U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Datums Page Page 1 of 5
Station ID: 9419551 PUBLICATION DATE: 01/22/2024
Name: REQUA DOCK,KLAMATH RIVER
CA
NOAA Chart: 18600 Latitude: 41° 32.7' N ( 41.54500)
USGS Quad: REQUA Longitude: 124° 4.2' W (-124.07000)
To reach the station from the intersection of HWY 101 and Requa Road north of
Klamath, head west on Requa Road and proceed 1.4 km (0.9 mi) to the fork in the
road at the Requa Hotel, follow Mouth of Klamath Road which is the left fork
leading downhill 0.6 km (0.4 mi) west to the parking lot and the boat launch on
the left. The tide station is located at the boat ramp and further west along
the river bank in front of the campground. The bench marks are in the area from
the boat ramp west to the old rock quarry.
T I D A L B E N C H M A R K S
PRIMARY BENCH MARK STAMPING: 9551 B 2017
DESIGNATION: 941 9551 B
MONUMENTATION: Bench Mark disk VM#: 22372
AGENCY: National Ocean Service IDB PID#:
SETTING CLASSIFICATION: Rock outcrop OPUS PID#: BBFS45
LATITUDE: 41° 32.8' N ( 41.54631) LONGITUDE: 124° 4.4' W (-124.07397)
The primary bench mark is a disk set in a bedrock outcrop, 43 m (141 ft) NE of
end of pampas grass up from a two track road from west, 17.5 m (57.4 ft) north
of corner of intersection of two track road, 15.86 m (52.0 ft) SE of southern
end of rock wall face, 5.91 m (19.4 ft) SSE of edge of gravel two track road,
and 0.72 m (2.4 ft) NE of high point of rock outcrop.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 2 of 5
Station ID: 9419551 PUBLICATION DATE: 01/22/2024
Name: REQUA DOCK,KLAMATH RIVER
CA
NOAA Chart: 18600 Latitude: 41° 32.7' N ( 41.54500)
USGS Quad: REQUA Longitude: 124° 4.2' W (-124.07000)
T I D A L B E N C H M A R K S
BENCH MARK STAMPING: 9551 A 2017
DESIGNATION: 941 9551 A
MONUMENTATION: Bench Mark disk VM#: 22373
AGENCY: National Ocean Service IDB PID#:
SETTING CLASSIFICATION: Rock outcrop OPUS PID:
LATITUDE: 41° 32.8' N ( 41.54586) LONGITUDE: 124° 4.5' W (-124.07475)
The bench mark is a disk set in a bedrock, 33.9 m (111.2 ft) WNW of curve in
armor wall, 4.9 m (16.1 ft) NE of brush line to the NE, 4.61 m (15.1 ft) north
of v shape in side curve where jerry ends and bedrock begins, and 3.63 m (11.9
ft) west of a large boulder to the west.
BENCH MARK STAMPING: 9551 C 2017
DESIGNATION: 941 9551 C
MONUMENTATION: Bench Mark disk VM#: 22374
AGENCY: National Ocean Service IDB PID#:
SETTING CLASSIFICATION: Foundation OPUS PID:
LATITUDE: 41° 32.8' N ( 41.54594) LONGITUDE: 124° 4.3' W (-124.07169)
The bench mark is a disk set in the concrete sill of a garage door opening of a
maintenance building, 49.95 m (163.9 ft) WSW of utility pole with green sirens,
17.60 m (57.7 ft) NW of a light pole, 13.12 m (43.0 ft) south of the north
corner of building, 5.23 m (17.2 ft) NW of the NE privacy fence corner, and 0.15
m (0.5 ft) south of the north jam of door.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 3 of 5
Station ID: 9419551 PUBLICATION DATE: 01/22/2024
Name: REQUA DOCK,KLAMATH RIVER
CA
NOAA Chart: 18600 Latitude: 41° 32.7' N ( 41.54500)
USGS Quad: REQUA Longitude: 124° 4.2' W (-124.07000)
T I D A L B E N C H M A R K S
BENCH MARK STAMPING: 9551 D 2017
DESIGNATION: 941 9551 D
MONUMENTATION: Bench Mark disk VM#: 22375
AGENCY: National Ocean Service IDB PID#:
SETTING CLASSIFICATION: Concrete pad OPUS PID:
LATITUDE: 41° 32.7' N ( 41.54533) LONGITUDE: 124° 4.3' W (-124.07172)
The bench mark is a disk set in a concrete pad, 78.9 m (258.9 ft) SSW of utility
pole with green siren, 48.76 m (160.0 ft) WSW of SW most crane, 5.05 m (16.6 ft)
north of the SW corner of south end of the pier, and 2.45 m (8.0 ft) WSW of
light with outlet with concrete base.
BENCH MARK STAMPING: 9551 E 2017
DESIGNATION: 941 9551 E
MONUMENTATION: Bench Mark disk VM#: 22376
AGENCY: National Ocean Service IDB PID#:
SETTING CLASSIFICATION: Concrete pad OPUS PID:
LATITUDE: 41° 32.7' N ( 41.54536) LONGITUDE: 124° 4.3' W (-124.07089)
The bench mark is a disk set in a concrete boat launch ramp, 18.40 m (60.4 ft)
SE of the center top of boat launch fee station, 12.01 m (39.4 ft) NNE of the
east most crane, 3.92 m (12.9 ft) NW of the SW corner of concrete, and 2.15 m
(7.1 ft) NNW of a utility light.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 4 of 5
Station ID: 9419551 PUBLICATION DATE: 01/22/2024
Name: REQUA DOCK,KLAMATH RIVER
CA
NOAA Chart: 18600 Latitude: 41° 32.7' N ( 41.54500)
USGS Quad: REQUA Longitude: 124° 4.2' W (-124.07000)
T I D A L D A T U M S
Tidal datums at REQUA DOCK,KLAMATH RIVER based on:
LENGTH OF SERIES: 2 MONTHS
TIME PERIOD: July 2017 - August 2017
TIDAL EPOCH: 1983-2001
CONTROL TIDE STATION: 9419750 CRESCENT CITY, PACIFIC OCEAN
Elevations of tidal datums referred to Mean High Water (MHW), in METERS:
MEAN HIGHER HIGH WATER MHHW = 0.182
MEAN HIGH WATER MHW = 0.000
North American Vertical Datum (NAVD88)
Bench Mark Elevation Information In METERS above:
Stamping or Designation MHW
9551 B 2017 8.985
9551 A 2017 2.725
9551 C 2017 3.712
9551 D 2017 3.146
9551 E 2017 2.923
Foot Notes:
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 5 of 5
Station ID: 9419551 PUBLICATION DATE: 01/22/2024
Name: REQUA DOCK,KLAMATH RIVER
CA
NOAA Chart: 18600 Latitude: 41° 32.7' N ( 41.54500)
USGS Quad: REQUA Longitude: 124° 4.2' W (-124.07000)
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.