U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Datums Page Page 1 of 5
Station ID: 9440581 PUBLICATION DATE: 12/17/2019
Name: CAPE DISAPPOINTMENT
NOAA Chart: 18521 Latitude: 46° 18.0' N ( 46.30000)
USGS Quad: CAPE DISAPPOINTMENT Longitude: 124° 0.0' W (-124.00000)
From Longview, WA, cross the Lewis & Clark Bridge (WA 433) into Oregon and turn
west (right) on OR 30. Proceed 47 miles to Astoria, OR and turn north (right)
onto US 101 and cross the bridge into Washington, then turn left to continue
north on US 101, 10 miles to Ilwaco. Turn left on Second Ave (WA 100 Spur) 1.7
miles to intersection with Ft. Canby Road. Turn left on Ft. Canby 0.6 miles to
left turn onto Coast Guard Road. You will need to use call box at gate to gain
entrance to base. Once through gate continue 0.35 miles on Coast Guard Rd to
boat houses and dock on the left. The tide station is located inside the first
boathouse and the benchmarks are located along Coast Guard Road.
T I D A L B E N C H M A R K S
PRIMARY BENCH MARK STAMPING: 0581 C 2015
DESIGNATION: 944 0581 C
MONUMENTATION: Flange-encased Rod VM#: 21625
AGENCY: National Ocean Service IDB PID:
SETTING CLASSIFICATION: OPUS PID#: BBDX15
LATITUDE: 46° 16.8' N ( 46.28067) LONGITUDE: 124° 2.8' W (-124.04681)
The primary bench mark is a 9/16 inch (14 mm) stainless steel rod driven 2.1 m(7
ft) to refusal on the north side of Coast Guard Road on USCG Cape Disappointment
station, located 3.7 m (12.1 ft) south of a NOAA witness post, 3.55 m (11.6 ft)
north of the northern edge of Coast Guard Road, 2.98 m (9.8 ft) west of the
western side of a weapon unloading station.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 2 of 5
Station ID: 9440581 PUBLICATION DATE: 12/17/2019
Name: CAPE DISAPPOINTMENT
NOAA Chart: 18521 Latitude: 46° 18.0' N ( 46.30000)
USGS Quad: CAPE DISAPPOINTMENT Longitude: 124° 0.0' W (-124.00000)
T I D A L B E N C H M A R K S
BENCH MARK STAMPING: 0581 A 2015
DESIGNATION: 944 0581 A
MONUMENTATION: Bench Mark disk VM#: 21626
AGENCY: National Ocean Service IDB PID:
SETTING CLASSIFICATION: Concrete manhole OPUS PID:
LATITUDE: 46° 16.8' N ( 46.27922) LONGITUDE: 124° 2.9' W (-124.04831)
The bench mark is a brass NOS disk set flush in the west side of a 1.95 m (6.4
ft) X 1.95 m (6.4 ft) concrete manhole structure on the east side of Coast Guard
Road on the US Coast Guard Cape Disappointment base, located 3.71 m (12.2 ft)
east of the centerline of Coast Guard Road, 2.95 m (9.7 ft) north of National
Motor Life Boat School sign, 0.75 m (2.5 ft) NW of the center of a manhole, and
0.2 m (0.7 ft) above ground level.
