U.S. DEPARTMENT OF COMMERCE National Oceanic and Atmospheric Administration National Ocean Service Datums Page Page 1 of 7 Station ID: 8726657 PUBLICATION DATE: 02/05/2004 Name: DAVIS ISLAND, HILLSBOROUGH BAY FL NOAA Chart: 11417 Latitude: 27° 54.5' N ( 27.90830) USGS Quad: TAMPA Longitude: 82° 27.1' W ( -82.45170) To reach the tidal marks from the Peter O. Knight Airport administration building on Severn Road, proceed east and then south on Severn Road (around the seaplane basin) to the Davis Island Yacht Club. The bench marks are around the seaplane basin. The tide station was located on the westernmost pier at the yacht club. T I D A L B E N C H M A R K S PRIMARY BENCH MARK STAMPING: 6657 B 1976 DESIGNATION: 872 6657 B TIDAL MONUMENTATION: Tidal Station disk VM#: 6797 AGENCY: National Ocean Survey (NOS) IDB PID#: AG7511 SETTING CLASSIFICATION: Concrete base OPUS PID#: AG7511 LATITUDE: 27° 54.5' N ( 27.90830) LONGITUDE: 82° 27.0' W ( -82.45000) The primary bench mark is a disk set in the concrete base for a former boat hoist west of the inshore end of the center of three piers located along the south wall of the seaplane basin, 48 m (158 ft) east of the NW corner of the seawall, 29 m (95 ft) NE of the NW corner of the yacht club building, and 8.23 m (27.0 ft) west of a telephone booth.
U.S. DEPARTMENT OF COMMERCE National Oceanic and Atmospheric Administration National Ocean Service Page 2 of 7 Station ID: 8726657 PUBLICATION DATE: 02/05/2004 Name: DAVIS ISLAND, HILLSBOROUGH BAY FL NOAA Chart: 11417 Latitude: 27° 54.5' N ( 27.90830) USGS Quad: TAMPA Longitude: 82° 27.1' W ( -82.45170) T I D A L B E N C H M A R K S BENCH MARK STAMPING: 6657 A 1976 DESIGNATION: 872 6657 A TIDAL MONUMENTATION: Tidal Station disk VM#: 6796 AGENCY: National Ocean Survey (NOS) IDB PID#: AG7512 SETTING CLASSIFICATION: Sea wall OPUS PID#: AG7512 LATITUDE: 27° 54.5' N ( 27.90830) LONGITUDE: 82° 27.1' W ( -82.45170) The bench mark is a disk set in the top of a concrete seawall at the inshore end of the westernmost pier located along the south wall of the seaplane basin, 54 m (177 ft) west of bench mark 6657 B 1976, 49 m (160 ft) NW of the NW corner of the yacht club building, 0.46 m (1.5 ft) SE of the corner of the seawall, and 0.30 m (1.0 ft) south of the westernmost pier. BENCH MARK STAMPING: 6657 C 1976 DESIGNATION: 872 6657 C TIDAL MONUMENTATION: Tidal Station disk VM#: 6798 AGENCY: National Ocean Survey (NOS) IDB PID#: AG7510 SETTING CLASSIFICATION: Sea wall OPUS PID: LATITUDE: 27° 54.5' N ( 27.90830) LONGITUDE: 82° 27.0' W ( -82.45000) The bench mark is a disk set in a concrete seawall west of the inshore end of the easternmost pier located along the south wall of the seaplane basin, 48 m (158 ft) NE of NE corner of the yacht club building, and 10.97 m (36.0 ft) SW of a double-wing boat davit.
U.S. DEPARTMENT OF COMMERCE National Oceanic and Atmospheric Administration National Ocean Service Page 3 of 7 Station ID: 8726657 PUBLICATION DATE: 02/05/2004 Name: DAVIS ISLAND, HILLSBOROUGH BAY FL NOAA Chart: 11417 Latitude: 27° 54.5' N ( 27.90830) USGS Quad: TAMPA Longitude: 82° 27.1' W ( -82.45170) T I D A L B E N C H M A R K S BENCH MARK STAMPING: 6657 G 1990 DESIGNATION: 872 6657 G TIDAL MONUMENTATION: Flange-encased Rod VM#: 6801 AGENCY: National Ocean Service (NOS) IDB PID#: AG9408 SETTING CLASSIFICATION: Stainless steel rod OPUS PID: LATITUDE: 27° 54.6' N ( 27.91000) LONGITUDE: 82° 26.8' W ( -82.44670) The bench mark is a flange-encased rod located on the east side of Severn Road east of a beach area at the eastern shore of the seaplane basin, 110 m (360 ft) north of the entrance to Davis Island Yacht Club, 6.61 m (21.7 ft) west of a 0.37 m (1.2 ft) diameter cabbage palm, 5.12 m (16.8 ft) east of the centerline of Severn Road, and 5.12 m (16.8 ft) west of a witness post. The datum point is the top of a stainless steel rod driven 17.1 m (56 ft) to refusal, and encased in a PVC pipe and logo cap.
