U.S. DEPARTMENT OF COMMERCE National Oceanic and Atmospheric Administration National Ocean Service Datums Page Page 1 of 5 Station ID: 9440572 PUBLICATION DATE: 12/12/2003 Name: JETTY A, COLUMBIA RIVER WA NOAA Chart: 18521 Latitude: 46° 16.1' N ( 46.26830) USGS Quad: CAPE DISAPPOINTMENT Longitude: 124° 2.2' W (-124.03700) To reach the tidal bench marks from Astoria, Oregon, proceed towards Washington on U.S. Highway 101, cross the Astoria-Megler bridge, turn left (west) at the north end of the bridge and follow U.S. Highway 101 for 16 km (10 mi) to the town of Illwaco. At the main intersection in the town of Illwaco, turn left, follow the signs posted to the Cape Disappointment Coast Guard Station. Stay on the main road through the coast guard station to an unpaved road, pass a firing range on the right and a helicopter pad on the left to the end of the unpaved road and the beginning of the jetty. Most of the bench marks are located on the jetty and one is located at the very beginning of the jetty. The tide gauge was located on a U.S. Army Corps of Engineers dredging marker 30 m (100 ft) offshore. T I D A L B E N C H M A R K S PRIMARY BENCH MARK STAMPING: MID 1970 DESIGNATION: 944 0572 MID MONUMENTATION: Tidal Station disk VM#: 8922 AGENCY: National Ocean Survey (NOS) IDB PID#: SETTING CLASSIFICATION: Boulder OPUS PID: LATITUDE: 46° 16.1' N ( 46.26830) LONGITUDE: 124° 2.2' W (-124.03700) The primary bench mark is a disk set flush in a large flat boulder marked by an aerial survey cross in the middle of Jetty A, 457 m (1500 ft) SE of bench mark 0572 A 1981, 457 m (1500 ft) NW of bench mark BEND 1970 U.S.E., 114 m (374 ft) SE of a turning point stamped 5 which is a lag bolt cemented in boulder and marked by aerial survey cross.
U.S. DEPARTMENT OF COMMERCE National Oceanic and Atmospheric Administration National Ocean Service Page 2 of 5 Station ID: 9440572 PUBLICATION DATE: 12/12/2003 Name: JETTY A, COLUMBIA RIVER WA NOAA Chart: 18521 Latitude: 46° 16.1' N ( 46.26830) USGS Quad: CAPE DISAPPOINTMENT Longitude: 124° 2.2' W (-124.03700) T I D A L B E N C H M A R K S BENCH MARK STAMPING: BETTY M 1976 DESIGNATION: BETTY M MONUMENTATION: Survey disk VM#: 8923 AGENCY: Pacific County IDB PID#: SD0640 SETTING CLASSIFICATION: Concrete monument OPUS PID: LATITUDE: 46° 16.6' N ( 46.27670) LONGITUDE: 124° 2.5' W (-124.04200) The bench mark is a disk set flush in a concrete monument at the intersection of two roads just north of the jetty, and 1 m (3 ft) east of a witness post. BENCH MARK STAMPING: 0572 A 1981 DESIGNATION: 944 0572 A MONUMENTATION: Tidal Station disk VM#: 8926 AGENCY: National Ocean Survey (NOS) IDB PID#: SETTING CLASSIFICATION: Boulder OPUS PID: LATITUDE: 46° 16.1' N ( 46.26830) LONGITUDE: 124° 2.2' W (-124.03700) The bench mark is a disk set flush in a large flat boulder, 457 m (1500 ft) NW of bench mark MID 1970, 110 m (360 ft) NW of a turning point stamped 6 which is a stainless steel lag bolt cemented in boulder, and marked by aerial survey cross.
U.S. DEPARTMENT OF COMMERCE National Oceanic and Atmospheric Administration National Ocean Service Page 3 of 5 Station ID: 9440572 PUBLICATION DATE: 12/12/2003 Name: JETTY A, COLUMBIA RIVER WA NOAA Chart: 18521 Latitude: 46° 16.1' N ( 46.26830) USGS Quad: CAPE DISAPPOINTMENT Longitude: 124° 2.2' W (-124.03700) T I D A L B E N C H M A R K S BENCH MARK STAMPING: 0572 B 1997 DESIGNATION: 944 0572 B MONUMENTATION: Tidal Station disk VM#: 13722 AGENCY: National Ocean Service (NOS) IDB PID#: SETTING CLASSIFICATION: Boulder OPUS PID: LATITUDE: 46° 16.1' N ( 46.26830) LONGITUDE: 124° 2.2' W (-124.03700) The bench mark is a disk set flush in a large boulder on the west side of Jetty A, 140 m (459 ft) north of bench mark 0572 A 1981, and 120 m (393 ft) south of bench mark Betty M 1976. BENCH MARK STAMPING: BEND 1970 U.S.E DESIGNATION: 944 0572 BEND USE MONUMENTATION: Survey disk VM#: 13723 AGENCY: US Army Corps of Engineers (USE) IDB PID#: SETTING CLASSIFICATION: Large rock OPUS PID: LATITUDE: 46° 16.1' N ( 46.26830) LONGITUDE: 124° 2.2' W (-124.03700) The bench mark is a disk set in a large rock at point where Jetty turns to west a little, and is 0.76 m (2.5 ft) higher than normal rocks. Note: The bench mark is painted with a white cross.
U.S. DEPARTMENT OF COMMERCE National Oceanic and Atmospheric Administration National Ocean Service Page 4 of 5 Station ID: 9440572 PUBLICATION DATE: 12/12/2003 Name: JETTY A, COLUMBIA RIVER WA NOAA Chart: 18521 Latitude: 46° 16.1' N ( 46.26830) USGS Quad: CAPE DISAPPOINTMENT Longitude: 124° 2.2' W (-124.03700) T I D A L D A T U M S Tidal datums at JETTY A, COLUMBIA RIVER based on: LENGTH OF SERIES: 1 MONTH TIME PERIOD: March 1997 - March 1997 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 = 2.585 MEAN HIGH WATER MHW = 2.357 MEAN TIDE LEVEL MTL = 1.396 MEAN SEA LEVEL MSL = 1.396 MEAN LOW WATER MLW = 0.435 MEAN LOWER LOW WATER MLLW = 0.000 North American Vertical Datum (NAVD88) Bench Mark Elevation Information In METERS above: Stamping or Designation MLLW MHW MID 1970 8.026 5.669 BETTY M 1976 6.830 4.473 0572 A 1981 7.545 5.188 0572 B 1997 6.954 4.597 BEND 1970 U.S.E 8.486 6.129
U.S. DEPARTMENT OF COMMERCE National Oceanic and Atmospheric Administration National Ocean Service Page 5 of 5 Station ID: 9440572 PUBLICATION DATE: 12/12/2003 Name: JETTY A, COLUMBIA RIVER WA NOAA Chart: 18521 Latitude: 46° 16.1' N ( 46.26830) USGS Quad: CAPE DISAPPOINTMENT Longitude: 124° 2.2' W (-124.03700) 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.