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Water-Year Summary for Site 12086500

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  • Water-Year Summary reports summarize a year of hydrologic data in a printer-friendly format.
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Available Parameters
00060 Discharge(Mean)  
00065 Gage height(Mean)  

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

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USGS Water-Year Summary 2023
LOCATION - Lat 46°50'22", long 122°19'41" referenced to North American Datum of 1927, in NW 1/4 SE 1/4 sec.29, T.16 N., R.4 E., Pierce County, WA, Hydrologic Unit 17110015, on right bank 0.4 mi downstream from Tacoma Public Utilities power plant, 0.6 mi northwest of La Grande, 0.8 mi upstream of Mashel River, and at mile 40.4.
DRAINAGE AREA - 292 mi².

WSP 1216: Drainage area. WSP 1316: 1927-28(M), 1949-50. WRD WA-74: 1956(M), 1959-61(M), 1965.

Discharge for the period July 21-23, 2021 was revised on April 28, 2022 based on changes to the estimations for missing data.

PERIOD OF RECORD - September 1906 to October 1911, November to December 1911 (gage heights only), October 1919 to September 1931, October 1943 to current year. Monthly discharge only for some periods, published in WSP 1316. Published as "below Little Nisqually River, near La Grande" September 1906 to October 1911, and as "near La Grande" November to December 1911 and October 1919 to September 1931.
GAGE - Water-stage recorder and crest-stage gage. Elevation of gage is 490 ft above NGVD of 1929 (from river-profile map) and is 497.00 ft above NAVD of 1988 (GNSS survey by USGS on June 27, 2022). See WSP 1932 for history of changes prior to Feb. 8, 1945.
REMARKS - Flow regulated by Tacoma Public Utilities powerplant at La Grande since December 1943, by Alder Reservoir (station 12085000) since November 1944, and by La Grande Reservoir (station 12085500) since February 1945. All diversions returned to river upstream from gage. U.S. Geological Survey satellite telemeter at station. Chemical analyses October 1972 to September 1985. Water temperatures October 1965 to September 1982. 
EXTREMES FOR PERIOD OF RECORD - Maximum discharge, 39,500 ft³/s, Feb. 8, 1996, gage height, 15.30 ft, from rating curve extended above 5,300 ft³/s, and computed flow over dam as provided by Tacoma Public Utilities; practically no flow on many days at site "near La Grande" (which excluded diversion between 1920 and 1930) as a result of regulation.