U.S. DEPARTMENT OF COMMERCE National Oceanic and Atmospheric Administration National Ocean Service Page 1 of 5 Station ID: 9450970 PUBLICATION DATE: 08/03/2004 Name: ENTRANCE TO ZIMOVIA STRAIT ALASKA NOAA Chart: 17385 Latitude: 56° 7.1' N USGS Quad: PETERSBURG (A-1) Longitude: 132° 4.7' W To reach the tidal marks from Wrangell via boat, proceed 26.3 km (14.3 nm) south from Wrangell Harbor through Zimovia Strait until abeam of Anita Point. Then proceed 21.5 km (11.7 nm) SE through Zimovia Strait until abeam of Thoms Point located north of the north tip of Frost Island, on the southernmost tip of Wrangell Island. Then proceed 1.1 km (0.6 nm) NW of the southernmost extent of Wrangell Island. The bench marks, staff, and tide gauge were located on the beach in the vicinity. T I D A L B E N C H M A R K S PRIMARY BENCH MARK STAMPING: 0970 E 2001 DESIGNATION: 945 0970 E MONUMENTATION: Tidal Station disk VM#: 16490 AGENCY: National Ocean Service (NOS) PID: SETTING CLASSIFICATION: Rock outcrop The primary bench mark is a disk set flush in a bedrock outcrop, 31 m (102 ft) NNW of the seaward most extent of the point of land just west of the southern-most extent of Thoms Point, 20.51 m (67.3 ft) SE of a clearing that extends from the west to the south shore of the point, 14.50 m (47.6 ft) NW (345 degrees magnetic) from bench mark 0970 D 2001, 12.30 m (40.4 ft) east of the vegetation line, and 6.50 m (21.3 ft) north of a 3 m x 3 m (10 ft x 10 ft) triangular granite rock. BENCH MARK STAMPING: 0970 A 2001 DESIGNATION: 945 0970 A MONUMENTATION: Tidal Station disk VM#: 16486 AGENCY: National Ocean Service (NOS) PID: SETTING CLASSIFICATION: Rock outcrop The bench mark is a disk set flush in a black bedrock outcrop with intrusions of quartz, located on Thoms Point, approximately 355 m (1,165 ft) NW from the southern-most tip of Wrangell Island, NW (319 degrees magnetic) of the west extent of Found Island, and WNW (293 degrees magnetic) of the east extent of Found Island, 15.60 m (51.2 ft) WNW (293 degrees magnetic) from bench mark 0970 B 2001, and 8 m (26 ft) seaward of the vegetation line.
U.S. DEPARTMENT OF COMMERCE National Oceanic and Atmospheric Administration National Ocean Service Page 2 of 5 Station ID: 9450970 PUBLICATION DATE: 08/03/2004 Name: ENTRANCE TO ZIMOVIA STRAIT ALASKA NOAA Chart: 17385 Latitude: 56° 7.1' N USGS Quad: PETERSBURG (A-1) Longitude: 132° 4.7' W T I D A L B E N C H M A R K S BENCH MARK STAMPING: 0970 B 2001 DESIGNATION: 945 0970 B MONUMENTATION: Tidal Station disk VM#: 16487 AGENCY: National Ocean Service (NOS) PID: SETTING CLASSIFICATION: Rock outcrop The bench mark is a disk set flush in a black bedrock located on the SW extent of Thoms Point, approximately 350 m (1,148 ft) NW (264 degrees magnetic) of the southern-most extent of Thoms Point, SE (140 degrees magnetic) from a day marker located on the west side of Found Island, ESE (113 degrees magnetic) from the east extent of Found Island, 15.6 m (51.2 ft) ESE (113 degrees magnetic) from bench mark 0970 A 2001, 10 m (33 ft) seaward from the vegetation line, and 4 m (13 ft) shoreward of the apparent high water line. BENCH MARK STAMPING: 0970 C 2001 DESIGNATION: 945 0970 C MONUMENTATION: Tidal Station disk VM#: 16488 AGENCY: National Ocean Service (NOS) PID: SETTING CLASSIFICATION: Rock outcrop The bench mark is a disk set flush in a bedrock outcrop located on the SW extent of Thoms Point, 330 m (1,083 ft) NW (264 degrees magnetic) of the southern-most extent of Thoms Point, 19 m (63 ft) seaward of the vegetation line, 13.01 m (42.7 ft) ESE (109 degress magnetic) of bench mark 0970 A 2001, and 13.01 m (42.7 ft) south (175 degrees magnetic) from bench mark 0970 D 2001.
