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Current Datum Value: 3.37

Datums for 9440571, ALTOONA, COLUMBIA RIVER WA

NOTICE: All data values are relative to the MLLW.

Elevations on Mean Lower Low Water

Status: Accepted (Nov 20 2003)
Units: Feet
Control Station: 9439040 Astoria, OR
T.M.: 120
Epoch: 1983-2001
Datum: MLLW
MHHW8.12Mean Higher-High Water
MHW7.46Mean High Water
MTL4.23Mean Tide Level
MSL4.21Mean Sea Level
DTL4.06Mean Diurnal Tide Level
MLW1.00Mean Low Water
MLLW0.00Mean Lower-Low Water
STND-3.37Station Datum
GT8.12Great Diurnal Range
MN6.46Mean Range of Tide
DHQ0.66Mean Diurnal High Water Inequality
DLQ1.00Mean Diurnal Low Water Inequality
HWI9.50Greenwich High Water Interval (in hours)
LWI3.60Greenwich 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
HATHighest Astronomical Tide
HAT Date & Time HAT Date and Time
LATLowest Astronomical Tide
LAT Date & Time LAT Date and Time
Tidal Datum Analysis Periods
07/01/1981 - 11/30/1981
To refer water level heights to NAVD88 (North American Vertical Datum of 1988), apply the values located at National Geodetic Survey.

Products available at 9440571 ALTOONA, COLUMBIA RIVER, WA

Revised: 08/08/2018
NOAA / National Ocean Service
Web site owner: Center for Operational Oceanographic Products and Services