USGS Water-Year Summary 2019
14242580 TOUTLE RIVER AT TOWER ROAD, NEAR SILVER LAKE, WA
LOCATION - Lat 46°20'06", long 122°50'27" referenced to North American Datum of 1983, in NW 1/4 SW 1/4 sec.20, T.10 N., R.1 W., Cowlitz County, WA, Hydrologic Unit 17080005, on right bank, 70 ft downstream from Tower Road bridge at river mile 6.5, 3 miles northwest of Silver Lake and 10 miles downstream from confluence of North and South Fork Toutle Rivers. Datum of gage is 113.58 ft above NGVD of 1929. To convert to NAVD of 1988, add 3.40 ft (USGS Level 2 GNSS survey as per USGS T&M 11-D1).
DRAINAGE AREA - 496 mi². A large debris avalanche generated by the eruption of Mount St. Helens on May 18, 1980 blocked tributaries in the upper North Fork Toutle River valley. As a result, from May 19, 1980 to Jul. 7, 1981, approximately 40 mi² was noncontributing. From Jul. 7, 1981 to Oct. 1981, the Coldwater Lake basin (12 mi²) was noncontributing; from Oct. 1981 to Nov. 1982, the Castle Lake basin (3 mi²) was noncontributing. Since November 1982 all areas, including the Spirit Lake basin (18 mi²), are effectively contributing.
- WDR WA-86-1: 1982 (M)(P), 1983 (M)(P), 1984 (M)(P), 1985 (M).
PERIOD OF RECORD - March 1981 to current year.
GAGE - Water-stage recorder. Datum of gage is 113.58 ft above NGVD of 1929. To convert to NAVD of 1988, add 3.40 feet (USGS Level 2 GNSS survey as per USGS T&M 11-D1).
EXTREMES OUTSIDE PERIOD OF RECORD - Floods occurred on May 18, 1980, from mudflows caused by the eruption of Mount St. Helens. A flood about 1200 hours was due to mudflow from South Fork Toutle River and a larger flood about 2100 hours was due to mudflow from North Fork Toutle River.
EXTREMES FOR PERIOD OF RECORD - Maximum discharge, 61,800 ft³/s, Feb. 8, 1996, gage height, 24.91 ft; maximum gage height, 28.03 ft Dec. 3, 1982; minimum daily, 215 ft³/s estimated, Oct. 6, 2012.
PERIOD OF DAILY RECORD - SPECIFIC CONDUCTANCE: May to October 1990, May to September 1991.
WATER TEMPERATURE: May to October 1990, May to September 1991.
SUSPENDED SEDIMENT DISCHARGE: February 1981 to current year. Records prior to October 1985 are published in U.S. Geological Survey Open-File Report 85-632; records for 1984-87 are published in U.S. Geological Survey Open-File Report 91-219.
TURBIDITY: April 2010 to current year.
INSTRUMENTATION - Water-quality monitor May 1990 to September 1991. Automatic pumping sediment sampler since February 1981. Turbidity sensor (FTS DTS-12), with a 15-minute logging interval, since April 2010. Any use of trade, product, or firm names in this publication is for descriptive purposes only and does not imply endorsement by the U.S. Government.
EXTREMES FOR PERIOD OF DAILY RECORD - SPECIFIC CONDUCTANCE: Maximum recorded, 917 microsiemens May 8, 1991; minimum recorded, 138 microsiemens, Oct. 24, 1990.
WATER TEMPERATURE: Maximum recorded, 27.0°C, July 23, 1991; minimum recorded, 3.0°C, Oct. 8, 1990.
SEDIMENT CONCENTRATION: Maximum daily, 232,000 mg/L, Mar. 20, 1982; minimum daily, 1 mg/L, Oct. 3, 1989.
SEDIMENT DISCHARGE: Maximum daily, 5,930,000 tons, Feb. 20, 1982; minimum daily, 0.71 tons, Oct. 3, 1989.
TURBIDITY: Maximum recorded, 2,430 FNU, Sept. 29, 30, 2013; minimum recorded 3.1 FNU, Sept. 14, 2010, but may have been lower during periods of missing record.
EXTREMES FOR CURRENT YEAR - SEDIMENT CONCENTRATION: Maximum daily, 9,410 mg/L, Oct. 14; minimum daily, 7 mg/L, Sept. 26.
SEDIMENT DISCHARGE: Maximum daily, 324,000 tons, Feb. 9; minimum daily 7.9 tons, Oct. 1.