U.S. DEPARTMENT OF COMMERCE National Oceanic and Atmospheric Administration National Ocean Service Datums Page Page 1 of 6 Station ID: 8724189 PUBLICATION DATE: 09/15/2004 Name: WATER KEY, BIG SPANISH CHANNEL FL NOAA Chart: 11448 Latitude: 24° 44.4' N ( 24.74000) USGS Quad: BIG PINE KEY Longitude: 81° 20.5' W ( -81.34170) To reach the tidal bench marks from No Name Key, proceed north by boat 3.9 km (2.4 statute mi) to the west point of Water Key. The bench marks are located on the west point in the center clearing surrounded by mangrove bushes. The tide gage and staff were located north of the west point of the key. T I D A L B E N C H M A R K S PRIMARY BENCH MARK STAMPING: NO 1 1935 DESIGNATION: 872 4189 TIDAL 1 MONUMENTATION: Tidal Station disk VM#: 6409 AGENCY: US Coast and Geodetic Survey (USC&GS) IDB PID#: SETTING CLASSIFICATION: Concrete monument OPUS PID: LATITUDE: 24° 44.4' N ( 24.74000) LONGITUDE: 81° 20.5' W ( -81.34170) The primary bench mark is a disk set in a concrete monument located at the northwest tip of the west end of the key, 30 m (98 ft) NNW of bench mark NO 5 1974, 0.30 m (1.0 ft) SE of a wooden witness post with a sign attached, 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 6 Station ID: 8724189 PUBLICATION DATE: 09/15/2004 Name: WATER KEY, BIG SPANISH CHANNEL FL NOAA Chart: 11448 Latitude: 24° 44.4' N ( 24.74000) USGS Quad: BIG PINE KEY Longitude: 81° 20.5' W ( -81.34170) T I D A L B E N C H M A R K S BENCH MARK STAMPING: GRASSY 1935 DESIGNATION: GRASSY MONUMENTATION: Gravity Station disk VM#: 6406 AGENCY: US Coast and Geodetic Survey (USC&GS) IDB PID#: AA1529 SETTING CLASSIFICATION: Set in concrete in a clay tile pipe OPUS PID: LATITUDE: 24° 44.3' N ( 24.73830) LONGITUDE: 81° 20.5' W ( -81.34170) The bench mark is a disk set in concrete in the top of a 0.15 m (0.5 ft) diameter terra cotta pipe, 100 m (328 ft) NE of the extreme southerwesten point, 30 m (98 ft) NW of the south side of the key, 0.18 m (0.6 ft) east 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 3 of 6 Station ID: 8724189 PUBLICATION DATE: 09/15/2004 Name: WATER KEY, BIG SPANISH CHANNEL FL NOAA Chart: 11448 Latitude: 24° 44.4' N ( 24.74000) USGS Quad: BIG PINE KEY Longitude: 81° 20.5' W ( -81.34170) T I D A L B E N C H M A R K S BENCH MARK STAMPING: GRASSY NO 1 1935 DESIGNATION: GRASSY RM 1 MONUMENTATION: Reference Mark disk VM#: 6407 AGENCY: US Coast and Geodetic Survey (USC&GS) IDB PID#: AE4393 SETTING CLASSIFICATION: Concrete monument OPUS PID: LATITUDE: 24° 44.4' N ( 24.74000) LONGITUDE: 81° 20.5' W ( -81.34170) The bench mark is a disk set in a concrete monument, 18.32 m (60.1 ft) NE of bench mark GRASSY NO 2 1935, 12.59 m (41.3 ft) north of bench mark GRASSY 1935, 0.30 m (1.0 ft) south of a witness post, and 0.03 m (0.1 ft) above ground level.
U.S. DEPARTMENT OF COMMERCE National Oceanic and Atmospheric Administration National Ocean Service Page 4 of 6 Station ID: 8724189 PUBLICATION DATE: 09/15/2004 Name: WATER KEY, BIG SPANISH CHANNEL FL NOAA Chart: 11448 Latitude: 24° 44.4' N ( 24.74000) USGS Quad: BIG PINE KEY Longitude: 81° 20.5' W ( -81.34170) T I D A L B E N C H M A R K S BENCH MARK STAMPING: GRASSY NO 2 1935 DESIGNATION: GRASSY RM 2 MONUMENTATION: Reference Mark disk VM#: 6408 AGENCY: US Coast and Geodetic Survey (USC&GS) IDB PID#: AE4394 SETTING CLASSIFICATION: Concrete monument OPUS PID: LATITUDE: 24° 44.4' N ( 24.74000) LONGITUDE: 81° 20.5' W ( -81.34170) The bench mark is a disk set in a concrete monument, 13.26 m (43.5 ft) west of bench mark GRASSY 1935, 0.24 m (0.8 ft) WSW of a witness post, and 3 cm (0.1 ft) above ground level. BENCH MARK STAMPING: NO 5 1974 DESIGNATION: 872 4189 TIDAL 5 MONUMENTATION: Tidal Station disk VM#: 6410 AGENCY: National Ocean Survey (NOS) IDB PID#: SETTING CLASSIFICATION: Copper-clad steel rod OPUS PID: LATITUDE: 24° 44.4' N ( 24.74000) LONGITUDE: 81° 20.5' W ( -81.34170) The bench mark is a disk located 56 m (185 ft) NNW of bench mark GRASSY 1935, 30 m (100 ft) SE of bench mark NO 1 1935, 4.42 m (14.5 ft) NNE of a witness sign nailed to a tree, and 0.30 m (1.0 ft) SE of a witness post. The mark is set 0.09 m (0.3 ft) above ground level, crimped to the top of a copper-clad steel rod driven an unspecified depth to refusal, and encased in concrete.
U.S. DEPARTMENT OF COMMERCE National Oceanic and Atmospheric Administration National Ocean Service Page 5 of 6 Station ID: 8724189 PUBLICATION DATE: 09/15/2004 Name: WATER KEY, BIG SPANISH CHANNEL FL NOAA Chart: 11448 Latitude: 24° 44.4' N ( 24.74000) USGS Quad: BIG PINE KEY Longitude: 81° 20.5' W ( -81.34170) T I D A L D A T U M S Tidal datums at WATER KEY, BIG SPANISH CHANNEL based on: LENGTH OF SERIES: 1 MONTH TIME PERIOD: August 1974 - August 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 = 0.444 MEAN HIGH WATER MHW = 0.372 MEAN TIDE LEVEL MTL = 0.223 MEAN SEA LEVEL MSL = 0.222 MEAN LOW WATER MLW = 0.074 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 1 1935 0.467 0.095 GRASSY 1935 0.642 0.270 GRASSY NO 1 1935 0.622 0.250 GRASSY NO 2 1935 0.551 0.179 NO 5 1974 0.571 0.199
U.S. DEPARTMENT OF COMMERCE National Oceanic and Atmospheric Administration National Ocean Service Page 6 of 6 Station ID: 8724189 PUBLICATION DATE: 09/15/2004 Name: WATER KEY, BIG SPANISH CHANNEL FL NOAA Chart: 11448 Latitude: 24° 44.4' N ( 24.74000) USGS Quad: BIG PINE KEY Longitude: 81° 20.5' W ( -81.34170) 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.