Notice: CO-OPS recently determined that water level data from Longview (9440422) contained an error due to the conversion of pressure to water level in our database. This error resulted in water level measurements several centimeters higher than actual, and impacted data products from March 27, 2002 to October 21, 2015. Water level products from October 21, 2015 to present, including real-time data, are correct. We are currently working on correcting the historical water level data and downstream products and aim to have them updated by 2024. We will provide a notification once the historical data products have been updated. Any data products downloaded from this time will need to be re-downloaded. If you have any questions, please send an email to Tide.Predictions.gov and we will get back to you as soon as possible.

Datums for 9440422, Longview 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: 9440422, Longview, WA
Status: Accepted (Jun 16 2017)
Units: Feet
Control Station: 9439040 Astoria, OR
T.M.: 0
Epoch: 1983-2001
Datum: MLLW
DatumValueDescription
MHHW4.55Mean Higher-High Water
MHW4.08Mean High Water
MTL2.20Mean Tide Level
MSL2.05Mean Sea Level
DTL2.28Mean Diurnal Tide Level
MLW0.33Mean Low Water
MLLW0.00Mean Lower-Low Water
NAVD88
CRD_OFFSET-2.26Columbia River Datum Offset
STND-2.53Station Datum
GT4.55Great Diurnal Range
MN3.74Mean Range of Tide
DHQ0.48Mean Diurnal High Water Inequality
DLQ0.34Mean Diurnal Low Water Inequality
HWI11.17Greenwich High Water Interval (in hours)
LWI6.52Greenwich 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
HAT5.29Highest Astronomical Tide
HAT Date & Time11/24/2003 23:06HAT Date and Time
LAT-0.79Lowest Astronomical Tide
LAT Date & Time01/12/2009 07:42LAT Date and Time
Tidal Datum Analysis Periods
08/01/2002 - 10/31/2002
08/01/2003 - 10/31/2003
07/01/2004 - 11/30/2004
08/01/2005 - 10/31/2005
08/01/2006 - 10/31/2006
08/01/2007 - 11/30/2007
09/01/2008 - 10/31/2008
08/01/2009 - 10/31/2009
08/01/2010 - 10/31/2010
09/01/2011 - 10/31/2011


Products available at 9440422 Longview, WA