U.S. DEPARTMENT OF COMMERCE National Oceanic and Atmospheric Administration National Ocean Service Datums Page Page 1 of 6 Station ID: 8724373 PUBLICATION DATE: 02/05/2004 Name: PUMPKIN KEY, SUGARLOAF CHANNEL FL NOAA Chart: 11448 Latitude: 24° 43.0' N ( 24.71670) USGS Quad: SUGARLOAF KEY Longitude: 81° 33.7' W ( -81.56170) To reach the tidal bench marks by boat from the U.S. Highway 1 bridge over Bow (Sugarloaf) Channel, proceed NW on Bow Channel for 7.6 km (4.7 statute mi) to the south end of an unnamed island, 0.8 km (0.5 mi) NW of Pumpkin Key and 1.4 km (0.9 mi) SE of the NE end of Johnston Key. The bench marks are just north of the south end of the unnamed island. The tide gage and staff were offshore, about 91 m (300 ft) NW of the south end of the island. T I D A L B E N C H M A R K S PRIMARY BENCH MARK STAMPING: EASTON 1934 DESIGNATION: EASTON 1934 MONUMENTATION: NOS Hydrographic disk VM#: 7028 AGENCY: US Coast and Geodetic Survey (USC&GS) IDB PID#: AA1030 SETTING CLASSIFICATION: Concrete monument OPUS PID: LATITUDE: 24° 43.0' N ( 24.71670) LONGITUDE: 81° 33.6' W ( -81.56000) The primary bench mark is a disk set in a 0.24 m (0.8 ft) square concrete monument in a small open rocky area on the south end of the island, 50 m (164 ft) north of the outer mangroves at the south end of the island, 40 m (131 ft) east of the outer mangroves on the west side of the island, and 0.24 m (0.8 ft) above the rock.
U.S. DEPARTMENT OF COMMERCE National Oceanic and Atmospheric Administration National Ocean Service Page 2 of 6 Station ID: 8724373 PUBLICATION DATE: 02/05/2004 Name: PUMPKIN KEY, SUGARLOAF CHANNEL FL NOAA Chart: 11448 Latitude: 24° 43.0' N ( 24.71670) USGS Quad: SUGARLOAF KEY Longitude: 81° 33.7' W ( -81.56170) T I D A L B E N C H M A R K S BENCH MARK STAMPING: NO 1 1973 DESIGNATION: 872 4373 TIDAL 1 MONUMENTATION: Tidal Station disk VM#: 7029 AGENCY: National Ocean Survey (NOS) IDB PID#: SETTING CLASSIFICATION: Rock OPUS PID: LATITUDE: 24° 43.0' N ( 24.71670) LONGITUDE: 81° 33.7' W ( -81.56170) The bench mark is a disk set in a rock located 91 m (300 ft) NW of the south end of the island, 16.18 m (53.1 ft) SE of bench mark NO 3 1973, and 13.26 m (43.5 ft) NW of bench mark EASTON 1934. BENCH MARK STAMPING: NO 2 1973 DESIGNATION: 872 4373 TIDAL 2 MONUMENTATION: Tidal Station disk VM#: 7030 AGENCY: National Ocean Survey (NOS) IDB PID#: SETTING CLASSIFICATION: Rock OPUS PID: LATITUDE: 24° 43.0' N ( 24.71670) LONGITUDE: 81° 33.7' W ( -81.56170) The bench mark is a disk set in a rock located 104 m (342 ft) NW of the south end of the island, 26.06 m (85.5 ft) NNW of bench mark EASTON 1934, 23 m (75 ft) east of the west edge of the rock outcropping on the west side of the island, 19.57 (64.2 ft) NNE of "Lag Screw", and 17.13 m (56.2 ft) north of bench mark NO 1 1973.