BENCH MARK STAMPING: 0581 B 2015
DESIGNATION: 944 0581 B
MONUMENTATION: Flange-encased Rod VM#: 21627
AGENCY: National Ocean Service IDB PID:
SETTING CLASSIFICATION: OPUS PID:
LATITUDE: 46° 16.8' N ( 46.27975) LONGITUDE: 124° 2.8' W (-124.04744)
The bench mark is a 9/16 inch (14 mm) stainless steel rod driven 8.2 m (27 ft)
to refusal on the west side of Coast Guard Road on the US Coast Guard Cape
Disappointment station, located 5.86 m (19.2 ft) south of southern end of a rock
slide protection fence, 1.66 m (5.4 ft) east of a NOAA witness post, 1.30 m (4.3
ft) west of the western edge of pavement.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 3 of 5
Station ID: 9440581 PUBLICATION DATE: 12/17/2019
Name: CAPE DISAPPOINTMENT
NOAA Chart: 18521 Latitude: 46° 18.0' N ( 46.30000)
USGS Quad: CAPE DISAPPOINTMENT Longitude: 124° 0.0' W (-124.00000)
T I D A L B E N C H M A R K S
BENCH MARK STAMPING: 0581 E 2015
DESIGNATION: 944 0581 E
MONUMENTATION: Flange-encased Rod VM#: 21628
AGENCY: National Ocean Service IDB PID:
SETTING CLASSIFICATION: OPUS PID:
LATITUDE: 46° 16.8' N ( 46.27928) LONGITUDE: 124° 2.7' W (-124.04522)
The bench mark is a 9/16 inch (14 mm) stainless steel rod driven 1.2 m (4 ft) to
refusal at the end of Coast Guard road on USCG Cape Disappointment station,
located 5.2 m (17.1 ft) SE of the southern end of the landslide protection
fence, 3.7 m (12.1 ft) NE of a 2 m (6.6 ft) x 3 m (9.8 ft) boulder, 2 m (6.6 ft)
south of the south corner of a concrete electric vault.
BENCH MARK STAMPING: 0581 D 2015
DESIGNATION: 944 0581 D
MONUMENTATION: Bench Mark disk VM#: 21629
AGENCY: National Ocean Service IDB PID:
SETTING CLASSIFICATION: Concrete slab OPUS PID:
LATITUDE: 46° 16.8' N ( 46.28022) LONGITUDE: 124° 2.7' W (-124.04528)
The bench mark is a brass NOS disk set flush in the concrete foundation of the
roll up door at the entrance to the US Coast Guard boat repair building numbered
71718 and 12741, located 21.2 m (69.6 ft) SSE from the center of a boatlift, 7.7
m (25.3 ft) east from the west corner of a roll up door of the US Coast Guard
boat repair building, 0.3 m (1.0 ft) west from east corner of the roll up door
of a US Coast Guard repair building.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 4 of 5
Station ID: 9440581 PUBLICATION DATE: 12/17/2019
Name: CAPE DISAPPOINTMENT
NOAA Chart: 18521 Latitude: 46° 18.0' N ( 46.30000)
USGS Quad: CAPE DISAPPOINTMENT Longitude: 124° 0.0' W (-124.00000)
T I D A L D A T U M S
Tidal datums at CAPE DISAPPOINTMENT based on:
LENGTH OF SERIES: 3 YEARS
TIME PERIOD: August 2015 - July 2018
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:
HIGHEST OBSERVED WATER LEVEL (03/10/2016) = 3.507
MEAN HIGHER HIGH WATER MHHW = 2.459
MEAN HIGH WATER MHW = 2.246
MEAN TIDE LEVEL MTL = 1.328
MEAN SEA LEVEL MSL = 1.312
MEAN LOW WATER MLW = 0.410
North American Vertical Datum NAVD88 = 0.141
MEAN LOWER LOW WATER MLLW = 0.000
LOWEST OBSERVED WATER LEVEL (12/05/2017) = -0.899
North American Vertical Datum (NAVD88)
Bench Mark Elevation Information In METERS above:
Stamping or Designation MLLW MHW
0581 C 2015 4.068 1.822
0581 A 2015 5.836 3.590
0581 B 2015 5.081 2.835
0581 E 2015 5.391 3.145
0581 D 2015 4.894 2.648
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 5 of 5
Station ID: 9440581 PUBLICATION DATE: 12/17/2019
Name: CAPE DISAPPOINTMENT
NOAA Chart: 18521 Latitude: 46° 18.0' N ( 46.30000)
USGS Quad: CAPE DISAPPOINTMENT Longitude: 124° 0.0' W (-124.00000)
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.