U.S. DEPARTMENT OF COMMERCE National Oceanic and Atmospheric Administration National Ocean Service Datums Page Page 1 of 4 Station ID: 9451005 PUBLICATION DATE: 11/09/2011 Name: POINT HARRINGTON, CLARENCE STRAIT AK NOAA Chart: 17382 Latitude: 56° 10.7' N ( 56.17830) USGS Quad: PETERSBURG (A-3) Longitude: 132° 41.8' W (-132.69700) To reach the tidal bench marks from Wrangell, navigate west out of Wrangell Harbor to Stikine Starit, continue south to Steamer Bay, then 2.76 km (1.5 nm) east of the Mariposa Rock Red Buoy4. The tidal bench marks are located along the beach. The tide station was located on the NE shore. T I D A L B E N C H M A R K S PRIMARY BENCH MARK STAMPING: 1005 A 2000 DESIGNATION: 945 1005 A MONUMENTATION: Tidal Station disk VM#: 16162 AGENCY: National Ocean Service (NOS) IDB PID#: SETTING CLASSIFICATION: Bedrock ledge OPUS PID: LATITUDE: 56° 10.7' N ( 56.17830) LONGITUDE: 132° 43.8' W (-132.73000) The primary bench mark is a disk embedded flush on a bedrock ledge 90 m (295 ft) north of a beach which is located in a southerly bend of the shoreline, 3.0 m (9.8 ft) from the tree line, and approximately 0.3 m (1 ft) below the apparent high water line. Note: At low water, the bedrock ledge extends approximately 20 m (66 ft) seaward.
U.S. DEPARTMENT OF COMMERCE National Oceanic and Atmospheric Administration National Ocean Service Page 2 of 4 Station ID: 9451005 PUBLICATION DATE: 11/09/2011 Name: POINT HARRINGTON, CLARENCE STRAIT AK NOAA Chart: 17382 Latitude: 56° 10.7' N ( 56.17830) USGS Quad: PETERSBURG (A-3) Longitude: 132° 41.8' W (-132.69700) T I D A L B E N C H M A R K S BENCH MARK STAMPING: 1005 B 2000 DESIGNATION: 945 1005 B MONUMENTATION: Tidal Station disk VM#: 16163 AGENCY: National Ocean Service (NOS) IDB PID#: SETTING CLASSIFICATION: Bedrock OPUS PID: LATITUDE: 56° 10.7' N ( 56.17830) LONGITUDE: 132° 43.8' W (-132.73000) The bench mark is a disk embedded in bedrock located on the south edge of a point located 130 m (426 ft) north of a beach in the southerly bend of the shoreline, 3.0 m (9.8 ft) from tree line, and approximately 0.3 m (1 ft) below the apparent high water line. BENCH MARK STAMPING: 1005 C 2000 DESIGNATION: 945 1005 C MONUMENTATION: Tidal Station disk VM#: 16164 AGENCY: National Ocean Service (NOS) IDB PID#: SETTING CLASSIFICATION: Bedrock ledge OPUS PID: LATITUDE: 56° 10.7' N ( 56.17830) LONGITUDE: 132° 43.8' W (-132.73000) The bench mark is a disk embedded in a bedrock ledge located 40 m (131 ft) north of a beach which is located in a southerly bend in the shoreline, 5 m (16 ft) from the tree line, and 0.3 m (1 ft) below the apparent high water line. Note: The high point of bench mark 1005 C 2000 used in leveling is "DC" in "Washington DC".
U.S. DEPARTMENT OF COMMERCE National Oceanic and Atmospheric Administration National Ocean Service Page 3 of 4 Station ID: 9451005 PUBLICATION DATE: 11/09/2011 Name: POINT HARRINGTON, CLARENCE STRAIT AK NOAA Chart: 17382 Latitude: 56° 10.7' N ( 56.17830) USGS Quad: PETERSBURG (A-3) Longitude: 132° 41.8' W (-132.69700) T I D A L D A T U M S Tidal datums at POINT HARRINGTON, CLARENCE STRAIT based on: LENGTH OF SERIES: 1 MONTH TIME PERIOD: April 2000 - April 2000 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 = 4.863 MEAN HIGH WATER MHW = 4.591 MEAN TIDE LEVEL MTL = 2.526 MEAN SEA LEVEL MSL = 2.516 MEAN LOW WATER MLW = 0.462 MEAN LOWER LOW WATER MLLW = 0.000 North American Vertical Datum (NAVD88) Bench Mark Elevation Information In METERS above: Stamping or Designation MLLW MHW 1005 A 2000 5.411 0.820 1005 B 2000 5.664 1.073 1005 C 2000 5.258 0.667
U.S. DEPARTMENT OF COMMERCE National Oceanic and Atmospheric Administration National Ocean Service Page 4 of 4 Station ID: 9451005 PUBLICATION DATE: 11/09/2011 Name: POINT HARRINGTON, CLARENCE STRAIT AK NOAA Chart: 17382 Latitude: 56° 10.7' N ( 56.17830) USGS Quad: PETERSBURG (A-3) Longitude: 132° 41.8' W (-132.69700) 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.