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Water-Year Summary for Site 12105800

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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
00054 Reservoir storage(Obs.)  
62614 Elevation, lake/res, NGVD29(Obs.)  

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

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USGS Water-Year Summary 2023
12105800 HOWARD A. HANSON RESERVOIR NEAR PALMER, WA
LOCATION - Lat 47°16'38", long 121°47'03" referenced to North American Datum of 1927, in NW 1/4 NW 1/4 sec.28, T.21 N., R.8 E., King County, WA, Hydrologic Unit 17110013, near left bank on outlet gate structure, just upstream from Howard A. Hanson Dam on Green River, 1.4 mi upstream from Bear Creek, 5.1 mi southeast of Palmer, and at mile 64.5.
DRAINAGE AREA - 220 mi².
REVISIONS HISTORY - WDR WA-96-1: 1985-1995 maximum and minimum contents.
SURFACE-WATER RECORDS
PERIOD OF RECORD - December 1961 to current year.
GAGE - Water-stage recorder. Prior to Oct. 1, 1999, non-recording gage at same site and datum. Datum of gage is NGVD of 1929, supplementary adjustment of 1947.
COOPERATION - Elevations and capacity table furnished by Corps of Engineers.
REMARKS - Reservoir is formed by earth-fill dam; completed Mar. 31, 1962; storage began Dec. 5, 1961. Capacity (Capacity Table updated Oct. 1, 2011 supersedes previous Capacity Table 1984), 104,266 acre-ft between elevations 1,035 ft, invert of outlet tunnel, and 1,206 ft, top of spillway gates. Retained during initial flood conditions, storage is released as soon as possible after a flood to attenuate flows downstream and to maintain reservoir capacity for possible future floods. Storage is used during summer months to augment the natural river flow. 
EXTREMES FOR PERIOD OF RECORD - Maximum contents observed, 78,759 acre-ft, Jan. 9, 2009, elevation, 1,189.2 ft; minimum contents observed, 34 acre-ft, Nov. 2, 1962, elevation, 1,037.6 ft (capacity table then in use).