U.S. DEPARTMENT OF COMMERCE National Oceanic and Atmospheric Administration National Ocean Service Datums Page Page 1 of 5 Station ID: 9439008 PUBLICATION DATE: 01/23/2004 Name: FORT STEVENS OR NOAA Chart: 18521 Latitude: 46° 12.4' N ( 46.20670) USGS Quad: WARRENTON Longitude: 123° 57.0' W (-123.95000) To reach the tidal bench marks from Astoria, take U.S. Highway 101/26 south across Youngs Bay, turn right at the first intersection after crossing the bay onto State Route 105 and follow it to Warrenton, turn right onto State Route 104 and follow the signs to Fort Stevens, turn right on Lake Drive (in Hammond) and follow it for 1.21 km (0.75 mi) to the end of the road and the Columbia River Bar Pilots Association Pier. The bench marks are located in the vicinity of the pier and on Fort Stevens Military Reservation. The tide staff and gage were located on the west side of the pier. T I D A L B E N C H M A R K S PRIMARY BENCH MARK STAMPING: 9008 A 1981 DESIGNATION: 943 9008 A TIDAL MONUMENTATION: Tidal Station disk VM#: 11264 AGENCY: National Ocean Survey (NOS) IDB PID#: SETTING CLASSIFICATION: Concrete piling OPUS PID: LATITUDE: 46° 12.4' N ( 46.20670) LONGITUDE: 123° 57.0' W (-123.95000) The primary bench mark is a disk set flush in the east end of a 0.52 m (1.7 ft) x 3.35 m ( 11 ft) concrete piling located at the foot of the Columbia River Bar Pilots Association Pier, 9.24 m (30.3 ft) NNW of a telephone pole, and 5.88 m (19.3 ft) south of the SE corner of a second concrete piling.
U.S. DEPARTMENT OF COMMERCE National Oceanic and Atmospheric Administration National Ocean Service Page 2 of 5 Station ID: 9439008 PUBLICATION DATE: 01/23/2004 Name: FORT STEVENS OR NOAA Chart: 18521 Latitude: 46° 12.4' N ( 46.20670) USGS Quad: WARRENTON Longitude: 123° 57.0' W (-123.95000) T I D A L B E N C H M A R K S BENCH MARK STAMPING: USBM 3 1940 DESIGNATION: 943 9008 TIDAL 3 MONUMENTATION: Tidal Station disk VM#: 11263 AGENCY: US Coast & Geodetic Survey (USC&GS) IDB PID#: SC0586 SETTING CLASSIFICATION: Manhole foundation OPUS PID: LATITUDE: 46° 12.4' N ( 46.20670) LONGITUDE: 123° 57.3' W (-123.95500) The bench mark is a disk set in the top and at the NW corner of a concrete basin of an old manhole located north of the centerline of the entrance road, 46 m (150 ft) west of the entrance gate to Fort Stevens Historic Army Coast Artillery Base site, 13.75 m (45.1 ft) SSE of the SW corner of "Search Light Generator Shack", and 10.21 m (33.5 ft) south of the SE corner of the generator shack.
U.S. DEPARTMENT OF COMMERCE National Oceanic and Atmospheric Administration National Ocean Service Page 3 of 5 Station ID: 9439008 PUBLICATION DATE: 01/23/2004 Name: FORT STEVENS OR NOAA Chart: 18521 Latitude: 46° 12.4' N ( 46.20670) USGS Quad: WARRENTON Longitude: 123° 57.0' W (-123.95000) T I D A L B E N C H M A R K S BENCH MARK STAMPING: GUN DESIGNATION: GUN RESET MONUMENTATION: Survey disk VM#: 11266 AGENCY: US Corp of Engineers (USE) IDB PID#: SC0583 SETTING CLASSIFICATION: Concrete monument OPUS PID: LATITUDE: 46° 12.4' N ( 46.20670) LONGITUDE: 123° 57.7' W (-123.96200) The bench mark is a disk set in the top of a concrete monument is located next to a flagpole at the center of an earthen fort. BENCH MARK STAMPING: USGS BM DESIGNATION: 943 9008 USGS BM MONUMENTATION: Nail VM#: 11267 AGENCY: US Geological Survey (USGS) IDB PID#: SETTING CLASSIFICATION: Concrete manhole OPUS PID: LATITUDE: 46° 12.4' N ( 46.20670) LONGITUDE: 123° 57.0' W (-123.95000) The bench mark is a nail set in the SW corner of a concrete manhole located near the entrance road to Fort Stevens Historic Army Coast Artillery Base site, 146 m (480 ft) west of the main entrance gate, 26.55 m (87.1 ft) east of a sign designating the site, 17.34 m (56.9 ft) ESE of the center of the gate leading to the site, and 2 m (5 ft) north of the entrance road to the site.
U.S. DEPARTMENT OF COMMERCE National Oceanic and Atmospheric Administration National Ocean Service Page 4 of 5 Station ID: 9439008 PUBLICATION DATE: 01/23/2004 Name: FORT STEVENS OR NOAA Chart: 18521 Latitude: 46° 12.4' N ( 46.20670) USGS Quad: WARRENTON Longitude: 123° 57.0' W (-123.95000) T I D A L D A T U M S Tidal datums at FORT STEVENS based on: LENGTH OF SERIES: 7 MONTHS TIME PERIOD: May 1981 - November 1981 TIDAL EPOCH: 1983-2001 CONTROL TIDE STATION: 9439040 ASTORIA, TONGUE POINT, COLUMBIA RIVER Elevations of tidal datums referred to Mean Lower Low Water (MLLW), in METERS: MEAN HIGHER HIGH WATER MHHW = 2.624 MEAN HIGH WATER MHW = 2.410 MEAN TIDE LEVEL MTL = 1.401 MEAN SEA LEVEL MSL = 1.385 MEAN LOW WATER MLW = 0.391 North American Vertical Datum NAVD88 = 0.054 MEAN LOWER LOW WATER MLLW = 0.000 North American Vertical Datum (NAVD88) Bench Mark Elevation Information In METERS above: Stamping or Designation MLLW MHW 9008 A 1981 3.204 0.794 USBM 3 1940 3.324 0.914 GUN 5.667 3.257 USGS BM 4.317 1.907
U.S. DEPARTMENT OF COMMERCE National Oceanic and Atmospheric Administration National Ocean Service Page 5 of 5 Station ID: 9439008 PUBLICATION DATE: 01/23/2004 Name: FORT STEVENS OR NOAA Chart: 18521 Latitude: 46° 12.4' N ( 46.20670) USGS Quad: WARRENTON Longitude: 123° 57.0' W (-123.95000) 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.