U.S. DEPARTMENT OF COMMERCE National Oceanic and Atmospheric Administration National Ocean Service Datums Page Page 1 of 4 PUBLICATION DATE: 09/13/1983 Station ID: 8725383 SUPERCEDED DATE: 04/21/2003 Name: CAPTIVA ISLAND, SOUTH END, GULF OF MEXICO FLORIDA NOAA Chart: 11426 Latitude: 26° 28.7' N USGS Quad: WULFERT Longitude: 82° 11.0' W To reach the tidal bench marks from Punta Rassa, go SW over the toll bridge to Sanibel Island, and continue west from the town of Sanibel to the bridge over Blind Pass connnecting Sanibel Island to Captiva Island. The bench marks are on Sanibel Island and Captiva Island along the road leading from the town of Sanibel to the bridge over Blind Pass. The staff was on the Gulf of Mexico on the west side of the south end of Captiva Island. T I D A L B E N C H M A R K S PRIMARY BENCH MARK STAMPING: NO 1 1965 MONUMENTATION: Survey Disk VM#: 7315 AGENCY: PID#: AG1761 SETTING CLASSIFICATION: Concrete Base of Rafter The bench mark is set in top of the SW corner of the west one of 5 concrete bases which support rafters of the Castaway Motel and Novelty Shop, 45 feet (13.7 m) east of the centerline of the highway, 7.7 feet (2.3 m) SW of the SW corner of the motel office at the Novelty Shop, and 1.5 feet (0.5 m) SSE of the SW corner of the sidewalk along the south side of the building and level with the highway. BENCH MARK STAMPING: NO 2 1965 MONUMENTATION: Survey Disk VM#: 7316 AGENCY: PID#: AG1764 SETTING CLASSIFICATION: Bridge Abutment The bench mark is set in the top of the NW abutment of the bridge over Blind Pass, between Sanibel and Captiva Islands, 23 feet (7.0 m) SW of the centerline of the highway about 1.0 foot (0.3 m) from the edge of the foundation and 4 feet (1.2 m) lower than the bridge floor.
U.S. DEPARTMENT OF COMMERCE National Oceanic and Atmospheric Administration National Ocean Service Page 2 of 4 PUBLICATION DATE: 09/13/1983 Station ID: 8725383 SUPERCEDED DATE: 04/21/2003 Name: CAPTIVA ISLAND, SOUTH END, GULF OF MEXICO FLORIDA NOAA Chart: 11426 Latitude: 26° 28.7' N USGS Quad: WULFERT Longitude: 82° 11.0' W T I D A L B E N C H M A R K S BENCH MARK STAMPING: Y 242 MONUMENTATION: Survey Disk VM#: 7317 AGENCY: PID#: AG1762 SETTING CLASSIFICATION: Bridge Abutment The bench mark is set in the top of the SW end of the SE concrete abutment of the bridge over Blind Pass between Captiva and Sanibel Island, 18.5 feet (5.6 m) SW of the centerline of the highway and level with the road. BENCH MARK STAMPING: X 241 1965 MONUMENTATION: Survey Disk VM#: 7318 AGENCY: PID#: AG1760 SETTING CLASSIFICATION: Copper Clad Rod The bench mark is 0.05 miles (0.08 km) south of the Castaway Hotel on the inside of a long curve, 44.8 feet (13.7 m) east of the centerline of the highway, 24 feet (7.3 m) south of the stump of a tree that projects 7 feet (2.1 m) and 1.5 feet (0.5 m) north of power pole #477. The bench mark is set on top of a copper rod driven 58.5 feet (17.8 m) and protected by a 4-inch iron pipe and level with the highway flush with the ground.
U.S. DEPARTMENT OF COMMERCE National Oceanic and Atmospheric Administration National Ocean Service Page 3 of 4 PUBLICATION DATE: 09/13/1983 Station ID: 8725383 SUPERCEDED DATE: 04/21/2003 Name: CAPTIVA ISLAND, SOUTH END, GULF OF MEXICO FLORIDA NOAA Chart: 11426 Latitude: 26° 28.7' N USGS Quad: WULFERT Longitude: 82° 11.0' W T I D A L D A T U M S Tidal datums at CAPTIVA ISLAND, SOUTH END, GULF OF MEXICO based on: LENGTH OF SERIES: 11 MONTHS TIME PERIOD: APRIL 1965 - MARCH 1966 TIDAL EPOCH: 1960-1978 CONTROL TIDE STATION: 8725110 NAPLES Elevations of tidal datums referred to Mean Lower Low Water (MLLW), in FEET: HIGHEST OBSERVED WATER LEVEL (09/09/1965) = 4.01 MEAN HIGHER HIGH WATER MHHW = 2.46 MEAN HIGH WATER MHW = 2.21 MEAN TIDE LEVEL MTL = 1.36 * NATIONAL GEODETIC VERTICAL DATUM NGVD29 = 0.94 MEAN LOW WATER MLW = 0.52 MEAN LOWER LOW WATER MLLW = 0.00 LOWEST OBSERVED WATER LEVEL (02/04/1966) = -1.99 * NGVD reference based on adjustment of 1966 and NOS levels of1965. North American Vertical Datum (NAVD88) Bench Mark Elevation Information In FEET above: Stamping or Designation MLLW MHW NO 1 1965 5.37 3.16 NO 2 1965 7.47 5.26 Y 242 10.58 8.37 X 241 1965 3.65 1.44
U.S. DEPARTMENT OF COMMERCE National Oceanic and Atmospheric Administration National Ocean Service Page 4 of 4 PUBLICATION DATE: 09/13/1983 Station ID: 8725383 SUPERCEDED DATE: 04/21/2003 Name: CAPTIVA ISLAND, SOUTH END, GULF OF MEXICO FLORIDA NOAA Chart: 11426 Latitude: 26° 28.7' N USGS Quad: WULFERT Longitude: 82° 11.0' 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.