U.S. DEPARTMENT OF COMMERCE National Oceanic and Atmospheric Administration National Ocean Service Datums Page Page 1 of 5 Station ID: 9452421 PUBLICATION DATE: 07/02/2018 Name: CHILKAT INLET AK NOAA Chart: 16700 Latitude: 59° 10.2' N ( 59.17000) USGS Quad: SKAGWAY (A-2) Longitude: 135° 24.0' W (-135.40000) To reach the tidal bench marks, proceed to the eastern bank of Chilkat Inlet, 400 m (1312 ft) south of Letnikof Cove Light F1 R 4 sec. The bench marks are located in the vicinity on the SE to south side. The tide gauge was placed on a small wooden platform, behind a rock cluster, 40 m (131 ft) inland from the water's edge, approximately 6 m (20 ft) above the apparent high water. T I D A L B E N C H M A R K S PRIMARY BENCH MARK STAMPING: 2421 C 1998 DESIGNATION: 945 2421 C MONUMENTATION: Tidal Station disk VM#: 14041 AGENCY: National Ocean Service (NOS) IDB PID#: SETTING CLASSIFICATION: Rock outcrop OPUS PID: LATITUDE: 59° 10.2' N ( 59.17000) LONGITUDE: 135° 24.0' W (-135.40000) The primary bench mark is a disk set on top of one of the highest points of a prominent dark-coloured, steep-faced, mussel-encrusted, rocky ledge, sharp-featured rock, on the eastern bank of Chilkat Inlet, 320 m (1050 ft) south of Letnikof Cove Light F1 R 4 sec, 66 m (216 ft) NW (290 degrees magnetic) from bench mark 2421 B 1998, 10 m (33 ft) inland of the water's edge, and 2.50 m (8.2 ft) above the apparent high water line.
U.S. DEPARTMENT OF COMMERCE National Oceanic and Atmospheric Administration National Ocean Service Page 2 of 5 Station ID: 9452421 PUBLICATION DATE: 07/02/2018 Name: CHILKAT INLET AK NOAA Chart: 16700 Latitude: 59° 10.2' N ( 59.17000) USGS Quad: SKAGWAY (A-2) Longitude: 135° 24.0' W (-135.40000) T I D A L B E N C H M A R K S BENCH MARK STAMPING: 2421 A 1998 DESIGNATION: 945 2421 A MONUMENTATION: Tidal Station disk VM#: 14039 AGENCY: National Ocean Service (NOS) IDB PID#: SETTING CLASSIFICATION: Rock outcrop OPUS PID: LATITUDE: 59° 10.2' N ( 59.17000) LONGITUDE: 135° 24.0' W (-135.40000) The bench mark is a disk set on top of a distinctive, flat, light-coloured, 1m x 1 m x 1 m (4 ft x 3 ft x 2 ft) rock on the eastern bank of Chilkat Inlet, 400 m (1312 ft) south of Letnikof Cove Light F1 R 4 sec, along a relatively flat section shore heavily strewn with small boulders and drift wood and sparsely covered with tall grass, 100 m (328 ft) north of an isolated waterfront house, 39 m (128 ft) SE (60 degrees magnetic) from bench mark 2421 B 1998, 30 m (98 ft) inland from the waterline, and 2 m (7 ft) away from the treeline. BENCH MARK STAMPING: 2421 B 1998 DESIGNATION: 945 2421 B MONUMENTATION: Tidal Station disk VM#: 14040 AGENCY: National Ocean Service (NOS) IDB PID#: SETTING CLASSIFICATION: Rock outcrop OPUS PID: LATITUDE: 59° 10.2' N ( 59.17000) LONGITUDE: 135° 24.0' W (-135.40000) The bench mark is a disk set on top of a distinctive, flat, light-coloured, 1m x 1 m x 1 m (4 ft x 3 ft x 2 ft) rock on the eastern bank of Chilkat Inlet, 400 m (1312 ft) south of Letnikof Cove Light F1 R 4 sec, along a relatively flat section shore heavily strewn with small boulders and drift wood and sparsely covered with tall grass, 100 m (328 ft) north of an isolated waterfront house, 39 m (128 ft) NW (300 degrees magnetic) from bench mark 2421 A 1998, 30 m (98 ft) inland from the waterline, and 2 m (7 ft) away from the treeline.
