USGS Water-Year Summary for Site 12200500

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	Available Parameters
	00010 Temperature, water(Max.,Min.,Mean)
	00060 Discharge(Mean)
	00065 Gage height(Mean)
	63680 Turbidity, Form Neph(Med.,Max.,Min.) [Discontinued 10/3/2017]

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Water year 2023: 2022-10-01 to 2023-09-30

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USGS Water-Year Summary 2023

12200500 SKAGIT RIVER NEAR MOUNT VERNON, WA

LOCATION - Lat 48°26'42", long 122°20'03" referenced to North American Datum of 1927, in SE 1/4 SE 1/4 sec.07, T.34 N., R.4 E., Skagit County, WA, Hydrologic Unit 17110007, on right bank 220 ft downstream of bridge on U.S. Highway 99, 1.5 mi north of Skagit Valley Junior College in Mount Vernon, and at mile 15.7.

DRAINAGE AREA - 3,093 mi². of which 400 mi² is in Canada.

REVISIONS HISTORY - WSP 1932: Drainage area.

SURFACE-WATER RECORDS

PERIOD OF RECORD - October 1940 to current year. Monthly discharge only October 1940, published in WSP 1316.

GAGE - Water-stage recorder and crest-stage gage. Datum of gage is NGVD of 1929 and is 3.82 ft above NAVD of 1988 (USGS GNSS RTN survey July 20, 2021). Supplementary water-stage recorder in bridge pier 0.2 mi downstream from base gage from Dec. 3, 1957, to Oct. 15, 1964. Water-stage recorder located on downstream pier of the Highway 99 bridge from Oct. 15, 1964, to Jan. 6, 1993.

REMARKS - Flow regulated by Ross Reservoir (station 12175000), Diablo Reservoir (station 12176500), Gorge Reservoir (station 12177700), Baker Lake (station 12191600), and Lake Shannon (station 12193000). Small diversions for domestic and municipal use. Chemical analyses July 1959 to September 1971, October 1973 to September 1994. Prior to November 1962, published as "at Lawrence." Specific conductance February 1974 to November 1981. Water temperature July 1962 to August 1970, February 1974 to November 1981. U.S. Geological Survey satellite telemeter at station.

EXTREMES OUTSIDE PERIOD OF RECORD - Flood of 1906 reached a stage of 37 ft, from Great Northern Railway high-water profile, discharge 180,000 ft³/s.

EXTREMES FOR PERIOD OF RECORD - Maximum discharge, 152,000 ft³/s, Nov. 25, 1990, elevation, 37.37 ft, from floodmarks; minimum daily discharge, 3,050 ft³/s, Oct. 26, 1942.

WATER-QUALITY RECORDS

PERIOD OF RECORD - Water years 1962-70, 1974-82, 2006-07.

PERIOD OF DAILY RECORD - SPECIFIC CONDUCTANCE: February 1974 to November 1981. WATER TEMPERATURE: July 1962 to August. February 1974 to November 1981. May to November 2009. October 2016 to current year. SEDIMENT CONCENTRATION: March 2006 to September 2007. TURBIDITY: May to November 2009. October 2016 to December 2017.

INSTRUMENTATION - Water quality monitor July 1962 to Aug. 1970 and Feb. 1971 to Nov. 1981. Automatic pumping sampler Mar. 2006 to Sept. 2007. YSI 600OMS data sonde from May to Nov. 2009. FTS DTS-12 turbidity monitor, May to November 2009, October 2016 to December 2017. 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 - In addition to the water-quality monitor record, EDI samples were collected on an event driven basis. U.S. Geological Survey satellite telemeter at station.

EXTREMES OUTSIDE PERIOD OF RECORD - A water temperature of 17.8 °C was observed on Aug. 3, 1961.

EXTREMES FOR PERIOD OF DAILY RECORD - SPECIFIC CONDUCTANCE: Maximum observed, 95 microsiemens Mar. 15, 1978; minimum, 25 microsiemens July 7, 1975, Feb. 27 and Dec. 27, 1980. WATER TEMPERATURE: Maximum, 19.3 °C, Aug. 16, 2023; minimum 0.6 °C, Dec. 22, 2022. SEDIMENT CONCENTRATION: Maximum daily mean, 2,200 mg/L Nov. 7, 2006; minimum daily mean, 15 mg/L Sept. 17, 2006. SEDIMENT DISCHARGE: Maximum daily, 681,000 tons/day Nov. 7, 2006; minimum daily, 227 tons/day Sept. 17, 2006. TURBIDITY: Maximum, 637 FNU, Nov. 23, 2017; minimum 0.9 FNU, July 10, 2009.