U.S. DEPARTMENT OF COMMERCE National Oceanic and Atmospheric Administration National Ocean Service Page 3 of 6 Station ID: 8724373 PUBLICATION DATE: 02/05/2004 Name: PUMPKIN KEY, SUGARLOAF CHANNEL FL NOAA Chart: 11448 Latitude: 24° 43.0' N ( 24.71670) USGS Quad: SUGARLOAF KEY Longitude: 81° 33.7' W ( -81.56170) T I D A L B E N C H M A R K S BENCH MARK STAMPING: NO 3 1973 DESIGNATION: 872 4373 TIDAL 3 MONUMENTATION: Tidal Station disk VM#: 7031 AGENCY: National Ocean Survey (NOS) IDB PID#: SETTING CLASSIFICATION: Rock OPUS PID: LATITUDE: 24° 43.0' N ( 24.71670) LONGITUDE: 81° 33.7' W ( -81.56170) The bench mark is a disk set in a rock located on the west side of the island, 104 m (342 ft) NW of the south end of the island, 29.41 m (96.5 ft) NW of hydrographic mark EASTON 1934, 14.84 m (48.7 ft) ENE of bench mark NO 2 1973, 12.77 m (49.1 ft) SSE of "Lag Screw", 8.05 m (26.4 ft) east of the rock edge, and 4.30 m (14.1 ft) north of a metal witness post.
U.S. DEPARTMENT OF COMMERCE National Oceanic and Atmospheric Administration National Ocean Service Page 4 of 6 Station ID: 8724373 PUBLICATION DATE: 02/05/2004 Name: PUMPKIN KEY, SUGARLOAF CHANNEL FL NOAA Chart: 11448 Latitude: 24° 43.0' N ( 24.71670) USGS Quad: SUGARLOAF KEY Longitude: 81° 33.7' W ( -81.56170) T I D A L B E N C H M A R K S BENCH MARK STAMPING: DESIGNATION: 872 4373 LAG BOLT ALIAS: NO STAMPING 1 MONUMENTATION: See descriptive text VM#: 7032 AGENCY: Unknown IDB PID#: SETTING CLASSIFICATION: Rock OPUS PID: LATITUDE: 24° 43.0' N ( 24.71670) LONGITUDE: 81° 33.7' W ( -81.56170) The bench mark is a copper lag screw set in rock, 91 m (300 ft) NW of the south end of the island, 19.05 m (62.5 ft) WNW of bench mark EASTON 1934, 12.77 m (41.9 ft) NNW of bench mark NO 3 1973, and 6.58 m (21.6 ft) west of bench mark NO 1 1973.
U.S. DEPARTMENT OF COMMERCE National Oceanic and Atmospheric Administration National Ocean Service Page 5 of 6 Station ID: 8724373 PUBLICATION DATE: 02/05/2004 Name: PUMPKIN KEY, SUGARLOAF CHANNEL FL NOAA Chart: 11448 Latitude: 24° 43.0' N ( 24.71670) USGS Quad: SUGARLOAF KEY Longitude: 81° 33.7' W ( -81.56170) T I D A L D A T U M S Tidal datums at PUMPKIN KEY, SUGARLOAF CHANNEL based on: LENGTH OF SERIES: 3 MONTHS TIME PERIOD: December 1973 - February 1974 TIDAL EPOCH: 1983-2001 CONTROL TIDE STATION: 8724580 KEY WEST Elevations of tidal datums referred to Mean Lower Low Water (MLLW), in METERS: MEAN HIGHER HIGH WATER MHHW = 0.813 MEAN HIGH WATER MHW = 0.724 MEAN TIDE LEVEL MTL = 0.405 MEAN SEA LEVEL MSL = 0.389 MEAN LOW WATER MLW = 0.087 MEAN LOWER LOW WATER MLLW = 0.000 North American Vertical Datum (NAVD88) Bench Mark Elevation Information In METERS above: Stamping or Designation MLLW MHW EASTON 1934 0.941 0.217 NO 1 1973 0.780 0.056 NO 2 1973 0.886 0.162 NO 3 1973 0.800 0.076 872 4373 LAG BOLT 0.766 0.042
U.S. DEPARTMENT OF COMMERCE National Oceanic and Atmospheric Administration National Ocean Service Page 6 of 6 Station ID: 8724373 PUBLICATION DATE: 02/05/2004 Name: PUMPKIN KEY, SUGARLOAF CHANNEL FL NOAA Chart: 11448 Latitude: 24° 43.0' N ( 24.71670) USGS Quad: SUGARLOAF KEY Longitude: 81° 33.7' W ( -81.56170) 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.