE: 05/23/2003 Name: PT. CHARLES, GAGE 'C', KEY LARGO FL NOAA Chart: 11462 Latitude: 25° 4.9' N ( 25.08170) USGS Quad: ROCK HARBOR Longitude: 80° 27.0' W ( -80.45000) T I D A L D A T U M S Tidal datums at PT. CHARLES, GAGE 'C', KEY LARGO based on: LENGTH OF SERIES: 3 MONTHS TIME PERIOD: May 1975 - July 1975 TIDAL EPOCH: 1983-2001 CONTROL TIDE STATION: 8723747 TAVERNIER HAWK CHANNEL Elevations of tidal datums referred to Mean Lower Low Water (MLLW), in METERS: MEAN HIGHER HIGH WATER MHHW = 0.604 MEAN HIGH WATER MHW = 0.576 North American Vertical Datum NAVD88 = 0.524 MEAN TIDE LEVEL MTL = 0.301 MEAN SEA LEVEL MSL = 0.275 MEAN LOW WATER MLW = 0.026 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 2 1975 1.053 0.477 NO 1 1975 1.052 0.476 NO 4 1975 1.077 0.501 NO 5 1975 3.339 2.763 NO 3 1975 1.187 0.611
U.S. DEPARTMENT OF COMMERCE National Oceanic and Atmospheric Administration National Ocean Service Page 5 of 5 Station ID: 8723691 PUBLICATION DATE: 05/23/2003 Name: PT. CHARLES, GAGE 'C', KEY LARGO FL NOAA Chart: 11462 Latitude: 25° 4.9' N ( 25.08170) USGS Quad: ROCK HARBOR Longitude: 80° 27.0' W ( -80.45000) 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.