U.S. DEPARTMENT OF COMMERCE National Oceanic and Atmospheric Administration National Ocean Service Datums Page Page 1 of 7 Station ID: 8760595 PUBLICATION DATE: 06/09/2003 Name: BRETON ISLAND LA NOAA Chart: 11363 Latitude: 29° 29.6' N ( 29.49330) USGS Quad: BRETON ISLANDS Longitude: 89° 10.4' W ( -89.17330) To reach the tidal bench marks from Venice, proceed by boat across the Mississippi River, then NE on Baptiste Collette Bayou for 13 km (8 mi) to the end of the channel markers, then NE across Breton Sound for 18 km (11 mi) to the Kerr-McGee oil facility on Breton Island. The bench marks are on the grounds of the oil facility and in the marsh to the north. The tide gage and staff were on the west side and NW corner, respectively, of the T-shaped wooden dock. T I D A L B E N C H M A R K S PRIMARY BENCH MARK STAMPING: 0595 A 1980 DESIGNATION: 876 0595 A MONUMENTATION: Tidal Station disk VM#: 7089 AGENCY: National Ocean Survey (NOS) IDB PID#: SETTING CLASSIFICATION: Stainless steel rod OPUS PID: LATITUDE: 29° 29.6' N ( 29.49330) LONGITUDE: 89° 10.4' W ( -89.17330) The primary bench mark is a disk located in the marsh NE of the circular bulkhead around the oil facility, 61 m (200 ft) NNE of Corps of Engineers (COE) bench mark 876 0595 USE 1, 55 m (182 ft) NNE of the bulkhead around the oil facility, 30 m (98 ft) north of the NE anchor pile of the radio tower guy wire system, and 24 m (80 ft) west of the west shoreline of the bay inside the east side of the island. The bench mark is set 9 cm (0.3 ft) below ground level, crimped to the top of a stainless steel rod driven 15.2 m (50 ft) to refusal, and encased in a 4-inch PVC pipe.
U.S. DEPARTMENT OF COMMERCE National Oceanic and Atmospheric Administration National Ocean Service Page 2 of 7 Station ID: 8760595 PUBLICATION DATE: 06/09/2003 Name: BRETON ISLAND LA NOAA Chart: 11363 Latitude: 29° 29.6' N ( 29.49330) USGS Quad: BRETON ISLANDS Longitude: 89° 10.4' W ( -89.17330) T I D A L B E N C H M A R K S BENCH MARK STAMPING: 0595 B 1980 DESIGNATION: 876 0595 B MONUMENTATION: Tidal Station disk VM#: 7090 AGENCY: National Ocean Survey (NOS) IDB PID#: SETTING CLASSIFICATION: Stainless steel rod OPUS PID: LATITUDE: 29° 29.6' N ( 29.49330) LONGITUDE: 89° 10.4' W ( -89.17330) The bench mark is a disk located in the marsh, 117 m (385 ft) NNE of the west radio tower guy wire anchor, 112 m (369 ft) north of COE bench mark 876 0595 USE 2, 110 m (360 ft) north of the circular bulkhead around the oil facility, 95 m (311 ft) NNW of the NE radio tower guy wire anchor, 67 m (219 ft) NNW of bench mark 0595 A 1980, and 18 m (58 ft) south of the shoreline of the small bay which is north of the oil facility. The bench mark is set 6 cm (0.2 ft) below ground level, crimped to the top of a stainless steel rod driven 16.8 m (55 ft) to refusal, and encased in a 4-inch PVC pipe. BENCH MARK STAMPING: 0595 C 1980 DESIGNATION: 876 0595 C MONUMENTATION: Tidal Station disk VM#: 7091 AGENCY: National Ocean Survey (NOS) IDB PID#: SETTING CLASSIFICATION: Stainless steel rod OPUS PID: LATITUDE: 29° 29.6' N ( 29.49330) LONGITUDE: 89° 10.4' W ( -89.17330) The bench mark is a disk located in the marsh, 107 m (350 ft) WNW of the NW radio tower guy wire anchor, 93 m (306 ft) NW of bench mark 876 0595 USE 2, 86 m (281 ft) NNW of the circular bulkhead around the oil facility, 77 m (251 ft) SW of bench mark 0595 B 1980, 43 m (140 ft) north of the west anchor pile of the radio tower, and 18 m (59 ft) north of the NW end of the facility. The bench mark is set 9 cm (0.3 ft) below ground level, crimped to the top of a stainless steel rod driven 18.3 m (60 ft) to refusal, and encased in a 4-inch PVC pipe.
U.S. DEPARTMENT OF COMMERCE National Oceanic and Atmospheric Administration National Ocean Service Page 3 of 7 Station ID: 8760595 PUBLICATION DATE: 06/09/2003 Name: BRETON ISLAND LA NOAA Chart: 11363 Latitude: 29° 29.6' N ( 29.49330) USGS Quad: BRETON ISLANDS Longitude: 89° 10.4' W ( -89.17330) T I D A L B E N C H M A R K S BENCH MARK STAMPING: BRETON RM NO 2 DESIGNATION: 876 0595 BRETON RM 2 MONUMENTATION: Reference Mark disk VM#: 7092 AGENCY: US Coast and Geodetic Survey (USC&GS) IDB PID#: SETTING CLASSIFICATION: Concrete monument OPUS PID: LATITUDE: 29° 29.6' N ( 29.49330) LONGITUDE: 89° 10.4' W ( -89.17330) The bench mark is a disk set on the west side of the oil facility near the NW radio tower guy wire anchor, 5 m (17 ft) NW of the NW corner of a generator house, and 1 m (2 ft) east of the bulkhead.
