U.S. DEPARTMENT OF COMMERCE National Oceanic and Atmospheric Administration National Ocean Service Datums Page Page 1 of 6 Station ID: 8727348 PUBLICATION DATE: 12/12/2003 Name: TWIN RIVERS MARINA, CRYSTAL RIVER FL NOAA Chart: 11409 Latitude: 28° 54.3' N ( 28.90500) USGS Quad: RED LEVEL Longitude: 82° 38.3' W ( -82.63830) To reach the tidal bench marks from the intersection of U.S. Highway 19/98 and State Road 44 in Crystal River, proceed 1.8 km (1.1 mi) SE along U.S. Highway 19/98 to County Road C-44 (Fort Island Road), then 8.5 km (5.3 mi) west on County Road C-44 to Seabreeze Point Road, then 0.6 km (0.4 mi) north along Seabreeze Point Road to Twin Rivers Marina. The bench marks are located in the vicinty of the marina and along Fort Island Road. The tide gage and staff were located on the wooden seawall at the marina. T I D A L B E N C H M A R K S PRIMARY BENCH MARK STAMPING: 4.70 DESIGNATION: 4.70 MONUMENTATION: Survey disk VM#: 7804 AGENCY: Florida Department of Transportation (FLDT) IDB PID#: AL7276 SETTING CLASSIFICATION: Culvert head wall OPUS PID: LATITUDE: 28° 54.0' N ( 28.90000) LONGITUDE: 82° 38.2' W ( -82.63670) The primary bench mark is a disk set in the top of the south concrete culvert headwall for a creek under County Road C-444, 7 m (24 ft) west of the east end of the head wall, 5 m (18 ft) south of the centerline of the highway, 4 m (12 ft) east of the west end of the headwall, and 0.3 m (1 ft) below the highway.
U.S. DEPARTMENT OF COMMERCE National Oceanic and Atmospheric Administration National Ocean Service Page 2 of 6 Station ID: 8727348 PUBLICATION DATE: 12/12/2003 Name: TWIN RIVERS MARINA, CRYSTAL RIVER FL NOAA Chart: 11409 Latitude: 28° 54.3' N ( 28.90500) USGS Quad: RED LEVEL Longitude: 82° 38.3' W ( -82.63830) T I D A L B E N C H M A R K S BENCH MARK STAMPING: NO 2 1973 DESIGNATION: 872 7348 TIDAL 2 MONUMENTATION: Tidal Station disk VM#: 7801 AGENCY: National Ocean Survey (NOS) IDB PID#: AL7279 SETTING CLASSIFICATION: Concrete base OPUS PID: LATITUDE: 28° 54.3' N ( 28.90500) LONGITUDE: 82° 38.4' W ( -82.64000) The bench mark is a disk set flush in the top south corner of a concrete base for a steel upright for the boat shed, 1 m (3 ft) inside the boat shed door, 0.3 m (1 ft) NW of the NW side of the boat ramp, and 0.3 m (1 ft) above the ramp.
U.S. DEPARTMENT OF COMMERCE National Oceanic and Atmospheric Administration National Ocean Service Page 3 of 6 Station ID: 8727348 PUBLICATION DATE: 12/12/2003 Name: TWIN RIVERS MARINA, CRYSTAL RIVER FL NOAA Chart: 11409 Latitude: 28° 54.3' N ( 28.90500) USGS Quad: RED LEVEL Longitude: 82° 38.3' W ( -82.63830) T I D A L B E N C H M A R K S BENCH MARK STAMPING: 18.32 DESIGNATION: 18.32 SE ALIAS: SE MONUMENTATION: Survey disk VM#: 7802 AGENCY: Florida Department of Transportation (FLDT) IDB PID#: AL7277 SETTING CLASSIFICATION: Bridge abutment OPUS PID: LATITUDE: 28° 54.1' N ( 28.90170) LONGITUDE: 82° 38.7' W ( -82.64500) The bench mark is a disk set in the top of the concrete curb at the SE abutment of the County Road C-44 bridge over the Salt River, 5 m (15 ft) NE of the centerline of the highway, 0.3 m (1 ft) SW of a concrete rail, 0.24 m (0.8 ft) SE of the SE end of the bridge, 0.3 m (1 ft) above the road.
U.S. DEPARTMENT OF COMMERCE National Oceanic and Atmospheric Administration National Ocean Service Page 4 of 6 Station ID: 8727348 PUBLICATION DATE: 12/12/2003 Name: TWIN RIVERS MARINA, CRYSTAL RIVER FL NOAA Chart: 11409 Latitude: 28° 54.3' N ( 28.90500) USGS Quad: RED LEVEL Longitude: 82° 38.3' W ( -82.63830) T I D A L B E N C H M A R K S BENCH MARK STAMPING: 18.32 DESIGNATION: 18.32 NW ALIAS: NW MONUMENTATION: Survey disk VM#: 7803 AGENCY: Florida Department of Transportation (FLDT) IDB PID#: AL7278 SETTING CLASSIFICATION: Bridge abutment OPUS PID: LATITUDE: 28° 54.1' N ( 28.90170) LONGITUDE: 82° 38.8' W ( -82.64670) The bench mark is a disk set in the top of the concrete curb at the NW abutment of the County Road C-44 bridge over the Salt River, 5 m (15 ft) SW of the centerline of the highway, 0.3 m (1 ft) NW of a concrete rail, 0.24 m (0.8 ft) NW of the NW end of the bridge, and 0.09 m (0.3 ft) SE of the end of a metal guardrail.
U.S. DEPARTMENT OF COMMERCE National Oceanic and Atmospheric Administration National Ocean Service Page 5 of 6 Station ID: 8727348 PUBLICATION DATE: 12/12/2003 Name: TWIN RIVERS MARINA, CRYSTAL RIVER FL NOAA Chart: 11409 Latitude: 28° 54.3' N ( 28.90500) USGS Quad: RED LEVEL Longitude: 82° 38.3' W ( -82.63830) T I D A L D A T U M S Tidal datums at TWIN RIVERS MARINA, CRYSTAL RIVER based on: LENGTH OF SERIES: 6 MONTHS TIME PERIOD: January 1977 - June 1977 TIDAL EPOCH: 1983-2001 CONTROL TIDE STATION: 8727520 CEDAR KEY, GULF OF MEXICO Elevations of tidal datums referred to Mean Lower Low Water (MLLW), in METERS: MEAN HIGHER HIGH WATER MHHW = 0.773 MEAN HIGH WATER MHW = 0.673 North American Vertical Datum NAVD88 = 0.404 MEAN TIDE LEVEL MTL = 0.383 MEAN SEA LEVEL MSL = 0.377 MEAN LOW WATER MLW = 0.093 MEAN LOWER LOW WATER MLLW = 0.000 North American Vertical Datum (NAVD88) Bench Mark Elevation Information In METERS above: Stamping or Designation MLLW MHW 4.70 1.458 0.785 NO 2 1973 1.712 1.039 18.32 5.620 4.947 18.32 5.623 4.950
U.S. DEPARTMENT OF COMMERCE National Oceanic and Atmospheric Administration National Ocean Service Page 6 of 6 Station ID: 8727348 PUBLICATION DATE: 12/12/2003 Name: TWIN RIVERS MARINA, CRYSTAL RIVER FL NOAA Chart: 11409 Latitude: 28° 54.3' N ( 28.90500) USGS Quad: RED LEVEL Longitude: 82° 38.3' W ( -82.63830) 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.