Location.--Latitude 46°20'06", Longitude
122°50'27", in NW 1/4 SW 1/4 Section 20, Township 10 North,
Range 1 West, in Cowlitz County, Hydrologic Unit 17080005, on
right bank 10.7 mile downstream from confluence of North and South
Forks, 2.9 miles northwest of Silver Lake, and at river mile
6.5. Drainage
area is 496 mi2, see notes on drainage area in the
annual
data report (PDF). Elevation
of gage is 160 feet above NGVD of 1929, from topographic map.
Maps.--Locate
this station on a
map of the basin (PDF) or on a map of Mount
St. Helens.
Additional Data and Information.--Station data
inventory, information, annual data report,
and latest shifted
rating.
Flood Stage.--The National Weather Service Flood
Stage for this station is 137 feet.
Funding for this site is provided by the
cooperators / programs below:
Station Notes
Gage height datum conversion to
the NAVD88 datum for this streamgage was made effective as of
August 9, 2018. Instantaneous gage heights previous to that date
will remain as originally reported. However, mean gage heights
associated with all discharge measurements have been converted to
be consistent with elevations based on the NAVD88 datum. The
conversion factor used to adjust gage heights to NAVD88 from the
previously used arbitrary datum is 116.98 ft. For example,
prior to August 9, 2018 the gage height at a flow of 366 ft3/s had
a gage height of 3.51 feet. After August 9, 2018 and at the same
discharge, the gage height is 120.49 feet (3.51ft + 116.98 = 120.49
ft).
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