U.S. DEPARTMENT OF COMMERCE National Oceanic and Atmospheric Administration National Ocean Service Datums Page Page 1 of 5 PUBLICATION DATE: 09/11/2000 Station ID: 9454616 SUPERCEDED DATE: 04/21/2003 Name: MONTAGUE ISLAND ALASKA NOAA Chart: 16701 Latitude: 60° 1.8' N USGS Quad: SEWARD (A-4) Longitude: 147° 35.5' W To reach the tidal bench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, upon passage of Applegate Rock, head SSW, upon passing The Needle, head SE toward Montague Island. The tide station is located 8.3 km (4.5 nm) NE of Point Bazil. The bench marks were installed 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: 4616 A 1999 DESIGNATION: 945 4616 A MONUMENTATION: Tidal Station disk VM#: 15981 AGENCY: National Ocean Service (NOS) PID: SETTING CLASSIFICATION: Bedrock The primary bench mark is a disk set in a flat bedrock, 83 m (272 ft) NE (040 degrees magnetic) of bench mark 4616 B 1999, 15 m (49 ft) from the vegetation line, approximately 3 m (10 ft) above the apparent high water line. BENCH MARK STAMPING: 4616 B 1999 DESIGNATION: 945 4616 B MONUMENTATION: Tidal Station disk VM#: 15982 AGENCY: National Ocean Service (NOS) PID: SETTING CLASSIFICATION: Boulder The bench mark is a disk set in a large boulder, set directly in front of a grass area, 83 m (272 ft) SW (220 degrees magnetic) of bench mark 4616 A 1999, 42 m (138 ft) north (000 degrees magnetic) of bench mark 4616 C 1999, 7 m (23 ft) from the tree line, and 4 m (13 ft) above the apparent high water line.
U.S. DEPARTMENT OF COMMERCE National Oceanic and Atmospheric Administration National Ocean Service Page 2 of 5 PUBLICATION DATE: 09/11/2000 Station ID: 9454616 SUPERCEDED DATE: 04/21/2003 Name: MONTAGUE ISLAND ALASKA NOAA Chart: 16701 Latitude: 60° 1.8' N USGS Quad: SEWARD (A-4) Longitude: 147° 35.5' W T I D A L B E N C H M A R K S BENCH MARK STAMPING: 4616 C 1999 DESIGNATION: 945 4616 C MONUMENTATION: Tidal Station disk VM#: 15983 AGENCY: National Ocean Service (NOS) PID: SETTING CLASSIFICATION: Boulder The bench mark is a disk set in a mid-size boulder, set directly in front of a grass area, 44 m (144 ft) NE (040 degrees magnetic) of bench mark 4616 D 1999, 42 m (138 ft) south (180 degrees magnetic) of bench mark 4616 B 1999, 8 m (26 ft) from the tree line, and approximately 2 m (7 ft) above the apparent high water line. BENCH MARK STAMPING: 4616 D 1999 DESIGNATION: 945 4616 D MONUMENTATION: Tidal Station disk VM#: 15984 AGENCY: National Ocean Service (NOS) PID: SETTING CLASSIFICATION: Bedrock The bench mark is a disk set in bedrock upon a ledge, set directly in front of a small stream and grassy area, 44 m (144 ft) SW (220 degrees magnetic) of bench mark 4616 C 1999, 34 m (112 ft) NE (080 degrees magnetic) of bench mark 4616 E 1999, 5 m (16 ft) from the tree line, and approximately 8 m (26 ft) above the apparent high water line.
U.S. DEPARTMENT OF COMMERCE National Oceanic and Atmospheric Administration National Ocean Service Page 3 of 5 PUBLICATION DATE: 09/11/2000 Station ID: 9454616 SUPERCEDED DATE: 04/21/2003 Name: MONTAGUE ISLAND ALASKA NOAA Chart: 16701 Latitude: 60° 1.8' N USGS Quad: SEWARD (A-4) Longitude: 147° 35.5' W T I D A L B E N C H M A R K S BENCH MARK STAMPING: 4616 E 1999 DESIGNATION: 945 4616 E MONUMENTATION: Tidal Station disk VM#: 15985 AGENCY: National Ocean Service (NOS) PID: SETTING CLASSIFICATION: Boulder The bench mark is a disk set in a mid-size boulder on a stony beach, 34 m (112 ft) SW (260 degrees magnetic) of bench mark 4616 D 1999, 5 m (15 ft) from the vegetation line, and approximately 1 m (3 ft) above the apparent high water line.
U.S. DEPARTMENT OF COMMERCE National Oceanic and Atmospheric Administration National Ocean Service Page 4 of 5 PUBLICATION DATE: 09/11/2000 Station ID: 9454616 SUPERCEDED DATE: 04/21/2003 Name: MONTAGUE ISLAND ALASKA NOAA Chart: 16701 Latitude: 60° 1.8' N USGS Quad: SEWARD (A-4) Longitude: 147° 35.5' W T I D A L D A T U M S Tidal datums at MONTAGUE ISLAND based on: LENGTH OF SERIES: 1 MONTH TIME PERIOD: SEPTEMBER 1999 TIDAL EPOCH: 1960-1978 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 = 3.478 MEAN HIGH WATER MHW = 3.201 MEAN SEA LEVEL MSL = 1.843 MEAN TIDE LEVEL MTL = 1.816 MEAN LOW WATER MLW = 0.432 MEAN LOWER LOW WATER MLLW = 0.000 Bench Mark Elevation Information In METERS above: Stamping or Designation MLLW MHW 4616 A 1999 4.899 1.698 4616 B 1999 5.700 2.499 4616 C 1999 5.109 1.908 4616 D 1999 5.793 2.592 4616 E 1999 4.099 0.898
U.S. DEPARTMENT OF COMMERCE National Oceanic and Atmospheric Administration National Ocean Service Page 5 of 5 PUBLICATION DATE: 09/11/2000 Station ID: 9454616 SUPERCEDED DATE: 04/21/2003 Name: MONTAGUE ISLAND ALASKA NOAA Chart: 16701 Latitude: 60° 1.8' N USGS Quad: SEWARD (A-4) Longitude: 147° 35.5' W 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 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.