U.S. DEPARTMENT OF COMMERCE National Oceanic and Atmospheric Administration National Ocean Service Datums Page Page 1 of 6 Station ID: 8726574 PUBLICATION DATE: 09/16/2003 Name: BOCA CIEGA BAY FL NOAA Chart: 11412 Latitude: 27° 48.5' N ( 27.80830) USGS Quad: SEMINOLE Longitude: 82° 47.7' W ( -82.79500) To reach the tidal bench marks from the intersection of State Road 699 (Gulf Boulevard) and Welch Causeway (State Road 666, 150th Avenue) in Madeira Beach, proceed NE on Welch Causeway for 1.3 km (0.8 mi) to the Madeira Shopping Center and McDonalds entrance, turn left and go 0.2 km (0.1 mi) to a stop sign at Black Hawk Road, turn left and go 152 m (500 ft) to the end of the parking lot at Brown Derby Restaurant (on the left) and American Legion Post 273 (on the right). The bench marks are between Brown Derby Restaurant and the Welch Causeway bridge. The tide gauge and staff were on the SE corner of the wooden pier behind the post. Access to the pier is through the American Legion Post 273 building. T I D A L B E N C H M A R K S PRIMARY BENCH MARK STAMPING: 6574 A 1976 DESIGNATION: 872 6574 A TIDAL MONUMENTATION: Tidal Station disk VM#: 6577 AGENCY: National Ocean Survey (NOS) IDB PID#: AG7426 SETTING CLASSIFICATION: Concrete foundation OPUS PID: LATITUDE: 27° 48.6' N ( 27.81000) LONGITUDE: 82° 47.7' W ( -82.79500) The primary bench mark is a disk set in the top of the foundation of the American Legion Hall (Post 273) flagpole, 6.46 m (21.2 ft) east of the front door of the building, 4.11 m (13.5 ft) west of the curb of the road leading to the building, and 0.15 m (0.5 ft) east of the flagpole.
U.S. DEPARTMENT OF COMMERCE National Oceanic and Atmospheric Administration National Ocean Service Page 2 of 6 Station ID: 8726574 PUBLICATION DATE: 09/16/2003 Name: BOCA CIEGA BAY FL NOAA Chart: 11412 Latitude: 27° 48.5' N ( 27.80830) USGS Quad: SEMINOLE Longitude: 82° 47.7' W ( -82.79500) T I D A L B E N C H M A R K S BENCH MARK STAMPING: 6574 B 1976 DESIGNATION: 872 6574 B TIDAL MONUMENTATION: Tidal Station disk VM#: 6578 AGENCY: National Ocean Survey (NOS) IDB PID#: AG7424 SETTING CLASSIFICATION: Concrete wing wall OPUS PID: LATITUDE: 27° 48.5' N ( 27.80830) LONGITUDE: 82° 47.7' W ( -82.79500) The bench mark is a disk set in the NE wingwall of the Madeira Beach Causeway bascule bridge, 10.76 m (35.3 ft) north of the bridge guardrail, 10.18 m (33.4 ft) NE of the NE end of the wingwall, 0.37 m (1.2 ft) west of the east end of the wingwall, and 4 m (13 ft) below the highway.
U.S. DEPARTMENT OF COMMERCE National Oceanic and Atmospheric Administration National Ocean Service Page 3 of 6 Station ID: 8726574 PUBLICATION DATE: 09/16/2003 Name: BOCA CIEGA BAY FL NOAA Chart: 11412 Latitude: 27° 48.5' N ( 27.80830) USGS Quad: SEMINOLE Longitude: 82° 47.7' W ( -82.79500) T I D A L B E N C H M A R K S BENCH MARK STAMPING: 209 NO 2 RESET 1975 DESIGNATION: 209 2 RESET ALIAS: SRD 209 MONUMENTATION: Survey disk VM#: 6580 AGENCY: Florida State Road Department (FLSRD) IDB PID#: AG0166 SETTING CLASSIFICATION: Concrete bridge guardrail OPUS PID: LATITUDE: 27° 48.5' N ( 27.80830) LONGITUDE: 82° 47.6' W ( -82.79330) The bench mark is a disk set in the top of the concrete bridge guardrail in the NE corner of the Welch Causeway bridge, 1.1 km (0.7 mi) east of the intersection of Welch Causeway and Gulf Boulevard. BENCH MARK STAMPING: 6574 C 1990 DESIGNATION: 872 6574 C TIDAL MONUMENTATION: Tidal Station disk VM#: 6581 AGENCY: Florida Department of Natural Resources (FLDNR) IDB PID#: AG9392 SETTING CLASSIFICATION: Concrete foundation OPUS PID: LATITUDE: 27° 48.5' N ( 27.80830) LONGITUDE: 82° 47.7' W ( -82.79500) The bench mark is a disk set in the foundation that supports an old anchor and two cannon barrels, 6.19 m (20.3 ft) ) SW of the bow of the fixed boat that is Brown Derby Restaurant, 0.70 m (2.3 ft) north of the south side of a seawall, and 0.27 m (0.9 ft) north of the south edge of the foundation.