U.S. DEPARTMENT OF COMMERCE National Oceanic and Atmospheric Administration National Ocean Service Page 3 of 5 Station ID: 9450970 PUBLICATION DATE: 08/03/2004 Name: ENTRANCE TO ZIMOVIA STRAIT ALASKA NOAA Chart: 17385 Latitude: 56° 7.1' N USGS Quad: PETERSBURG (A-1) Longitude: 132° 4.7' W T I D A L B E N C H M A R K S BENCH MARK STAMPING: 0970 D 2001 DESIGNATION: 945 0970 D MONUMENTATION: Tidal Station disk VM#: 16489 AGENCY: National Ocean Service (NOS) PID: SETTING CLASSIFICATION: Rock outcrop The bench mark is a disk set flush in a bedrock outcrop, located approximately 325 m (1,066 ft) WNW (268 degrees magnetic) of the southern-most extent of Thoms Point, 14.51 m (47.6 ft) SSW (165 degrees magnetic) from bench mark 0970 E 2001, 13.01 m (42.7 ft) north (355 degrees magnetic) of bench mark 0970 C 2001, and 11.50 m (37.7 ft) seaward of the vegetation line.
U.S. DEPARTMENT OF COMMERCE National Oceanic and Atmospheric Administration National Ocean Service Page 4 of 5 Station ID: 9450970 PUBLICATION DATE: 08/03/2004 Name: ENTRANCE TO ZIMOVIA STRAIT ALASKA NOAA Chart: 17385 Latitude: 56° 7.1' N USGS Quad: PETERSBURG (A-1) Longitude: 132° 4.7' W T I D A L D A T U M S Tidal datums at ENTRANCE TO ZIMOVIA STRAIT based on: LENGTH OF SERIES: 1 MONTH 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) = 4.978 MEAN HIGH WATER (MHW) = 4.710 MEAN TIDE LEVEL (MTL) = 2.592 MEAN SEA LEVEL (MSL) = 2.590 MEAN LOW WATER (MLW) = 0.474 MEAN LOWER LOW WATER (MLLW) = 0.000 Bench Mark Elevation Information In METERS above: Stamping or Designation MLLW MHW 0970 E 2001 5.391 0.682 0970 A 2001 4.564 -0.146 0970 B 2001 5.405 0.695 0970 C 2001 4.330 -0.379 0970 D 2001 5.541 0.831
U.S. DEPARTMENT OF COMMERCE National Oceanic and Atmospheric Administration National Ocean Service Page 5 of 5 Station ID: 9450970 PUBLICATION DATE: 08/03/2004 Name: ENTRANCE TO ZIMOVIA STRAIT ALASKA NOAA Chart: 17385 Latitude: 56° 7.1' N USGS Quad: PETERSBURG (A-1) Longitude: 132° 4.7' 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 (NAVD 88). NGVD 29 is a fixed datum adopted as a national standard geodetic reference for heights but is now considered superseded. NGVD 29 is sometimes referred to as Sea Level Datum of 1929 or as Mean Sea Level on some early issues of Geological Survey Topographic Quads. NGVD 29 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 NGVD 29 are available from the National Geodetic Survey (NGS) data base via the World Wide Web at National Geodetic Survey. NAVD 88 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. NAVD 88 replaces NGVD 29 as the national standard geodetic reference for heights. Bench mark elevations relative to NAVD 88 are available from NGS through the World Wide Web at National Geodetic Survey. NGVD 29 and NAVD 88 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 NAVD 88 elevation is shown on the Elevations of Tidal Datums Table Referred to MLLW only when two or more of the bench marks listed have NAVD 88 elevations. The NAVD 88 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, NAVD 88 bench mark elevations computed indirectly from the tidal datums elevation table may differ slightly from NAVD 88 elevations listed for each bench mark in the NGS database.