PROVISIONAL DATA SUBJECT TO REVISION

Station operated in cooperation with Clean Water Services, city of Lake Oswego, city of West Linn,
and Clackamas County.

STATION.--14207500 TUALATIN RIVER AT WEST LINN, OR

LOCATION.--Lat 45° 21'03", long 122° 40'30, in SW 1/4 sec.34, T.2 S., R.1 E., Clackamas 
    County, Hydrologic Unit 17090010, on left bank 300 ft upstream from bridge on State 
    Highway 212, 0.4 mi west of West Linn city limits, and at mile 1.8.[location map]  
DRAINAGE AREA.--706 mi2. 
PERIOD OF RECORD.--July 1928 to current year. Prior to October 1960, published as 'near 
    Willamette'. 
GAGE.--Water-stage recorder. Datum of gage is 85.61 ft above NGVD of 1929 (levels by Corps of 
    Engineers). Prior to June 12, 1941, nonrecording gage at datum 1.02 ft higher. 
REMARKS.--Discharges for June 15, 16 computed from data obtained through U.S. Army Corps 
    of Engineers Columbia River Operational Hydromet System (CROHMS) database. Octber 1951 to 
    September 1970, records published for this station included the daily flow in Oswego Canal, 
    which diverts at point 5.0 mi upstream from station for development of power between outlet 
    of Lake Oswego and Willamette River. Adjustment for diversion to Lake Oswego provided by 
    Oregon Water Resources Department since October 1, 1991. Some regulation in low-water season 
    by flashboards on crest of diversion dam for Oswego Canal and regulation by Henry Hagg Lake 
    since January 1975. Several diversions upstream from station for irrigation. U.S. Geological 
    Survey satellite telemeter at station. 
EXTREMES FOR PERIOD OF RECORD.--Maximum discharge, 26,400 ft3/s Feb. 10, 1996, gage height, 
    18.32 ft, does not include an estimated 3,600 ft3/s flowing in Oswego Canal; minimum 
    daily discharge, 0.20 ft3/s July 30 to Aug. 2, 1966.

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