USGS Water-Year Summary for Site 09469500

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Water year 2024: 2024-10-01 to 2025-09-30

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USGS Water-Year Summary 2024

09469500 GILA RIVER BELOW COOLIDGE DAM, AZ

LOCATION - Lat 33°10'10", long 110°31'50" referenced to North American Datum of 1927, in SW 1/4 sec.17, T.3 S., R.18 E., Pinal County, AZ, Hydrologic Unit 15050100, on left bank 2,200 ft downstream from Coolidge Dam. (unsurveyed).

DRAINAGE AREA - 12,886 mi².

SURFACE-WATER RECORDS

PERIOD OF RECORD - July to Oct. 1899, Apr. 1900 to Mar. 1902, July to Sept. 1902, Dec. 1902 to Dec. 1904, Jan. to May 1905 (gage heights only), June to Nov. 1905; Aug. 1910 to Feb. 1911 (gage heights only); Apr. 1914 to current year. Published as "at San Carlos" 1899-1911, as "near San Carlos" 1914-26, and as "at Coolidge Dam" 1927-38.

REVISED RECORDS - WSP 629: 1915-16. WSP 1049: 1899-1904. WSP 1149: 19M), 1921, 1922(M), 1923, 1924(M). WSP 1283: Drainage area.

GAGE - Water-stage recorder and Parshall flume. Datum of gage is 2,309.33 ft above sea level. Prior to Feb. 5, 1911, nonrecording gage at various sites and datums upstream from mouth of San Carlos River. Apr. 29, 1914, to Mar. 8, 1937, water-stage recorder at various sites within 1 mi upstream from present site at different datums. Mar. 27, 1979 to Oct. 10, 1980, and since Oct. 4, 1983, supplementary water-stage recorder at site on left bank 1,000 ft upstream at datum 2,309.5 ft above sea level, used above discharges at approximately 2,000 ft³/s, maximum capacity of parshall flume.

REMARKS - Records good except for estimated daily discharges and those below 20 ft³/s, which are fair. Flow regulated by San Carlos Reservoir since Nov. 15, 1928 (See sta. 09469000). Record includes flow of Warm Springs, which enters between the dam and gage. Large diversions above San Carlos Reservoir for irrigation, metallurgical treatment of ore, and municipal supply; about 69,000 acres of land was irrigated, a considerable portion by pumping from ground water.

EXTREMES FOR PERIOD OF RECORD - 1914-1928: Maximum discharge, 130,000 ft³/s, Jan. 20, 1916, estimated on basis of peak discharge near Solomon and at Kelvin; minimum, no flow at times. 1928-2014: Maximum discharge, 32,800 ft³/s, Jan. 20, 21, 1993 from calculated discharge over Coolidge Dam; minimum, no flow at times prior to 1938; minimum daily since 1938, 0.18 ft³/s, Oct. 5-9, 19-21, 2000, Nov. 29, 2008.

AVERAGE DISCHARGE FOR PERIOD OF RECORD - 101 years (water years, 1901, 1904, 1915-2015) 381 ft³/s, 275,886 acre-ft/yr; median of yearly mean discharges, 230 ft³/s, 167,000 acre-ft/yr. All figures adjusted for storage in San Carlos Reservoir.