U.S. DEPARTMENT OF COMMERCE National Oceanic and Atmospheric Administration National Ocean Service Datums Page Page 1 of 5 Station ID: 9451204 PUBLICATION DATE: 07/15/2004 Name: WRANGELL, WRANGELL ISLAND AK NOAA Chart: 17385 Latitude: 56° 28.2' N ( 56.47000) USGS Quad: PETERSBURG (B-1) Longitude: 132° 23.2' W (-132.38700) To reach the tidal bench marks from Ketchikan via boat, proceed NW along Clarence Strait for approximately 139 km (75 nm) to Stikine Strait, then NE along Stikine Strait for approximately 46 km (25 nm) to Wrangell on the northern end of Wrangell Island. The tidal bench marks are in the vicinity of the Post Office, Front Street, and Presbyterian Parsonage. The tide gage was located SE from the city dock in a shed along the breakwater in a container yard in Wrangell Harbor. T I D A L B E N C H M A R K S PRIMARY BENCH MARK STAMPING: NO 6 1954 DESIGNATION: 945 1204 TIDAL 6 MONUMENTATION: Tidal Station disk VM#: 11800 AGENCY: US Coast and Geodetic Survey (USC&GS) IDB PID#: TT8546 SETTING CLASSIFICATION: Rock outcrop OPUS PID: LATITUDE: ' °deg (0) LONGITUDE: ' °deg (0) The primary bench mark is a disk set in the highest point of the north end of a large rock outcrop between the Stikine Avenue and Front Street in front of the Post Office, 34.56 m (113.4 ft) NW from bench mark 1204 A 2001, and 29.14 m (95.6 ft) WSW of the SE corner of the Post Office.
U.S. DEPARTMENT OF COMMERCE National Oceanic and Atmospheric Administration National Ocean Service Page 2 of 5 Station ID: 9451204 PUBLICATION DATE: 07/15/2004 Name: WRANGELL, WRANGELL ISLAND AK NOAA Chart: 17385 Latitude: 56° 28.2' N ( 56.47000) USGS Quad: PETERSBURG (B-1) Longitude: 132° 23.2' W (-132.38700) T I D A L B E N C H M A R K S BENCH MARK STAMPING: NO 9 1971 DESIGNATION: 945 1204 TIDAL 9 MONUMENTATION: Tidal Station disk VM#: 11802 AGENCY: National Ocean Service (NOS) IDB PID#: SETTING CLASSIFICATION: Concrete steps OPUS PID: LATITUDE: ' °deg (0) LONGITUDE: ' °deg (0) The bench mark is a disk set in the top concrete step of the stairs leading to the basement on the back side of the Post Office, NW of the NE corner of the same building, 71.87 m (235.8 ft) NNW of bench mark 1204 A 2001, and 0.09 m (0.3 ft) NE of the NE wall of the Post Office building. BENCH MARK STAMPING: DESIGNATION: 945 1204 BM 5 ALIAS: 5 MONUMENTATION: Bench Mark disk VM#: 16496 AGENCY: Unknown IDB PID#: SETTING CLASSIFICATION: Boulder OPUS PID#: BBDG97 LATITUDE: ' °deg (0) LONGITUDE: ' °deg (0) The bench mark is an unstamped brass disk set in a large white boulder 2 m x 1 m x 1 m (5 ft x 3 ft x 3 ft) located in front of the Presbyterian parsonage, 15.42 m (50.6 ft) SW of the SW corner of the Parsonage, and 10.24 m (33.6 ft) north of the center line of Church Street.
U.S. DEPARTMENT OF COMMERCE National Oceanic and Atmospheric Administration National Ocean Service Page 3 of 5 Station ID: 9451204 PUBLICATION DATE: 07/15/2004 Name: WRANGELL, WRANGELL ISLAND AK NOAA Chart: 17385 Latitude: 56° 28.2' N ( 56.47000) USGS Quad: PETERSBURG (B-1) Longitude: 132° 23.2' W (-132.38700) T I D A L B E N C H M A R K S BENCH MARK STAMPING: 1204 A 2001 DESIGNATION: 945 1204 A MONUMENTATION: Tidal Station disk VM#: 16497 AGENCY: National Ocean Service (NOS) IDB PID#: SETTING CLASSIFICATION: Concrete sidewalk OPUS PID: LATITUDE: ' °deg (0) LONGITUDE: ' °deg (0) The bench mark is a disk set in the concrete sidewalk on the corner of Stikine Street and Front Street, 71.87 m (235.8 ft) SSW of bench mark NO 9 1971, 34.56 m (113.4 ft) SE from the highest point of the north end of a large rock outcrop, 29.14 m (95.6 ft) WSW of the SE corner of the Post Office. BENCH MARK STAMPING: 1204 B 2001 DESIGNATION: 945 1204 B MONUMENTATION: Tidal Station disk VM#: 16498 AGENCY: National Ocean Service (NOS) IDB PID#: SETTING CLASSIFICATION: Concrete sidewalk OPUS PID: LATITUDE: ' °deg (0) LONGITUDE: ' °deg (0) The bench mark is a disk set in the concrete sidewalk on the west corner of McKinnon and Front Street, 9 m (31 ft) west of the east side of McKinnon Street, 8 m (25 ft) from the center of intersection of McKinnon and Front Streets, and 0.53 m (1.7 ft) south from a stop sign located on the north side of the intersection.
U.S. DEPARTMENT OF COMMERCE National Oceanic and Atmospheric Administration National Ocean Service Page 4 of 5 Station ID: 9451204 PUBLICATION DATE: 07/15/2004 Name: WRANGELL, WRANGELL ISLAND AK NOAA Chart: 17385 Latitude: 56° 28.2' N ( 56.47000) USGS Quad: PETERSBURG (B-1) Longitude: 132° 23.2' W (-132.38700) T I D A L D A T U M S Tidal datums at WRANGELL, WRANGELL ISLAND based on: LENGTH OF SERIES: 2 MONTHS TIME PERIOD: April 2001 - May 2001 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 = 4.864 MEAN HIGH WATER MHW = 4.595 MEAN TIDE LEVEL MTL = 2.528 MEAN SEA LEVEL MSL = 2.519 MEAN LOW WATER MLW = 0.460 MEAN LOWER LOW WATER MLLW = 0.000 North American Vertical Datum (NAVD88) Bench Mark Elevation Information In METERS above: Stamping or Designation MLLW MHW NO 6 1954 12.275 7.680 NO 9 1971 13.958 9.363 945 1204 BM 5 17.591 12.996 1204 A 2001 7.802 3.207 1204 B 2001 7.676 3.081
U.S. DEPARTMENT OF COMMERCE National Oceanic and Atmospheric Administration National Ocean Service Page 5 of 5 Station ID: 9451204 PUBLICATION DATE: 07/15/2004 Name: WRANGELL, WRANGELL ISLAND AK NOAA Chart: 17385 Latitude: 56° 28.2' N ( 56.47000) USGS Quad: PETERSBURG (B-1) Longitude: 132° 23.2' W (-132.38700) 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.