U.S. DEPARTMENT OF COMMERCE National Oceanic and Atmospheric Administration National Ocean Service Page 3 of 5 Station ID: 9452421 PUBLICATION DATE: 07/02/2018 Name: CHILKAT INLET AK NOAA Chart: 16700 Latitude: 59° 10.2' N ( 59.17000) USGS Quad: SKAGWAY (A-2) Longitude: 135° 24.0' W (-135.40000) T I D A L B E N C H M A R K S BENCH MARK STAMPING: 2421 D 1998 DESIGNATION: 945 2421 D MONUMENTATION: Tidal Station disk VM#: 14042 AGENCY: National Ocean Service (NOS) IDB PID#: SETTING CLASSIFICATION: Rock outcrop OPUS PID#: BBDX55 LATITUDE: 59° 10.2' N ( 59.17000) LONGITUDE: 135° 24.0' W (-135.40000) The bench mark is a disk set on top of a low-lying flat 1 m x 1 m x 0.3 m (2 ft x 3 ft x 1 ft) rock located on the eastern bank of Chilkat Inlet, 290 m (951 ft) SSE of Letnikof Cove Light F1 R 4 sec, on a boulder strewn section of beach just north of the prominent, dark-coloured, steep-faced, mussel-encrusted rocky ledge, 65 m (213 ft) NE (010 degrees magnetic) from bench mark 2421 C 1998, and 8 m (26 ft) inland of the apparent high water line. BENCH MARK STAMPING: 2421 E 1998 DESIGNATION: 945 2421 E MONUMENTATION: Tidal Station disk VM#: 14043 AGENCY: National Ocean Service (NOS) IDB PID#: SETTING CLASSIFICATION: Rock outcrop OPUS PID#: BBDX54 LATITUDE: 59° 10.2' N ( 59.17000) LONGITUDE: 135° 24.0' W (-135.40000) The bench mark is a disk set on top of a low-lying flat 1 m x 1 m x 0.3 m (2 ft x 3 ft x 1 ft) rock located on the eastern bank of Chilkat Inlet, 235 m (771 ft) SE of Letnikof Cove Light F1 R 4 sec, on a boulder strewn section of beach just north of the prominent, dark-coloured, steep-faced, mussel-encrusted rocky ledge, 56 m (184 ft) NW (340 degrees magnetic) from bench mark 2421 D 1998, 15 m (49 ft) inland of the apparent high water line, and 10 m (33 ft) below the treeline.
U.S. DEPARTMENT OF COMMERCE National Oceanic and Atmospheric Administration National Ocean Service Page 4 of 5 Station ID: 9452421 PUBLICATION DATE: 07/02/2018 Name: CHILKAT INLET AK NOAA Chart: 16700 Latitude: 59° 10.2' N ( 59.17000) USGS Quad: SKAGWAY (A-2) Longitude: 135° 24.0' W (-135.40000) T I D A L D A T U M S Tidal datums at CHILKAT INLET based on: LENGTH OF SERIES: 30 DAYS TIME PERIOD: May 15 1998 - June 14 1998 TIDAL EPOCH: 2012-2016 CONTROL TIDE STATION: 9452400 SKAGWAY, TAIYA INLET Elevations of tidal datums referred to Mean Lower Low Water (MLLW), in METERS: MEAN HIGHER HIGH WATER MHHW = 5.021 MEAN HIGH WATER MHW = 4.713 MEAN SEA LEVEL MSL = 2.639 MEAN TIDE LEVEL MTL = 2.598 MEAN LOW WATER MLW = 0.482 MEAN LOWER LOW WATER MLLW = 0.000 North American Vertical Datum (NAVD88) Bench Mark Elevation Information In METERS above: Stamping or Designation MLLW MHW 2421 C 1998 6.457 1.743 2421 A 1998 7.345 2.632 2421 B 1998 7.768 3.055 2421 D 1998 6.336 1.622 2421 E 1998 7.311 2.597
U.S. DEPARTMENT OF COMMERCE National Oceanic and Atmospheric Administration National Ocean Service Page 5 of 5 Station ID: 9452421 PUBLICATION DATE: 07/02/2018 Name: CHILKAT INLET AK NOAA Chart: 16700 Latitude: 59° 10.2' N ( 59.17000) USGS Quad: SKAGWAY (A-2) Longitude: 135° 24.0' W (-135.40000) 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.