U.S. DEPARTMENT OF COMMERCE National Oceanic and Atmospheric Administration National Ocean Service Datums Page Page 1 of 5 Station ID: 9452318 PUBLICATION DATE: 08/22/2018 Name: BARLOW COVE, LYNN CANAL AK NOAA Chart: 17316 Latitude: 58° 19.3' N ( 58.32170) USGS Quad: JUNEAU (B-3) Longitude: 134° 52.7' W (-134.87800) To reach the tidal bench marks proceed to the southern end of Barlow Cove, along the base of the rocky cliff that divides the beach in two parts. The tide station was located among the trees and rock outcrop on shore and the bench marks were located in the vicinity on the rock outcrop along the shore. T I D A L B E N C H M A R K S PRIMARY BENCH MARK STAMPING: 2318 B 1999 DESIGNATION: 945 2318 B MONUMENTATION: Tidal Station disk VM#: 15941 AGENCY: National Ocean Service (NOS) IDB PID#: SETTING CLASSIFICATION: Rock ledge OPUS PID: LATITUDE: 58° 19.3' N ( 58.32170) LONGITUDE: 134° 52.7' W (-134.87800) The primary bench mark is a disk set in a rock ledge near the base at the east side of a cliff that divides the beach at the southern end of Barlow Cove, 30 m (100 ft) east (95 degrees magnetic) of bench mark 2318 C 1999, 12 m (40 ft) WNW (290 degrees magnetic) of bench mark 2318 A 1999, and 6 m (20 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: 9452318 PUBLICATION DATE: 08/22/2018 Name: BARLOW COVE, LYNN CANAL AK NOAA Chart: 17316 Latitude: 58° 19.3' N ( 58.32170) USGS Quad: JUNEAU (B-3) Longitude: 134° 52.7' W (-134.87800) T I D A L B E N C H M A R K S BENCH MARK STAMPING: 2318 A 1999 DESIGNATION: 945 2318 A MONUMENTATION: Tidal Station disk VM#: 15940 AGENCY: National Ocean Service (NOS) IDB PID#: SETTING CLASSIFICATION: Rock ledge OPUS PID: LATITUDE: 58° 19.3' N ( 58.32170) LONGITUDE: 134° 52.7' W (-134.87800) The bench mark is a disk set in the quartz vein of a rock ledge at the base of a cliff that divides the beach at the southern end of Barlow Cove, 12 m (40 ft) ESE (110 degrees magnetic) of bench mark 2318 B 1999, and 6 m (20 ft) above the apparent high water line. BENCH MARK STAMPING: 2318 C 1999 DESIGNATION: 945 2318 C MONUMENTATION: Tidal Station disk VM#: 15942 AGENCY: National Ocean Service (NOS) IDB PID#: SETTING CLASSIFICATION: Rock ledge OPUS PID: LATITUDE: 58° 19.3' N ( 58.32170) LONGITUDE: 134° 52.7' W (-134.87800) The bench mark is a disk set in the quartz vein of a rock ledge at the base of a cliff that divides the beach at the southern end of Barlow Cove, directly under trees hanging over the cliff edge, 30 m (100 ft) west (275 degrees magnetic) of bench mark 2318 B 1999, 24 m (80 ft) east (92 degrees magnetic) of bench mark 2318 D 1999, and 5 m (15 ft) above the apparent high water.
U.S. DEPARTMENT OF COMMERCE National Oceanic and Atmospheric Administration National Ocean Service Page 3 of 5 Station ID: 9452318 PUBLICATION DATE: 08/22/2018 Name: BARLOW COVE, LYNN CANAL AK NOAA Chart: 17316 Latitude: 58° 19.3' N ( 58.32170) USGS Quad: JUNEAU (B-3) Longitude: 134° 52.7' W (-134.87800) T I D A L B E N C H M A R K S BENCH MARK STAMPING: 2318 D 1999 DESIGNATION: 945 2318 D MONUMENTATION: Tidal Station disk VM#: 15943 AGENCY: National Ocean Service (NOS) IDB PID#: SETTING CLASSIFICATION: Rock ledge OPUS PID: LATITUDE: 58° 19.3' N ( 58.32170) LONGITUDE: 134° 52.7' W (-134.87800) The bench mark is a disk set in a quartz vein surrounded by shale near the northern point of a rock ledge of a cliff that divides the beach at the southern end of Barlow Cove, 24 m (80 ft) west (272 degrees magnetic) of bench mark 2318 C 1999, 15 m (48 ft) ENE of bench mark 2318 E 1999, and 6 m (20 ft) above the apparent high water line. BENCH MARK STAMPING: 2318 E 1999 DESIGNATION: 945 2318 E MONUMENTATION: Tidal Station disk VM#: 15944 AGENCY: National Ocean Service (NOS) IDB PID#: SETTING CLASSIFICATION: Granite rock OPUS PID: LATITUDE: 58° 19.3' N ( 58.32170) LONGITUDE: 134° 52.7' W (-134.87800) The bench mark is a disk set in a granite rock at the base of the treeline, west of the west end of the shale rock ledge of a cliff that divides the beach at the southern end of Barlow Cove, 15 m (48 ft) WSW of bench mark 2318 D 1999, and 15 m (50 ft) above the apparent high water line.
U.S. DEPARTMENT OF COMMERCE National Oceanic and Atmospheric Administration National Ocean Service Page 4 of 5 Station ID: 9452318 PUBLICATION DATE: 08/22/2018 Name: BARLOW COVE, LYNN CANAL AK NOAA Chart: 17316 Latitude: 58° 19.3' N ( 58.32170) USGS Quad: JUNEAU (B-3) Longitude: 134° 52.7' W (-134.87800) T I D A L D A T U M S Tidal datums at BARLOW COVE, LYNN CANAL based on: LENGTH OF SERIES: 60 DAYS TIME PERIOD: APRIL 07 - JUNE 05, 1999 TIDAL EPOCH: 2012-2016 CONTROL TIDE STATION: 9452210 JUNEAU, GASTINEAU CHANNEL, STEPHENS PASS Elevations of tidal datums referred to Mean Lower Low Water (MLLW), in METERS: MEAN HIGHER HIGH WATER MHHW = 4.816 MEAN HIGH WATER MHW = 4.523 MEAN SEA LEVEL MSL = 2.536 MEAN TIDE LEVEL MTL = 2.503 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 2318 B 1999 6.485 1.962 2318 A 1999 6.303 1.780 2318 C 1999 6.370 1.847 2318 D 1999 6.070 1.547 2318 E 1999 6.964 2.441
U.S. DEPARTMENT OF COMMERCE National Oceanic and Atmospheric Administration National Ocean Service Page 5 of 5 Station ID: 9452318 PUBLICATION DATE: 08/22/2018 Name: BARLOW COVE, LYNN CANAL AK NOAA Chart: 17316 Latitude: 58° 19.3' N ( 58.32170) USGS Quad: JUNEAU (B-3) Longitude: 134° 52.7' W (-134.87800) 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.