Datums for 9440569, Skamokawa WA

Columbia River Datum Columbia River Datum (CRD) is the adopted fixed low water reference plane for this area. CRD is a U.S. Army Corps of Engineers non-tidal datum defined at distinct river miles relative to NAVD88, and is used as chart datum above river mile 23 on the Columbia River. Datums are computed using observations from the low river stages of the year, generally August through October due to the masking of the tidal signal from strong seasonal river runoff during other portions of the year. Depending on river flow, water levels can be significantly higher than Columbia River Datum. As of 2014, the U.S. Army Corps of Engineers provided updated offsets for CRD that have been applied to this station. Station Datum (STND) is no longer set equal to CRD.
NOTICE: All data values are relative to the MLLW.

Elevations on Mean Lower Low Water

Station: 9440569, Skamokawa, WA
Status: Accepted (Jun 12 2017)
Units: Feet
Control Station: 9439040 Astoria, OR
T.M.: 120
Epoch: 1983-2001
Datum: MLLW
MHHW7.49Mean Higher-High Water
MHW6.86Mean High Water
MTL3.82Mean Tide Level
MSL3.73Mean Sea Level
DTL3.75Mean Diurnal Tide Level
MLW0.77Mean Low Water
MLLW0.00Mean Lower-Low Water
CRD_OFFSET-0.54Columbia River Datum Offset
STND-0.48Station Datum
GT7.49Great Diurnal Range
MN6.08Mean Range of Tide
DHQ0.64Mean Diurnal High Water Inequality
DLQ0.77Mean Diurnal Low Water Inequality
HWI9.92Greenwich High Water Interval (in hours)
LWI4.36Greenwich Low Water Interval (in hours)
Max TideHighest Observed Tide
Max Tide Date & Time Highest Observed Tide Date & Time
Min TideLowest Observed Tide
Min Tide Date & Time Lowest Observed Tide Date & Time
HAT9.36Highest Astronomical Tide
HAT Date & Time12/15/2039 21:00HAT Date and Time
LAT-1.71Lowest Astronomical Tide
LAT Date & Time07/31/2000 17:06LAT Date and Time
Tidal Datum Analysis Periods
08/01/2002 - 10/31/2002
07/01/2004 - 09/30/2004
08/01/2005 - 10/31/2005
07/01/2006 - 10/31/2006
08/01/2007 - 11/30/2007
09/01/2008 - 10/31/2008
07/01/2009 - 10/31/2009
07/01/2010 - 10/31/2010
08/01/2011 - 09/30/2011
08/01/2012 - 10/31/2012

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