U.S. DEPARTMENT OF COMMERCE National Oceanic and Atmospheric Administration National Ocean Service Datums Page Page 1 of 5 Station ID: 9458779 PUBLICATION DATE: 04/29/2004 Name: NAKCHAMIK ISLAND, PACIFIC OCEAN AK NOAA Chart: 16566 Latitude: 56° 21.1' N ( 56.35170) USGS Quad: SUTWIK ISLAND (B-6) Longitude: 157° 48.7' W (-157.81200) To reach the tidal bench marks from Alaska Peninsula, go to the east side of Nakchamik Island on the northern coast of the Chignik Bay. The bench marks were located on the southern end of Cobble Beach. The tide gauge was located on the beach. T I D A L B E N C H M A R K S PRIMARY BENCH MARK STAMPING: 8779 A 1996 DESIGNATION: 945 8779 A MONUMENTATION: Tidal Station disk VM#: 13146 AGENCY: National Ocean Service (NOS) IDB PID#: SETTING CLASSIFICATION: Rock outcrop OPUS PID: LATITUDE: 56° 21.1' N ( 56.35170) LONGITUDE: 157° 48.7' W (-157.81200) The primary bench mark is a disk set at the base of a rocky outcrop, 250 m (820 ft) NW (340 degrees magnetic) from bench mark 8779 B 1996, and 0.50 m (1.6 ft) above the north end of a cobble beach. BENCH MARK STAMPING: 8779 B 1996 DESIGNATION: 945 8779 B MONUMENTATION: Tidal Station disk VM#: 13147 AGENCY: National Ocean Service (NOS) IDB PID#: SETTING CLASSIFICATION: Boulder OPUS PID: LATITUDE: 56° 21.1' N ( 56.35170) LONGITUDE: 157° 48.7' W (-157.81200) The bench mark is a disk set on top of a flat boulder lying in a cut between the cliff face and an east-west running rock outcrop, 250 m (820 ft) SE (160 degrees magnetic) from bench mark 8779 A 1996, 56 m (184 ft) NW (336 degrees magnetic) from 8779 C 1996, 0.50 m (1.6 ft) from a cliff face and immediately south of a small stream, and 0.34 m (1.1 ft) above southern end of cobble beach.
U.S. DEPARTMENT OF COMMERCE National Oceanic and Atmospheric Administration National Ocean Service Page 2 of 5 Station ID: 9458779 PUBLICATION DATE: 04/29/2004 Name: NAKCHAMIK ISLAND, PACIFIC OCEAN AK NOAA Chart: 16566 Latitude: 56° 21.1' N ( 56.35170) USGS Quad: SUTWIK ISLAND (B-6) Longitude: 157° 48.7' W (-157.81200) T I D A L B E N C H M A R K S BENCH MARK STAMPING: 8779 C 1996 DESIGNATION: 945 8779 C MONUMENTATION: Tidal Station disk VM#: 13148 AGENCY: National Ocean Service (NOS) IDB PID#: SETTING CLASSIFICATION: Rock outcrop OPUS PID: LATITUDE: 56° 21.1' N ( 56.35170) LONGITUDE: 157° 48.7' W (-157.81200) The bench mark is a disk set at the base of a rock cliff, 56 m (184 ft) SE (156 degrees magnetic) from bench mark 8779 B 1996, 40 m (131 ft) NW (330 degrees magnetic) from bench mark 8779 D 1996, and 0.50 m (1.6 ft) above the sand and cobble beach. BENCH MARK STAMPING: 8779 D 1996 DESIGNATION: 945 8779 D MONUMENTATION: Tidal Station disk VM#: 13149 AGENCY: National Ocean Service (NOS) IDB PID#: SETTING CLASSIFICATION: Boulder OPUS PID: LATITUDE: 56° 21.1' N ( 56.35170) LONGITUDE: 157° 48.7' W (-157.81200) The bench mark is a disk set on top of a boulder embedded in a sand and cobble beach at the base of a slide area, 40 m (131 ft) SE (150 degrees magnetic) from bench mark 8779 C 1996, 34 m (112 ft) NW (328 degrees magnetic) from bench mark 8779 E 1996, and 5 m (16 ft) east of a cliff face.
U.S. DEPARTMENT OF COMMERCE National Oceanic and Atmospheric Administration National Ocean Service Page 3 of 5 Station ID: 9458779 PUBLICATION DATE: 04/29/2004 Name: NAKCHAMIK ISLAND, PACIFIC OCEAN AK NOAA Chart: 16566 Latitude: 56° 21.1' N ( 56.35170) USGS Quad: SUTWIK ISLAND (B-6) Longitude: 157° 48.7' W (-157.81200) T I D A L B E N C H M A R K S BENCH MARK STAMPING: 8779 E 1996 DESIGNATION: 945 8779 E MONUMENTATION: Tidal Station disk VM#: 13150 AGENCY: National Ocean Service (NOS) IDB PID#: SETTING CLASSIFICATION: Boulder OPUS PID: LATITUDE: 56° 21.1' N ( 56.35170) LONGITUDE: 157° 48.7' W (-157.81200) The bench mark is a disk set on top of a boulder, 34 m (112 ft) SE (148 degrees magnetic) from bench mark 8779 D 1996, 0.80 m (2.6 ft) east of an overhanging cliff face, and 0.10 m (0.3 ft) above a sand and cobble beach.
U.S. DEPARTMENT OF COMMERCE National Oceanic and Atmospheric Administration National Ocean Service Page 4 of 5 Station ID: 9458779 PUBLICATION DATE: 04/29/2004 Name: NAKCHAMIK ISLAND, PACIFIC OCEAN AK NOAA Chart: 16566 Latitude: 56° 21.1' N ( 56.35170) USGS Quad: SUTWIK ISLAND (B-6) Longitude: 157° 48.7' W (-157.81200) T I D A L D A T U M S Tidal datums at NAKCHAMIK ISLAND, PACIFIC OCEAN based on: LENGTH OF SERIES: 2 MONTHS TIME PERIOD: June 1996 - July 1996 TIDAL EPOCH: 1983-2001 CONTROL TIDE STATION: 9459450 SAND POINT, POPOF ISLAND Elevations of tidal datums referred to Mean Lower Low Water (MLLW), in METERS: MEAN HIGHER HIGH WATER MHHW = 2.741 MEAN HIGH WATER MHW = 2.495 MEAN TIDE LEVEL MTL = 1.469 MEAN SEA LEVEL MSL = 1.444 MEAN LOW WATER MLW = 0.444 MEAN LOWER LOW WATER MLLW = 0.000 North American Vertical Datum (NAVD88) Bench Mark Elevation Information In METERS above: Stamping or Designation MLLW MHW 8779 A 1996 4.763 2.267 8779 B 1996 3.313 0.817 8779 C 1996 5.251 2.755 8779 D 1996 4.988 2.493 8779 E 1996 4.604 2.108
U.S. DEPARTMENT OF COMMERCE National Oceanic and Atmospheric Administration National Ocean Service Page 5 of 5 Station ID: 9458779 PUBLICATION DATE: 04/29/2004 Name: NAKCHAMIK ISLAND, PACIFIC OCEAN AK NOAA Chart: 16566 Latitude: 56° 21.1' N ( 56.35170) USGS Quad: SUTWIK ISLAND (B-6) Longitude: 157° 48.7' W (-157.81200) 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.