U.S. DEPARTMENT OF COMMERCE National Oceanic and Atmospheric Administration National Ocean Service Page 4 of 7 Station ID: 8726657 PUBLICATION DATE: 02/05/2004 Name: DAVIS ISLAND, HILLSBOROUGH BAY FL NOAA Chart: 11417 Latitude: 27° 54.5' N ( 27.90830) USGS Quad: TAMPA Longitude: 82° 27.1' W ( -82.45170) T I D A L B E N C H M A R K S BENCH MARK STAMPING: KNIGHT NO 2 1946 DESIGNATION: KINGHT RM 2 MONUMENTATION: Reference Mark disk VM#: 6802 AGENCY: US Coast and Geodetic Survey (USC&GS) IDB PID#: AG6026 SETTING CLASSIFICATION: Concrete sea wall OPUS PID: LATITUDE: 27° 54.7' N ( 27.91170) LONGITUDE: 82° 26.9' W ( -82.44830) The bench mark is a disk set in the east end of a concrete seawall along the north shore of the seaplane basin, 114 m (375 ft) SE of the airport administration building, 12.80 m (42.0 ft) west of the extended east/west wall of a large brick hangar, and 7.62 m (25.0 ft) south of the centerline of the paved road along the south end of the airport.
U.S. DEPARTMENT OF COMMERCE National Oceanic and Atmospheric Administration National Ocean Service Page 5 of 7 Station ID: 8726657 PUBLICATION DATE: 02/05/2004 Name: DAVIS ISLAND, HILLSBOROUGH BAY FL NOAA Chart: 11417 Latitude: 27° 54.5' N ( 27.90830) USGS Quad: TAMPA Longitude: 82° 27.1' W ( -82.45170) T I D A L B E N C H M A R K S BENCH MARK STAMPING: Q 261 1966 DESIGNATION: Q 261 MONUMENTATION: Bench Mark disk VM#: 6803 AGENCY: US Coast and Geodetic Survey (USC&GS) IDB PID#: AG6024 SETTING CLASSIFICATION: Concrete sea wall OPUS PID: LATITUDE: 27° 54.8' N ( 27.91330) LONGITUDE: 82° 26.8' W ( -82.44670) The bench mark is a disk set in the top of a former concrete seawall which has had fill installed around it, 0.2 km (0.1 mi) east of the airport administration building, 55 m (180 ft) west of the south end of the extended centerline of the north/south runway, 20.12 m (66.0 ft) SE of the center of the junction of a paved road and a drive leading to the hangars, and 15.54 m (51.0 ft) SW of a fence corner.
U.S. DEPARTMENT OF COMMERCE National Oceanic and Atmospheric Administration National Ocean Service Page 6 of 7 Station ID: 8726657 PUBLICATION DATE: 02/05/2004 Name: DAVIS ISLAND, HILLSBOROUGH BAY FL NOAA Chart: 11417 Latitude: 27° 54.5' N ( 27.90830) USGS Quad: TAMPA Longitude: 82° 27.1' W ( -82.45170) T I D A L D A T U M S Tidal datums at DAVIS ISLAND, HILLSBOROUGH BAY based on: LENGTH OF SERIES: 1 YEAR TIME PERIOD: June 1990 - May 1991 TIDAL EPOCH: 1983-2001 CONTROL TIDE STATION: 8726520 ST. PETERSBURG, TAMPA BAY Elevations of tidal datums referred to Mean Lower Low Water (MLLW), in METERS: HIGHEST OBSERVED WATER LEVEL (03/03/1991) = 1.362 MEAN HIGHER HIGH WATER MHHW = 0.800 MEAN HIGH WATER MHW = 0.699 North American Vertical Datum NAVD88 = 0.523 MEAN SEA LEVEL MSL = 0.431 MEAN TIDE LEVEL MTL = 0.421 MEAN LOW WATER MLW = 0.143 MEAN LOWER LOW WATER MLLW = 0.000 LOWEST OBSERVED WATER LEVEL (01/19/1977) = -0.622 North American Vertical Datum (NAVD88) Bench Mark Elevation Information In METERS above: Stamping or Designation MLLW MHW 6657 B 1976 2.286 1.587 6657 A 1976 1.974 1.275 6657 C 1976 2.039 1.340 6657 G 1990 2.163 1.464 KNIGHT NO 2 1946 2.088 1.389 Q 261 1966 2.103 1.405
U.S. DEPARTMENT OF COMMERCE National Oceanic and Atmospheric Administration National Ocean Service Page 7 of 7 Station ID: 8726657 PUBLICATION DATE: 02/05/2004 Name: DAVIS ISLAND, HILLSBOROUGH BAY FL NOAA Chart: 11417 Latitude: 27° 54.5' N ( 27.90830) USGS Quad: TAMPA Longitude: 82° 27.1' W ( -82.45170) 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.