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USGS Water-Year Summary 2024
12500450 YAKIMA RIVER ABOVE AHTANUM CREEK, AT UNION GAP, WA
LOCATION - Lat 46°32'04", long 120°27'58" referenced to North American Datum of 1927, in NW 1/4 NE 1/4 sec.17, T.12 N., R.19 E., Yakima County, WA, Hydrologic Unit 17030003, on left bank 2,200 ft upstream from Ahtanum Creek, 0.8 mi upstream from Wapato Dam, 1.4 mi southeast of Union Gap, and at about mile 107.3.
DRAINAGE AREA - 3,479 mi².
SURFACE-WATER RECORDS
PERIOD OF RECORD - October 1966 to current year.
GAGE - Water-stage recorder. Datum of gage is 900.00 ft above NGVD of 1929; gage readings have been reduced to elevations above NGVD of 1929. Prior to Apr. 4, 1967, at site 1,200 ft downstream at same datum.
REMARKS - Diversions upstream from station for irrigation of about 212,000 acres. Flow partly regulated by Keechelus, Kachess, Cle Elum, Bumping, and Rimrock Lakes. Records at this site plus those for Ahtanum Creek at Union Gap (station 12502500) are equivalent to discontinued station 12503000, Yakima River at Union Gap. Chemical analyses, water years 1969, 1971, March 1975 to September 1993. Water temperature, March 1981 to December 1981.
EXTREMES FOR PERIOD OF RECORD - Maximum discharge, 53,300 ft³/s, Feb. 9, 1996, elevation, 953.88 ft, from high-water mark, from rating curve extended above 18,000 ft³/s, on basis of discharge information provided by the Bureau of Reclamation for their station on the Yakima River near Parker; minimum daily discharge, 300 ft³/s, Jan. 1, 1979.
WATER-QUALITY RECORDS
PERIOD OF RECORD - Water years 1969, 1971, 1975 to 1999, August 2004.
PERIOD OF DAILY RECORD - WATER TEMPERATURE: March 1981 to December 1981, May 2005 to December 2006.
INSTRUMENTATION - Temperature recorder May 2005 to December 2006 with at a 60-minute logging interval.
REMARKS - Water quality records affected by Moxee Drain during the summer months when it accounts for about three percent of the flow of the Yakima River at the entry point of Moxee Creek, about 0.7 miles above the sampling point. Moxee Drain contributes significant suspended sediment load and nutrients to the river, during the irrigation season.
EXTREMES FOR PERIOD OF DAILY RECORD - Maximum recorded, 23.0°C, July 28, 31, Aug. 8, 9, 2005; minimum recorded, 0.0°C, Dec. 8-15, 17-19, 2005.
