U.S. DEPARTMENT OF COMMERCE National Oceanic and Atmospheric Administration National Ocean Service Datums Page Page 1 of 5 Station ID: 9449828 PUBLICATION DATE: 07/15/2004 Name: HANBURY POINT, SAN JUAN ISLAND WA NOAA Chart: 18433 Latitude: 48° 34.9' N ( 48.58170) USGS Quad: ROCHE HARBOR Longitude: 123° 10.2' W (-123.17000) To reach the tidal bench marks from Roche Harbor on San Juan Island, proceed by boat WSW for about 3.7 km (2.3 statute mi) via Mosquito Pass to Hanbury Point. The bench marks are located at Hanbury Point, south of a pier and along the shore between the shoreline and a rock bluff. The gage and staff were located at the offshore end of the pier. T I D A L B E N C H M A R K S PRIMARY BENCH MARK STAMPING: BM 1 1973 DESIGNATION: 944 9828 TIDAL 1 MONUMENTATION: Tidal Station disk VM#: 9310 AGENCY: National Ocean Survey (NOS) IDB PID#: SETTING CLASSIFICATION: Bedrock outcrop OPUS PID: LATITUDE: 48° 34.7' N ( 48.57830) LONGITUDE: 123° 10.4' W (-123.17300) The primary bench mark is a disk set in a bedrock ledge of the bluff, 8 m (26 ft) south of the pier and boat house, and about level with the floor of the fixed pier. BENCH MARK STAMPING: BM 2 1973 DESIGNATION: 944 9828 TIDAL 2 MONUMENTATION: Tidal Station disk VM#: 9311 AGENCY: National Ocean Survey (NOS) IDB PID#: SETTING CLASSIFICATION: Bedrock outcrop OPUS PID: LATITUDE: 48° 34.7' N ( 48.57830) LONGITUDE: 123° 10.4' W (-123.17300) The bench mark is a disk set in a bedrock ledge of the bluff, 34 m (112 ft) south of the pier, 26 m (86 ft) south of bench mark BM 1 1973, and 1 m (3 ft) above the approximate high water line.
U.S. DEPARTMENT OF COMMERCE National Oceanic and Atmospheric Administration National Ocean Service Page 2 of 5 Station ID: 9449828 PUBLICATION DATE: 07/15/2004 Name: HANBURY POINT, SAN JUAN ISLAND WA NOAA Chart: 18433 Latitude: 48° 34.9' N ( 48.58170) USGS Quad: ROCHE HARBOR Longitude: 123° 10.2' W (-123.17000) T I D A L B E N C H M A R K S BENCH MARK STAMPING: BM 3 1973 DESIGNATION: 944 9828 TIDAL 3 MONUMENTATION: Tidal Station disk VM#: 9312 AGENCY: National Ocean Survey (NOS) IDB PID#: SETTING CLASSIFICATION: Bedrock outcrop OPUS PID: LATITUDE: 48° 34.7' N ( 48.57830) LONGITUDE: 123° 10.4' W (-123.17300) The bench mark is a disk set in a bedrock ledge of the bluff, 74 m (242 ft) south of the pier, 40 m (130 ft) south of bench mark BM 2 1973, and 1 m (3 ft) above the approximate high water line. BENCH MARK STAMPING: BM 4 1973 DESIGNATION: 944 9828 TIDAL 4 MONUMENTATION: Tidal Station disk VM#: 9313 AGENCY: National Ocean Survey (NOS) IDB PID#: SETTING CLASSIFICATION: Bedrock outcrop OPUS PID: LATITUDE: 48° 34.7' N ( 48.57830) LONGITUDE: 123° 10.4' W (-123.17300) The bench mark is a disk set in a bedrock ledge of the bluff, 98 m (320 ft) south of the pier, 24 m (78 ft) south of bench mark BM 3 1973, 3 m (9 ft) north of the west corner of the bottom concrete step of the stairs leading up the bluff, and 1 m (3 ft) above the approximate high water line.
U.S. DEPARTMENT OF COMMERCE National Oceanic and Atmospheric Administration National Ocean Service Page 3 of 5 Station ID: 9449828 PUBLICATION DATE: 07/15/2004 Name: HANBURY POINT, SAN JUAN ISLAND WA NOAA Chart: 18433 Latitude: 48° 34.9' N ( 48.58170) USGS Quad: ROCHE HARBOR Longitude: 123° 10.2' W (-123.17000) T I D A L B E N C H M A R K S BENCH MARK STAMPING: BM 5 1973 DESIGNATION: 944 9828 TIDAL 5 MONUMENTATION: Tidal Station disk VM#: 9314 AGENCY: National Ocean Survey (NOS) IDB PID#: SETTING CLASSIFICATION: Bedrock outcrop OPUS PID: LATITUDE: 48° 34.7' N ( 48.57830) LONGITUDE: 123° 10.4' W (-123.17300) The bench mark is a disk set in a bedrock ledge of the bluff, 138 m (454 ft) south of the pier, 41 m (134 ft) south of bench mark BM 4 1973, and 1 m (3 ft) above the approximate high water line.
U.S. DEPARTMENT OF COMMERCE National Oceanic and Atmospheric Administration National Ocean Service Page 4 of 5 Station ID: 9449828 PUBLICATION DATE: 07/15/2004 Name: HANBURY POINT, SAN JUAN ISLAND WA NOAA Chart: 18433 Latitude: 48° 34.9' N ( 48.58170) USGS Quad: ROCHE HARBOR Longitude: 123° 10.2' W (-123.17000) T I D A L D A T U M S Tidal datums at HANBURY POINT, SAN JUAN ISLAND based on: LENGTH OF SERIES: 2 MONTHS TIME PERIOD: September 1974 - October 1974 TIDAL EPOCH: 1983-2001 CONTROL TIDE STATION: 9449880 FRIDAY HARBOR, SAN JUAN CHANNEL Elevations of tidal datums referred to Mean Lower Low Water (MLLW), in METERS: MEAN HIGHER HIGH WATER MHHW = 2.325 MEAN HIGH WATER MHW = 2.123 MEAN TIDE LEVEL MTL = 1.416 MEAN SEA LEVEL MSL = 1.367 MEAN LOW WATER MLW = 0.709 MEAN LOWER LOW WATER MLLW = 0.000 North American Vertical Datum (NAVD88) Bench Mark Elevation Information In METERS above: Stamping or Designation MLLW MHW BM 1 1973 3.921 1.798 BM 2 1973 3.559 1.436 BM 3 1973 3.505 1.382 BM 4 1973 3.859 1.736 BM 5 1973 3.697 1.574
U.S. DEPARTMENT OF COMMERCE National Oceanic and Atmospheric Administration National Ocean Service Page 5 of 5 Station ID: 9449828 PUBLICATION DATE: 07/15/2004 Name: HANBURY POINT, SAN JUAN ISLAND WA NOAA Chart: 18433 Latitude: 48° 34.9' N ( 48.58170) USGS Quad: ROCHE HARBOR Longitude: 123° 10.2' W (-123.17000) 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.