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Water-Year Summary for Site 12436000

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  • Water-Year Summary reports summarize a year of hydrologic data in a printer-friendly format.
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Available Parameters
62614 Elevation, lake/res, NGVD29(Obs.)  

Water year 2020: 2019-10-01 to 2020-09-30

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USGS Water-Year Summary 2020
LOCATION - Lat 47°57'20", long 118°59'02" referenced to North American Datum of 1927, in sec.01, T.28 N., R.30 E., Grant County, WA, Hydrologic Unit 17020005, in block 12 of Grand Coulee Dam on Columbia River, and at mile 596.6.
DRAINAGE AREA - 74,700 mi².
REVISIONS HISTORY - WSP 1286: 1942, 1945(M). WSP 1316: 1942 (May monthend contents). WSP 1933: Drainage area. WDR WA-73-1: 1965, 1967. WDR WA-75-1: 1974 monthend contents.
PERIOD OF RECORD - April 1938 to current year. Prior to October 1943, published as Columbia River Reservoir at Grand Coulee Dam.
GAGE - U.S. Geological Survey water-stage recorder. Datum of gage is NGVD of 1929, adjustment of 1937 (Bureau of Reclamation datum), or 1.425 ft above NGVD of 1929 (levels by Bureau of Reclamation). Prior to Apr. 24, 1942, nonrecording gage at site 2,000 ft upstream at same datum.
REMARKS - Reservoir is formed by concrete dam; construction of dam began in 1934; completed in 1941; storage began early in construction period. Capacity, 5,022,000 acre-ft between elevations 1,208 ft, proposed lower limit of operation, and 1,288 ft, top of gates. Capacity increased to 5,186,420 acre-ft by use of 2-ft flashboards installed after high-water period each year beginning August 1961. Storage below 1,208 ft, 4,365,786 acre-ft. Figures given herein represent total contents. Water is used for power generation and irrigation. Flow is regulated by nine major reservoirs and numerous smaller reservoirs and powerplants. Diversion by Feeder Canal (station 12435500) for irrigation of about 600,000 acres in the United States plus additional diversions in Canada for irrigation of about 66,500 acres.


(Prepared by Bureau of Reclamation, dated March 9, 2012)
Elevation (feet)   Contents (acre-feet)
1,210.0            4,462,147            
1,230.0            5,520,927            
1,250.0            6,763,427
1,270.0            8,163,965
1,291.0            9,797,556
EXTREMES FOR PERIOD OF RECORD - Maximum contents 9,586,000 acre-ft, July 17, 1942, June 3, 1945, elevation, 1,290.3 ft; maximum elevation, 1,290.36 ft, Aug. 6, 1976; minimum contents observed, 16,200 acre-ft, Aug. 29, 1938, elevation, 956.1 ft.