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Water-Year Summary for Site 14219950

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  • Water-Year Summary reports summarize a year of hydrologic data in a printer-friendly format.
  • For water years 2014 onward, choose a water year and parameter and an on-demand Water-Year Summary report will be generated.
  • For water years 2006 through 2013, choose a water year and an Annual Water Data Report will be provided.
  • For water years 2005 and earlier, Annual Water Data Reports may be available in digital format.
  • Not all sites have reports available for every water year.
Available Parameters
62614 Elevation, lake/res, NGVD29(Mean)  

Water year 2023: 2022-10-01 to 2023-09-30

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USGS Water-Year Summary 2023
LOCATION - Lat 45°58'17", long 122°23'02" referenced to North American Datum of 1927, in NW 1/4 SW 1/4 sec.25, T.6 N., R.3 E., Cowlitz County, WA, Hydrologic Unit 17080002, on the east end of Lake Merwin, 8 mi NE of Amboy, 8 mi SW of Cougar.
PERIOD OF RECORD - October 2017 to current year. (February 2010 to September 2017 are unpublished, data available in files of Washington Water Science Center.) 
GAGE - Water-stage recorder. Datum of gage is NGVD of 1929. 
COOPERATION - Gage is on the property of and in cooperation with Pacificorp.
REMARKS - Reservoir is formed by combination gravity-concrete-arch dam; some storage began March 1931; completed May 13, 1931. Usable capacity, 251,000 acre-ft between elevations 165 ft, lower limit of regulation set by Federal Energy Regulatory Commission, and 235 ft, top of spillway gates. Additional storage of 18,100 acre-ft is provided by flashboards to elevation 239.6 ft. Unused storage below elevation 165 ft, 155,500 acre-ft. Water is used by PacifiCorp for power generation.
EXTREMES FOR PERIOD OF RECORD - (Since Water Year 2018) Maximum elevation, 239.68 ft, Apr. 20, 2019; minimum elevation, 227.60 ft, Nov. 13, 2018.