"Real-Time" Monitoring Information Menu

Historical Graphics of Interest

[Graphic,13K,GIF]
Flood of February 1996 -- stage in feet above gage ... (Info)

[Graphic,13K,GIF]
Flood of November-December 1995 -- stage in feet above gage ... (Info)

Station Information

Latitude (degrees, minutes, and seconds) ......  462002
Longitude (degrees, minutes, and seconds) .....  1225020
State Code ....................................  53
County Code ...................................  015
County Name ...................................  Cowlitz
Basin Name ....................................  Lower Cowlitz
Hydrologic Unit Code ..........................  17080005
Drainage Area (square miles) ..................  496.00*
Gage Datum (feet, from topo map) ..............  160.00 (WA-97-1) **

Location ...................... NW/SW Sec.20, T.10 N., R.1 W.,
				on right bank 10.7 mi downstream from
				confluence of North and South Forks Toutle
				River, 2.9 mi northwest of Silver Lake, at
				mile 6.5. (Water-Data Report WA-94-1)

----Period(s) of Record----
March 1981 to current year

   * Approximately 21 sq.mi. is noncontributing.  
     Prior to July 7, 1981, approximately 40 sq.mi. was noncontributing.

  ** 1) USGS Surface Water Data Retrieval Program (1998) lists Gage Datum 
        120.0 feet above NGVD

Site History and Remarks

Prior to December 7, 1981, at site 500 ft upstream on left bank. (internal communication)

A station on the same river ( 14242500 - Toutle River near Silver Lake, Wa) was operated 9.2 miles upstream, from September 1909 to August 1912, October 1919 to October 1921, May 1922 to December 1923, and September 1929 to May 18, 1980, on which date the station was destroyed by a large debris and mud flow that came down the North and South Forks of the Toutle River after an explosive eruption of Mount St. Helens. (internal communication, 1995)

The muddy debris flows that inundated the North and South Forks of the Toutle River channel on May 18, 1980, passed through the main Toutle River. The highway bridge at Tower Road was destroyed by the North Fork Toutle River lahar on May 18, 1980, and it was replaced in 1981. Vertical-profile data were collected at the upstream side of the bridge. The bridge is 1,300 feet upstream from the cableway measuring section for the Toutle River at Tower Road gaging station. (Dinehart, 1987)

Reach Description

One channel at all stages. The channel makes a slight bend in the vicinity of the gage and is straight for about ___ mile upstream and downstream. Both banks are wooded, fairly steep, and not subject to overflow. (internal communication, 1995)

During storm runoff, the approach section of the channel was nearly perpendicular to the bridge; but during low flow, the approach deviated from perpendicular by as much as 20 degrees. The cross-section is deepest between the right bank and the rightmost pier. Flow converges from the approach as it passes through this section. The section to the left of the rightmost pier is shallower and less affected by convergent flow. To avoid the convergent flow, most vertical-profile measurements were made at a single vertical located to the left of the rightmost pier. The right bank of the approach consists of unprotected lahar deposits and older consolidated soils. The left bank is riprapped from a point 300 feet upstream of the bridge to the bridge wingwalls. (Dinehart, 1987)

The data-collection reach extends from the gage, which is adjacent to Tower Road bridge, to a cableway located about 330 meters downstream. The channel bends to the left at the bridge, curves gently to the right near the cableway and is straight for about 500 meters downstream. Flow is confined to a single channel except during intermediate discharges (about 75-150 cubic meters/second), when it usually divides into a main channel, normally on the left, and a lesser secondary channel. The unstable streambed typically consists of sediments ranging in size from sand to cobbles. Stream banks near the cableway are bordered by large trees, stumps, and saplings and generally are stable. Substantial erosion on the left bank near the bridge has required the emplacement of riprap, but erosion on the right bank at the bridge has been limited by the presence of bedrock. (Childers, et.al., 1988)

Location Map

-- base map courtesy USGS Mapping Information Server

Useful Links

• Tacoma WRD Site Information and Current Conditions
• NOAA/NWS Northwest River Forecast Center

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