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Water-Year Summary for Site 12177700

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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
12177700 GORGE RESERVOIR NEAR NEWHALEM, WA
LOCATION - Lat 48°41'53", long 121°12'25" referenced to North American Datum of 1927, in NW 1/4 sec.14, T.37 N., R.12 E., Whatcom County, WA, Hydrologic Unit 17110005, Ross Lake National Recreation Area, at Gorge Dam on Skagit River, 2.4 mi upstream from Gorge powerplant at Newhalem, and at mile 96.6.
DRAINAGE AREA - 1,159 mi². includes 400 mi² in Canada.
SURFACE-WATER RECORDS
PERIOD OF RECORD - June 1960 to current year.
GAGE - Water-stage recorder; prior to Apr. 1, 1962, reference point on Gorge Dam or water-stage indicator in powerhouse. Datum of gage is 0.00 ft City of Seattle Gorge High Dam datum, and 1.792 ft below NGVD of 1929 (Corps of Engineers' benchmark).
REMARKS - Reservoir is formed by concrete-arch and gravity dam, completed Dec. 27, 1960; storage began June 27, 1960. Usable storage, 2,115 acre-ft between elevations 865 ft, normal lower limit of operation, and 875 ft, top of gates. Lowest outlet at elevation 760 ft. No dead storage. Crest of spillway is at elevation 825 ft. Water used by City of Seattle for power development at Gorge powerplant. Capacity table furnished by City of Seattle. Figures given herein represent total contents.
EXTREMES FOR PERIOD OF RECORD - Maximum contents, 9,761 acre-ft June 1, 1982, elevation, 880.01 ft; minimum observed contents since normal low operating level was reached in Dec. 1960, 172 acre-ft Aug. 13, 1997, elevation, 781.75 ft (City of Seattle).