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USGS Water-Year Summary 2024
12117500 CEDAR RIVER NEAR LANDSBURG, WA
LOCATION - Lat 47°23'38", long 121°57'12" referenced to North American Datum of 1927, in NW 1/4 SW 1/4 sec.17, T.22 N., R.7 E., King County, WA, Hydrologic Unit 17110012, on left bank 1.8 mi upstream from intake of Seattle water-supply system near Landsburg, 4.0 mi east of Maple Valley, 5.9 mi downstream from Taylor Creek, and at mile 23.4.
DRAINAGE AREA - 121 mi². excludes Walsh Lake diversion, which enters Cedar River at mile 19.5, and excludes 1.9 mi² of Walsh Lake drainage in Cedar River basin, which is normally diverted into Issaquah Creek.
REVISIONS HISTORY - WSP 313: 1895-98, 1902-09. WSP 1286: 1912. WSP 1316: 1896-98(M), 1902-11(M). WSP 1736: 1960. WSP 1932: 1947, drainage area.
SURFACE-WATER RECORDS
PERIOD OF RECORD - August 1895 to current year (prior to October 1948, flow of Rock Creek included). Monthly discharge only for some periods, published in WSP 1316. Published as "near Seattle" 1895-98, "near Maple Valley" 1902, and as "near Ravensdale" 1898-1901, 1903-12.
GAGE - Water-stage recorder. Datum of gage is 565.9 ft above NGVD of 1929. Prior to Oct. 1, 1898, nonrecording gage at site 2.2 mi downstream at different datum. Mar. 24, 1901, to May 15, 1913, nonrecording gage at site 2 mi downstream at datum 535.84 ft NGVD of 1929 (levels by City of Seattle). Apr. 30, 1914, to Oct. 22, 1928, water-stage recorder 0.2 mi downstream at different datum.
REMARKS - All diversions except Rock Creek returned to river upstream from station. Rock Creek, a tributary which entered naturally just upstream from station prior to 1932, is diverted during summer months to enter river at a point about 3.9 mi downstream from station. Some regulation by Chester Morse Lake (station 12115900) and Cedar Lake (station 12116060), 12.2 mi upstream. Chemical analyses July 1959 to July 1960. Water temperatures published August 1953 to September 1985. U.S. Geological Survey satellite telemeter at station.
EXTREMES FOR PERIOD OF RECORD - Maximum discharge, 14,200 ft³/s, Nov. 19, 1911, gage height, 10.0 ft, from graph based on gage readings, site and datum then in use, by computation of peak flow over dam, peak caused by failure of flashboards at Chester Morse Lake; minimum discharge observed, 83 ft³/s, Sept. 19, 1898.
WATER-QUALITY RECORDS
PERIOD OF DAILY RECORD - WATER TEMPERATURE: September 2018 to current year. TURBIDITY: December 2021 to current year.
INSTRUMENTATION - Temperature recorder since September 2018 and turbidity sensor since December 2021, both interfaced with a Data Collection Platform / Electronic Datalogger, with 15-minute recording interval. Turbidity sensor is an Observator Analite NEP-5000. Any use of trade, product, or firm names in this publication is for descriptive purposes only and does not imply endorsement by the U.S. Government.
REMARKS - Additional details are available from the Washington Water Science Center. Continuous water quality record is no longer rated, as of water year 2021. Prior ratings can be obtained via request to the Washington Water Science Center.
EXTREMES FOR PERIOD OF DAILY RECORD - WATER TEMPERATURE: Maximum, 17.1°C, July 12, 2021; minimum 2.8°C, Dec. 23, 2022. TURBIDITY: Maximum recorded, 86 FNU, Jan. 6, 2022; minimum recorded, 0.1 FNU, Apr, 27, 28, May 1, and Aug 10, 2023.
