U.S. DEPARTMENT OF COMMERCE National Oceanic and Atmospheric Administration National Ocean Service Datums Page Page 1 of 5 Station ID: 9454511 PUBLICATION DATE: 11/09/2011 Name: PORT CHALMERS AK NOAA Chart: 16701 Latitude: 60° 14.5' N ( 60.24180) USGS Quad: SEWARD (A-1) Longitude: 147° 14.9' W (-147.24900) To reach the tidal bench marks, from Cordova head north out of Orca Inlet to Orca Bay, continue west through Orca Bay to Prince William Sound, northeast of Green Island, head south to Port Chalmers. The tide station is located 0.9 km (0.5 nm) west of Wilby Island. The bench marks were located on bedrocks in the vicinity along the shore. T I D A L B E N C H M A R K S PRIMARY BENCH MARK STAMPING: 4511 D 1998 DESIGNATION: 945 4511 D MONUMENTATION: Tidal Station disk VM#: 15205 AGENCY: National Ocean Service (NOS) IDB PID#: SETTING CLASSIFICATION: Bedrock OPUS PID: LATITUDE: 60° 14.5' N ( 60.24180) LONGITUDE: 147° 14.9' W (-147.24900) The primary bench mark is a disk set in bedrock, 36 m (119 ft) NW (340 degrees magnetic) of bench mark 4511 E 1998, and 14 m (46 ft) NE (30 degrees magnetic) of bench mark 4511 C 1998. BENCH MARK STAMPING: 4511 A 1998 DESIGNATION: 945 4511 A MONUMENTATION: Tidal Station disk VM#: 15202 AGENCY: National Ocean Service (NOS) IDB PID#: SETTING CLASSIFICATION: Bedrock OPUS PID: LATITUDE: 60° 14.5' N ( 60.24180) LONGITUDE: 147° 14.9' W (-147.24900) The bench mark is a disk set in bedrock, 21 m (68 ft) SE (170 degrees magnetic) of bench mark 4511 B 1998, and 20 m (67 ft) SW (220 degrees magnetic) of bench mark 4511 E 1998.
U.S. DEPARTMENT OF COMMERCE National Oceanic and Atmospheric Administration National Ocean Service Page 2 of 5 Station ID: 9454511 PUBLICATION DATE: 11/09/2011 Name: PORT CHALMERS AK NOAA Chart: 16701 Latitude: 60° 14.5' N ( 60.24180) USGS Quad: SEWARD (A-1) Longitude: 147° 14.9' W (-147.24900) T I D A L B E N C H M A R K S BENCH MARK STAMPING: 4511 B 1998 DESIGNATION: 945 4511 B MONUMENTATION: Tidal Station disk VM#: 15203 AGENCY: National Ocean Service (NOS) IDB PID#: SETTING CLASSIFICATION: Bedrock OPUS PID: LATITUDE: 60° 14.5' N ( 60.24180) LONGITUDE: 147° 14.9' W (-147.24900) The bench mark is a disk set in bedrock, 21 m (68 ft) NW (350 degrees magnetic) of bench mark 4511 A 1998, and 14 m (46 ft) south (180 degrees magnetic) of bench mark 4511 C 1998. BENCH MARK STAMPING: 4511 C 1998 DESIGNATION: 945 4511 C MONUMENTATION: Tidal Station disk VM#: 15204 AGENCY: National Ocean Service (NOS) IDB PID#: SETTING CLASSIFICATION: Bedrock OPUS PID: LATITUDE: 60° 14.5' N ( 60.24180) LONGITUDE: 147° 14.9' W (-147.24900) The bench mark is a disk set in bedrock, 14 m (46 ft) north (360 degrees magnetic) of bench mark 4511 B 1998, and 14 m (46 ft) SW (210 degrees magnetic) of bench mark 4511 D 1998.
U.S. DEPARTMENT OF COMMERCE National Oceanic and Atmospheric Administration National Ocean Service Page 3 of 5 Station ID: 9454511 PUBLICATION DATE: 11/09/2011 Name: PORT CHALMERS AK NOAA Chart: 16701 Latitude: 60° 14.5' N ( 60.24180) USGS Quad: SEWARD (A-1) Longitude: 147° 14.9' W (-147.24900) T I D A L B E N C H M A R K S BENCH MARK STAMPING: 4511 E 1998 DESIGNATION: 945 4511 E MONUMENTATION: Tidal Station disk VM#: 15206 AGENCY: National Ocean Service (NOS) IDB PID#: SETTING CLASSIFICATION: Bedrock OPUS PID: LATITUDE: 60° 14.5' N ( 60.24180) LONGITUDE: 147° 14.9' W (-147.24900) The bench mark is a disk set in bedrock, 36 m (119 ft) SE (160 degrees magnetic) of bench mark 4511 D 1998, and 20 m (67 ft) NE (40 degrees magnetic) of bench mark 4511 A 1998.
U.S. DEPARTMENT OF COMMERCE National Oceanic and Atmospheric Administration National Ocean Service Page 4 of 5 Station ID: 9454511 PUBLICATION DATE: 11/09/2011 Name: PORT CHALMERS AK NOAA Chart: 16701 Latitude: 60° 14.5' N ( 60.24180) USGS Quad: SEWARD (A-1) Longitude: 147° 14.9' W (-147.24900) T I D A L D A T U M S Tidal datums at PORT CHALMERS based on: LENGTH OF SERIES: 1 MONTH TIME PERIOD: September 1999 - September 1999 TIDAL EPOCH: 1983-2001 CONTROL TIDE STATION: 9454050 CORDOVA, ORCA INLET, PRINCE WILLIAM SD Elevations of tidal datums referred to Mean Lower Low Water (MLLW), in METERS: MEAN HIGHER HIGH WATER MHHW = 3.630 MEAN HIGH WATER MHW = 3.349 MEAN SEA LEVEL MSL = 1.929 MEAN TIDE LEVEL MTL = 1.897 MEAN LOW WATER MLW = 0.445 MEAN LOWER LOW WATER MLLW = 0.000 North American Vertical Datum (NAVD88) Bench Mark Elevation Information In METERS above: Stamping or Designation MLLW MHW 4511 D 1998 5.154 1.805 4511 A 1998 4.379 1.030 4511 B 1998 5.011 1.662 4511 C 1998 4.726 1.377 4511 E 1998 4.278 0.929
U.S. DEPARTMENT OF COMMERCE National Oceanic and Atmospheric Administration National Ocean Service Page 5 of 5 Station ID: 9454511 PUBLICATION DATE: 11/09/2011 Name: PORT CHALMERS AK NOAA Chart: 16701 Latitude: 60° 14.5' N ( 60.24180) USGS Quad: SEWARD (A-1) Longitude: 147° 14.9' W (-147.24900) 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.