USGS Water-Year Summary 2019
12175000 ROSS RESERVOIR NEAR NEWHALEM, WA
LOCATION - Lat 48°43'58", long 121°04'02" referenced to North American Datum of 1927, in SE 1/4 sec.35, T.38 N., R.13 E., Whatcom County, WA, Hydrologic Unit 17110005, Ross Lake National Recreation Area, at Ross Dam on Skagit River, 1.0 mi downstream from Ruby Creek, 9.1 mi northeast of Newhalem, and at mile 105.2.
DRAINAGE AREA - 999 mi². of which 400 mi² is in Canada.
- WSP 1932: Drainage area.
PERIOD OF RECORD - March 1940 to current year (monthend elevations and contents only prior to October 1946). Prior to October 1945, published as "Ruby Reservoir near Newhalem."
GAGE - Water stage recorder. Datum of gage is City of Seattle Ross Dam datum; 1.79 ft above NGVD of 1929, U.S. Coast and Geodetic Survey datum; and 0.88 ft above NGVD of 1929, Geodetic Survey of Canada 1959 datum (by water level transfer of elevation from the international boundary). Prior to Sept. 24, 1940, nonrecording gage on west shore at site upstream from Ross Dam at same datum. June 29, 1943, to Apr. 29, 1948, nonrecording gage on right bank at site 500 ft upstream from dam at present datum.
COOPERATION - Capacity table furnished by City of Seattle. This station is maintained by the United States under agreement with Canada.
EXTREMES FOR PERIOD OF RECORD
- Maximum contents, 1,443,460 acre-ft, July 20, 1981, elevation, 1,603.23 ft; minimum contents observed since dam was completed in 1949, 51,760 acre-ft, Apr. 5, 1952, elevation, 1,348.50 ft.
(Based on 25-foot contour intervals furnished by City of Seattle in 1943)
Elevation Contents Elevation Contents Elevation Contents
(feet) (acre-feet) (feet) (acre-feet) (feet) (acre-feet)
1,490 454,480 1,525 678,950 1,575 1,130,200
1,500 509,240 1,550 888,320 1,603 1,440,700