U.S. DEPARTMENT OF COMMERCE National Oceanic and Atmospheric Administration National Ocean Service Datums Page Page 1 of 5 PUBLICATION DATE: 09/29/1989 Station ID: 8723409 SUPERCEDED DATE: 04/21/2003 Name: ELLIOTT KEY HARBOR, ELLIOTT KEY, BISCAYNE BAY FLORIDA NOAA Chart: 11463 Latitude: 25° 27.2' N USGS Quad: ELLIOTT KEY Longitude: 80° 11.8' W To reach the tidal bench marks from the intersection of U.S. Highway 1 and Lucy Street (SW 328th Street) in Florida City, proceed east on Lucy Street for 8.8 miles (14.2 km) to the boat ramp at Biscayne National Park. Continue east by boat for 8.7 miles (14.0 km) to the Elliott Key Visitor Center Boat Basin on the west side of Elliott Key. The bench marks are in the vicinity of the boat basin visitor center, and maintenance dock. The tide gage and staff were on the maintenance dock south of the basin. T I D A L B E N C H M A R K S PRIMARY BENCH MARK STAMPING: NO 3 1974 MONUMENTATION: Survey Disk VM#: 5837 AGENCY: PID: SETTING CLASSIFICATION: Rock Outcrop The bench mark is set in a rock outcrop east of the boat basin, 135.2 feet (41.2 m) SSE of a light pole at the boat basin, 56.2 feet (17.1 m) east of the easternmost corner of the south basin, 25.5 feet (7.8 m) ENE of Bench Mark 19, and 4 feet (1 m) north of a tree. BENCH MARK STAMPING: 3409 F 1987 MONUMENTATION: Survey Disk VM#: 5838 AGENCY: PID: SETTING CLASSIFICATION: Concrete Foundation The bench mark is set flush in the east corner of a concrete foundation for a flag pole at the westernmost end of the center of three piers of the boat basin.
U.S. DEPARTMENT OF COMMERCE National Oceanic and Atmospheric Administration National Ocean Service Page 2 of 5 PUBLICATION DATE: 09/29/1989 Station ID: 8723409 SUPERCEDED DATE: 04/21/2003 Name: ELLIOTT KEY HARBOR, ELLIOTT KEY, BISCAYNE BAY FLORIDA NOAA Chart: 11463 Latitude: 25° 27.2' N USGS Quad: ELLIOTT KEY Longitude: 80° 11.8' W T I D A L B E N C H M A R K S BENCH MARK STAMPING: 3409 G 1987 MONUMENTATION: Survey Disk VM#: 5839 AGENCY: PID: SETTING CLASSIFICATION: Concrete Footing The bench mark is set in the concrete footing at the east end of the maintenance dock, 14.0 feet (4.3 m) west of the NE corner of the dock, 0.5 foot (0.2 m) south of the north edge of the dock, and level with the dock. BENCH MARK STAMPING: 3409 H 1987 MONUMENTATION: Survey Disk VM#: 5840 AGENCY: PID: SETTING CLASSIFICATION: Stainless Steel Rod The bench mark is set in the WSW corner of a deck located between the Visitor Center and the public restroom, 28.5 feet (8.7 m) ENE of the east corner of the restroom building, 11.7 feet (3.6 m) SSW of the south corner of the Visitor Center, and 2.0 feet (0.6 m) WSW of the deck corner. The bench mark is level with the ground, driven 2 feet (1 m) to refusal, and encased in a PVC pipe with concrete kickblock. BENCH MARK STAMPING: 3409 J 1987 MONUMENTATION: Survey Disk VM#: 5841 AGENCY: PID: SETTING CLASSIFICATION: Concrete Step The bench mark is set in the first step at the SW corner of the generator building, about 315 feet (96 m) ESE of the maintenance dock, 1.6 feet (0.5 m) SE of the SW corner of the building, and 0.7 foot (0.2 m) SSW of the west side of the building.
U.S. DEPARTMENT OF COMMERCE National Oceanic and Atmospheric Administration National Ocean Service Page 3 of 5 PUBLICATION DATE: 09/29/1989 Station ID: 8723409 SUPERCEDED DATE: 04/21/2003 Name: ELLIOTT KEY HARBOR, ELLIOTT KEY, BISCAYNE BAY FLORIDA NOAA Chart: 11463 Latitude: 25° 27.2' N USGS Quad: ELLIOTT KEY Longitude: 80° 11.8' W T I D A L B E N C H M A R K S BENCH MARK STAMPING: 19 MONUMENTATION: Survey Disk VM#: 5842 AGENCY: PID: SETTING CLASSIFICATION: Rock Outcrop The bench mark is set in a rock outcrop east of the boat basin, 128.5 feet (39.2 m) SSE of a light pole at the boast basin, 104.8 feet (31.9 m) north of the northernmost corner of a picnic shelter, 31.4 feet (9.6 m) east of the easternmost corner of the south basin, and level with the ground.
U.S. DEPARTMENT OF COMMERCE National Oceanic and Atmospheric Administration National Ocean Service Page 4 of 5 PUBLICATION DATE: 09/29/1989 Station ID: 8723409 SUPERCEDED DATE: 04/21/2003 Name: ELLIOTT KEY HARBOR, ELLIOTT KEY, BISCAYNE BAY FLORIDA NOAA Chart: 11463 Latitude: 25° 27.2' N USGS Quad: ELLIOTT KEY Longitude: 80° 11.8' W T I D A L D A T U M S Tidal datums at ELLIOTT KEY HARBOR, ELLIOTT KEY, BISCAYNE BAY based on: LENGTH OF SERIES: 1 MONTH TIME PERIOD: JULY 1974 TIDAL EPOCH: 1960-1978 CONTROL TIDE STATION: 8723350 RAGGED KEY #3 Elevations of tidal datums referred to Mean Lower Low Water (MLLW), in FEET: HIGHEST OBSERVED WATER LEVEL (10/20/1987) = 2.60 MEAN HIGHER HIGH WATER MHHW = 1.64 MEAN HIGH WATER MHW = 1.57 MEAN TIDE LEVEL MTL = 0.83 MEAN LOW WATER MLW = 0.09 MEAN LOWER LOW WATER MLLW = 0.00 LOWEST OBSERVED WATER LEVEL (06/27/1974) = -0.28 Bench Mark Elevation Information In FEET above: Stamping or Designation MLLW MHW NO 3 1974 5.74 4.17 3409 F 1987 4.29 2.72 3409 G 1987 4.08 2.51 3409 H 1987 7.50 5.93 3409 J 1987 9.79 8.22 19 5.11 3.54
U.S. DEPARTMENT OF COMMERCE National Oceanic and Atmospheric Administration National Ocean Service Page 5 of 5 PUBLICATION DATE: 09/29/1989 Station ID: 8723409 SUPERCEDED DATE: 04/21/2003 Name: ELLIOTT KEY HARBOR, ELLIOTT KEY, BISCAYNE BAY FLORIDA NOAA Chart: 11463 Latitude: 25° 27.2' N USGS Quad: ELLIOTT KEY Longitude: 80° 11.8' W 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 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.