U.S. DEPARTMENT OF COMMERCE National Oceanic and Atmospheric Administration National Ocean Service Page 4 of 7 Station ID: 8760595 PUBLICATION DATE: 06/09/2003 Name: BRETON ISLAND LA NOAA Chart: 11363 Latitude: 29° 29.6' N ( 29.49330) USGS Quad: BRETON ISLANDS Longitude: 89° 10.4' W ( -89.17330) T I D A L B E N C H M A R K S BENCH MARK STAMPING: DESIGNATION: 876 0595 USE 1 ALIAS: NO STAMPING 1 MONUMENTATION: Survey disk VM#: 7093 AGENCY: US Army Corps Of Engineers (USE) IDB PID#: SETTING CLASSIFICATION: Concrete monument OPUS PID: LATITUDE: 29° 29.6' N ( 29.49330) LONGITUDE: 89° 10.4' W ( -89.17330) The bench mark is a disk set in a concrete monument at the foot of the dock on the east side of the oil facility, 20.27 m (66.5 ft) NE of the centerline of a concrete ramp leading SSE from the island, 6.64 m (21.8 ft) south of the centerline of the wood ramp leading east to the wooden dock, 5.64 m (18.5 ft) ESE of the NE corner of the metal generator building, 1.52 m (5.0 ft) west of the outside face of the circular bulkhead around the oil facility, and 0.15 m (0.5 ft) above ground level.
U.S. DEPARTMENT OF COMMERCE National Oceanic and Atmospheric Administration National Ocean Service Page 5 of 7 Station ID: 8760595 PUBLICATION DATE: 06/09/2003 Name: BRETON ISLAND LA NOAA Chart: 11363 Latitude: 29° 29.6' N ( 29.49330) USGS Quad: BRETON ISLANDS Longitude: 89° 10.4' W ( -89.17330) T I D A L B E N C H M A R K S BENCH MARK STAMPING: DESIGNATION: 876 0595 USE 2 ALIAS: NO STAMPING 2 MONUMENTATION: Survey disk VM#: 7094 AGENCY: US Army Corps Of Engineers (USE) IDB PID#: SETTING CLASSIFICATION: Concrete monument OPUS PID: LATITUDE: 29° 29.6' N ( 29.49330) LONGITUDE: 89° 10.4' W ( -89.17330) The bench mark is a disk set on the north side of the oil facility, 40.08 m (131.5 ft) SW of the NE guy wire post for the antenna tower on the west side of the island, 28.59 m (93.8 ft) NE of the center of the concrete base of the antenna tower, 4.15 m (13.6 ft) NE of the NW corner of the metal walkway along the north side of the crew quarters, 2.32 m (7.6 ft) south of the outside face of the circular bulkhead around the oil facility, and 0.21 m (0.7 ft) above ground level.
U.S. DEPARTMENT OF COMMERCE National Oceanic and Atmospheric Administration National Ocean Service Page 6 of 7 Station ID: 8760595 PUBLICATION DATE: 06/09/2003 Name: BRETON ISLAND LA NOAA Chart: 11363 Latitude: 29° 29.6' N ( 29.49330) USGS Quad: BRETON ISLANDS Longitude: 89° 10.4' W ( -89.17330) T I D A L D A T U M S Tidal datums at BRETON ISLAND based on: LENGTH OF SERIES: 6 MONTHS TIME PERIOD: July 1981 - December 1981 TIDAL EPOCH: 1983-2001 CONTROL TIDE STATION: 8747437 BAY WAVELAND YC, BAY ST. LOUIS Elevations of tidal datums referred to Mean Lower Low Water (MLLW), in METERS: MEAN HIGHER HIGH WATER MHHW = 0.417 MEAN HIGH WATER MHW = 0.417 MEAN SEA LEVEL MSL = 0.218 MEAN TIDE LEVEL MTL = 0.210 MEAN LOW WATER MLW = 0.001 MEAN LOWER LOW WATER MLLW = 0.000 North American Vertical Datum (NAVD88) Bench Mark Elevation Information In METERS above: Stamping or Designation MLLW MHW 0595 A 1980 0.490 0.073 0595 B 1980 0.445 0.028 0595 C 1980 0.850 0.433 BRETON RM NO 2 1.878 1.461 876 0595 USE 1 2.218 1.801 876 0595 USE 2 2.161 1.744
U.S. DEPARTMENT OF COMMERCE National Oceanic and Atmospheric Administration National Ocean Service Page 7 of 7 Station ID: 8760595 PUBLICATION DATE: 06/09/2003 Name: BRETON ISLAND LA NOAA Chart: 11363 Latitude: 29° 29.6' N ( 29.49330) USGS Quad: BRETON ISLANDS Longitude: 89° 10.4' W ( -89.17330) 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.