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National Ocean Service
Datums Page Page 1 of 4
Station ID: 9447855 PUBLICATION DATE: 08/03/2004
Name: HOLLY HARBOR FARMS
WA
NOAA Chart: 18441 Latitude: 48° 1.6' N ( 48.02670)
USGS Quad: FREELAND Longitude: 122° 32.6' W (-122.54300)
To reach the tidal bench marks on Whidley Island from Freeland, proceed north
along the road paralleling the west shore of Holmes Harbor for 1.3 km (0.8 mi).
The bench marks are along the shore east and west of the pier at Harbor Holly
Farms. The tide gage and staff were located on the pier at Harbor Holly Farms.
T I D A L B E N C H M A R K S
PRIMARY BENCH MARK STAMPING: 7855 B 1977
DESIGNATION: 944 7855 B TIDAL
MONUMENTATION: Tidal Station disk VM#: 9227
AGENCY: National Ocean Survey (NOS) IDB PID#:
SETTING CLASSIFICATION: Copper clad steel rod OPUS PID:
LATITUDE: 48° 1.6' N ( 48.02670) LONGITUDE: 122° 32.1' W (-122.53500)
The primary bench mark is a disk located near the NW end of the Harbor Holly
Farms Pier, 7.99 m (26.2 ft) north of the east-west bulkhead, at the north end
of the pier, and 2.01 m (6.6 ft) east of the north-south bulkhead. The bench
mark is crimped to the top of a copper rod driven 1.2 m (4.0 ft) encased in a
PVC pipe.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 2 of 4
Station ID: 9447855 PUBLICATION DATE: 08/03/2004
Name: HOLLY HARBOR FARMS
WA
NOAA Chart: 18441 Latitude: 48° 1.6' N ( 48.02670)
USGS Quad: FREELAND Longitude: 122° 32.6' W (-122.54300)
T I D A L B E N C H M A R K S
BENCH MARK STAMPING: 7855 C 1977
DESIGNATION: 944 7855 C TIDAL
MONUMENTATION: Tidal Station disk VM#: 9228
AGENCY: National Ocean Survey (NOS) IDB PID#:
SETTING CLASSIFICATION: Copper clad steel rod OPUS PID:
LATITUDE: 48° 1.6' N ( 48.02670) LONGITUDE: 122° 32.1' W (-122.53500)
The bench mark is a disk located near the NE end of the Harbor Holly Farms Pier,
24.99 m (82.0 ft) east of bench mark 7855 B 1977, 7.99 m (26.2 ft) north of the
east-west bulkhead, and 1.01 m (3.3 ft) west of the north-south bulkhead. The
bench mark is set 6 cm (0.2 ft) above ground, crimped to the top of a copper rod
driven 1.2 m (4.0 ft) and encased in a PVC pipe.
BENCH MARK STAMPING: 7855 E 1977
DESIGNATION: 944 7855 E TIDAL
MONUMENTATION: Tidal Station disk VM#: 9230
AGENCY: National Ocean Survey (NOS) IDB PID#:
SETTING CLASSIFICATION: Copper clad steel rod OPUS PID:
LATITUDE: 48° 1.6' N ( 48.02670) LONGITUDE: 122° 32.1' W (-122.53500)
The bench mark is a disk located at the golf course on the north side of Holmes
Harbor near the NW end of the golf course pier, 44.01 m (144.4 ft) east of bench
mark 7855 D 1977, and 1.25 m (4.1 ft) north of the east-west bulkhead. The
bench mark is set above ground, crimped to the top of a copper rod driven 1.2 m
(4.0 ft) 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: 9447855 PUBLICATION DATE: 08/03/2004
Name: HOLLY HARBOR FARMS
WA
NOAA Chart: 18441 Latitude: 48° 1.6' N ( 48.02670)
USGS Quad: FREELAND Longitude: 122° 32.6' W (-122.54300)
T I D A L D A T U M S
Tidal datums at HOLLY HARBOR FARMS based on:
LENGTH OF SERIES: 1 MONTH
TIME PERIOD: February 1977 - February 1977
TIDAL EPOCH: 1983-2001
CONTROL TIDE STATION: 9447130 SEATTLE, PUGET SOUND
Elevations of tidal datums referred to Mean Lower Low Water (MLLW), in METERS:
MEAN HIGHER HIGH WATER MHHW = 3.487
MEAN HIGH WATER MHW = 3.215
MEAN TIDE LEVEL MTL = 2.032
MEAN SEA LEVEL MSL = 2.024
MEAN LOW WATER MLW = 0.849
MEAN LOWER LOW WATER MLLW = 0.000
North American Vertical Datum (NAVD88)
Bench Mark Elevation Information In METERS above:
Stamping or Designation MLLW MHW
7855 B 1977 5.581 2.366
7855 C 1977 5.387 2.172
7855 E 1977 5.078 1.863
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 4 of 4
Station ID: 9447855 PUBLICATION DATE: 08/03/2004
Name: HOLLY HARBOR FARMS
WA
NOAA Chart: 18441 Latitude: 48° 1.6' N ( 48.02670)
USGS Quad: FREELAND Longitude: 122° 32.6' W (-122.54300)
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.