U.S. DEPARTMENT OF COMMERCE National Oceanic and Atmospheric Administration National Ocean Service Datums Page Page 1 of 5 Station ID: 8770625 PUBLICATION DATE: 07/26/2011 Name: UMBRELLA POINT, TRINITY BAY TX NOAA Chart: 11327 Latitude: 29° 40.8' N ( 29.68000) USGS Quad: UMBRELLA POINT Longitude: 94° 52.1' W ( -94.86833) To reach the tidal bench marks from Texas Hwy. 146 south of Baytown, proceed 4.3 km (2.7 mi) east on Spur 55 (Fisher Dr.) to FM 1405, south on FM 1405 9.5 km (5.9 mi) to its end at FM 2354 and 5.6 km (3.5 mi) on North FM 2354 to Crawley's Fishing Camp. The bench marks are located in and around the parking area which is 0.3 km (0.2 mi) from the road at the end of the dirt driveway. T I D A L B E N C H M A R K S PRIMARY BENCH MARK STAMPING: 0625A 1994 DESIGNATION: 877 0625 A MONUMENTATION: Survey disk VM#: 16466 AGENCY: National Ocean Service (NOS) IDB PID#: SETTING CLASSIFICATION: Concrete slab OPUS PID: LATITUDE: 29° 40.8' N ( 29.68000) LONGITUDE: 94° 52.1' W ( -94.86830) The primary bench mark is a disk set flush in a concrete slab 13.72 m (45.0 ft) NW of the western end of the southern breakwater which encloses the boat basin, 11.28 m (37.0 ft) west of the seaward corner of the wall which extends along the southern-most boat ramp and 28.65 m (94.0 ft) south of Bench Mark 0625B 1994.
U.S. DEPARTMENT OF COMMERCE National Oceanic and Atmospheric Administration National Ocean Service Page 2 of 5 Station ID: 8770625 PUBLICATION DATE: 07/26/2011 Name: UMBRELLA POINT, TRINITY BAY TX NOAA Chart: 11327 Latitude: 29° 40.8' N ( 29.68000) USGS Quad: UMBRELLA POINT Longitude: 94° 52.1' W ( -94.86833) T I D A L B E N C H M A R K S BENCH MARK STAMPING: 0625B 1994 DESIGNATION: 877 0625 B MONUMENTATION: Survey disk VM#: 16467 AGENCY: National Ocean Service (NOS) IDB PID#: SETTING CLASSIFICATION: Boat ramp OPUS PID: LATITUDE: 29° 40.8' N ( 29.68000) LONGITUDE: 94° 52.1' W ( -94.86830) The bench mark is a disk set flush in the west end of the northern-most boat ramp in the Crawly boat basin, 1.22 m (4.0 ft) south of the northern wall which extends along the boat ramp, 7.32 m (24.0 ft) east of the SE corner of the bait shed, and 21 m (69 ft) west of the eastern-most piling of the pier which extends east from the bait shed. BENCH MARK STAMPING: 0625D 1994 DESIGNATION: 877 0625 D MONUMENTATION: Survey disk VM#: 16469 AGENCY: National Ocean Service (NOS) IDB PID#: SETTING CLASSIFICATION: Concrete slab OPUS PID: LATITUDE: 29° 40.8' N ( 29.68000) LONGITUDE: 94° 52.1' W ( -94.86830) The bench mark is a disk set flush in a concrete slab 1.22 m (4.0 ft) south of the south side of the fish cleaning shed, 1.83 m (6.0 ft) SW of the SE corner of the fish cleaning shed, 13.72 m (45.0 ft) SE of the mechanical boat lift ruins, and 8.23 m (27.0 ft) west of the SW corner of a small aluminum building next to the bait shed.
U.S. DEPARTMENT OF COMMERCE National Oceanic and Atmospheric Administration National Ocean Service Page 3 of 5 Station ID: 8770625 PUBLICATION DATE: 07/26/2011 Name: UMBRELLA POINT, TRINITY BAY TX NOAA Chart: 11327 Latitude: 29° 40.8' N ( 29.68000) USGS Quad: UMBRELLA POINT Longitude: 94° 52.1' W ( -94.86833) T I D A L B E N C H M A R K S BENCH MARK STAMPING: 0625E 1994 DESIGNATION: 877 0625 E MONUMENTATION: Survey disk VM#: 16470 AGENCY: National Ocean Service (NOS) IDB PID#: SETTING CLASSIFICATION: Concrete sea wall OPUS PID: LATITUDE: 29° 40.8' N ( 29.68000) LONGITUDE: 94° 52.1' W ( -94.86830) Bench mark is a disk set flush in the top of a concrete seawall 15.85 m (52.0 ft) north of the north end of the slab surrounding the boat lift ruins, 41.45 m (136.0 ft) NNW of Bench Mark 0625D 1994, and 9.45 m (31.0 ft) south of the northern corner of the sea wall.
U.S. DEPARTMENT OF COMMERCE National Oceanic and Atmospheric Administration National Ocean Service Page 4 of 5 Station ID: 8770625 PUBLICATION DATE: 07/26/2011 Name: UMBRELLA POINT, TRINITY BAY TX NOAA Chart: 11327 Latitude: 29° 40.8' N ( 29.68000) USGS Quad: UMBRELLA POINT Longitude: 94° 52.1' W ( -94.86833) T I D A L D A T U M S Tidal datums at UMBRELLA POINT, TRINITY BAY based on: LENGTH OF SERIES: 9 MONTHS TIME PERIOD: September 1995 - May 1996 TIDAL EPOCH: 1983-2001 CONTROL TIDE STATION: 8771450 GALVESTON PIER 21, GALVESTON CHANNEL Elevations of tidal datums referred to Mean Lower Low Water (MLLW), in METERS: MEAN HIGHER HIGH WATER MHHW = 0.388 MEAN HIGH WATER MHW = 0.376 MEAN SEA LEVEL MSL = 0.212 MEAN TIDE LEVEL MTL = 0.203 MEAN LOW WATER MLW = 0.029 MEAN LOWER LOW WATER MLLW = 0.000 North American Vertical Datum (NAVD88) Bench Mark Elevation Information In METERS above: Stamping or Designation MLLW MHW 0625A 1994 1.067 0.691 0625B 1994 0.799 0.423 0625D 1994 1.186 0.810 0625E 1994 0.834 0.458
U.S. DEPARTMENT OF COMMERCE National Oceanic and Atmospheric Administration National Ocean Service Page 5 of 5 Station ID: 8770625 PUBLICATION DATE: 07/26/2011 Name: UMBRELLA POINT, TRINITY BAY TX NOAA Chart: 11327 Latitude: 29° 40.8' N ( 29.68000) USGS Quad: UMBRELLA POINT Longitude: 94° 52.1' W ( -94.86833) 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.