U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Datums Page Page 1 of 5
Station ID: 9414874 PUBLICATION DATE: 07/14/2003
Name: CORTE MADERA CREEK
CA
NOAA Chart: 18649 Latitude: 37° 56.6' N ( 37.94330)
USGS Quad: SAN RAFAEL Longitude: 122° 30.8' W (-122.51300)
To reach the tidal bench marks from Marin City, proceed north on U.S. Highway
101 for 10 km (6 mi) to the exit for Sir Francis Drake Boulevard. The bench
marks are located along the network of exit roads off U.S. Highway 101 at the
Sir Francis Boulevard exit. The tide gage and staff were located on the
northwestern Pacific Railroad Greenbrae lift span south of the Victoria Station
Restaurant.
T I D A L B E N C H M A R K S
PRIMARY BENCH MARK STAMPING: 4874 A 1977
DESIGNATION: 941 4874 A
MONUMENTATION: Tidal Station disk VM#: 8474
AGENCY: National Ocean Survey (NOS) IDB PID#:
SETTING CLASSIFICATION: Copper-clad steel rod OPUS PID:
LATITUDE: 37° 56.6' N ( 37.94330) LONGITUDE: 122° 30.8' W (-122.51300)
The primary bench mark is a disk located along the Northwestern Pacific Railroad
Bridge, 14.63 m (48.0 ft) west of a street light pole, 12.50 m (41.0 ft) SE of
the centerline of the off ramp from U.S. Highway 10l North, westbound to Sir
Francis Drake Boulevard, 6.10 m (20.0 ft) SE of the asphalt path walkway
parallel to off ramp, 2.59 m (8.5 ft) WSW of the centerline of the railroad
north-south crossing the boulevard and creek, and 0.61 m (2.0 ft) WSW of the
westernmost of 5 piles comprising the third stanchion of the off ramp and
surrounded by concrete kickblock flush with the ground. The bench mark is
crimped to the top of a copper-clad steel rod driven to 5.8 m (19 ft) and
encased in a PVC pipe projecting 0.15 m (0.5 ft) above ground.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 2 of 5
Station ID: 9414874 PUBLICATION DATE: 07/14/2003
Name: CORTE MADERA CREEK
CA
NOAA Chart: 18649 Latitude: 37° 56.6' N ( 37.94330)
USGS Quad: SAN RAFAEL Longitude: 122° 30.8' W (-122.51300)
T I D A L B E N C H M A R K S
BENCH MARK STAMPING: 4874 B 1977
DESIGNATION: 941 4874 B
MONUMENTATION: Tidal Station disk VM#: 8475
AGENCY: National Ocean Survey (NOS) IDB PID#:
SETTING CLASSIFICATION: Copper-clad steel rod OPUS PID:
LATITUDE: 37° 56.6' N ( 37.94330) LONGITUDE: 122° 30.8' W (-122.51300)
The bench mark is a disk located along Sir Francis Drake Boulevard west of U.S.
Highway 101, 17 m (56 ft) NW of the center of the concrete culvert, 14.87 m
(48.8 ft) south of the bike path sign on the SW side of Sir Francis Drake
Boulevard near the beginning of the on ramp from the eastbound lane leading to
U.S. Highway 101 South, and 2.13 m (7.0 ft) north of an 8-inch diameter
eucaluptus tree. The bench mark is crimped to the top of a copper-clad steel
rod driven 3.7 m (12 ft), and surrounded by a concrete kickblock projecting 0.09
m (0.3 ft) above the ground.
