USGS Water-Year Summary 2024
14243000 COWLITZ RIVER AT CASTLE ROCK, WA
LOCATION - Lat 46°16'30", long 122°54'48" referenced to North American Datum of 1927, in SW 1/4 SE 1/4 sec.10, T.9 N., R.2 W., Cowlitz County, WA, Hydrologic Unit 17080005, on left bank 40 ft downstream from Arkansas Valley Road bridge in Castle Rock, 2.7 mi downstream from Toutle River, and at mile 17.3.
DRAINAGE AREA - 2,238 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 July 7, 1981, approximately 40 mi² was noncontributing. From July 7, 1981 to October 1981, the Coldwater Lake release, approximately 21 mi², was noncontributing. From October 1981 to November 1982, the Castle Lake release, approximately 19.7 mi², was noncontributing. Since November 1982, all areas, including the Spirit Lake release, are effectively contributing.
REVISIONS HISTORY - WSP 1218: Drainage area. WSP 1638: 1947(P), 1951.
SURFACE-WATER RECORDS
PERIOD OF RECORD - December 1926 to current year; October 1985 to April 2000 (seasonal records).
GAGE - Water-stage recorder. Datum of gage is NAVD of 1988. Prior to Dec. 18, 1933, nonrecording gage at site 2 mi upstream at datum 38.58 ft higher. Dec. 18, 1933, to June 13, 1934, nonrecording gage, and June 14 to Sept. 30, 1934, water-stage recorder, at present site at datum 28.65 ft higher. Oct. 1, 1934, to May 21, 1980, water-stage recorder, on right bank at datum 23.65 ft higher. May 23, 1980, to July 29, 1997, water-stage recorder at present site at datum 23.65 higher.
EXTREMES FOR PERIOD OF RECORD - Maximum discharge observed, 139,000 ft³/s Dec. 23, 1933, gage height, 55.25 ft present datum, from rating curve extended above 80,000 ft³/s; maximum gage height, 55.76 ft Feb. 8, 1996; minimum discharge, 998 ft³/s Nov. 7, 8, 1935.
WATER-QUALITY RECORDS
EXTREMES FOR PERIOD OF DAILY RECORD - TURBIDITY: Maximum, 853 FNU, Jan. 13, 2021; minimum, 1.2 FNU, Aug. 02, 2021.