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Water-Year Summary for Site 14234800

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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(Obs.)  

Water year 2019: 2019-10-01 to 2020-09-30

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USGS Water-Year Summary 2019
LOCATION - Lat 46°32'07", long 122°25'25" referenced to North American Datum of 1927, in SW 1/4 SW 1/4 sec.10, T.12 N., R.3 E., Lewis County, WA, Hydrologic Unit 17080005, in emergency generator room on top of Mossyrock Dam on Cowlitz River, 2.8 mi east of Mossyrock, and at mile 65.5.
DRAINAGE AREA - 1,154 mi².
PERIOD OF RECORD - April 1968 to current year.
GAGE - Water-stage recorder; nonrecording gage prior to July 25, 1968. Datum of gage is NGVD of 1929 (levels by City of Tacoma).
REMARKS - Reservoir is formed by concrete arch dam, completed in April 1968; storage began Apr. 3, 1968. Useable capacity, 1,297,400 acre-ft between elevations 600 ft, minimum operating level, and 770 ft, normal operating pool. Unused storage below elevation 600 ft, 288,900 acre-ft. Crest of spillway is at elevation 728.5 ft and top of taintor gates are at elevation 778.5 ft. Water used by City of Tacoma for power generation. Figures given herein represent total contents. Capacity table furnished by City of Tacoma. Chemical analyses December 1973 to September 1983 (samples were taken near the dam).
EXTREMES FOR PERIOD OF RECORD - Maximum contents, 1,686,300 acre-ft, July 31, 1972, elevation, 778.63 ft; minimum contents since normal low operating level was attained, 517,233 acre-ft, Mar. 9, 2001, elevation, 644.93 ft.