BENCH MARK STAMPING: 4874 C 1977
DESIGNATION: 941 4874 C
MONUMENTATION: Tidal Station disk VM#: 8476
AGENCY: National Ocean Survey (NOS) IDB PID#:
SETTING CLASSIFICATION: Pier of highway OPUS PID:
LATITUDE: 37° 56.6' N ( 37.94330) LONGITUDE: 122° 30.8' W (-122.51300)
The bench mark is a disk set vertically in the north face of Pier 9 of the
northbound lanes of U.S. Highway 101 at the Greenbrae overpass over Sir Francis
Drake Boulevard, 44 m (145 ft) SSE from the centerline of Sir Francis Drake
Boulevard, 23 m (75 ft) SSW from the SW corner of a cinderblock utility shack, 3
m (10 ft) ENE from the west corner of the pier, 0.49 m (1.6 ft) WSW from the
north corner of the pier, flush in the north face of Pier 9, and 1.01 m (3.3 ft)
above the ground.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 3 of 5
Station ID: 9414874 PUBLICATION DATE: 07/14/2003
Name: CORTE MADERA CREEK
CA
NOAA Chart: 18649 Latitude: 37° 56.6' N ( 37.94330)
USGS Quad: SAN RAFAEL Longitude: 122° 30.8' W (-122.51300)
T I D A L B E N C H M A R K S
BENCH MARK STAMPING: 4874 D 1977
DESIGNATION: 941 4874 D
MONUMENTATION: Tidal Station disk VM#: 8477
AGENCY: National Ocean Survey (NOS) IDB PID#:
SETTING CLASSIFICATION: Concrete culvert retaining wall OPUS PID:
LATITUDE: 37° 56.6' N ( 37.94330) LONGITUDE: 122° 30.8' W (-122.51300)
The bench mark is a disk set flush in the top of a concrete culvert retaining
wall, in the planted area between the eastbound and westbound Sir Francis Drake
Boulevard, 30 m (100 ft) NW of the centerline of the eastbound lane of Sir
Francis Drake Boulevard, 9.14 m (30.0 ft) SE from the centerline of the on ramp
to southbound U.S. Highway 101 from westbound Sir Francis Drake Boulevard, and
1.07 m (3.5 ft) above the ground.
BENCH MARK STAMPING: HUB 1961
DESIGNATION: 941 4874 HUB
MONUMENTATION: Survey disk VM#: 8478
AGENCY: US Army Corps of Engineers (USE) IDB PID#:
SETTING CLASSIFICATION: Concrete block OPUS PID:
LATITUDE: 37° 56.6' N ( 37.94330) LONGITUDE: 122° 30.8' W (-122.51300)
The bench mark is a disk set in the top of a 0.3 m (1 ft) square concrete block,
11.28 m (37.0 ft) west of the west corner of a concrete pillar supporting the
U.S. Highway 101 freeway southbound on-ramp from Sir Francis Drake Boulevard
eastbound labeled D-10, 4.88 m (16.0 ft) NE of the NE corner of a concrete
culvert, 4.72 m (15.5 ft) NW of the asphalt foot path, 0.61 m (2.0 ft) east of
white witness post, and flush with the ground.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 4 of 5
Station ID: 9414874 PUBLICATION DATE: 07/14/2003
Name: CORTE MADERA CREEK
CA
NOAA Chart: 18649 Latitude: 37° 56.6' N ( 37.94330)
USGS Quad: SAN RAFAEL Longitude: 122° 30.8' W (-122.51300)
T I D A L D A T U M S
Tidal datums at CORTE MADERA CREEK based on:
LENGTH OF SERIES: 12 MONTHS
TIME PERIOD: September 1977 - August 1978
TIDAL EPOCH: 1983-2001
CONTROL TIDE STATION: 9414290 SAN FRANCISCO, SAN FRANCISCO BAY
Elevations of tidal datums referred to Mean Lower Low Water (MLLW), in METERS:
HIGHEST OBSERVED WATER LEVEL (02/06/1978) = 2.421
MEAN HIGHER HIGH WATER MHHW = 1.768
MEAN HIGH WATER MHW = 1.585
MEAN TIDE LEVEL MTL = 0.957
MEAN SEA LEVEL MSL = 0.946
MEAN LOW WATER MLW = 0.329
MEAN LOWER LOW WATER MLLW = 0.000
LOWEST OBSERVED WATER LEVEL (06/02/1977) = -0.633
North American Vertical Datum (NAVD88)
Bench Mark Elevation Information In METERS above:
Stamping or Designation MLLW MHW
4874 A 1977 2.621 1.036
4874 B 1977 4.378 2.793
4874 C 1977 3.455 1.870
4874 D 1977 3.529 1.944
HUB 1961 2.576 0.991
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 5 of 5
Station ID: 9414874 PUBLICATION DATE: 07/14/2003
Name: CORTE MADERA CREEK
CA
NOAA Chart: 18649 Latitude: 37° 56.6' N ( 37.94330)
USGS Quad: SAN RAFAEL Longitude: 122° 30.8' W (-122.51300)
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.