USGS Water-Year Summary 2024

12115900 CHESTER MORSE LAKE AT CEDAR FALLS, WA

LOCATION - Lat 47°24'34", long 121°43'22" referenced to North American Datum of 1927, in SW 1/4 NE 1/4 sec.12, T.22 N., R.8 E., King County, WA, Hydrologic Unit 17110012, at the overflow dike, 3.1 mi southeast of town of Cedar Falls, and at mile 37.2.

DRAINAGE AREA - 78.4 mi².

SURFACE-WATER RECORDS

PERIOD OF RECORD - October 1977 to current year.

GAGE - Water-stage recorder. Prior to Aug. 22, 2001, nonrecording gage at same site and datum. Datum of gage is 11.39 ft above NAVD 88 (2019 levels by USGS) and 7.39 ft above NGVD of 1929 (levels by City of Seattle). 

COOPERATION - Prior to Aug. 22, 2001, gage-height record furnished by City of Seattle Water Department. 

REMARKS - Reservoir is formed by concrete overflow dike (wooden crib dam prior to 1989). Usable capacity, 37,186 acre-ft between gage heights 1,532 ft, minimum operation level, and 1,550 ft, top of overflow dike. Prior to 1989, gage height of wooden crib dam gage height was 1,555 ft. Unused storage below gage height 1,532 ft is 38,137 acre-ft. When the elevation of downstream Cedar Lake exceeds 1,550 ft and the overflow dike is submerged, Chester Morse Lake is then controlled by masonry gravity dam at Cedar Lake. Water is used by City of Seattle for municipal water supply and power production. U.S. Geological Survey satellite telemeter at station. 

EXTREMES FOR PERIOD OF RECORD - Maximum gage height observed, 1,568.59 ft, Nov. 25, 1990; minimum observed, 1,533.24 ft, Nov. 8, 1987.