U.S. DEPARTMENT OF COMMERCE National Oceanic and Atmospheric Administration National Ocean Service Datums Page Page 1 of 5 Station ID: 9445478 PUBLICATION DATE: 08/09/2004 Name: UNION, HOOD CANAL WA NOAA Chart: 18476 Latitude: 47° 21.5' N ( 47.35830) USGS Quad: POTLATCH Longitude: 123° 5.9' W (-123.09800) To reach the tidal bench marks from the Post Office in Union, proceed west on State Route 106 for 100 m (328 ft) to the Hood Canal Marina building. The bench marks are located along State Route 106. The tide gage and staff were located on the pier east of the Hood Canal Marina building. T I D A L B E N C H M A R K S PRIMARY BENCH MARK STAMPING: 3 1935 DESIGNATION: 944 5478 TIDAL 3 MONUMENTATION: Tidal Station disk VM#: 9060 AGENCY: US Coast & Geodetic Survey (USC&GS) IDB PID#: SY1271 SETTING CLASSIFICATION: Concrete slab OPUS PID: LATITUDE: 47° 21.4' N ( 47.35670) LONGITUDE: 123° 6.3' W (-123.10500) The primary bench mark is a disk set in the concrete slab at the southernmost corner of the Mobile Service station on the north side of State Highway 106, 0.3 km (0.2 mi) west of the post office, 120 m (394 ft) west of the remains of the Masonic Hall, 13 m (42 ft) north of the centerline of State Highway 106, 0.76 m (2.5 ft) west of the SE corner of the building, and 0.15 m (0.5 ft) south of the south face of the building.
U.S. DEPARTMENT OF COMMERCE National Oceanic and Atmospheric Administration National Ocean Service Page 2 of 5 Station ID: 9445478 PUBLICATION DATE: 08/09/2004 Name: UNION, HOOD CANAL WA NOAA Chart: 18476 Latitude: 47° 21.5' N ( 47.35830) USGS Quad: POTLATCH Longitude: 123° 5.9' W (-123.09800) T I D A L B E N C H M A R K S BENCH MARK STAMPING: 4 1935 DESIGNATION: 944 5478 TIDAL 4 MONUMENTATION: Tidal Station disk VM#: 9061 AGENCY: US Coast & Geodetic Survey (USC&GS)` IDB PID#: SY1274 SETTING CLASSIFICATION: Retaining wall OPUS PID: LATITUDE: 47° 21.4' N ( 47.35670) LONGITUDE: 123° 6.1' W (-123.10200) The bench mark is a disk set vertically in the north face of a concrete retaining wall in front of a private home, 177 m (580 ft) west of the post office, 25 m (81 ft) SE of the SE corner of the remains of the Masonic Hall, 7 m (22 ft) south of the centerline of State Highway 106, 1 m (3 ft) east of the west end of the retaining wall, and 0.3 m (1 ft) above the level of the highway. BENCH MARK STAMPING: BM 1 1972 DESIGNATION: 944 5478 TIDAL 1 MONUMENTATION: Tidal Station disk VM#: 9063 AGENCY: US Coast & Geodetic Survey (USC&GS) IDB PID#: SY1272 SETTING CLASSIFICATION: Concrete slab OPUS PID: LATITUDE: 47° 21.4' N ( 47.35670) LONGITUDE: 123° 6.3' W (-123.10500) The bench mark is a disk set flush in the center of the north end of a 5 x 8 m (17 x 27 ft) concrete slab that served as the floor to an old firehouse adjacent to and east of the Mobile Gas Station, 0.3 km (0.2 mi) west of the post office, 29 m (94 ft) north of the centerline of State Highway 106, 23 m (74 ft) NW of power pole U 105 bearing a transformer and a light, 21.76 m (71.4 ft) NE of bench mark 3 1935, 1.83 m (6.0 ft) east of the NW corner of the concrete slab, and 1 m (2 ft) below the level of the highway.
U.S. DEPARTMENT OF COMMERCE National Oceanic and Atmospheric Administration National Ocean Service Page 3 of 5 Station ID: 9445478 PUBLICATION DATE: 08/09/2004 Name: UNION, HOOD CANAL WA NOAA Chart: 18476 Latitude: 47° 21.5' N ( 47.35830) USGS Quad: POTLATCH Longitude: 123° 5.9' W (-123.09800) T I D A L B E N C H M A R K S BENCH MARK STAMPING: NO 7 1973 DESIGNATION: 944 5478 TIDAL 7 MONUMENTATION: Tidal Station disk VM#: 9064 AGENCY: National Ocean Survey (NOS) IDB PID#: SETTING CLASSIFICATION: Concrete slab OPUS PID: LATITUDE: 47° 21.5' N ( 47.35830) LONGITUDE: 123° 5.9' W (-123.09800) The bench mark is a disk set in concrete slab (walkway) around the Hood Canal Marina building, next to the building and at the SE corner of the door to the men's restroom, 5 m (16 ft) back and 2 m (6 ft) over from the corner of the concrete slab.
U.S. DEPARTMENT OF COMMERCE National Oceanic and Atmospheric Administration National Ocean Service Page 4 of 5 Station ID: 9445478 PUBLICATION DATE: 08/09/2004 Name: UNION, HOOD CANAL WA NOAA Chart: 18476 Latitude: 47° 21.5' N ( 47.35830) USGS Quad: POTLATCH Longitude: 123° 5.9' W (-123.09800) T I D A L D A T U M S Tidal datums at UNION, HOOD CANAL based on: LENGTH OF SERIES: 4 MONTHS TIME PERIOD: June 1977 - September 1977 TIDAL EPOCH: 1983-2001 CONTROL TIDE STATION: 9447130 SEATTLE, PUGET SOUND Elevations of tidal datums referred to Mean Lower Low Water (MLLW), in METERS: MEAN HIGHER HIGH WATER MHHW = 3.613 MEAN HIGH WATER MHW = 3.312 MEAN SEA LEVEL MSL = 2.122 MEAN TIDE LEVEL MTL = 2.115 MEAN LOW WATER MLW = 0.917 North American Vertical Datum NAVD88 = 0.865 MEAN LOWER LOW WATER MLLW = 0.000 North American Vertical Datum (NAVD88) Bench Mark Elevation Information In METERS above: Stamping or Designation MLLW MHW 3 1935 5.605 2.293 4 1935 6.483 3.171 BM 1 1972 4.741 1.429 NO 7 1973 4.681 1.369
U.S. DEPARTMENT OF COMMERCE National Oceanic and Atmospheric Administration National Ocean Service Page 5 of 5 Station ID: 9445478 PUBLICATION DATE: 08/09/2004 Name: UNION, HOOD CANAL WA NOAA Chart: 18476 Latitude: 47° 21.5' N ( 47.35830) USGS Quad: POTLATCH Longitude: 123° 5.9' W (-123.09800) 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.