U.S. DEPARTMENT OF COMMERCE National Oceanic and Atmospheric Administration National Ocean Service Datums Page Page 1 of 6 Station ID: 9450753 PUBLICATION DATE: 08/06/2009 Name: MAGNETIC POINT, UNION BAY, ERNEST SOUND AK NOAA Chart: 17423 Latitude: 55° 47.3' N ( 55.78828) USGS Quad: CRAIG (D-1) Longitude: 132° 11.5' W (-132.19088) To reach the Magnetic Point tidal benchmarks, travel to the eastern shore of Ernest Sound south of Union Point and north of Magnetic Point within Union Bay; in the NE portion of Union Bay there are two islands; on the east shore of Union Bay, proceed about 0.6 km (0.4 mi) north along the west shore of Magnetic Point, east of a small island, in the northerly of two rock outcroppings both topped by moss and stunted trees. Specifically, the tidal bench marks are located on the eastern shore due east of the southern island. The bench marks are on private property that consists of densely wooded area surrounding intertidal grassland protected by two rock ledge peninsulas. The staff was positioned on a flat faced rock wall facing west located on a west facing rock ledge. T I D A L B E N C H M A R K S PRIMARY BENCH MARK STAMPING: 0753 A 2009 DESIGNATION: 945 0753 A MONUMENTATION: Tidal Station disk VM#: 19229 AGENCY: National Ocean Service (NOS) IDB PID#: SETTING CLASSIFICATION: Rock ledge OPUS PID: LATITUDE: 55° 47.3' N ( 55.78827) LONGITUDE: 132° 11.5' W (-132.19085) The primary bench mark is a disk set flush on a rock ledge just in front of the intertidal zone, located on the shore facing the west.
U.S. DEPARTMENT OF COMMERCE National Oceanic and Atmospheric Administration National Ocean Service Page 2 of 6 Station ID: 9450753 PUBLICATION DATE: 08/06/2009 Name: MAGNETIC POINT, UNION BAY, ERNEST SOUND AK NOAA Chart: 17423 Latitude: 55° 47.3' N ( 55.78828) USGS Quad: CRAIG (D-1) Longitude: 132° 11.5' W (-132.19088) T I D A L B E N C H M A R K S BENCH MARK STAMPING: 0753 B 2009 DESIGNATION: 945 0753 B MONUMENTATION: Tidal Station disk VM#: 19230 AGENCY: National Ocean Service (NOS) IDB PID#: SETTING CLASSIFICATION: Inshore edge OPUS PID: LATITUDE: 55° 47.3' N ( 55.78805) LONGITUDE: 132° 11.4' W (-132.19073) The bench mark is a disk located on the southern inshore edge of the forest and the intertidal zone. BENCH MARK STAMPING: 0753 C 2009 DESIGNATION: 945 0753 C MONUMENTATION: Tidal Station disk VM#: 19231 AGENCY: National Ocean Service (NOS) IDB PID#: SETTING CLASSIFICATION: Inshore edge OPUS PID: LATITUDE: 55° 47.3' N ( 55.78838) LONGITUDE: 132° 11.4' W (-132.19053) The bench mark is a disk located on the northern inshore edge of the forest and intertidal zone.
U.S. DEPARTMENT OF COMMERCE National Oceanic and Atmospheric Administration National Ocean Service Page 3 of 6 Station ID: 9450753 PUBLICATION DATE: 08/06/2009 Name: MAGNETIC POINT, UNION BAY, ERNEST SOUND AK NOAA Chart: 17423 Latitude: 55° 47.3' N ( 55.78828) USGS Quad: CRAIG (D-1) Longitude: 132° 11.5' W (-132.19088) T I D A L B E N C H M A R K S BENCH MARK STAMPING: 0753 D 2009 DESIGNATION: 945 0753 D MONUMENTATION: Tidal Station disk VM#: 19232 AGENCY: National Ocean Service (NOS) IDB PID#: SETTING CLASSIFICATION: Bedrock OPUS PID: LATITUDE: 55° 47.3' N ( 55.78865) LONGITUDE: 132° 11.4' W (-132.19072) The bench mark is a disk set flush into bedrock north of the intertidal zone, and located on the shore facing west. BENCH MARK STAMPING: 0753 E 2009 DESIGNATION: 945 0753 E MONUMENTATION: Tidal Station disk VM#: 19233 AGENCY: National Ocean Service (NOS) IDB PID#: SETTING CLASSIFICATION: Rock ledge OPUS PID: LATITUDE: 55° 47.3' N ( 55.78798) LONGITUDE: 132° 11.5' W (-132.19105) The bench mark is a disk set flush into bedrock horizontally south of the intertidal zone, and located on a rock ledge that faces the west.