U.S. DEPARTMENT OF COMMERCE National Oceanic and Atmospheric Administration National Ocean Service Page 4 of 6 Station ID: 8726574 PUBLICATION DATE: 09/16/2003 Name: BOCA CIEGA BAY FL NOAA Chart: 11412 Latitude: 27° 48.5' N ( 27.80830) USGS Quad: SEMINOLE Longitude: 82° 47.7' W ( -82.79500) T I D A L B E N C H M A R K S BENCH MARK STAMPING: WELCH JAX 1985 DESIGNATION: WELCH JAX MONUMENTATION: Survey disk VM#: 6582 AGENCY: US Army Corps of Engineers (USCOE) IDB PID#: AG9393 SETTING CLASSIFICATION: Sidewalk OPUS PID: LATITUDE: 27° 48.5' N ( 27.80830) LONGITUDE: 82° 47.7' W ( -82.79500) The bench mark is a disk set in the sidewalk on the Welch Causeway bridge, 58.70 m (192.6 ft) NE of the point where the concrete ends and the metal lift begins, 43.80 m (143.7 ft) SE of the NE end of the bridge and of bench mark 209 NO 2 RESET 1975, and 8.11 m (26.6 ft) north of the centerline of Welch Causeway.
U.S. DEPARTMENT OF COMMERCE National Oceanic and Atmospheric Administration National Ocean Service Page 5 of 6 Station ID: 8726574 PUBLICATION DATE: 09/16/2003 Name: BOCA CIEGA BAY FL NOAA Chart: 11412 Latitude: 27° 48.5' N ( 27.80830) USGS Quad: SEMINOLE Longitude: 82° 47.7' W ( -82.79500) T I D A L D A T U M S Tidal datums at BOCA CIEGA BAY based on: LENGTH OF SERIES: 1 MONTH TIME PERIOD: August 1990 - August 1990 TIDAL EPOCH: 1983-2001 CONTROL TIDE STATION: 8726724 CLEARWATER BEACH, GULF OF MEXICO Elevations of tidal datums referred to Mean Lower Low Water (MLLW), in METERS: MEAN HIGHER HIGH WATER MHHW = 0.736 MEAN HIGH WATER MHW = 0.648 North American Vertical Datum NAVD88 = 0.498 MEAN SEA LEVEL MSL = 0.396 MEAN TIDE LEVEL MTL = 0.392 MEAN LOW WATER MLW = 0.136 MEAN LOWER LOW WATER MLLW = 0.000 North American Vertical Datum (NAVD88) Bench Mark Elevation Information In METERS above: Stamping or Designation MLLW MHW 6574 A 1976 1.895 1.247 6574 B 1976 1.480 0.832 209 NO 2 RESET 1975 6.419 5.771 6574 C 1990 1.959 1.311 WELCH JAX 1985 7.647 6.999
U.S. DEPARTMENT OF COMMERCE National Oceanic and Atmospheric Administration National Ocean Service Page 6 of 6 Station ID: 8726574 PUBLICATION DATE: 09/16/2003 Name: BOCA CIEGA BAY FL NOAA Chart: 11412 Latitude: 27° 48.5' N ( 27.80830) USGS Quad: SEMINOLE Longitude: 82° 47.7' W ( -82.79500) 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.