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- Water-Year Summary reports summarize a year of hydrologic data in a printer-friendly format.
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USGS Water-Year Summary 2024
12061500 SKOKOMISH RIVER NEAR POTLATCH, WA
LOCATION - Lat 47°18'36", long 123°10'33" referenced to North American Datum of 1927, in sec.15, T.21 N., R.4 W., Mason County, WA, Hydrologic Unit 17110017, on upstream side of bridge on U.S. Highway 101, 3.7 mi downstream from confluence of North and South Forks, 4.7 mi southwest of Potlatch, and at mile 5.3.
DRAINAGE AREA - 227 mi². including 97.9 mi² (revised) upstream from Cushman Dam No. 2, which is noncontributing except during spillage.
REVISIONS HISTORY - WSP 1716: 1950(M), 1956. WSP 1932: Drainage area. WDR WA-72: 1968(M), 1971(M). WDR WA-75: 1974, 2012.
SURFACE-WATER RECORDS
PERIOD OF RECORD - July 1943 to current year. No high flows October 2003 to September 2022.
GAGE - Water-stage recorder. Datum of gage is 13.99 ft above NAVD of 1988 (USGS Levels Oct. 4, 2019) and 10.53 ft above NGVD of 1929 (topographical map). Prior to May 27, 1964, water-stage recorders or nonrecording gage at several sites about 0.6 mi upstream at different datums. Supplementary water-stage recorder on right bank at site 0.6 mi upstream at datum 16.47 ft above NGVD of 1929 used Nov. 16 to Dec. 10, 1964, June 11 to July 7, and Nov. 2-24, 1965.
REMARKS - Flow partly regulated at Lake Cushman and Cushman Reservoir No. 2. In normal years, about half of the flow of North Fork is diverted at Cushman Dam No. 2 and is discharged into Hood Canal through Cushman powerplant No. 2. U.S. Geological Survey satellite telemeter at station. Due to bank overflow, discharges above 16.40 ft gage height could not be determined by direct methods for water years 2004 to 2022. Beginning with the 2023 water year, methods were adjusted to measure all overflow channels during high flows.
EXTREMES OUTSIDE PERIOD OF RECORD - Flood of December 1933 reached an elevation of 30.8 ft above NGVD of 1929 at site on left bank 150 ft upstream from old highway bridge, discharge, 18,600 ft³/s.
EXTREMES FOR PERIOD OF RECORD - Maximum discharge, 36,600 ft³/s, Nov. 23, 1990, gage height, 16.80 ft (floodmark), from rating curve extended above 14,000 ft³/s; maximum gage height, 18.16 ft, Dec. 3, 2007; minimum discharge, 99 ft³/s, Oct. 27, 28, Nov. 6-9, 1987.
WATER-QUALITY RECORDS
PERIOD OF RECORD - CHEMICAL DATA: August 1960 to September 1961, October 1961 to September 1970 (partial-record station), October 1971 to September 1974.
PERIOD OF DAILY RECORD - SPECIFIC CONDUCTANCE: July 1996 to April 1998. WATER TEMPERATURE: May 1955 to September 1962, October 1963 to September 1982, July 1996to April 1998. TURBIDITY: November 2011 to September 2012.
INSTRUMENTATION - Turbidity sensor (FTS DTS-12) interfaced with a Data Collection Platform/Electronic Datalogger, with 15-minute recording interval, since November 2011. 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.
REMARKS - Additional details are available from the Washington Water Science Center. Continuous water quality record is no longer rated, as of water year 2021. Prior ratings can be obtained via request to the Washington Water Science Center.
EXTREMES FOR PERIOD OF DAILY RECORD - TURBIDITY: Maximum, 576 FNU, Nov. 23, 2011; minimum, 0.0 FNU on several days in August and September 2012.
