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.
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).
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).