U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Datums Page Page 1 of 5
PUBLICATION DATE: 08/04/1989
Station ID: 9432796 SUPERCEDED DATE: 04/21/2003
Name: ISTHMUS SLOUGH, COOS BAY
OREGON
NOAA Chart: 18587 Latitude: 43° 21.2' N
USGS Quad: COOS BAY Longitude: 124° 11.5' W
To reach the tidal bench marks from the intersection of U.S. Highway 101 and
State Highway 243 in Coos Bay, proceed south on U.S. Highway 101 to State
Highway 241 (Newport Street), travel east on State Highway 241 for 0.5 mile (0.8
km) over the Isthmus Slough bridge, at the immediate end of the bridge turn
south onto Olive Barber Road and travel 1 mile (2 km) to Coos Head Timber
Company McKenna Plant, follow the road through the entrance gate and NW to the
plywood plant. The bench marks are on the Coos Head Timber Company McKenna
Plant property. The tide gage and staff were at the SW corner of the plywood
plant.
T I D A L B E N C H M A R K S
PRIMARY BENCH MARK STAMPING: 2796 A 1982
MONUMENTATION: Survey Disk VM#: 8792
AGENCY: PID:
SETTING CLASSIFICATION: Concrete Footing
The bench mark is set vertically and flush on the east face of the 8 x 1.5-foot
(2 x 0.5 m) north concrete footing of a 50 x 8-foot (15 x 2 m) diameter propane
tank elevated 5 feet (2 m) above the ground at the SW corner of the property,
103 feet (31 m) south of the south face of the plywood plant, 26 feet (8 m) east
of the east edge of the shipping dock, 8 feet (2 m) west of the centerline of
the road, and 2 feet (1 m) above ground level.
BENCH MARK STAMPING: 2796 B 1982
MONUMENTATION: Survey Disk VM#: 8793
AGENCY: PID:
SETTING CLASSIFICATION: Concrete Foundation
The bench mark is set flush in the west edge of a 36 x 10 x 3-foot (11 x 3 x 1
m) abandoned concrete foundation at the south end of the property, 132.2 feet
(40.3 m) south of the south face of the plywood plant, 106.8 feet (32.6 m) ESE
of Bench Mark 2796 A 1982, 27 feet (8 m) SE of the centerline of the road, 22.4
feet (6.8 m) SW of the SW corner of a shed, 16.8 feet (5.1 m) NE of the SW
corner of the foundation, and 3 feet (1 m) above ground level.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 2 of 5
PUBLICATION DATE: 08/04/1989
Station ID: 9432796 SUPERCEDED DATE: 04/21/2003
Name: ISTHMUS SLOUGH, COOS BAY
OREGON
NOAA Chart: 18587 Latitude: 43° 21.2' N
USGS Quad: COOS BAY Longitude: 124° 11.5' W
T I D A L B E N C H M A R K S
BENCH MARK STAMPING: 2796 C 1982
MONUMENTATION: Survey Disk VM#: 8794
AGENCY: PID:
SETTING CLASSIFICATION: Concrete Footing
The bench mark is set flush in the west concrete footing of the paint booth
attached to the SW end of the planer building on the east side of the property,
60.0 feet (18.3 m) west of the west face of the sorter, 27.5 feet (8.4 m) east
of the centerline of the road, 18.6 feet (5.7 m) SE of the SW corner of the
planer building, 10.9 feet (3.3 m) south of the south face of the planer
building, and at ground level.
BENCH MARK STAMPING: 2796 D 1982
MONUMENTATION: Survey Disk VM#: 8795
AGENCY: PID:
SETTING CLASSIFICATION: Concrete Foundation
The bench mark is set flush in the top of a concrete foundation at the east end
of the resaw building, at the center of the property, east of the conveyor
belts, 38.4 feet (11.7 m) NW of the SW corner of a fire wall, 33.0 feet (10.1 m)
SW of the SE corner of an elevated chip bin, 19.3 feet (5.9 m) north of the
south end of the concrete foundation, and 2 feet (1 m) above ground level.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 3 of 5
PUBLICATION DATE: 08/04/1989
Station ID: 9432796 SUPERCEDED DATE: 04/21/2003
Name: ISTHMUS SLOUGH, COOS BAY
OREGON
NOAA Chart: 18587 Latitude: 43° 21.2' N
USGS Quad: COOS BAY Longitude: 124° 11.5' W
T I D A L B E N C H M A R K S
BENCH MARK STAMPING: 2796 E 1982
MONUMENTATION: Survey Disk VM#: 8796
AGENCY: PID:
SETTING CLASSIFICATION: Concrete Retaining Wall
The bench mark is set flush in a 36.3-foot (11.1 m) long concrete retaining wall
at the north end of the chipper building, west of an abandoned circular burner
foundation, at the north end of the property, 30 feet (9 m) north of the north
face of the chipper building, and 24.5 feet (7.5 m) west of the east end of the
retaining wall.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 4 of 5
PUBLICATION DATE: 08/04/1989
Station ID: 9432796 SUPERCEDED DATE: 04/21/2003
Name: ISTHMUS SLOUGH, COOS BAY
OREGON
NOAA Chart: 18587 Latitude: 43° 21.2' N
USGS Quad: COOS BAY Longitude: 124° 11.5' W
T I D A L D A T U M S
Tidal datums at ISTHMUS SLOUGH, COOS BAY based on:
LENGTH OF SERIES: 1 MONTH
TIME PERIOD: SEPTEMBER 1982
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 (10/06/1982) = 9.84
MEAN HIGHER HIGH WATER MHHW = 8.74
MEAN HIGH WATER MHW = 8.08
MEAN TIDE LEVEL MTL = 4.71
MEAN LOW WATER MLW = 1.34
MEAN LOWER LOW WATER MLLW = 0.00
LOWEST OBSERVED WATER LEVEL (09/15/1982) = -1.07
Bench Mark Elevation Information In FEET above:
Stamping or Designation MLLW MHW
2796 A 1982 12.80 4.72
2796 B 1982 15.90 7.82
2796 C 1982 13.08 5.00
2796 D 1982 15.40 7.32
2796 E 1982 28.57 20.49
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 5 of 5
PUBLICATION DATE: 08/04/1989
Station ID: 9432796 SUPERCEDED DATE: 04/21/2003
Name: ISTHMUS SLOUGH, COOS BAY
OREGON
NOAA Chart: 18587 Latitude: 43° 21.2' N
USGS Quad: COOS BAY Longitude: 124° 11.5' 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.