U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Datums Page Page 1 of 4
PUBLICATION DATE: 06/01/1988
Station ID: 9434938 SUPERCEDED DATE: 04/21/2003
Name: DRIFT CREEK, ALSEA RIVER
OREGON
NOAA Chart: 18561 Latitude: 44° 24.8' N
USGS Quad: TIDEWATER Longitude: 123° 59.4' W
To reach the tidal bench marks from the intersection of U.S. Highway 101 and
State Highway 34 in Waldport, proceed east on State Highway 34 for about 5 miles
(8 km) to 4015 Highway 34 and Drift Creek Boat Dock on Alsea River. The bench
marks are located along State Highway 34 at Oaklands Fish Camp and at Bosworths
Boat Repair. The tide gage and staff were on the boat dock.
T I D A L B E N C H M A R K S
PRIMARY BENCH MARK STAMPING: 4938 B 1976
MONUMENTATION: Survey Disk VM#: 8821
AGENCY: PID:
SETTING CLASSIFICATION: Unspecified Steel Rod
The bench mark is 162 feet (49 m) north of the centerline of State Highway 34,
99 feet (30 m) east of Bench Mark 4938 A 1976, 70 feet (21 m) NNW of the NW
corner of Bosworths Boat Repair Shop, 2 feet (1 m) north of a utility pole, and
1.4 feet (0.4 m) north of a metal witness post. The bench mark is at ground
level, crimped to an unspecified steel rod driven an unspecified depth to
refusal, and encased in a 4-inch plastic pipe and concrete kickblock.
BENCH MARK STAMPING: 4938 A 1976
MONUMENTATION: Survey Disk VM#: 8820
AGENCY: PID:
SETTING CLASSIFICATION: Concrete Boat Ramp
The bench mark is set flush in concrete at the SW corner of the foot of the boat
ramp at Oaklands Fish Camp, 174 feet (53 m) north of the centerline of State
Highway 34, 26.6 feet (8.1 m) WSW of the SW corner of a house, and 10.6 feet
(3.2 m) SE of the SE corner of Oaklands Marina building.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 2 of 4
PUBLICATION DATE: 06/01/1988
Station ID: 9434938 SUPERCEDED DATE: 04/21/2003
Name: DRIFT CREEK, ALSEA RIVER
OREGON
NOAA Chart: 18561 Latitude: 44° 24.8' N
USGS Quad: TIDEWATER Longitude: 123° 59.4' W
T I D A L B E N C H M A R K S
BENCH MARK STAMPING: 4938 C 1976
MONUMENTATION: Survey Disk VM#: 8822
AGENCY: PID:
SETTING CLASSIFICATION: Concrete Foundation
The bench mark is set flush in concrete at the north side of the garage door on
the west side of Bosworths Boat Repair Shop, 95.2 feet (29.0 m) SE of Bench Mark
4938 B 1976, and 71 feet (22 m) north of the centerline of State Highway 34.
BENCH MARK STAMPING: 4938 D 1976
MONUMENTATION: Survey Disk VM#: 8823
AGENCY: PID:
SETTING CLASSIFICATION: Unspecified Steel Rod
The bench mark is 89 feet (27 m) SW of the SW corner of Bosworths Boat Repair
Shop, 36.5 feet (11.1 m) south of the centerline of State Highway 34, 11 feet (3
m) ENE of a utility pole, and 1 foot (0.3 m) NE of a metal witness post. The
bench mark is 0.1 foot (0.03 m) above ground level, crimped to an unspecified
steel rod driven an unspecified depth to refusal, and encased in a 4-inch
plastic pipe and concrete kickblock.
BENCH MARK STAMPING: 4938 E 1976
MONUMENTATION: Survey Disk VM#: 8824
AGENCY: PID:
SETTING CLASSIFICATION: Unspecified Steel Rod
The bench mark is 216 feet (66 m) SW of Bench Mark 4938 A 1976, 40 feet (12 m)
north of the centerline of State Highway 34, 25 feet (8 m) east of a utility
pole, and 1.7 feet (0.5 m) SE of a metal witness post. The bench mark is 0.1
foot (0.03 m) above ground level, crimped to an unspecified steel rod driven an
unspecified depth to refusal, and encased in a 4-inch plastic pipe and concrete
kickblock.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 3 of 4
PUBLICATION DATE: 06/01/1988
Station ID: 9434938 SUPERCEDED DATE: 04/21/2003
Name: DRIFT CREEK, ALSEA RIVER
OREGON
NOAA Chart: 18561 Latitude: 44° 24.8' N
USGS Quad: TIDEWATER Longitude: 123° 59.4' W
T I D A L D A T U M S
Tidal datums at DRIFT CREEK, ALSEA RIVER based on:
LENGTH OF SERIES: 12 MONTHS
TIME PERIOD: NOVEMBER 1976 - OCTOBER 1977
TIDAL EPOCH: 1960-1978
CONTROL TIDE STATION: 9432780 CHARLESTON
Elevations of tidal datums referred to Mean Lower Low Water (MLLW), in FEET:
HIGHEST OBSERVED WATER LEVEL (01/05/1978) = 10.99
MEAN HIGHER HIGH WATER MHHW = 6.62
MEAN HIGH WATER MHW = 5.93
MEAN TIDE LEVEL MTL = 3.31
MEAN LOW WATER MLW = 0.69
MEAN LOWER LOW WATER MLLW = 0.00
LOWEST OBSERVED WATER LEVEL (07/15/1977) = -0.88
Bench Mark Elevation Information In FEET above:
Stamping or Designation MLLW MHW
4938 B 1976 18.94 13.01
4938 A 1976 11.44 5.51
4938 C 1976 19.74 13.81
4938 D 1976 24.67 18.74
4938 E 1976 18.59 12.66
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 4 of 4
PUBLICATION DATE: 06/01/1988
Station ID: 9434938 SUPERCEDED DATE: 04/21/2003
Name: DRIFT CREEK, ALSEA RIVER
OREGON
NOAA Chart: 18561 Latitude: 44° 24.8' N
USGS Quad: TIDEWATER Longitude: 123° 59.4' W
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 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.