U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Datums Page Page 1 of 4
Station ID: 9413663 PUBLICATION DATE: 03/20/2009
Name: ELKHORN SLOUGH RAILROAD BRIDGE
CA
NOAA Chart: 18680 Latitude: 36° 51.4' N ( 36.85667)
USGS Quad: MOSS LANDING Longitude: 121° 45.3' W (-121.75500)
To reach the tidal bench marks from the intersection of Elkhorn Road and Hudon
Landing Road, north of Elkhorn, proceed south along Hudson Landing Road to end
of the public portion, then travel south on the dirt road along the west side of
Southern Pacific Railroad tracks. The bench marks are along the railroad
tracks. The tide gage and staff were located on the north side of slough and
west of railroad bridge over slough.
T I D A L B E N C H M A R K S
PRIMARY BENCH MARK STAMPING: 3663 A 1976
DESIGNATION: 941 3663 A TIDAL
MONUMENTATION: Tidal Station disk VM#: 8081
AGENCY: National Ocean Survey (NOS) IDB PID#: GU3198
SETTING CLASSIFICATION: Copper-clad steel rod OPUS PID:
LATITUDE: 36° 51.5' N ( 36.85830) LONGITUDE: 121° 45.3' W (-121.75500)
The primary bench mark is a disk located 81 m (265 ft) south of bench mark 3663
B 1976, 20 m (64 ft) north of north end of railroad bridge, 8 m (26 ft) NE of a
telephone pole, 6 m (19 ft) west of westernmost rail, 0.76 m (2.5 ft) east of a
witness post, and 0.90 m (3.0 ft) below the level of the railroad tracks. The
bench mark is crimped to the top of a copper-clad steel rod driven to 17.1 m (56
ft) to substantial resistance and encased in a PVC pipe.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 2 of 4
Station ID: 9413663 PUBLICATION DATE: 03/20/2009
Name: ELKHORN SLOUGH RAILROAD BRIDGE
CA
NOAA Chart: 18680 Latitude: 36° 51.4' N ( 36.85667)
USGS Quad: MOSS LANDING Longitude: 121° 45.3' W (-121.75500)
T I D A L B E N C H M A R K S
BENCH MARK STAMPING: 3663 B 1976
DESIGNATION: 941 3663 B TIDAL
MONUMENTATION: Tidal Station disk VM#: 8082
AGENCY: National Ocean Survey (NOS) IDB PID#: GU3197
SETTING CLASSIFICATION: Copper-clad steel rod OPUS PID:
LATITUDE: 36° 51.5' N ( 36.85830) LONGITUDE: 121° 45.3' W (-121.75500)
The bench mark is a disk located 102 m (335 ft) south of bench mark 3663 C 1976,
81 m (265 ft) north of bench mark 3663 A 1976, 25 m (82 ft) south of a silver
painted signal station, 11 m (36 ft) east of a fence parallel to railroad
tracks, 0.9 m (3 ft) SE of a witness post and 1.07 m (3.5 ft) below level of
railroad tracks. The bench mark is crimped to the top of a copper-clad steel
rod driven 14.6 m (48 ft) to substantial resistance and encased in a PVC pipe.
BENCH MARK STAMPING: 3663 D 1976
DESIGNATION: 941 3663 D TIDAL
MONUMENTATION: Tidal Station disk VM#: 8084
AGENCY: National Ocean Survey (NOS) IDB PID#: GU3195
SETTING CLASSIFICATION: Copper-clad steel rod OPUS PID:
LATITUDE: 36° 51.7' N ( 36.86170) LONGITUDE: 121° 45.3' W (-121.75500)
The bench mark is a disk located 118 m (387 ft) south of bench mark 3663 E 1976,
56 m (183 ft) NE of bench mark 3663 C 1976, 8 m (25 ft) east of a fence, 8 m (25
ft) north of a witness post, 7 m (22 ft) west of west rail of tracks, and 0.76
m (2.5 ft) below level of tracks. The bench mark is crimped to the top of a
copper-clad steel rod driven 9.8 m (32 ft) to substantial resistance and encased
in a PVC pipe.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 3 of 4
Station ID: 9413663 PUBLICATION DATE: 03/20/2009
Name: ELKHORN SLOUGH RAILROAD BRIDGE
CA
NOAA Chart: 18680 Latitude: 36° 51.4' N ( 36.85667)
USGS Quad: MOSS LANDING Longitude: 121° 45.3' W (-121.75500)
T I D A L D A T U M S
Tidal datums at ELKHORN SLOUGH RAILROAD BRIDGE based on:
LENGTH OF SERIES: 4 MONTHS
TIME PERIOD: November 2007 - February 2008
TIDAL EPOCH: 1983-2001
CONTROL TIDE STATION: 9413450 MONTEREY, MONTEREY HARBOR
Elevations of tidal datums referred to Mean Lower Low Water (MLLW), in METERS:
MEAN HIGHER HIGH WATER MHHW = 1.680
MEAN HIGH WATER MHW = 1.460
MEAN SEA LEVEL MSL = 0.893
MEAN TIDE LEVEL MTL = 0.891
MEAN LOW WATER MLW = 0.323
MEAN LOWER LOW WATER MLLW = 0.000
North American Vertical Datum NAVD88 = -0.022
North American Vertical Datum (NAVD88)
Bench Mark Elevation Information In METERS above:
Stamping or Designation MLLW MHW
3663 A 1976 2.465 1.005
3663 B 1976 3.096 1.636
3663 D 1976 4.744 3.284
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 4 of 4
Station ID: 9413663 PUBLICATION DATE: 03/20/2009
Name: ELKHORN SLOUGH RAILROAD BRIDGE
CA
NOAA Chart: 18680 Latitude: 36° 51.4' N ( 36.85667)
USGS Quad: MOSS LANDING Longitude: 121° 45.3' W (-121.75500)
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.