U.S. DEPARTMENT OF COMMERCE National Oceanic and Atmospheric Administration National Ocean Service Page 4 of 6 Station ID: 9450753 PUBLICATION DATE: 08/06/2009 Name: MAGNETIC POINT, UNION BAY, ERNEST SOUND AK NOAA Chart: 17423 Latitude: 55° 47.3' N ( 55.78828) USGS Quad: CRAIG (D-1) Longitude: 132° 11.5' W (-132.19088) T I D A L B E N C H M A R K S BENCH MARK STAMPING: VIXEN HBR 2009 DESIGNATION: VIXEN HBR 2009 MONUMENTATION: Tidal Station disk VM#: 19234 AGENCY: National Ocean Service (NOS) IDB PID#: SETTING CLASSIFICATION: Solid rock OPUS PID#: BBBK46 LATITUDE: 55° 47.3' N ( 55.78840) LONGITUDE: 132° 11.5' W (-132.19085) The bench mark is a disk set in a solid rock, at the South end of the mossy cap, about 1.83 m (6.0 ft) south of a dwarf hemlock, and approximately 0.9 m (3 ft) above high water.
U.S. DEPARTMENT OF COMMERCE National Oceanic and Atmospheric Administration National Ocean Service Page 5 of 6 Station ID: 9450753 PUBLICATION DATE: 08/06/2009 Name: MAGNETIC POINT, UNION BAY, ERNEST SOUND AK NOAA Chart: 17423 Latitude: 55° 47.3' N ( 55.78828) USGS Quad: CRAIG (D-1) Longitude: 132° 11.5' W (-132.19088) T I D A L D A T U M S Tidal datums at MAGNETIC POINT, UNION BAY, ERNEST SOUND based on: LENGTH OF SERIES: 1 MONTH TIME PERIOD: May 2009 - May 2009 TIDAL EPOCH: 1983-2001 CONTROL TIDE STATION: 9450460 KETCHIKAN, TONGASS NARROWS Elevations of tidal datums referred to Mean Lower Low Water (MLLW), in METERS: MEAN HIGHER HIGH WATER MHHW = 4.888 MEAN HIGH WATER MHW = 4.617 MEAN TIDE LEVEL MTL = 2.546 MEAN SEA LEVEL MSL = 2.539 MEAN LOW WATER MLW = 0.476 MEAN LOWER LOW WATER MLLW = 0.000 North American Vertical Datum (NAVD88) Bench Mark Elevation Information In METERS above: Stamping or Designation MLLW MHW 0753 A 2009 7.013 2.396 0753 B 2009 6.274 1.657 0753 C 2009 6.463 1.846 0753 D 2009 5.232 0.616 0753 E 2009 5.769 1.152 VIXEN HBR 2009 7.008 2.391
U.S. DEPARTMENT OF COMMERCE National Oceanic and Atmospheric Administration National Ocean Service Page 6 of 6 Station ID: 9450753 PUBLICATION DATE: 08/06/2009 Name: MAGNETIC POINT, UNION BAY, ERNEST SOUND AK NOAA Chart: 17423 Latitude: 55° 47.3' N ( 55.78828) USGS Quad: CRAIG (D-1) Longitude: 132° 11.5' W (-132.19088) 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.